Manifold gasket question: Mechanics!!

Question for you motorheads out there. Working on a 98 Buick Regal with a 3800 non supercharged motor. The low coolant light was staying on, during an internet search I learned that these motors have had MYRIADS of intake gasket problems. The car has 45k on it so I thought I'd go ahead and fix it straight away. Bought a Dorman upper intake repair kit and the new FelPro lower gaskets. Everything went fine, took me awhile since I don't do this everyday. When I opened the gasket set up, one of the end seals for the intake was missing. The car had been apart for two days, we needed it done. So I used blue silicone beads on the end seals. Everything was cleaned well and dry. During assembly the manifold was NOT moved at all. Torqued it in 3 steps in order, let it dry overnight. Finished job, car ran great, now it's leaking oil from the lower manifold on the drivers side. BUMMER! I have used silicone before on manifolds, actually it usually works better since factory end seals tend to slip out. Anybody have any suggestions on what might have gone wrong? I have checked some Buick forums, service info does not mention this happening. Plus a new gasket set is almost $75 too. Any suggestions? Thanks in advance. :sigh:

leaking oil as in drops or streams?
I have used black RTV, not sure of your brand of Blue RTV or if you laid beads that didn't adhere flat, leaving a little horizontal pass through that the oil is trickling through.
I have taken the bolts loose on my manifold half a turn to let it spring up, sprayed brake cleaner thoroughly into the end seal area, let it evaporate and then smeared generous amounts of black RTV since it is a non pressurized cavity other than blow by pressures from the crankcase.

This work was done on 60-80's big and small block Fords and Chevy's.

The red flag that went up for me reading your post was that antifreeze is a closed system, not to be consumed and when it is , it is by external leakage or being burned in the combustion chamber, either of those conditions is a head gasket not an intake gasket. So my question is, did the antifreeze stop leaking and why? Rhetorical, I don't need the response.
Russ

The way you've written your post, it sounds like you read about a common problem on your vehicle online, and then shoveled out the cash for the gasket and did a bit of work based on that alone? Without evidence of such a problem from YOUR vehicle, other than a low coolant light?

The first thing that comes to my mind with slow coolant leak is radiator cap and overflow bottle tubing, not intake manifold gaskets. I know the 3800 has problems there, but without direct evidence of a fault on MY vehicle, I'd go simplest/easiest/cheapest first, every single time. If you still have a coolant leak, I'd go get some UV dye, a black light, and do some diagnosings before throwing cash out again.

Did you crack open the radiator and make sure the car actually WAS low on coolant?

I've silicon'd the valley caps for intake manifolds lots of times too, works well. You have to make sure everything is CLEAN and use a LOT of silicone to fill the gap. If some didn't squish out all along the gap when you plunked down the intake then you didn't use enough. I don't like blue silicone so much, when I tear stuff apart later it's always turned to snot/goo if it's been in contact with oil or gasoline. Black, red, silver, or copper is what I keep around, I don't do thermostat housings often and that's all blue is good for.

The car was not leaking coolant. Oil was getting into the antifreeze and contaminating the sensor. I checked about 10 different websites and asked a couple garages around here. They all said the same thing, upper and usually lower intake gasket failure. The GM 3.1, 3.4 and 3.8 all have this issue. I saw many pictures of the upper intake removed and underneath was full of coolant. Many engines hydrolocked or had spun rod bearings because of antifreeze in the oil. Sure enough when I opened this one up the lower gaskets were almost ready to fail. So I believe I probably saved the engine from serious damage. I'm guessing I must not have used enough silicone, I thought I put a pretty thick bead on there, will check when I open it up again. GM has lawsuits filed against them, this has happened to thousands of cars, so I didn't wait. DB you mentioned direct evidence and I agree. However on many many of these cars people didn't find any evidence other than slow coolant loss. No visible leaks at all. Just a slow coolant loss, they would top it off and it was going into the oil. I was surprised myself. The upper manifold was warped around the throttle body but hadn't started leaking yet. I should have taken the gasket set back and gotten another one. I will also try black silicone next time.

Eek, oil in the coolant spells head gasket to me, not intake. You say yours wasn't loosing coolant, but the people on the websites DID have coolant loss? I've seen coolant in the oil from coolant passages in the intake leaking into the lifter valley, but never oil in the coolant from an intake gasket problem.

Good luck, I hope all goes well.

Just FYI, a used oil analysis(http://www.blackstone-labs.com) will show coolant in the oil without it being visible.

:buddies:

These engines whether they are 3.1, 3.4, or 3.8 are notorious for blowing intakes. They usually leak at the ends where you use rtv to seal it. The shop im at has done 10 of these jobs in the last 3 months. Normally oil in your water spells head gasket problems. I wouldnt use rtv on the gaskets at all, it usually compromises them. Just apply it at the ends, and the top where the valve cover meets. Ive seen the wrong gaskets on these, applied backwards, or over the pushrods even.

On the Buick/Pontiac forums I read they said an oily film gets on the sensor and keeps the low coolant light on. They also recommended removing the Dexcool coolant and using something else. So I used the "universal" coolant, and then I cleaned the sensor with brake cleaner and blew it out with air. No more low coolant light. But the oil leak started after about a week. Those lower gaskets could leak oil, AF, vacuum or all three. They really disintegrate bad, I've never seen anything like it.

I just replaced the lower manifold gasket on my 3100. If you were getting oil in antifreeze or antifreeze in oil, that is probably the problem. It sounds like you need to redo the repair and put more silicone (I used the black stuff) on the sides. That silicone should also extend slightly up under the metal gasket material.

While we are on the topic: did you get the revised torque specs for the bolts? Did you install the gasket properly - ie remove the pushrods and insert them in the guides, etc? Is there a possibility that there is an oil leak from something else?

Good luck getting this fixed. From what I have heard, if you replace the stock pos gasket with the upgraded Fel-Pro gasket, you should have a repair that lasts forever!

I didn't get any revised torque values, nothing in the gasket set at all. Buick lowers don't require pushrod removal. I torqued the lowers in three stages to about 10ft lbs and the uppers in three stages to 89 in lbs. Had to borrow a 1/4 in dr torque wrench. I looked at the 3100's too, that car is more involved than the Buick. Actually the hardest part of the Buick repair is cleaning everything up and fixing the plastic elbow that comes off the tensioner and goes into the intake. The stems that break off are buggers to get out without gouging the bore. http://www.automotiveforums.com/vbulletin/showthread.php?t=932171