Chevy 3.1L V6 with oil sludge! Intk man. leak?

Messages
998
Location
Lexington, SC
I am driving a 1996 4 dr. Chev Lumina with the 3.1L V6 and only 70k miles. The markings on the engine say 3100 SFI. I had noticed it was loosing coolant and at times running a little warm. I would add coolant and it would be okay. Then I checked the oil and it was down 1/2 qt. so I added 1/2 qt, I notice on the filler cap a light brown sludge that looked like chocolate mayonase. I have read many with the GM 3.1 V6 have had a problem with the intake manifold warping and allowing water anf oil to mix causing sludge. Is that the correct statement of the problem with these V6's? I also understand that Dorman had a 'solution' to fix these engines. It was an imprvoed gasket kit, I believe. I bought the Haynes Repair manual for this year and have been reading it to see if I want to do this procedure. I have some questions: Do you need to first remove the alternator to remove the int mani.? Do you need to remove the UPPER int man. only or remove both the upper and lower intake man to correct the problem. Any tips on the problem and the best solution, please let me know. Haynes can be vague and even leave big gaps in the step by step.
 
Messages
22,188
Location
Colorado Springs
It's the lower intake manifold gaskets that leak on these engines. You need to strip the engine down to the cylinder heads essentially, as the cylinder heads to the lower intake manifold is the mating surface that needs the gaskets replaced at, so it's a pretty involved job. The Fel Pro Problem Solver gasket kit is what you want to fix this engine.
 
Last edited:
Messages
4,838
Location
Kansas
 Originally Posted By: Jim Spahr
I also understand that Dorman had a 'solution' to fix these engines. It was an imprvoed gasket kit, I believe.
Dorman had the new and improved intake manifolds for the 3800 engines. Fel-Pro has the cures for the 3.1 and 3.4 intake gasket problems.
 
Messages
379
Location
Mi
Dorman has the better kit over the Fel Pro kit,it comes with new bolts which GM says to use new bolts on the 3100 and 3400s.Plus it is more complete.I did hear Fel Pro was sueing Dorman over the copy of the design of the upgraded intake gasket.On the 3100 and 3400s,make sure you have the push rods in the right spot or the valves will bend if you don't.The pushrods are two differant lengths,long and short.
 
Messages
9,808
Location
New Jersey
I agree with the above post but i have to admit as some of you know i have an engine shop and all we do is rebuilds and to make a long story short one of my sons 96 oldsmobile with the 3.1 started the same thing at 94,000 miles in july of last year and we put bars stop leak in after changing the coolant to prestone green because we were too busy on customers cars to even think about his car and 11,220 miles later it still does not leak! and runs good as new...
 
Messages
6,987
Location
Michigan
If you have time, a place and a digital camera to take pics for later help putting it back together you can do it.
 
Messages
379
Location
Mi
I like the Dorman kit better,cheaper than Fel Pro.Go ask the dealership,GM says to use new bolts for the intake on the 3400s.
 

Jim Spahr

Thread starter
Messages
998
Location
Lexington, SC
When looking in the catalogs for the intake man. gasket set for my 96 Lumina 3.1, there are apparently two versions: one with roller rockers one without. How do you tell which one you have? Also do I have to remove the alternator to remove the intake manifolds?
 
Messages
4,838
Location
Kansas
 Originally Posted By: Jim Spahr
When looking in the catalogs for the intake man. gasket set for my 96 Lumina 3.1, there are apparently two versions: one with roller rockers one without. How do you tell which one you have?
You'll know for sure when you get the intake off. I've got a '98 3.1 that is waiting for me. I'll probably start on it this weekend.
 
Messages
11,185
Location
Bad Axe, MI
 Originally Posted By: wafrederick1
I like the Dorman kit better,cheaper than Fel Pro.Go ask the dealership,GM says to use new bolts for the intake on the 3400s.
GM just wants you do buy there new bolts,i've done many of these repairs now on the 3100 v6 and the 5700 5.7 v8 vortec, no new bolts are needed just clean the threads good use high temp loc tight and your good to go no looking back.... i paid $55 for my last set of felpro(ms9800t) for a 5.7, great gaskets.
 
Messages
464
Location
CT
The 3400 engine is similar and this website shows the stuff that has to be removed.... http://www.gaownersclub.com/forum/showthread.php?threadid=44742&highlight=LIM The only good news is you do not need to remove the fuel rail as described in this website. About $ 200.00 to do yourself. About $1400 to have a dealer do it. About $ 10.00 to just put in the leak seal stuff as crazyoildude suggests and keep driving for another 10k miles... But if you put in too much leak stuff and overfill the radiator, the rtv seal below the intake will blow out and form a nice large puddle.
 
Messages
4,209
Location
Central Arkansastan
Yes, you will need to remove the alternator. it is not a big deal. If you have never done one (intake gasket kit) before, and your somewhat mechanically inclined, plan on about 10-12 hours. If you have done them before, considerably less.
 
Messages
22,188
Location
Colorado Springs
 Originally Posted By: Tim H.
Yes, you will need to remove the alternator. it is not a big deal. If you have never done one (intake gasket kit) before, and your somewhat mechanically inclined, plan on about 10-12 hours. If you have done them before, considerably less.
And then, when you factor in Hofstadter's LAW, you're lookin at a minimum of 3 days.
 
Messages
4,209
Location
Central Arkansastan
 Originally Posted By: Drew99GT
And then, when you factor in Hofstadter's LAW, you're lookin at a minimum of 3 days.
Oh, how could I omit such a commonly known item: "Double that time and add 20 minutes!!"
 

Jim Spahr

Thread starter
Messages
998
Location
Lexington, SC
I just changed out the alternator on this FWD car recently. Even though it is deceptively sitting on the top of the engine, it is a pain to get to the brace bolts. On my RWD Chevy V8 is a 15 min job to remove the alt. I understand you need to remove and replace both upper and lower intake manifolds. The Fel Pro and the Dorman split the votes. I am going to tackle this job, so any other helpful hints, this Shadetree mechanic would appreciate them.
 
Top