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N* teardown & inspection


jhall

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Hi all,

I'm well into a teardown and starting the part inspection on a '97 Deville 4.6L (down to the crank and pistons - block is split). I have a couple of questions for anyone who's knowledgeable on this (bbobynski??):

1) The gasket on the oil manifold frame (attaches to the lower block section) was damaged during removal. My Helms manual does not address the gasket on this part for some reason. If the gasket is damaged, must the entire oil manifold frame be replaced or is it possible to reseal with RTV (or hopefully a stock gasket)??

2) The engine has 130K miles on it (head gasket popped on # 7 cylinder), but I can still see the crosshatch from the factory honing in all cylinders. Oddly enough, the pistons seem to have excess play in the cylinders. I'm lazy, so I'm going to measure the bores at a couple of points before I pull out the pistons and crank. I don't want to waste time in the event the cylinders are over the wear limit. The oil was changed regularly per the DICS messages, but I am curious about just how hard the cylinder liners are in the N*. I would have expected the crosshatch to be long gone at 130K. Has anyone seen crosshatch on an engine with high miles?

3) Finally, I have read a couple of articles from people who claim to have "bored and installed oversize pistons" on a N*. Considering the close fit, it seems anything more than 0.010 ovesize would be pushing the limits of the head gasket sealing ring at the top of the cylinder. Has anyone seen any successful aftermarket piston installations in a N*??

If the block doesn't mike out, I need to make a decision on a long block, short block or (gulp) new engine - depending on what can be done and what's available. Any help on this would be appreciated.

P.S. - if anyone wants pics of a naked 4.6L, let me know. I've been taking shots at various stages of the teardown.

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I think Guru has said it can be bored but only 1mm if I recall correctly.

He has also said that it is not uncommon to see the factory cross hatch pattern at 250K. This is due to the Northstars appetite for oil, obviously not neccassarily a bad thing.

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I would have expected the crosshatch to be long gone at 130K. Has anyone seen crosshatch on an engine with high miles?

It's for this very reason why the Northstar engine will "use" oil throughout its life. Burning oil is traditionally seen as a "bad design", but the Northstar engine's 1 qt/1000 mile safe threashold ensures good oiling through the life of the engine. Ever tear apart an older small block Chevy with close to 100,000 miles? The bores are smooth and there's usually a heavy ridge at the top of the cylinder. Not so with the Northstar!

I'd love to see pictures. Can you post 'em here? If not, please send to my email direct (jnjadcock at yahoo.com) and I'll post 'em on a page.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Wow, I am totally blown away by the fact that you have been able to teardown a Northstar engine using a Helms manual. I would think a factory service manual would be the way to go, but of course I would not be able to attempt it even with my factory manuals. Way to go!! I would also love to see the pictures!

Charles

Charles

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Wow, I am totally blown away by the fact that you have been able to teardown a Northstar engine using a Helms manual.  I would think a factory service manual would be the way to go, but of course I would not be able to attempt it even with my factory manuals.  Way to go!!  I would also love to see the pictures!

Charles

Tell me if I am wrong but the Helms manual is the factory service manual isn't it?

Regardless, I always impressed with anyone that has time-serted these engines both in and out of the car. Its an incredible feat. I think we should have a hall of fame for the guys that have done major surgery! Recently I have seen time-serters, tranny pump changers, solenoid replacers, etc. The DIY time-serters however win my respect! Do we have any case-half DIYer's, I am not sure...

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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I am by no means a mechanic and could not have ever gotten the northstar out of my 94 sts without my Dad. As far as time-serting, it is not that difficult, a bit scary. The kit comes with everything you need to do it and it is pretty much follow the directions. It is a little scary drilling into the block and such but the kit made it relatively easy. It has guides to ensure that the drilling is perfectly straight and the right depth and whatnot. When I timesefted the engine, I didnt put enough oil on one of the inserts and it broke halfway through the process. This was quite scary and luckily enough my dad was able to drill it out again. As far as doing it with the engine in the car, now that would be difficult.

Chris

Christopher Petro

94 sts

67 coupe de Ville

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I am by no means a mechanic and could not have ever gotten the northstar out of my 94 sts without my Dad. As far as time-serting, it is not that difficult, a bit scary. The kit comes with everything you need to do it and it is pretty much follow the directions. It is a little scary drilling into the block and such but the kit made it relatively easy. It has guides to ensure that the drilling is perfectly straight and the right depth and whatnot. When I timesefted the engine, I didnt put enough oil on one of the inserts and it broke halfway through the process. This was quite scary and luckily enough my dad was able to drill it out again. As far as doing it with the engine in the car, now that would be difficult.

Chris

Exactly my point, taking the engine out is not so easy either. I am aware of how the time cert kit works but SEE, you are calling this easy and you broke a drill bit! :lol: Anyway you look at it, it's a hard job engine in or out of the car. Having done a handful of stardard head gaskets/valve jobs over the years including 500, 426 and 472 cu. in. caddies, I would be really reluctant to tackle that job.

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Has anyone seen crosshatch on an engine with high miles?

I´ve seen it on a Volvo B23K engine with about 200000 miles on it. But then again it only had 117 hp on 2.3 liters...

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Jhall and bbobinski,

I would be VERY careful about using anytype of RTV sealant on a oil distribution plate.

I used some on an aircraft engine several years ago and it pulled a piece loose and it found it's way into #6 rod bearing. I shortly had about $48,000.00 worth of JUNK aircarft engine. :(

It managed to by pass the oil filter (possibly on a cold start when the oil was thick.)

It caused the rod to sieze to the crank and break off. It then proceeded to beat the he!! out of the crankcase cam & other cylinders. As I was in the co-pilots seat when it happened, I have a vivid recollection of the events. (The other engine got us back on the ground with out bending anything else.) :D

But back to the N*. I don't know what the oil distribution plate costs, but I would have to think long and hard before I repaired it with RTV.

When I tore the aircraft engine down, I found the piece of RTV in the crankshaft oil passage. I fished it out with a wire. I kept it in a small jar with a price tag on it for several years as a reminder. By the way. I firmly believe that HiTemp RTV is the best sealant yet devised. And I like Guru only use a "skim" of RTV. Nothing looks worse than gobs of RTV sticking out from all joints. Not to mention the problems that develop when that stuff gets loose and blocks an oil passage. And I can vouch for the fact that it dosen't take much to cause trouble. The piece that caused the aircraft engine to fail was about the diameter of a pencil lead and about one inch long. Just enough to travel through the oil system until it got to a crank throw. It then coiled up & restricted the oil from getting out of the crank to the rod bearing. I wouldn't have believed it if I hadn't fished the stuff out of the crank myself.

Sorry for the long post. ;) I kind of get carried away when I get on this subject. For the price of a Northstar these days, :blink: I think that I would buy a distribution plate.

By the way, post those pictures when you can. I've got a 94 N* from my SLS on a stand. I've been thinking about going thru it. I pulled it for an oil leak between the lower & upper block. It is a good engine other than that. I just didn't like to see the darned oil on the garage floor.

Good Luck

Britt

Britt
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As Guru suggested I used a "Skim" coat of RTV on my oil manifold plate when I re-assemblied my motor. The motor has around 8K on it now and has had it's far share of beatings ;) with no problems to speak of... except a thermostat... but that's for a different post. If I had to do over again I would probably get another manifold. I know of one guy who didn't replace the manifold and it leaked in which case he had to pull it again to change it.

The motor I did still had the crosshatch as well, and BTW it doesn't burn any oil to speak of between oil changes via the OLM.

I replaced every gasket and seal rhat would be a bear to get at once the motor was reinstalled as well as the O2 sensors... especially the back one. And if I can make a suggetion... get a new thermostat if you haven't changed it already.

BTW in case you don't know... don't split any rods to look at the rod bearings.... if you do you will need to replace the bearing and the bolts. You can do it with the mains but not the rods.

Now that you have the motor that far apart isn't a thing of beauty inside?? The rod's look like carrillo's..... the oil drain backs from the heads are through drilled ports on the outside of the block to the are blow the crank and scraper reduce windage loss.

Having seen and built my fare share of endurance racing engines I was impressed.

Dennis
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Hi Guys,

Wow - thanks to everyone for the comments - very helpful and interesting. :) I'll send some pics for posting.

Bbobnsky- With regard to your comment about wear - I started to mic the bores this evening. I'm using an inside telescopic gauge and a micrometer. On my first pass with two cylinders, I'm getting 3.76 to 3.77 inch diameters on the bores.

Now the confusion - the Helms manual states a 3.66 inch diameter bore at the front of the book and then gives a 3.424 to 3.425 inch bore under "Cylinder Bore and Inspection". I am assuming the correct bore spec is supposed to be the 3.66 diameter, but now I question this number. If 3.66 is correct, it looks like the bores may be worn badly. I'll know for sure when I have time to go more slowly in the measuring process. I hope either the book goofed, or I read the micrometer wrong :blink:

Overall, I'd hate to find that the engine is worn this much. If it is, I'll be seeking new parts since I don't plan to remove it again. All new gaskets are planned. I'll probably replace the oil manifold frame / gasket if it won't drive the total repair over $2K. Beyond that, I think I can sell the car for parts and get that much for the body.....

About removing the engine:

I have prior experience with industrial air cooled engines - some of you may have heard of Wisconsin engines (made by Teledyne), as well as the much smaller Tecumseh and Briggs & Stratton. I worked at an engine distributor's shop which help put me through college. I learned quite a bit about making proper repairs. I do not have a great quantity of tools, but there's enough to keep the frustration to a minimum (I learned long ago to buy proper tools when they are needed!!).

This is my first N* teardown. We were forced to buy another car when the head gasket popped on the '97 Deville, but got lucky with a 2002 Deville from a local private owner (only 8,000 miles). Therefore, my wife has a 2002 Deville and MY car is now the '97 Deville - which is presently referred to as my "hobby" car. Funny how things work out like that........ : ;)

I removed the components and various items from the engine over a period of days, so I was not rushed. I also was lucky enough to have contacts for an engine hoist and a stand. I pulled the engine from the top with the transmission attached. This was a very close fit. I had to carefully lift a little and then bump the engine so it would clear the AC dryer, master brake cylinder and driver's side wheel well. Overall, it was not a bad experience. The toughest part was removing the exhaust pipe from the manifolds (did this first) since I had to get under the car and had limited room with the jack stands in place.

Most of all, the contributors from this forum were very helpful in helping me envision the removal process. Many thanks to all of you!!

I hope the engine pics I provide will help others. I'll be sendng them to jadcock for posting.

Best Regards,

Jeff

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I agree on the use of RTV sealants. When used in the proper amount, they do a great job. I saw these types of "gasketless" sealers in their initial use many years ago on - of all things - lawnmower engines. OMC used them on the crankcase halves of Lawnboy engines. It worked very well.

Sorry for my decimal error. It was supposed to be 0.010 inches as you correctly mentioned!! I feel a bit more at ease that I will not need to pull the pistons based on your comments. Thanks much.

BTW - I am already planning to reconfirm my micrometer reading skills. This would be an expensive error! Fortunately, I have calibation standards to check the micrometer, so my only problem is just as you stated - measuring tolerances- getting the values at the bore and then the variables in measuring the telescoping probe withthe micrometer. Anyway, it's a good refresher after being away from it for many years....

Maybe I can get out of this job for much less than I planned.... :D

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....."Your 97 has the teflon rear main seal that is identified by the inner "race" of the seal that is pressed onto the crank itself.  I would leave that seal alone and not touch it.  It will easily go 300K or more so if it is not leaking due to damage or something it is fine and does not need replacing." 

Bbobnski,

I noted a small amount of leakage at the rear seal when I pulled the engine. Closer inspection shows what appears to be some type of deposit on the inner seal ring that is mounted on the crankshaft. I'll take some pics before I try to clean it with some solvent.

I understand that there is an "improved" replacement rear seal design being sold. When replacing the seal, is the inner seal ring removed so the new seal rides on the shaft??

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jhall

another thing to look at while the engine is out of the car is the cover for the HVAC system on the fire wall. They are made of a pliable type plastic/rubber... most have deteriorated from the exhaust manifold heat over time. Mine wasn't in that bad of shape but I replaced it since the only way to do it is with the engine out of the car. The cost of it isn't bad especially if you are going to keep the car for awhile.

Mine has become a hobby type car as well. But they are great to drive on long trips... even lowered in the michigan snow, although the front lower valance tends to become a snow plow when the snow gets deep :huh: Drove it back from the Houghton in the UP in a snow storm about 3 weeks ago.... Had a daughter graduate from Michigan Tech... long drive.

Keep up the progress posts, some of us that have been there and done that can throw in some suggetions from time to time.... especially Guru... He was my answer guy when I ran into few problems and needed guidance. The motor I bought was a misfit... it had parts on it from a number of different years it seems, to the point it was becoming comical as to what I was find next. i.e. two piston in backwards.. arrows pointing to the rear.... that's how I know about the bearing rod bolt thing and pointed out by Guru.

Dennis
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jhall

another thing to look at while the engine is out of the car is the cover for the HVAC system on the fire wall. They are made of a pliable type plastic/rubber... most have deteriorated from the exhaust manifold heat over time. Mine wasn't in that bad of shape but I replaced it since the only way to do it is with the engine out of the car. The cost of it isn't bad especially if you are going to keep the car for awhile.

Mine has become a hobby type car as well. But they are great to drive on long trips... even lowered in the michigan snow, although the front lower valance tends to become a snow plow when the snow gets deep  :huh: Drove it back from the Houghton in the UP in a snow storm about 3 weeks ago.... Had a daughter graduate from Michigan Tech... long drive.

Keep up the progress posts, some of us that have been there and done that can throw in some suggetions from time to time.... especially Guru... He was my answer guy when I ran into few problems and needed guidance. The motor I bought was a misfit... it had parts on it from a number of different years it seems, to the point it was becoming comical as to what I was find next. i.e. two piston in backwards.. arrows pointing to the rear.... that's how I know about the bearing rod bolt thing and pointed out by Guru.

Bbobnyski - Thanks very much. I'll recheck the split line and shaft seal again. Your info has been great. I had a tiring couple of days and the comments you've provided have reminded me of the logical on the cross hatch and the cylinder wear issues. Thanks!!

Dloch - Thanks for the info on the HVAC cover. I'll check it. I planned on checking the heater hoses, etc anyway. I replaced the blower fan 2 years ago. Other items include new brakes, a check on the rack and pinion and a good look at the front bearings and drive shafts.

I sent some pics last night for posting on the forum. I'll check to see if they made it.

Interesting coincidence on the UP. I visited Houghton years ago in February with a good friend of mine. Did some snowshoeing and skiing at the local hill near the college (Rippley?) Pretty darn cold, but beautiful place.

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bbobynski, what is the time sert made of, I am surprised that it would break. I thought the drill bit broke when I read this above. I imagined that time-serts were made of case hardened steel, but looking at the photo on their site its pretty thin... By the way, I am amazed that locktite would be strong enough to back out a broken time-sert, great info! Thanks, Mike

http://www.timesert.com/

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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They are impressing little gadgets that they expand and lock in like that.. I did not know that about locktite.. Thanks

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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Yes, I did learn alot from the whole engine job. I learned that if I had attempted it myself than it would have taken me forever and I would have definately needed lots of help no matter what. I learned that taking a northstar out the top sucks because it is no fun to try and loosen all the correct cradle bolts underneath while dodging debris and not having great light(those new shop lights suck). I learned that it is alot easier coming out than going back in. haha. Additionally, upon taking the engine down the the block I realized that it is amazing that this engine can move at 6000 rpms or whatever and not break much sooner because it is amazing how much stuff is in there. The timing chains and tensioners really intimidated me, (my dad did the whole thing pretty much, i was his assistant). Upon messing with the actual insert itself, it definately didnt feel like metal, some sort of composite plastic material or something. Each insert was really light and the whole process as BBobynski described is pretty amazing. I have 3 pics that I have been meaning to post with the Old northstar out with the intake off. YOu should see the carbon, it is crazy how much carbon there was. THe other pics I have are of the engine bay with no engine. I will post them on this thread later tonite as I have to go to class right now. Additionally, the engine had 240,000 miles on it and was still running GREAT. The only problem was that is was eating coolant and any excessive RPMS caused overheating, but mechanically, if it wasnt for that darn headgasket, the engine was fine, I am curious to know how long it could have gone, It is still sitting in the garage. I will post the pics later. See ya guys.

CHris

Christopher Petro

94 sts

67 coupe de Ville

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look at all that carbon in the last one. it was a whole lot, 240000, the engine was running fine....

pic 3 with the empty bay, looking a little deserted...

post-3-1104954435.jpg

Christopher Petro

94 sts

67 coupe de Ville

user posted image

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Chris that's a hell of a job, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

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