Head gasket blown in 3800 series II motor

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As I was driving home from advanced auto parts today the head gasket blew out on my 96 Pontiac Bonneville. I'm 90% sure it was that due to the smoke out of the exhaust plus the smell right before it blew. I was at AA to get a code checked out, it was "multiple cylinder misfire" if I remember correctly, which would probably make sense. Now to put this into perspective I'm a 17 year old that lives by himself with a good selection of tools, I'm pretty mechanically inclined but I don't have a lot of money and I know getting it repaired won't be cheap. So I would like to know how hard it is to replace the head gasket on these motors. Thanks.
 
I don't know if this info is valuable at all but about 20 min before the head gasket went out the heat was not working. Could that point to a bad thermostat also?
 
It's probably not the head gasket! These engines have a lower intake manifold gasket that will give way and flood the cylinders with engine coolant; in effect showing the same symptoms as a blown head gasket on other types of engines.

The new and improved AC Delco gaskets have strips of aluminium sandwiching the the bolt holes; thereby totally preventing another failure!

I'll be back with more info shortly.
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The heat probably wasn't working because there wasn't any more anti-freeze in the cooling system. Does this car have a temperature gauge? Did the car overheat at all? Usually overheating is what causes head gaskets to blow. Are there any coolant leaks anywhere? The 3.8 engine is generally very reliable and not prone to head gasket failure, but any engine will blow a head gasket if it gets hot enough.

If I were you I would buy a repair manual for your car, look at the procedure to remove the cylinder heads, and see if it's something that you would feel comfortable doing.
 
Quote:


The heat probably wasn't working because there wasn't any more anti-freeze in the cooling system. Does this car have a temperature gauge? Did the car overheat at all? Usually overheating is what causes head gaskets to blow. Are there any coolant leaks anywhere? The 3.8 engine is generally very reliable and not prone to head gasket failure, but any engine will blow a head gasket if it gets hot enough.

If I were you I would buy a repair manual for your car, look at the procedure to remove the cylinder heads, and see if it's something that you would feel comfortable doing.




The temp gauge was fine. But I don't know how accurate they are.
 
Quote:


It's probably not the head gasket! These engines have a lower intake manifold gasket that will give way and flood the cylinders with engine coolant; in effect showing the same symptoms as a blown head gasket on other types of engines.

The new and improved AC Delco gaskets have strips of aluminium sandwiching the the bolt holes; thereby totally preventing another failure!

I'll be back with more info shortly.
smile.gif





Thanks!
 
Wow thanks for the links man, I really appreciate it. It doesn't really seem like a tough job at all.
 
I'm a little confused here. What is the problem, the lower intake manifold or upper?

Thanks again.
 
It could be either one. The original factory upper intake manifold (UIM) had an EGR tube that runs through it. That EGR tube was designed too large in diameter originally, which resulted in the tube melting the plastic UIM. The new one from APN eliminates that problem.

The lower intake manifold (LIM) originally had its gaskets without the supporting aluminium strips, so it distorted from a combination of clamping force under the pressure of the bolts AND the deterioration from acids in the coolant.

So you're much better off doing them both at the same time. As far as I know, the dealer stocks the second design LIM gaskets, but not the second design UIM and UIM gaskets.
 
Some stuff to remember:

Drain the coolant from the radiator first before starting anything else; that's so you can avoid a mess when you go to pull off the throttle body. The throttle body has coolant passages flowing coolant from the UIM.

Make sure you replace the plastic coolant elbows and THIS IS IMPORTANT: apply silicone grease to the elbow o-rings before you install the elbows.

Apply Permatex 2B to the threads of the LIM bolts. I'll explain more later.

Make sure you have an accurate inch pound torque wrench! Snug the bolts by hand first. Make at least two passes with the first pass at half the final torque.

Parts List:

UIM kit with included gaskets (it might include the elbows)
LIM gaskets from a GM dealer (make sure they're reinforced)
Coolant elbows
Throttle body gasket
Silicone grease or dielectric grease
Permatex 2B
Distilled water and new Dexcool


I'll post more info as I think of it.
smile.gif
 
This might be a good time to ask: You do in fact have the normally aspirated 3800 Series II L36 VIN K and not the supercharged version correct?
grin.gif
 
You know what a torque sequence is right? You just follow the numbers in the order shown in the drawing. 11 ft.lbs = 132 in.lbs. So your first pass will be at about 30 in.lbs, then 60 in.lbs, and then the final 132 in.lbs

LIMTorque.jpg
 
89 in.lbs for the UIM, so I'm thinking 20 in.lbs for the first pass, 40 in.lbs for the second pass, and then 89 in.lbs for the final pass.
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UIMTorque.jpg
 
Do not plug the EGR valve in until the second day. This ensures that there is no air bubble left in the upper intake and you should not have a problem. Still a better solution would be to buy the stepped down EGR stovepipe available online. If you do not one of these two things you will likely have a burnt intake soon after.
 
T-Keith, the APN upper intake manifold in the link above already has the revised EGR tube and the steel bushing installed.
 
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