What should I watch out for when doing head gaskets? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 11-26-2006, 06:48 PM   #1
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Default What should I watch out for when doing head gaskets?

Ok,

I'm going to put my new heads on this week and am buying the "gasket kit" on Monday (head gaskets, valve cover gaskets, intake manifold gaskets etc). I know I'm going to have to watch out for breaking off the head bolts when taking off the exaust manifolds etc, but is there any other "common" things that break when pulling everything off down to the heads?

I know to be careful when pulling off the alternator
I know to drain the coolant and oil first
I know to make sure to use the torque specs and torque every bolt to spec

Should I be concerned about breaking anything else? I want to have the parts available should I need them.

Thanks!
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Old 11-26-2006, 06:49 PM   #2
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I should add, it'* a 1997 K code 3.8L (series II)
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Old 11-26-2006, 06:57 PM   #3
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First question is: Are you sure it is the head gaskets? They rarely fail on these cars. It is much more likely that the problem is bad Lower Intake Manifold (LIM) gaskets, or a failed Upper Intake Manifold (UIM). Unless you are absolutely certain that the head gaskets are the problem, please read this: http://www.bonnevilleclub.com/forum/...e=article&k=38

Coolant in the oil or in the cylinders, white smoke out the exhaust, hydrolock upon starting, loss of coolant with no external leaks observed, rough running, are symptoms of failed UIM/LIM gaskets.

A blown head gasket will often appear as an engine that overheats quickly as exhaust gas under pressure displaces coolant in the engine. Does the coolant in the overflow tank appear to boil when the car has been running for just a few minutes? Also white smoke from the exhaust and coolant in the oil are common head gasket symptoms, but head gasket failures on this engine are practically unknown.

In any case, the first thing to do is to drain the oil to remove any coolant that might be attacking your engine bearings. I would also drain the coolant completely by pulling the knock sensors, then flush an oil change of cheap oil through the engine by refilling it, pulling the plugs and circulating the oil by turning the engine over until oil pressure showed on the gauge, then draining. That might save your bearings.
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Old 11-26-2006, 07:01 PM   #4
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it'* not the head gaskets that were the issue (I just stated that I was doing the head gaskets so everyone know the general scope of what I have to do), it was #3 and #4 valves are shot (we did all of the compression tests, replaced everything from the coil to the plugs, to the wires and yes, it'* bad valves). Rather than screwing around I got a new set of heads. Sooo....since I'm pulling the heads I'm going to have to do the head gaskets
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Old 11-26-2006, 07:06 PM   #5
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awesome link.....I'll be checking the Upper while I'm tearing it apart to see if that was occurring as well. I have a spare upper intake maniflod in the trunk that I'll be using
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Old 11-26-2006, 07:20 PM   #6
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Okay, in that case....
Quote:
Originally Posted by bill buttermore
Copied from an earlier post:

This is how I do 'em:

Drain the coolant from the block by removing the knock sensor/* and/or drain plugs. If you don't do this, debris will fall into the coolant and end up in your radiator or heater core or coolant will end up all over everything when you try to blow everything clean with compressed air.

Buy a Super Scraper. ($20 gets you a fat wooden handle and a thick, sharp carbide edge that is guaranteed for life.) http://www.johnsonmfg.com/temp/j248-01.htm Keeping the blade edge flat on the sealing surface, scrape any gasket residue, rust, grease, RTV or other buildup away from the holes so as not to introduce debris into the cooling passages, oil passages, or bolt holes. Don't worry so much about debris falling into the cylinders, as it is pretty easy to wipe and blow them clean.

Buy a bottoming tap and run the bolt holes with it to remove any rust, debris, or rough places in the threads. [edit: better to buy a thread chaser of the proper size, a regular tap will change the thread profile in the block.]

Blow any debris out of the bolt holes, cooling passages and cylinders with compressed air at 90 psi. (Use eye protection!) A portable tank with a blow-off nozzle can be used for this if you don't have a compressor.

Degrease the sealing surfaces with a solvent that leaves little residue such as carburetor cleaner (laquer thinner) or brake cleaner (perchloroethylene).

Check the flatness of the deck and the head with a straight edge placed diagonally in an X-pattern across each. Try to slide a feeler gauge (check the spec) under the straight edge at several points along the edge. If you find a gap greater than spec, the part must be surfaced to ensure that it will not leak.

Make sure the dowel pins and holes are clean. (Dorman sells new ones if you have lost one or have one that is distorted.)

Use new head bolts. (Most new head bolts come with a dry wax or lube on the threads which reduces the torque required to stretch the bolt; these do not require any additional lube. If the bolts appear to be without any factory lube, lightly oil the threads. It won't hurt to add a bit of oil on the ends of pre-lubed bolts, but be careful not to use too much. You don't want excess oil squeezing out under the gasket surface.)

Make sure you have the right extensions on hand to turn each bolt smoothly through the required tightening angles without stopping. Six-point sockets are less likely to slip at high torques. If you are working on an engine stand, make sure the base is secure and sufficiently fixed or blocked to hold against the required tightening torques.

I have a Snap-On torque angle meter, but most of the time, I use it as a guide to give me a point of reference for where the torque wrench handle will end up after tightening the required 135 degrees (or whatever).

Remove the pushrods and rocker arms so that the compression of the valve springs does not affect the even-ness of the clamping force you are trying to achieve as you tighten the bolts. Keep track of each valvetrain component (rockers in an egg carton, rods through a folded piece of clean cardboard) so you can put them back where they were to minimize wear.

Be careful to observe any markings telling you "this side up" or 'this end to the front" on the gasket or in the instructions that come with the new gasket.

Make sure you understand the tightening sequence and tightening procedure before you start. Use a magic marker (silver or black) to number the bolt holes on the head. Put a drop of oil under each bolt head flange to keep the bolt from binding on the head as it is tightened.

If there are different bolt lengths, place all the bolts in the holes before tightening any to make sure you have the proper length bolts in the appropriate holes.

Keep the torque wrench at right angles to the bolt and apply the force on the center of the handle. If you are using a beam-type wrench, make sure the pointer does not drag top or bottom.

I count aloud each number and avoid distractions while doing a tightening sequence so as not to lose my place in the sequence. Don't answer the phone in the middle of tightening.
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Old 11-26-2006, 07:26 PM   #7
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This is a great opportunity for you to upgrade to the new aluminum frame LIM gaskets from the GM dealer. Also, consider installing a heat shield around the EGR stovepipe, either in the form of a sleeve installed into the upper or a shield adapted to the aluminum stovepipe that comes with the Dorman upper kit. If you bought an APN upper kit, you are good to go. A search of this site on shield, sleeve, UIM, stovepipe, etc. will provide you with much information.
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Old 11-26-2006, 10:22 PM   #8
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Off the top of my head...I wouldn't say to watch out for the exhaust bolts going into the heads. Usually they come out very well. The 3.8 has a sizable bolt and they don't tend to have issues.

Be careful and examine the EGR to lower intake manifold tube. They like to crack where the retainer holds it to the intake.
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Old 11-27-2006, 11:26 AM   #9
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If you don't already have some, buy some penetrating oil called PB (Power Blaster). It comes in a yellow can and sells for about $4 at O'Reillys or WalMart. Give those exhaust nuts and bolts a good squirt the day before, especially those on the crossover pipe between the front and rear exhaust manifold. You will be amazed how much easier they are to remove.
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Old 11-27-2006, 05:36 PM   #10
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thanks guys....

I actually just ordered new head bolts. I also called to confirm the intake gasket was the most revised version, should know tomorrow when it arrives. Total price on all the gaskets was around $350 CAD including the head bolts etc.

now off to the general chat to see if it will be worth selling the spare parts. Hopefully I'll be able to work on the car this weekend.
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