The Jasper Engine

[BodybyFisher]

Jim, aftermarket wire look melts at too low a temp I have found. I usually visit a local scrap yard find a GM wreck and remove as much wire loom as I can. Do you have any scrap yards near you? If not, I need to visit the scrap yard next week and I can pick some up for you and mail it... Mike

[KHE]

Jim,

Rotate the plug wire boot back and forth, then pull the tab - they will usually come off.

[airmike]

Jim,

Rotate the plug wire boot back and forth, then pull the tab - they will usually come off.

This is why I asked if there were any secrets to removing them a while back. I have taken plug wires off cars for years, but on my daughters car there was one wire that would not release from the plug, period. I tried the longest pair of needle nose pliers I own, and rotating back and forth, but it would not rotate/release from the plug. Ended up with the wire torn off the end and no real way to get the plug out at that point. I ended up just tearing little bits of the wire boot off until I could get a socket on. Literally spent 45 minutes on one plug.

[Cadillac Jim]

First, the good news: I wiped all the static-electricity-cling dust that I could find off the wires, particularly the one for number 8 where all the misses were happening, and switched numbers 3 and 8 on their common coil because the wire from number 3 seemed to be a little tight. I cleared the codes on starting the car, and, voila, the miss is gone. No codes. Drove the car to the grocery store, started it cold again and drove home, and again no miss, no codes. This verifies that the problem is the plug wires.

BodybyFisher, I looked all over south Jersey when I needed the EBTCM clamp and found nothing with any Northstar cars available for parts. Please do get the looms and conduits and mail them to me. I suspect that the simplest thing to get would be the wires with looms and conduits included, as that is the easiest way to get what I need off a salvage car, and I'll take them that way. Don't forget the bolts for the looms and the clamp for the conduit for numbers 6 and 8, etc. I will PM you with the address. I'll pay the parts, your time, and shipping.

The only plug that I tried to get off the rear bank is number 1, the most accessible. The boot is firmly stuck to the plug and no amount of twisting has any effect. The new AC/Delco plugs came with a little packet of dielectric silicone compound and the instructions said to use it; I don't know what the Prestolite plug wires had or recommended, but it seems that they were put on dry and they adhered to the plug. That's not necessarily a bad thing unless you have to change the plugs, whereupon you are in for an experience similar to airmike's story. I was tempted to replace just the number 8 plug just to look at it, but the disappearance of the miss tells that story - apparently there is nothing wrong with number 8 other than a plug wire arc. I would rather have the savagery necessary here happen out of my sight.

Thanks to the offer by BodybyFisher, I'll cancel my appointment for the job and wait for the parts. That's a far better option than buying three feet of conduit from the parts store and delivering it with the plugs/wires/coils/seals to the maintenance shop.

EDIT: Ran a bunch of errands in 30 F temperatures. MIL light came on while on the way home; only code was P0300 HISTORY. Put the computer on the car later and P0300 was CURRENT. All the misses were again on no. 8. Arrgh. If necessary I will put a conduit around the wire for number 8 between the coil and the beauty cover to get time to obtain a used loom/conduits.

[Cadillac Jim]

I've found that some of the tiny parts are still available but not the loom and brackets. I have done a search and turned up some salvage yards within driving distance that claim to have Northstar parts but none that I have called so far actually do have them. One in particular shares the same search engine that I have seen on several salvage sites and I have been there looking for Northstar parts and they have no OBD II Northstar cars. I'll keep calling.

The relevant parts are a four wire to two wire conduit that clips to a holder held by a module mounting bolt. This one holds the wires from cylinders 2-4 and 6-8 from the front, then holds all four away from the firewall. The others are a clip that holds all the rear plug wires together, then one that holds 1-3-5 together. I believe that the one that holds 1-3-5-7 clips to the cam cover and holds the wires away from the A/C motor.

[Cadillac Jim]

Found a GM parts manual diagram of the conduits, loom and clamps:

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Need discontinued parts denoted by (3) in the diagram (maybe I can make this one myself) and the loom clamp that holds all four wires to the rear plugs, which apparently clips onto a mount on the rear of the cam cover - this one I can't make and really need to keep the wires to the rear plugs off the A/C motor.

[KHE]

Jim,

When I repaired my STS engine almost 7 years ago, those parts were not available. The plastic portion that clamps around the wires was OK - it was the portion that "plugged" into the metal piece that mounted to the cam cover that had disintegrated. I used wire zip ties and it has been fine ever since.

[Cadillac Jim]

KHE - aftermarket conduit and wire ties is my Plan B. The critical piece is that one that was missing on your car, which holds the wires to the rear bank against the cam cover and keeps them off the firewall. The wires to the front bank can be put through a conduit and tied to a tab bolted by one of the module bolts, and it's easy to make something like that.

Thanks for the encouragement. I won't have to rely on getting parts that probably haven't been available for ten years just to be able to have confidence in the longevity of my plug wires. This time I attacked it as a DIY job and found that the fellow who replaced the wires in July of 2011 did everything right and used OEM-quality plug wires, but that missing parts was the problem. The FSM warns specifically to use the looms and conduits or you will have problems with arcing. I also noticed that the plug wires are brushing against the A/C motor, which alarms me a lot more. I don't know if my car has the metal plate (the A/C motor is original, and the car was made early in the 1997 model year run) that was used to stop failures caused by the plug wires.

The interesting thing is that the problem is the plug wire for number 8, which is a really long plug wire. It comes from the coil next to the front and goes behind the coils, then under the beauty cover to the rear plug on the front bank. Somewhere behind the coils it is arcing against either the firewall or the cam cover because it's not in a conduit like in the picture above.

[Cadillac Jim]

Well, I had a reputable and competent local mechanic put in the plugs, wires, and coils, and, no change! I cut him loose to find the problem and he called back a couple of hours later and told me that the compression on number 8 was 75 psi, compared to 175 psi on numbers 2, 4, and 6. He hasn't checked the back bank.

They are a Jasper installer and they called Jasper, who told them not to pull down the engine because of the likelihood that the inserts would pull out. They will take the engine as core and pull it down themselves. It's well out of warranty as it was installed in July 2006.

I called myself just now and asked how a Jasper with only 45,000 miles on it would lose compression, something that I've never heard of. Since oil and coolant aren't involved, the compression is being lost in rings or valves. It can't go out the gasket without vast amounts of gas in the coolant, which isn't happening. It burns zero oil. The Jasper guy said that it could be a bad fuel injector that was causing detonation or fuel bleeding down the rings, and to check the plug for gas fouling. There is more, but the gist is that it is anything other than the metal that came on the Jasper palette, which, objectively, is a reasonable assumption. I will have my camera with the close-up lens and flash ready when we pull the cam covers, though, and will look for a flat cam or other visible issues.

I thought that a bad injector would throw another code, such as P0174 or P0175, but the Jasper guy said that there won't be any codes. Since the Northstar uses broadband oxygen sensors and measures the mixture on each cylinder separately, I'm not at all sure that a bad injector won't throw a code once the car is closed-loop. Does anyone have any experience with that?

I asked about a written pull-down report, and the Jasper guy said yes, they offer that for a fee, which he estimated at $175.

I'll be joining my mechanic/installer for a three-way phone conversation later today.

The whole issue is in doubt. I did a KBB.com check and the car is worth about $4.1 K and a new Jasper will cost about $2K more than that by the time I'm driving it again, so the decision won't be made until all the details are in, including all costs, warranty, and pull-down information. For example, if they won't warranty the motor without new injectors, that's part of the cost too.

[KHE]

Jim,

If they squirt some motor oil in #8, does the compression come up to acceptable range? If so, that would indicate the rings are worn. If it doesn't improve the reading, that would point to valves.

It could be something simple like a small piece of carbon preventing a valve from seating fully. What about running several WOT in 2nd gear and letting it coast back to 40-50 and hitting it again? That may be enough to clean away any carbon deposit that could be causing the issue. When I repaired my engine in 2006, I talked to the guru on the phone and asked him if I should have the valves ground, etc. and he said, "You could but what's the point - you'd be wasting your money." I took that to mean the valves were lifetime parts. Barry94 had an issue with a burned exhaust valve on his car that he repaired.

If the injectors are not leaking, I doubt they're bad. The injectors can be rebuilt for a fraction of the cost of new ones.

How bad is the miss? If it is not bad or present all the time, I'd be inclined to keep driving it.

The thing to remember is that even though the car may only be worth $4100 and it is hard to justify dumping $6100 into it to get it repaired, the thing you need to get your arms around is what kind of Cadillac can you buy for $6100?

Another thought is that 2-4-6-8 are on the front part of the engine. I wouldn't think the inserts would pull but if they did, it would be easy enough to install Bigserts on the front bank without pulling the engine. The front head could be removed and the valves checked/repaired and the head reinstalled.

[Cadillac Jim]

The out-the-door estimate is $7436.50 with tax.

The miss happens every time it starts cold when the car is cold, under about 45 F (outside temperature 35 F or colder). Idling cold, you can see the miss count on number 8 incrementing. In gear, creeping with the brake on, you can feel the miss pretty well. The MIL light is on, and comes back on if you reset the codes, so it won't pass emissions. The miss goes away when the car warms up, and if you drive it all day without letting it get cold, the MIL goes out.

Jasper has said everything I have heard of and them some to keep the mechanic from pulling the head, plus some things that I hadn't thought of. I have told him that doing the head here is one of the options I am considering, and he can do that. The problem is that the head bolts aren't Cadillac and we may need to get some from Jasper. I think I'll call Timsert and ask if they were selling Cadillac head bolt Timeserts to Jasper in 2006; if so, I can get Cadillac head bolts.

I've done some preliminary sniffing around and you can get a 2004-2006 CTS-V (non-supercharged) with the 6-speed with about 65,000 miles on it for under $20K these days. This compares favorably with a 1997 ETC with a new engine for $7500.

I think I'll take the car back and do some WOTs and a road trip. I haven't had the car out on the road in a long time. If that doesn't clear it up I'll re-evaluate the situation.

[KHE]

Jim,

Any update? I'm curious to see if it was just a piece of carbon on one of the valves.

[Cadillac Jim]

I started by puting top-end and injector cleaner in a full tank of 93 octane Sunoco last Thursday. I drove the car alone on the freeways in light traffic for about 100 miles. The next day my wife and I drove to Atlantic City and back taking the long way around both legs to keep on the freeways. No discernible change, other than the long-needed road trip tonic. I got a P0300 CURRENT when I stopped in the garage.

Tuesday I put it back in the shop for a wet/dry compression test. This morning the picked me up and I shop and talked to the owner. He showed me his notes and discussed the situation. He did a wet/dry compression check and a leak-down test, showing that the problem is the intake valve. Intake valve! That has got to be a first.

Here's what he found:

• Number 6, 180 psi dry, 285 psi wet (near hydro-lock!).
  
• Number 8, 90 psi dry, 130 psi wet. Increase probably due to volume of the oil, not wet rings.
  

Cylinder leakage test:

• Number 6, 9%
  
• Number 8, 78% (down to 22 psi)
  

The leak-down was through the intake valve. Work was done by owner, then re-done as a check by his best man for this type of work.

Based on what my research was telling me, and Jasper's hazarded guess, I was thinking that a leaky injector had caused cylinder bore wear to the point of a slick bore which would cause loss of compression on that cylinder. It seems that the Northstar and a lot of other modern engines depend on the cross-hatch to lubricate and thus seal the rings, and once the cross-hatch is gone you need a teardown. That's why you see the cross-hatch on every Northstar you open up.

This is NOT Jasper's problem. I've had the Jasper for six years and 45,000 miles, and whatever caused the intake valve problem wasn't there in July, 2006 when the motor was put in. Yes, it's a vanishingly rare problem, and yes, it's a Jasper, but there is no rational way that these two facts can be connected. I still swear by Jasper. For example, the case half and oil pan are totally and completely dry after six years and 45,000 miles, a feat that the original engine didn't match (I expect that replacement engines sold by GM in the 2006 time frame would stay dry too, though).

The car is reparable, but I am just a couple of hours away from signing the papers on a magnificent opportunity that I will announce in a week or so. The 1997 ETC is now surplus. It needs an intake valve on the front head. The miss count will turn on the MIL and keep it on so it must be repaired to pass emissions. There is an oil seep apparently at the front seal that I have decided to ignore.

The car has about 161,000 miles on it. It has new AC/Delco electronic shocks and struts from about six months ago, new PowerStop brakes from about a month ago, and new Timken front hubs from two weeks ago. It runs great, and has no codes other than the P0300.

Make me an offer by PM. Include your e-mail address and I will send you a CarFAX on the car. You come and get it in South Jersey near Philly (I will pick you up at the airport or train station). The car runs great except for a miss at idle and you can drive it home, even long distance.

Interestingly, the CarFAX says that this car is worth $1410 more than other ETCs of similar vintage and accessories. And, the new shocks/struts, brakes, front hubs, and Jasper are not on the CarFAX because they weren't done at a dealer (I have the invoices). In a couple of days, in the absence of an offer to come and get this car, I will donate it to charity. I already have a phone number to call when I am ready.

[BodybyFisher]

Jim based on your PM, I assumed that because the compression increased wet it was the rings, that does not seem to be what you are saying here.

You are saying that this is a bad valve. Why then did the compression increase wet?, I thought that was an indication of bad rings when that occurred?

This is the front bank correct? That would entail removing the front bank and having the head repaired. This engine has been timeserted? Do they use OEM bolts?

Did the mechanic hear pressure leaking into the intake during the leakdown test?

Thanks Jim

[KHE]

Jim,

The compression values as well as part of your description seem to indicate rings. If the compression value is basically unchanged when oil is added, that is usually a leaking valve. If the compression rises when a wet test is done, that indicates rings. It would be interesting to see what the inside of the cylinder looked like if you had access to a bore scope.

[Cadillac Jim]

The amount of oil and a one-revolution test accounts for the increase. The good cylinder went from 170 psi to 285 psi because of this. The combustion chamber is only 55.8 cc including the head gasket. No car has 285 psi compression. The leak-down test showed very little in number 6 and a bad intake valve on number 8.

[BodybyFisher]

Jim, I called Jasper and spoke to a tech. I have him the engine ID number. I was unable to find specifics regarding the build. What concerns me is 1) were any of the block holes Big Serted, and 2) do they use a proprietary head bolt. He was adament that they used OEM head bolts which differs from your impression and your description in Post #1 in this thread.

KHE (Kevin) and I have been PM'ing and I was asking him about the timeserts and what happens if a timesert comes out with a bolt, not pulled but it comes out because the thread locker broke loose. Is it simply a matter of installing a new time sert in that hole or must it be big serted?

I definately would like to speak to your mechanic to see how he confirmed it was an intake valve, I suspect he could hear the AIR LEAKING via the throttle body opening. The risk here is that it is in fact the rings. It is interesting to see that KHE suggested the scope to look into the cylinder as I did. I asked my son if he wanted to purchase my 02 Monte Carlo. If this is only the intake valve and I can R&R the head with no surprises I would love to have your car. This has a Bose system?

[KHE]

The Timeserts are held in place by both Loctite 262 and the swedge operation created with the installation tool when they are installed. The swedge operation mechanically locks them into the block. GM uses (used) them to allow changine of the heads during product validation so I doubt they'd pull loose if they were installed properly.

[Cadillac Jim]

I'll go with Jasper and say that the head bolts for the 1993-1999 Northstar apparently changed between the time my engine was built (probably 1996 or early 1997, since the dealer first saw in in mid 1997) and the bolt heads looked different when the Jasper was beside my original engine in July, 2006. The heads are larger. Note that the torque-and-twist specs for the 1993-1999 Northstar have been updated as well. I would go with the latest head bolts and the latest torque-and-twist specs.

Did you think to ask Jasper if the inserts come out when the head bolts are removed? They would likely know about their own engines from warranty work, and the would very likely have run into it in some of the cores.

This car has the Bose audio system and the 12-CD changer in the trunk, which I use regularly. The first CD is one that I made from songs I ripped from CDs or individual MP3's that I bought. Another is a duplicate of Billy Joel's Greatest Hits, a CD that is known to skip on one song, even for radio stations; the duplicate does not skip. I'll leave the CD's in it for when you drive the car.

This car is an ETC, which means that most options come standard, and some things like the ventilated leather seats are not available on the base Eldorado. It has all other available options except the heated windshield and the heated seats; this is an L.A. car and nobody bought those in L.A. that year. The sunroof is dealer-installed by the same manufacturer that makes the OEM sunroof and the center roof console is not deleted as it is with the factory sunroof, and it has the pop-down sunglasses holder and the Homelite garage door opener. Unlike the factory sunroof, this one has the auto-close feature where it closes when you turn off the key. If you push the rocker switch forward, the rear pops up for a vent. If you push the rocker back, it opens like an electric window. There is a cover that you can slide over it when it's closed but I leave it open. My wife sometimes closes it in the summertime if the sun shines on her and she is hot.

The car has Michelin Pilot Sport A/S Plus tires on it less than a year old. My experience with Michelins on this car is that they still have excellent tread depth when they time out (four years).

I'll take a picture of the option sheet and e-mail it to you Friday morning when I take pictures of the car. That's a good opportunity to remove my jumper cables and 12-volt tire pump, which I use to rescue others occasionally but have never needed for myself.

[Cadillac Jim]

Snow and rain today, so I don't have new photos, but sun is forecast for tomorrow. I will get it done tomorrow.

I looked into doing a valve job locally but the quotes I got convinced me that I need to look at the shops in Philly or let someone take it as a DIY job. Another Caddyinfo Supporter is going to take the car home in a few days and pull the front head. Then, we will decide what to do. If it's what we think it is, namely a minor problem with an intake valve, he will keep it. If not, we will decide together what to do depending on what we find.

This is pretty much the end of my involvement with the 1997 ETC as owner and daily driver. I'll continue to drive it until I leave for Texas to pick up a 2011 CTS-V that I bought this week. It's the Thunder Gray one. I'm driving back and will post along the way. When I get back, I'll order the 2011 shop manuals, change my avatar and signature photos, and find another display name that doesn't specify year and model. I'll be a lot more help with later models as I become more familiar with the car and the 2011 shop manuals.

[Cadillac Jim]

The mufflers on this car are straight-through Borla XS series, not Super Turbo or stock mufflers. This gives the car the sound of a big 1950's V8. This happened because Cadillac was out-of-stock with 1997 ETC/STS mufflers, and Borla was out-of-stock with Super Turbo mufflers, when I was rear-ended in September 2006. A Honda wiped out my exhaust system behind the rear Y-pipe and scratched my bumper cover. The only mufflers that I could find were the XS series, which a vendor (I think Summitt Racing) that I called for Borla Super Turbo mufflers said were "equivalent." When they came, I found that you could see two inches of daylight through them, in spite of the offset in one end. For reference, the Borla Super Turbo mufflers that some dealers installed on new and customer's cars as a performance upgrade are straight-through but have an S-turn in them. I had a lot of trepidation when I picked up the car but everyone loves the sound, including my wife, so the mufflers stayed.

The tips were ruined and not available from Cadillac on an expeditious basis and I needed the car every day, so it has tips from a 1994 STS. As far as I remember, these are identical to the factory exhaust tips for the 1997 ETC.

The tires are Michelin Pilot Sport A/S Plus, a little more than a year old. These are ultra high-performance all-season tires. I find them excellent in the wet and as good as you can get without winter tires in the snow.

This car will be picked up soon by a Caddyinfo supporter who will pull the front head and look around in there. What happens next depends on whether we have just an intake valve leaking, as expected, or whether we find other issues. Watch for posts with photos in a week or two in the new topic "The Engine Surgery."

[Cadillac Jim]

I have found that there has been a lot of PMs and email sent in debating the low compression on number 8, and a lot of very interesting opinions have been offered on what is causing the low compression, all by people who have never seen the car or talked to anyone who has. Please note that I am at present the owner of record for the car, and it is insured by me in my name. Since what happens to this car is my business, anyone considering disposition of this car that receives communication of any kind regarding this disposition is encouraged to make such communications available to me.

I spent a lot of time and money diagnosing the problem beginning the first week of February. Here are the results.

First, the car has no OBD codes other than the P0300/P0308. It has no performance problems, no fuel economy problems, no overheating problems, no starting problems hot or cold, does not loose coolant, and does not burn oil. I haven't added oil between changes (which I do when the OLM reads 40% to 45% or so) since I got the Jasper in 2006, and the engine has about 45,000 miles on it. The oil pan is dry as a bone, except for a seep at the front seal. Nor have I added coolant, except to flush and refill the system every two to three years.

Note that the results clearly show that the wet/dry compression test used too much oil. Enough oil was put in to get a very, very high compression reading on a good cylinder, Please keep that in mind when you look at these results. Also note that the 1997 FSM page 6-11 states that the "Compression Pressure at Cranking Speed (Throttle Open)" is 140 psi to 170 psi.

FIRST COMPRESSION TEST

All cylinders except number 8 are 160+ psi to 180 psi.

Number 8 was 75 psi

DRY/WET COMPRESSION TEST

Number 6 180/285 psi

Number 8 80/130 psi

NOTE: To conclude that the number 8 readings of 80/130 psi indicates ring leakage and not that too much oil was used would similarly conclude that number 6 also has ring leakage and all cylinders should read about 285 psi compression. To insist that 80/130 psi shows ring leakage begs explanation of the 170/285 psi readings for number 6. Note that number 4 showed results essentially identical to those of number 6.

LEAKDOWN TEST

Equipment: OTC Cylinder Leakage Tester Kit (CLICK HERE for Amazon offering) or equivalent.

Method: Two-gauge with shop air in spark plug hole of cylinder at TDC compression. One gauge reads pressure, the other flow (which is leakage rate at that pressure). Then a table that is supplied with the tool provides a percentage leakdown. This is apparently the percentage of compression leakdown at a given idle speed if the compression is similar to the shop air pressure used for the test.

Number 6: 5% leakdown

Number 8: 78% leakdown

Listening showed no audible leakage for number 6, or from the exhaust for number 8. A loud hiss was heard through the intake when number 8 was tested.

This was the basis for determining that the problem was one of the intake valves on number 8.

[airmike]

Thanks for the info. Sounds like a comprehensive test. Has the head been removed and any results yet?

[Cadillac Jim]

Thanks for the info. Sounds like a comprehensive test. Has the head been removed and any results yet?

The world has gotten in the way of progress here. Soon.

This is a very unusual problem in any modern engine. BodybyFisher has done some amazing research but this problem fits into no common categories; most valve problems happen with exhaust valves and are caused by rocker arm misalignment (perhaps a bad lifter surface in a DOHC engine with slider lifters, or a misaligned roller tappet in a 2000-up Norhstar), hot spots, poor valve seal installation or functioning, etc. and are heat-related. Intake valves are intake-cooled and not exhaust-heated and so run much cooler than exhaust valves and rarely give trouble, so there isn't much on them out there.

When we get done, there will be a lot out there on this particular problem.

[Cadillac Jim]

Here are the spark plugs for number 8 and one of the other plugs (they are all the same) that were pulled out of the engine when I first worked on it, thinking that the miss was a plug wire or possibly a coil. Note that they are identical except the insulator is darker on number 8 because it had been sitting idling for a few hours for testing.

Number 8:

One of the other plugs: