2002 Buick Lesabre 172k miles, 7700 mile OCI

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GM 3.8 L upper and lower intake gasket replacement

You can watch this guy do it with you in about 20 minutes for disassembly. I have personally done this more times than I can remember, for my own and friends and neighbors cars. Start by washing the engine gently from the top with Dawn dishwashing soap (or any gentle degreaser you are comfortable with) and idling it until dry, then vacuuming any debris remaining from the intake manifold. Remember, you are opening the engine internally, so you cannot be too clean.

I can save a LOT of time and trouble by using a battery syringe with a long pickup tube on it and patiently dipping and sucking coolant out the radiator cap: http://www.ebay.com/itm/Lubrimatic-Syringe-Battery-Filler-/281815440372?hash=item419d825bf4:g:e~IAAOSwgZ1XvQsv Twist it, work it down into the radiator until you have the bulb sitting on the radiator cap opening, go as deep into the radiator as you can to suck out fluid.

It seems tedious when you are sucking fluid out the radiator a few ounces at a time, then removing the upper radiator hose at the thermostat, jacking the car a little on the passenger side to get the engine to tilt and sucking all the antifreeze you can reach, and soaking up the last few drops with rags, but the payback is that I leave NO mess of antifreeze on the garage floor, vacuum and use clean rags carefully and meticulously to immediately "sponge up" any remaining liquid from the intake valley when you first lift the lower intake (and have clean rags immediately at hand). The payback is not only in no wasted antifreeze and a clean garage floor, but I have done this several times WITHOUT changing my $50 of synthetic oil and followed with UOA to verify results in a few thousand miles, no contamination in oil.

These GM 3.8L are wonderful engines, with ideal oil pressure and all steel timing chains and gears, but the intake gaskets are weak points that need to be addressed. Make sure you use the aluminum lower gaskets with neoprene liners; and don't forget to use aluminum coolant elbows rather than the OEM plastic trash: http://zzperformance.com/3800/gaskets-adhesives/intake-gasket.html Coolant elbows: http://zzperformance.com/3800/gaskets-adhesives/aluminum-coolant-elbows.html

I also work through the torquing sequence going 22-44-89 INCH PUONDS about 3 times; use motor oil and lubricate the injector O-rings really well, clean out the machined holes they go in with brake fluid and rags like a gun barrel, then re-assemble things just enough to start the car...Let it idle just enough to get to operating temperature, shut it down and re-torque your upper intake bolts to 90 inch pounds a couple more times.

Short of some old lady T boning your car and destroying it, there is no reason NOT to get another 175K out of this car.
 
Myself, I would dump the oil. In most cases it will have coolant contamination which is the reason you would change the lower manifold gasket in the first place. The oil analysis would buy your synthetic oil change.I'm not going to risk engine damage for the price of an oil change.
 
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Just throw some Bars leaks tabs in there and call it a day. Problem solved. Cheap at NAPA - GM sells the exact same tabs at GM parts depts for a lot more money. They work.
 
Originally Posted By: bigt61
Just throw some Bars leaks tabs in there and call it a day. Problem solved. Cheap at NAPA - GM sells the exact same tabs at GM parts depts for a lot more money. They work.



I've actually used these for a while mine were leaking, it will buy you time. Between oil analysis (Na & K) and you could see the coolant pool by the injectors. I finally developed a vacuum leak in the upper gasket (L67) and figured might as well replace it all. Job took me about 5.5 hours including clean up and it was my first time.
 
Originally Posted By: Lubener
Sodium could be from the oil but potassium is from coolant.Upper intake manifold could be leaking coolant because the EGR passage burned through and/or the plastic lower intake gasket is shot. . It's just begining and the coolant leak will get worse and do not put sealer in there. Replace both, the upper manifold with the ATP unit, coolant elbows and the lower gasket with the Felpro METAL gasket and you will won't have any further issues.This was a design problem from the begining.



Best advice in this thread.
 
Originally Posted By: jayg
Originally Posted By: Lubener
Sodium could be from the oil but potassium is from coolant.Upper intake manifold could be leaking coolant because the EGR passage burned through and/or the plastic lower intake gasket is shot. . It's just begining and the coolant leak will get worse and do not put sealer in there. Replace both, the upper manifold with the ATP unit, coolant elbows and the lower gasket with the Felpro METAL gasket and you will won't have any further issues.This was a design problem from the begining.



Best advice in this thread.


Agreed, this and similar advice is good.

I did not do the work myself, but I had a 2001 Grand Prix GT with the 3800 V6 and I had the original lower gaskets replaced with GM aluminum framed gaskets at around 80k miles. I did replace with an aftermarket upper intake with a steel sleeve for the EGR chimney, I don't recall what brand. I forgot to ask them to replace the elbows and they did fail on me 1-2 years later so make sure you replace them. At 200,000 miles it needed the lower gaskets done again. Perhaps the Felpro ones are better? Not sure. Great engine otherwise. It was still running and shifting great at 230,000 miles when I gave it away. Transmission needed a shift kit ($25? and I installed myself) around 120k miles but other than that was perfect. Dropped the pan and changed the filter every 30k miles.
 
Swap complete. Fel-pro gaskets, manifold and elbows ran about $145 shipped from Rockauto. Everything seems to be humming along fine. We're almost to 180k miles and this has been the first major issue.
 
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