GM Vehicle Leaking Intake Manifolds-Anyone? - READ ONLY

29 messages, Last post on Aug 08, 2002 at 8:53 AM

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#7 of 29 95 Silverado Pick Up by chuckm6 May 13, 2002 (10:22 am)
My wife drives a '95 Silverado, which she bought new with the 5 liter V8. She changes oil and filter at 3,500 miles. The truck now has 71,000 easy miles on it. One day she said the oil pressure gauge was doing funny things and then stabilized. I checked her oil and found it to be down almost two quarts in about 2,500 miles. There are no external leaks, and no smoking, even at start up. The tail pipe has no oil residue in it. After the last oil change I added a quart at 1,700 miles. I just changed the spark plugs and the PVC valve. There was a little oil on the air cleaner cover. The Dexcool (late 95 trucks) is past due to be changed, which I will do very soon.---Might this problem have something to do with the leaky intake manifold you described?
#8 of 29 98 silverado by wtd May 14, 2002 (2:17 pm)
I had the intake manifold gaskets replaced on my 98 ext-cab Z-71 with the 5.7L V-8 at 24,000 miles. Luckily the truck was still under warrenty. Mine was leaking at the front and rear of the engine. This is a widely know problem with the Vortec V-8 engines. The mechanic that worked on mine said that the intake was torqued down too tight from the factory, eventually causing the gaskets to crack and leak. This might be the reason the intakes on the above mentioned cars are also leaking. Wayne
#9 of 29 by jc1973 May 14, 2002 (10:11 pm)
well i have a 1994 sunbird with the 3.1 engine which was very poorly maintained for the first 80000 miles have a 150000 on it now and still havnt had a problem how can you actually tell when the gasket is going
#10 of 29 3.1 Repair by rs_petty May 17, 2002 (6:54 am)
The gasket is plastic with the seals imbedded to just seal the runners. Mine had cracked causing the leak. The symptom is coolant loss. My wrench said it cracked from the heating/cooling cycle and he'll probably see more - probably exacerbated with 2 different metals (aluminum and cast iron). Confirmed the same on the Vortec engine and the lack of chevy putting enough bolts on the manifold - said there were only about 2-3. The repair is very difficult (8 hour shop time). Intake disassembled, fuel rails/injectors removed, rocker arms and pushrods removed, engine tilted forward, and then all put back together. The stinker is that GM part was all that was available - no better aftermarket design. Stupid GM engineers - my last chevy.
#11 of 29 by alcan May 17, 2002 (10:44 am)
Here's the book time for V6 Sunbird intake manifold replacement: 1984-2000 Models Sunbird Four... 3.9 hrs V6.... 5.4 hrs Includes: R&I plenum, runners, fuel rail, and injectors
#12 of 29 '99 Venture by davy1 May 20, 2002 (12:56 pm)
Intake manifold leak at 59k. Kicker is that the dealer says manifold gasket is back-ordered with no anticipated delivery date. Mentioned he has 2 others on the lot also needing the same repair. Same problem killed my 84 S-10 2.8Litre 4WD when it had 104k.
#13 of 29 '96 GMC Sierra by mcpdjohn May 20, 2002 (1:59 pm)
I just recently had that problem with my '96 Sierra 5.7 liter Vortec. I had 79K on the truck, but the coolant change interval is "100K miles or 5 years, whichever occurs first". I was two years beyond the time limit, and I believe my Dexcool went acidic as a result, costing me a new gasket. I did the job with a friend. It was a big job (IMHO). We had to pull the distributor too. I wouldn't recommend this job to just anyone. You need to be pretty competent under the hood to get this one done. I bought a Fel-Pro gasket set from Auto Zone and it worked fine. My lesson learned is, change coolant in accordance with the maintenance schedule. I don't blame this one on GMC. I blame myself.
#14 of 29 mcpdjohn by wtd May 28, 2002 (7:56 pm)
I doubt it was caused by your antifreeze even though it was in longer than it called for. The intake leak is a well documented problem for this engine and is caused by inproperly torqued intake bolts. I've read many topics and information on this where this leak occured at your milage or less. Mine leaked at 24,000 miles and 3 years on the coolant. I personally blame GM as it was a mistake on their part.
#15 of 29 1992 Corvette by corlt1 Jun 01, 2002 (3:28 pm)
My 92 LT1 Corvette with the 5.7L (350) V8 has had the intake manifold removed and replaced twice by the dealer. Each time the fix lasted about 3 years. It's leaking again, but alas, it's now my weekend only car that sits in the garage most of the time. Mine appears to leak only oil. Chevy uses a gasket only where the intake and water ports meet the head. They use RTV silicon sealer at the back and front of the manilfold and this is my problem. I wish someone made a gasket with the manifold end seals, like the older Chevys.
#16 of 29 '99 Tahoe intake manifold coolant leak by msm4 Jun 02, 2002 (4:59 pm)
I just had my 1999 Tahoe intake manifold coolant leak repaired. It has 44,000 miles on it. The dealer where I purchased it quoted over $500 for the repair. I complained that this was a known problem and should be covered by an extended warrantee. They would not pay for the entire repair but they did split the bill 50 50. The repair cost me $275. So, complain to the dealer and GM and hopefully you'll get a brake on the repair cost. Then complain to the FTC. Enough complaints and maybe GM will be forced to cover this repair.