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BBF, believe me, I wasn't addressing your points, other than mentioning that I agreed with your long post. I felt that people were drifting toward blaming the cars for bad metallurgy/mechanical engineering and such. I've heard techs say that Northstar head bolts are "weak" and one tech told me that I must trade my '97 for a 2000 or 2001 because the Northstar was redesigned "because they had to." By that time, I was a fan of http://chrfab.com ... When all you see are broken cars, and you see a *lot* of them, your viewpoint can be different from what it would be if you saw all the cars including the ones that didn't give problems. Maintaining a car out-of-warranty at the dealer can be expensive and the techs don't like them, so many of the old cars that they do see are broken beyond the point that DIY or independent mechanics can deal with them easily.

Of course, there is DIY and... there is DIY. We routinely support DIY here that arguably is better than most dealers, that is the ones who don't have an old tech handy that was trained and is experienced on the older models.

Please forgive me for any misunderstanding. I was rushed because I was trying to get out of the house for an appointment when I wrote the long post.


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-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Thank you Jim. As you know I am passionate about this. I detected a bias and biases drive me nuts. Objectivity is the only way to go. I appreciate your clarification and I am sorry to.

I am studying electronics and electronics diagnosis and the Tech2 which was leant to me by a good soul who I am indebted to. The freaking thing is mind blowing. A new horizon is in sight


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

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How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Maintaining a car out-of-warranty at the dealer can be expensive and the techs don't like them, so many of the old cars that they do see are broken beyond the point that DIY or independent mechanics can deal with them easily.

This statement has incorrect information. As technicians we are very much aware of the fact that we only see the bad ones, but when you see the same engine with the same problem day after day it is cause for concern, especially in a shop such as BARCZY01 has.

The dealership can be less expensive especially after the independent repair shop starts guessing and throwing parts at it in hopes it will be fixed. Cadillac techs love the older cars, and love to work on them. The older cars are;

1) Out of warranty, so the labor flat rate is more realistic which equals more take home pay.

2) They are usually easier to work on than the current model year ( more room ) and more often than not are easier to diagnose. Okay, with the exception of the 1976 472 fuel injection pin out box POS...

The 472 and 500 were my favorites to work on, that engine was first introduced in 1968 look how long its production run lasted. I agree with the statement about the oils of the day exacerbating the cylinder wall taper. Oil control rings did scrape off a lot of oil.

I do believe Jim, there is a lot of truth to BBF's statement that GM does not move fast to correct a problem and the head bolts were a problem, and the design was flawed, especially as it related to the 4.1. I don't believe the tech that stated you should trade for the 2000 - 2001 was operating on accurate information but he obviously formed an opinion that the 2000 - '01 was a better design. Compared to the 4.1 the 4.5 was a "better" design, and the 4.9 was even better. Did I think GM tried to evolve and work through the problem - YES - were they slow to provide a solution - most definitely.

I sent enough "samples" to GM ( NO - I wasn't the only one - nor was our dealership the only dealership that did ) to be examined (at their request). I don't profess to know the design cycle or process involved in R&D of component design and tooling changes not to mention supplier issues so maybe I was just too impatient for something good to happen.

Did a good thing happen with the NS? I think so. Could it have been better? I think so. Who else is there to blame for shortcomings if not GM? Can't blame Ford or Chrysler they didn't build Cadillac.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I would think that any tech that starts throwing parts at a car has given up on diagnosing the problem and needs to step back a bit and reevaluate.

I think that you misunderstand me; you seem to think I am saying to never take an old car to a dealer - that is not at all what I meant.

There are lots of situation where a dealer is the best place to take an old car. Whenever you need an expert with a Tech II or other expertise with Goodwrench training, or you want the Goodwrench warranty, a good dealer is the only place to go. Examples are when the A/C compressor or other A/C component that is either difficult to replace or expensive, like the evaporator, the alternator, etc. I bought an A/C compressor for a car out-of-warranty once, and over a year later, the clutch started slipping and I gradually lost A/C, including the ability of the defroster to clear the windshield on a cold autumn morning. The dealer replaced the whole compressor/clutch, no charge, including no labor charge. Some Goodwrench warranties are for the life of the car as long as you own it, and that is a valuable consideration. In my current car, I let the dealer do a brake job because I wanted to be absolutely sure that OEM parts (Brembo) were used in every case as well as the Goodwrench warranty, which in this case was 1 year and *unlimited* miles. You give some excellent examples too, and yes, the Goodwrench price is right for what you get.

But some people will recommend an aftermarket or rebuilt A/C compressor or alternator or brake job because the cost is about 2:1 higher at the dealer. I hold my peace when I see that because it's their choice. But I let an excellent mechanic do a brake job on my ETC once and when I got the invoice, he had put the "economy" line of rotors on it. As you know, the ETC/STS is built to run with the big dogs on the Autobahn, and I ran with the big dogs in all my high-speed commutes in my ETC, and I wasn't about to downgrade my brakes, so I went out and got Powerstop performance brakes for it. You really need to watch parts selection by independent mechanics for Cadillacs because most of them don't have a lot of experience with Cadillacs and don't understand the cars; they think "slow boats" and give you the Marty Feldman look if you talk sports performance.

As far as oil and the 472/500 is concerned, you are confusing me with another poster; I never mentioned those.

The tech that gave me bad advice in 2001 or so proved, over the years, to be... one to avoid for many, many reasons. As is his service manager. If you want to know more, much MUCH more, send me a PM.

I don't know much about problems with the 4.1. During those years I was driving big block Chevrolets and such. I thought that it was a reasonably reliable engine, overall. My impression of the 4.5 is that it was a huge improvement in performance and the 4.9 is on the same level as the early Northstar except for horsepower, i.e. under 45 mph. I never post on these engines except as general car advice.

I think that the problem with the Northstar head bolts is not just one thing. First, I'll stand by saying that except for the occasional idiosyncratic case, this is a problem that you see in cars over 100,000 miles or six or seven years old (even with low miles). Although it's hard to find maintenance information except in one-owner cars, it does seem that most of the owners can't recall having their coolant changed, or the car was already over five years old when they got it and changing it then wouldn't help. We had one guy here with a 1997 ETC that had a head gasket problem at about 60,000 miles in spite of good coolant and other maintenance, and he went on a crusade with the message that *all* Northstars would have head gasket problems. He even called me once to try to prove that my head gasket problem had occurred in spite of good coolant maintenance. But, no, when the coolant hit 5 years, that's when the tech called me and told me that the "head bolts were weak" and that I must trade my car ASAP; he did NOT recommend a coolant change.

Any aluminum engine will have problems if you run old coolant. The problem with the Northstar is that this problem is usually the worst possible thing, pulled head bolts. Well, one tech told me that the 3.4 liter V6 in my wife's car would eventually get antifreeze in the oil and seize the engine if I let the intake manifold coolant leak go forever, so I guess that's worse, and I'm sure that some people do just that. Could they have put channels in the head gasket to provided a path for trace coolant leakage away from the head bolt holes and crankcase? Mechanically speaking, I don't see an easy way to do this. The high-pressure seals in the head gasket are around the bores, but there are other hard seals around the oil passages and coolant too. Could these have been re-designed to keep trace coolant away from the head bolt bores? I think that possibly they could - but I know that a definitive opinion there would require qualified people working with lots of real engines in a power plant design facility to design and try different configurations, and I don't deign to second-guess that with any authority. But that has always bothered me too.


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Sorry, I just noticed this post going through the thread again.

I've never heard of coolant breaking a head bolt. I've never heard of coolant loosening a head bolt so that in can be removed by hand.

I've never heard about a head bolt being broken in an engine, either, except by huge abuse as with over-revved engines, dyno testing, or blown fuel dragster engines. They don't get loosened, either. The problem with Northstars usually is because the aluminum threads give out, and often the material that comes with the bolt threads is porous or otherwise shows signs that it is not the solid material that was there when the engine was new. Browse CHRFAB; they have a forum too. The last time I checked, their 400+ hp sand car engines were Timserted with stock head bolts.

To say that a 10 - 15 percent failure rate is an extremely low number or to insinuate that it is acceptable is like saying a 10 percent casualty rate in combat is acceptable, maybe, if you're not one of the 10 percent.

Please forgive any misunderstand; my point in giving the old 15% failure rate is that the failure rate isn't huge, and is consistent with the fraction of drivers forgetting the coolant maintenance and such.


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-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
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Every one of the newer head bolt style 11 x 2.0 had no signs of stripped threads. Every head bolt that was loose would retorque to 70lbs. I have never had an issue using timeserts and have been using time serts since 1994 when these motors came out. Off the top of my head the last 3 newer style head gasket jobs I have worked on had 73K, 125K, 80K.

Why on some of these northstar engines are the bolts coming loose, I have no idea. But don't the newer design LS engines use a multi layer gasket? GM has been using the same old asbestos head gasket for these northstar engines since 1993 but have a couple of other head gasket choices on the aftermarket.

Edited by barczy01

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Every one of the newer head bolt style 11 x 2.0 had no signs of stripped threads. Every head bolt that was loose would retorque to 70lbs. I have never had an issue using timeserts and have been using time serts since 1994 when these motors came out. Off the top of my head the last 3 newer style head gasket jobs I have worked on had 73K, 125K, 80K.

Why on some of these northstar engines are the bolts coming loose, I have no idea. But don't the newer design LS engines use a multi layer gasket? GM has been using the same old asbestos head gasket for these northstar engines since 1993 but have a couple of other head gasket choices on the aftermarket.

Yowww. If the head bolts get loose, there are a limited number of things that can reasonably do this:

  • The head gasket compresses.
  • The head bolt stretches.
  • The threads give.

I can't believe that GM would use a head gasket that compresses, although everybody gets caught by an unannounced change in a vendor part occasionally. The torque-and-twist bolts used by Cadillac aren't anywhere near yield when installed per spec, as in the factory. If the threads gave, you might or might not be able to torque to 70 lb-ft but you would probably feel give by that point of they held to that point.

I didn't address less likely things like the bolt turning or extreme things like the dimensions of the head or block changing. The only one that makes any sense at all to me is the head gasket taking a set, a huge no-no for a head gasket designed for an aluminum engine, even with long torque-and-twist head bolts. Aftermarket head bolts or studs, or aftermarket head gaskets would be suspect, but I gather that these engines had never been apart. If anyone can recommend a reason that this happened, please speak up.

It's interesting that all the loose bolts you tested would torque to 70 lb-ft. I've heard here that a lot of the bolts pull the threads when removed, due to the permanent thread-lock used at the factory, hence GM's recommendation that all head bolt holes be Timeserted, once the word got out that economizing there is not... thoughtful. The fact that they all broke loose without pulling the threads with them, implies that the threadlock wasn't there and/or someone or something broke the head bolts loose sometime in the car's history. Remember, nothing is foolproof because fools are so ingenious.

One last thing that could possibly explain these three motors: a huge overheating event, such as leaving a car idling and unattended in a situation where the wind prevents enough air going through the radiator...

barczy01, if you can remember, please tell us if all the head bolts were loose or just some, and, which ones? You note that two of the cars you fixed were low mileage; how old were they? Is there anything else you looked at with these motors?


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Yes, I was Jims_97_ETC before I changed cars.

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Every one of the newer head bolt style 11 x 2.0 had no signs of stripped threads. Every head bolt that was loose would retorque to 70lbs. I have never had an issue using timeserts and have been using time serts since 1994 when these motors came out. Off the top of my head the last 3 newer style head gasket jobs I have worked on had 73K, 125K, 80K.

Why on some of these northstar engines are the bolts coming loose, I have no idea. But don't the newer design LS engines use a multi layer gasket? GM has been using the same old asbestos head gasket for these northstar engines since 1993 but have a couple of other head gasket choices on the aftermarket.

I think this is actually good news, that there was no sign of stripped threads. I assume that means that you did not find any aluminum on the threads when the bolts were removed, and if that is the fact, that is great.

So the question is, how did the bolts loosen up, 1) compression of the head gasket or 2) stretching of the bolts resulting is lessening of the their clamping force.

Something tells me that there is not enough thickness for the head gasket to collapse sufficiently to cause the bolts to become loose/to lose their clamping force. This means to me that the bolts themselves must stretch from thermal cycling, is that possible?

Here is an analysis of head gasket problems with the MG Rover also 4 valves per cylinder, I found the analysis to be very interesting. I was especially intrigued by the theory of different expansion rates between the head bolts and the aluminum alloy which will effectively tighten the bolts at high operating temps and then return them to spec clamping force when cooled down. Now I know that we are speaking about longer M12 bolts in the MG Rover at 380mm, but I am simply looking at the theory they present. Please read the entire analysis, but especially see paragraph # 4 in the section titled "The thermal head bolt stretch theory" here > http://www.mgf.ultimatemg.com/group2/common_problems/HGF_pages/why_do_hgfs.htm

Here is an excerpt of Paragraph 4:

So the bolts will expand by 0.000012 x 100 x 380, which is 0.456 mm. The equivalent crankcase/head assembly will expand by 0.000024 x 100 x 380, which is 0.912 mm, almost half a millimetre more. With the threads of an ISO M12 coarse pitch bolt at 1.75 mm pitch, that's equivalent to tightening the head bolts by over a quarter of a turn each time the engine is run up to operating temperature, and then slackening them by the same amount each time it's cooled. Drive the car twice a day for 250 days a year, and that's 1500 times the bolts have been tightened and released by the time the car reaches its third birthday. Do the sums for a temperature rise of 150 deg C and the difference is even greater. This constant and repeated stretching and releasing of the head bolts must eventually result in a deterioration of clamping pressure.

My first, thought is, they stated that with an M12-1.75mm pitch, the differing expansion rates equated to almost a half millimeter more equivalent to a quarter of a turn each time the engine is run up to operating temp.. How would that impact an M11-2.0 and 1.75mm pitch relative to the tightening equivalent each time the engine is up to operating temp and overheated?. Again I know that the NS bolts are not that long, so the expansion will be less, but there WILL be a differing expansion rate. Cadillac Jim and Bruce, you are our resident math experts, I know KHE has spoken in these terms also. Gold stars await.

I want to point out something else, in the Mercedes AMG info I presented above, the head gasket failure was being blamed on the head bolts and members were being advised to use studs. Could head bolts at spec clamping force, yield because of heat cycling/uneven expansion of head alloy and bolts? If that were the case, I can see a strong argument for ARP studs, but then do you just transfer the stresses to the block threads?

Could there be a problem with head bolt quality control? If the bolts are not the problem, could this tightening every time the engine is at operating temp negatively impact the head gasket itself?, squeeze it harder, then release, over and over.

Interesting stuff guys, thanks barczy01 for the info.


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My 2cents worth -

One thing that always struck me was that no one realized way back in the beginning of the design stage of the 4.1, was the different expansion rates of dis-similar metals - cast iron heads and aluminum block and yes even the intake manifold. GM improved the failure rate of the 4.5 and 4.9 by using thicker HG and IM gaskets. I double-gasketed both HG's on a 4.1 for Cadillac as an experiment ( no that didn't work ). The point is - they new about the problem and wanted a solution that would cost the least amount of money to correct and last for the 50k miles of the warranty. The bolts were still a dis-similar metal with a different expansion rate and they went to a torque angle to improve holding and gasket compression.

This brings us to the NS - now we have similar metals for block and heads but we still have basically the same head bolts and the same issue. As BBF pointed out the engine should be rebuilt at 100K miles. The factory never designed the engine to last longer than the warranty - sorry, I know this for a fact. I have personally talked to factory reps.

One more thing to point out is that the majority of the NS's that have reached "high mileage" before they fail, is that they share one thing in common - lots of highway miles - fewer expansion/contraction cycles equal longer mileage.

You can agree or dis-agree - it is only my opinion, I'm entitled to that. I don't intend to tarnish the reputation of Cadillac, I love Cadillacs for what they are and the standard of comfort that they set at a high level for the industry to "shoot" for. It probably wasn't that long ago that you heard someone say "it rides like a Cadillac". I wouldn't have worked on them for so long or be on a site like CaddyInfo if I didn't like them . Do I have proof of the conversations with Cadillac factory reps - NO - I simply lived it.....

Hmmmm, I think I heard that somewhere before.......... Head - Bolts - Expansion - Contraction ......

Thanks BBF for bringing the point to life :)


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Thanks OldCadTech, you sure did bring it out! I missed the relevance and importance at the time but now that I read the detailed analysis of the Rover I get it and you nailed it!


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The point of long head bolts and torque-and-twist it to maintain the clamping force within specified limits over the temperature range of the engine. The clamping force will be highest when the engine is hottest, and it will be lowest when the engine is coldest. Installation is specified for the engine at room temperature, or between approximately 60 F (16 C) and 90 F (32 C).

Note that this is true for studs as well as bolts. This gives me strong pause about aftermarket studs, because they too must be designed for stretching spring constant over temperature. I have the same doubts about aftermarket head bolts, and always recommend that you look at the torque-and-twist recommendations that come with GM or aftermarket head bolts because even the GM head bolts change occasionally, and the torque-and-twist specs change with them.

Each engine will be designed this way. Making it work requires designing the head bolts so that the spring constant of the head bolts and their stretch at the temperatures involved keep the head clamping between limits appropriate to the yield strength of the bolts and the yield strength of the head gasket, and sufficient to maintain head sealing with running under load with a cold engine.

I see a couple of opportunities for failure here. The low temperature range is about -40 F (-40 C) for most GM engines. The high end is probably about 265 F (129 C), where 50-50 ethylene glycol antifreeze boils, perhaps bit more for margin.

I can't see 270 F as a temperature problem for head bolt steels, but the expansion might be closer to the yield point of the bolts. But the resilience of the head bolts over the life of the engine requires that the stretch over normal use be *very far* from the yield point, and an increase of, say 20% over what is normally seen *should* not cause a set in the head bolt yield.

This leaves head gasket compression taking a set on overheating. As BBF says, that's not very credible either. If we are talking about a say, 20% increase in clamping force over maximum spec, that should be well within the design margin of a head gasket designed for daily use for 10 to 20 years.

What we need are the head bolts and head gaskets from such an engine. We need to do dimensional comparisons between the thickness of the head gasket involved, blown or not, and also micrometer comparisons with the lengths of the head bolts involved.

Since this is a mystery, we need to be prepared for everything to check OK and that the problem be somewhere else.

EDIT: One last thing occurred to me: yield of the head at the base of the head bolt.

I'll not get into tinkering and tampering not known to the owner or current tech. But if the factory threadlock is not in heavy evidence when you start to pull the head bolt, that is a big suspicion on my part.


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Jim, right on, right on, right on! The idea that the block material yields was also covered in that article. When I read it, I did an extensive search for the type of aluminum the NS heads are constructed from with no success I searched LM25 and 226 to learn more, and found lots of charts. This exerpt starts out with that the engine was built for performance, as was the NS. In the back of my mind I keep thinking, OH NO, I hope not....see the link I provided above for the context of this clip:

"Why does this small phenomenon affect the gasket? - it doesn't. It affects the head. K is special, it was designed as a stand out engine, throwing all conventional practice aside, most of it's features came straight from F1 design - it was to be a ground breaking engine like the all ally bonded chassis it was designed for - ECV3 (this is not exactly true - see article written by someone on the ECV3 development team here - but we'll let Simon off the hook on this one - Ed). So it had the immensely stiff crank carrier design when, for instance, the Japanese have only just caught up, until the k20/FOC20/ VVTI all their engines relied on the old fashioned bearing cap design. Hand in hand with the new 4 cylinder design went the choice of material. LM25 is a very expensive alloy, the only other mass produced engines to use it up till now are all of Aston Martin's recent engines and AMGs engines For Mercedes. All BMWs Hondas, Toyotas , Fords etc are made of cheap 226. LM25 is much stronger - so you use much less of it to get the required mechanical strength. About 40% less - hence the weight advantage of the K compared to the "Industry standard " engines, but in order to get that strength LM25 undergoes a heat treatment - a quench. That treatment gives it it's strength but is also it's Achilles heal. If the operating temperatures and hence the temperatures the engine sees are not carefully controlled, the metal loses it's quench, it's hardness and goes soft - and over a period of time the fire ring frets it's way into the head surface. This results in a loss of clamping force, allowing cylinder gasses to escape and pressurise the coolant system, forcing water into the cylinders and oil, and oil into the water - and that's when you get the classic symptoms of "HGF". The reality is that failure is a slippery slope and occurs long before symptoms become visible."


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You are right Jim, I want to closely examine a blown head gasket. I want to examine the fire rings and as you noted mic it. barczy01 would you sending me a gasket set from an engine that had trouble?, we can send them around to members to look over. Thanks in advance.

Jim, I was looking at your engine today, I have it in my garage on an engine stand. I noticed something curious about the cylinder sleeves where adjoining cylinders touch. It appears the walls get thinner in that area. To the left the sleeve wall thickness is 0.3445 or approximately 11/32" where as where the sleeve nears the adjoining cylinder the sleeve wall thickness is 0.272 or approximately 17/64". I was surprised to see this, especially given that undoubtedly the hottest part of the block would be in the area between the cylinders where they come to a point exactly where the wall is the thinnest. That may mean nothing but since we are kicking this around I thought I would post an observation.

Cylinder%20Sleeve_zpskvekn8ta.jpg

Keep in mind that GM thickened the cylinder sleeve walls on the 4.4 supercharged engines for better sealing.


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Assuming that this is intentional, I can see it as equalizing the heat transfer into the coolant. The outside away from the twin cylinder has more coolant flow but also more aluminum outside the bore, while the inside has less coolant flow but thinner aluminum. But that's a casual arm-chair observation. Also, I'm not at all sure what difference equalizing temperature around the bore will make, because the effectiveness of any measures will be very slight and depend on operating conditions. If they are thinking about wear conditions == most of the running time == cruise at 2200 RPM and high vacuum, varying the aluminum jacket thickness to compensate for varying coolant flow might help. But most heading and cooling is in the heads, and the pistons are really oil-cooled, and not that much cooling is done on the bores.

Understand that this is a Jasper engine and I don't know anything about its provenance or history. I suspect that the bare blocks interchange over a wide range of model years, although the complete engines w/o manifolds or cam covers interchange only over 1996-1997.

I hope that is oil standing on the left piston.


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This has nothing to do with jasper, this is how the block was manufactured. I was surprised to see the thin wall in that area between the cylinders that will transfer more heat .

Yes that is oil, I have kept the cylinder walls well lubricated to prevent rust.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I mentioned that it was a Jasper because I don't know what model year that it was manufactured for. Do you have any plans for it?


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Hmm, I was not aware that there might have been those types of differences from 93 to 99, 96 through 99 for sure.


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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There may or may not have been minor alloy changes year-to-year or other details. But if the accessory mounting holes, or at least the pads if not the drilled and tapped holes, are all the same, they are mechanically interchangeable. In full rebuild sites, engines are stripped to the bare parts and the blocks and heads are cleaned and reconditioned, and new engines are built to specification from parts inventories. The bare block part number may not have changed as much as the long block part number. Since the engines are built by part number, the block could come from any year that uses that part number for the bare block. If there are other minor changes within the bare block part number year-to-year, then a long block built for the 1996-1997 model year with that part number can have a block from another model year that shares the part number for the bare block.


CTS-V_Dashboard.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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