: Rebuilding Heads for 96 Eldorado



eldorado7
05-01-05, 12:10 AM
Need some serious help....rebuilding heads for a 96 Eldorado...N* engine....what parts do I need, torque specs, bolts tighting sequence, and diagram of engine breakdown....

JC316
05-01-05, 01:35 AM
You know, www.helminc.com (http://www.helminc.com) has the factory service manuals for pretty cheap. If you are doing something as drastic as a head rebuild, you really need that manual.

Spyder
05-01-05, 07:03 AM
Why are ya rebuilding them, just out of curiosity...havn't heard of anyone ever really needing to do that...they're awful solidly built and seem to last forever...

eldorado7
05-01-05, 01:01 PM
Thanks JC316 for the web site...I will check it out...Spyder...it appears that I have a blown head gasket and the upper intake plenum gasket is leaking...I want to rebuild the head vs buying a new engine...this engine had 130,000 miles on it...you're right they are built great...we seem to think that the previous owner ran it hot because 2 weeks after I bought it coolent was leaking and found out it had a cracked radiator...of course the dealer I purchased it from said there was nothing wrong with the car and now I'm finding out everything is wrong with the car....turned out to be an expensive nightmare

Spyder
05-01-05, 09:33 PM
Without actually seeing it or knowing more, I would bet that you can still use the heads, if you timesert the block and put new headgaskets and plenum gasket in it...may save you some money and a lot of hassle... ...

eldorado7
05-02-05, 08:51 AM
thanks Spyder...there is also white smoke coming out the tail pipes which also leads us to believe it's a blown head gasket....I'm hoping I can still use the heads...I'm ordering the service manuals today...if I really didn't like the car I wouldn't be going this far with it, plus I still have to make payments on it....really got taken and am not a happy camper....

eldorado7
05-02-05, 02:52 PM
can you put the timeserts in without taking the engine out?

mechanix
05-02-05, 06:25 PM
Timeserts cannot be installed with the engine in place...it HAS to come out.

With a history of overheating, the valves and seats should be checked while you have the heads off. This is often overlooked. In many cases there is no problem. But if the engine got hot enough, often enough, there can be some metal depositing between valve and seat, particularly on the exhaust valves because they run the hottest. Mine were in terrible shape, but cleaned up real nice and I didn't have to buy any new valves, knock wood. Doing a valve grind is critical on a N*, and the Helm manual should be followed very closely. They are difficult heads to rebuild - just letting you know what you're in for!

Ranger
05-02-05, 09:28 PM
I know of one guy on another board who HAS Timeserted his engine while in the car but by his own admission it was not easy. Easier than dropping the drivetrain? I don't know but the thought of doing that in a garage makes me cringe.

mechanix
05-02-05, 11:25 PM
It figures! *lol* As soon as I say it can't be done, someone will say they did it! *lol* I suppose if you had a right angle drill and were willing to fight that timing set up on the rear head it could be done, but I'm at a loss to understand why anyone would want to. It would take twice as long, you wouldn't be able to see what you are doing and it would be an inferior job than if you just pulled the engine out to begin with. And I agree Ranger, that's no job for the family garage! *lol*

BeelzeBob
05-03-05, 12:48 PM
I certainly would not take the heads apart unless there is some really compelling evidence of a problem there. The heads/valves/seats/seals will run for hundreds of thousands of miles with no problems and the heads just don't "warp" even in severe overheats. The engine is pretty well protected with the limp home "loss of coolant" feature that disables cylinders to allow the air pumped to cool the engine so the heads are rarely if ever damaged.

Just R&R the heads, replace the gaskets and timesert the head bolt holes for insurance and carry on.

mechanix
05-03-05, 03:01 PM
I guess it depends on your definition of warpage, Bbob. Both my heads showed .003" variation when checked with a precision straight edge. The Helm manual says that < .002" is allowable. Would they have held a gasket with three? Probably. But as critical as these head gaskets are, coupled with the amount of labor involved in changing them, I wanted everything as near-perfect as I could get it.

When my engine overheated, in never did "limp home!" It just kept right on running up to 270+ degrees before I could get to a safe place to shut it down. By that time my valves were fried! If you want to keep telling everyone that N* heads are indestructable go ahead, but that just isn't true. Sorry, but I think they should at least be checked while the engine is down in order to minimize future problems.

eldorado7
05-03-05, 05:15 PM
thanks everyone for the advise...an angled drill was being considered vs removing the engine, however, it wouldn't be easy and you'd have to be percise plus know what you're doing....I personally didn't run the car hot...I was only guessing if the previous owner did simply because it had a cracked radiator...I'm not positive if this actually happened....that's why I'm not absolutely sure...we're going by the upper intake plenum leaking and the smoke coming out the tailpipe which suggests that there is some seepage...to what extent we won't know until we take the heads off...I'm hoping for the best and I hope bbob you're right....still doing the timeserts alone is a bugger....I JUST WANT MY CADDY BACK

BeelzeBob
05-03-05, 06:48 PM
I guess it depends on your definition of warpage, Bbob. Both my heads showed .003" variation when checked with a precision straight edge. The Helm manual says that < .002" is allowable. Would they have held a gasket with three? Probably. But as critical as these head gaskets are, coupled with the amount of labor involved in changing them, I wanted everything as near-perfect as I could get it.

When my engine overheated, in never did "limp home!" It just kept right on running up to 270+ degrees before I could get to a safe place to shut it down. By that time my valves were fried! If you want to keep telling everyone that N* heads are indestructable go ahead, but that just isn't true. Sorry, but I think they should at least be checked while the engine is down in order to minimize future problems.


If it got to 270 it wasn't hot enough for the limp home mode. It would normally engage around 272-275 F. The system will go to 265 F before it boils if there is 50/50 coolant and a decent pressure cap on it so 270 is not out of line at all. It would certainly not damage an engine or warp the head. I have seen indicated temps much hotter than that in a limp home event with no cylinder head problems at all.

.003 flatness.... That is fine. The head gasket could care less. If your head was within .003 flatness you could put it together with NO head gasket and it would proably run....LOL.

Since the exhaust gas on the exhaust valves is around 1700 degrees F I don't think the valve care whether the valve seat is at 270 F or 220 F. That didn't "fry" your valves. I suspect the valves were fine. If they had deposits on them so what. They probably have deposits on them now if you were to look. Does it matter..??? NO.

I say that the heads are nearly indestructable because , from my experience and observations they are. Plain and simple. There is absolutely no case of anyone on this forum or any others having to rebuild heads or having trouble with them. I have seen cylinder heads run far harder and far hotter than anything described on here in the last 3 years and have never seen heads warp or cause any problems. If you wanted to touch up things to satisfy yourself, fine, but the heads were perfectly fine the way you described them and would have worked just as well if you had left them alone....

BeelzeBob
05-03-05, 06:55 PM
thanks everyone for the advise...an angled drill was being considered vs removing the engine, however, it wouldn't be easy and you'd have to be percise plus know what you're doing....I personally didn't run the car hot...I was only guessing if the previous owner did simply because it had a cracked radiator...I'm not positive if this actually happened....that's why I'm not absolutely sure...we're going by the upper intake plenum leaking and the smoke coming out the tailpipe which suggests that there is some seepage...to what extent we won't know until we take the heads off...I'm hoping for the best and I hope bbob you're right....still doing the timeserts alone is a bugger....I JUST WANT MY CADDY BACK



I still don't understand what you mean by the "upper intake plenum" leaking...where is that and what is leaking.

I would definitely do the combustion chamber pressure test to confirm that you have a head gasket problem before taking the engine apart. It is very easy to pressurize each chamber to see if the head gasket is leaking and see which cylinders are the problem. The pressure check is quick and painless compared to pulling the engine and you may learn something about the problem.

mechanix
05-03-05, 07:11 PM
Point taken, Bbob! What you are saying makes sense. My engine reached in excess of 270, but just how far I don't know. I was too busy trying to get it shut down and wasn't paying attention to the readout. At any rate I hadn't seen valves with "dark lumps" on the faces before, so I went ahead and refaced them. I feel better about it, if nothing else. I ran the compression prior to teardown. Think I'll run it again and see what I get now, just for giggles.

dkozloski
05-03-05, 07:32 PM
Look for the edges of valves to look like the deposits have been burned from one area with an acetylene torch. Look for pie shaped chunks to be broken from the exhaust valves. With this look for spark plug gaps to be mashed closed and the combustion chamber to be all dinged up. Look for radial cracks in the valves. In short look for areas of localized heating of the valve edges. If you don't see these things you're going to be fine. Turn the head over and see if there are any mushroomed valve stems. This would indicate a stuck valve. The chances of this are pretty slim. A burned valve is something that shows up like a horse turd in a cream jar.

zonie77
05-04-05, 01:56 AM
Not really an expert but I've done 2...both had been run pretty long with bad gaskets and overheated a lot. The heads were still in good condition and all we did was clean the surface.

You can check valve sealing by pouring light oil or kerosene in the port and see if any seeps out around the valve. We didn't bother as the edges of the valves looked good and the head was straight. No problems.

Caddy makes some of the best heads.