Last minute sanity check about my rear main.

[Gokou]

I need advice quickly, as I'm probably going to dive into this job early tomorrow afternoon.

I thought the rear main on my TTA was bad (after parking my car in the driveway for literally 5 minutes, it will leave a 6" puddle of oil)

Symptoms:
Oil streaks on tranny pan
Drips from inspection cover
Starter is soaked
Crossover pipe is soaked after parking for a bit

However, tonight I started to prep the car... I yanked the crossover pipe, inspection cover, and starter. What I found shocked me... the flexplate and converter were BONE DRY. Not even the smallest hint of oil residue on them! I expected a bad rear main to SOAK the flexplate. Anyone had this experience?

I'm now thinking I might have a leaky oil pan gasket and that my rear main might be good. It's really hard to tell if the main is bad or not.

I could snake a new pan gasket in there without jacking the motor up, but I'm thinking while I'm there now is the time to change my original rear main (leaking or not) to a 2-piece Fel-Pro neoprene seal.

I have a couple questions about RTV usage on the seal itself-- Do you lightly coat the groove in the seal which slides over the groove in the cap and block (basically, RTV the main to the block and cap)? Do you put a light film of RTV where the 2 parts of the seals contact each other?

I do plan on clocking the seals a bit so they don't match with the cap/block seam.

Wish me luck... getting the pan off my F-body doesn't look fun. Guess I should have bought a GN

 

[John Larkin]

Look really well all over your engine. Back of intake under coil pack and top of trans as much as you can see. Turbo drain back line. Lower front cover. Jack the car up and lay on the ground, looking for trails coming down the side of the block. Look at the lower edges of the valve covers.

I just changed valve cover gaskets and my leak stopped. All the oil that was leaking ended up on the flywheel dust shield just like you are seeing. And I was leaving about the same size puddle. For $12 bucks and an hour's worth of time, it wouldn't be much of a waste and the cheapo parts place had Felpros in stock. I'd try tightening the oil pan once more, cleaning everything possible with starting fluid (cold engine and let it dissipate for a half hour afterward; starting fluid is the best and quickest degreaser ever and WalMart has $0.88 cans of the stuff, just don't breathe it). Then test it one last time.

 

[KWIKR 1]

Check the intake seal in the corners . I had a bad leak on mine and it drove me nuts trying to find it . I even used a GM tracer dye . It did end up being the intake . I had the same oil spots as you , eg: starter , crossover . I even found oil on the frost plugs on the side of the engine . Oil dripping was not bad when the car is running . It was only after it was shut down that it really leaked. Good luck !

 

[tim87tr]

KWIKR 1, can you explain more where the intake leak is and what you did to fix it? I have the exact leaks on my car after replacing the rear main, valve and oil pan gaskets. And it leaks most after the car is shut down like you describe. Thanks, Tim

 

[turbo buicks]

when i dropped the oil pan in my car the rear main was fine (even had a neoprene one it in) but the pan gasket was crap. replaced both but the gasket it what fixed it i believe. i used a rubber felpro oil pan gasket. i looked under there yesterday and i can see the rubber peeling off in some places. are these rubber gaskets crap or not?

 

[KWIKR 1]

Mine leaked in both back corners of the intake where it mates with the block . Is there oil "on top" of the starter and then drips off of the two starter bolts ? Or dripping from the frost plug boses ? Because the starter and frost plugs are "above" the oil pan gasket .

I do not think your supposed to 'lightly RTV coat the grove in the seal which slides over the grove in the cap and block' . This may cause the seal lip to adhere to the cap and not postion itself correctly on the crank.

 

[Gokou]

My starter is SOAKED, even the front of it, so I'm starting to doubt I have a rear main leak. How does oil walk upwards and forwards? I'll try my best to look at the intake manifold, but it's hard to get back there on my TTA to look.

The valvecovers and heads are dry, so I think my valve cover gaskets are ok.

I can see oil on top of the block in the rear under that little "window" at the top rear where the tranny bolts to the block... maybe my rear main is OK and my intake is leaking.

When I got the car, the turbo drain leaked like a sieve, but it's 100% dry now that I have a braided replacement on.

I'll do more investigating before I start jacking the motor up and dropping the pan.

 

[KWIKR 1]

Here's something that might work . Pack some paper towels in both corners where the manifold mates with the block . Take the car for decent ride . Then shut it down for a few mins and pull the paper towels out and look for any sign of oil . . Also check oil adapter O ring and pump area , including the turbo oil feed line .

 

[Gokou]

I found out a couple of my oil pan bolts near the back were loose, so before I go yanking the pan, I'm going to put the crossover pipe and starter back on (but leave the inspection cover off so I can see), start and run the car, and see if I can find the source. I'm just not convinced it's the rear main!

I'll also do the paper towel at the intake trick. I got an inspection mirror back there and it looks dry, but you never know....

If it helps, the driver's side of the block and panrail is dry, but the driver's side is wet (inspection cover, starter, etc).

My turbo oil drain no longer leaks, but maybe I have a front cover/adapter leak that is walking back along the pan rail.

This is a really frustrating project...

 

[KWIKR 1]

I know how you feel . I spend a whole week banging my head against a wall and laying under the car looking for my leak on a new rebuild . The last thing I wanted was having to pull the intake off . Mine as well looked dry . the give a way has when I ran my finger along the backside of the intake and the RTV that I used to seal the intake felt slippery . I had check everything else, even replacing the valve cover gaskets . Good luck , you'll find it !!!!

 

[tim87tr]

KWIK, yes, the oil is on top of the starter so it must be the back of the intake. Thanks, I will look at that first thing when I get home this weekend. And there is no oil from the valve cover gaskets, I just replaced them. I guess you have to put on a new intake gasket to properly fix this leak ?

 

[Gokou]

What a PITA. I cleaned up the bottom of the motor as best as I could, retorqued all the oil pan bolts, then put the starter and crossover pipe back on and ran it. I ran it for about 10 minutes with the nose jacked up (to slosh oil towards the rear) and another 10 minutes on the ground. NO LEAKS. Argh!

So, now I have to clean up and go for a drive... I'm guessing the leak only shows up when oil is sloshed towards the back of the motor under acceleration. I left the inspection cover off so I can see the rear main by laying on the ground.

As far as an intake leak goes... I found a tiny film of oil back there, but the back of the block, heads, and the top of the tranny is bone dry, so I don't think I have an intake leak. When I had a intake leak on my Chevelle the top of the tranny was soaked.

Hopefully just tightening my oil pan fixed it, but I know from past experience I'm NEVER that lucky. I'm guessing I'll bring it back from the drive and everything will be soaked again.

 

[KWIKR 1]

Well you need new rubber end seals or use RTV . And seeing that the intake has to come off the intake gasket will have to be replaced as well . tim87tr , I can not understand, did you not have a oil leak problem untill you replaced the main seal , valve cover gasket , oil pan gasket . Why would your intake all of a sudden start leaking ? Or were you orig chasing a leak in the first place ?

When my intake was leaking I had oil dripping from the lower front corner of the PS head . It throws you off because you ask your self "where the hell is this oil coming from". The last thing you figure is that it's from the rear of the intake . But it was .

 

[tim87tr]

KWIKR 1, I had leaks before the gasket replacements. I am pretty sure the rear main was leaking anyway since the oil traveled all the way back to the rear bumper . At least I learned how to do that job for the next time it leaks. I will check the intake, it should be one of the last places I could have a leak. I even found the oil pressure guage sending unit attachment to be loose and leaking oil there.

And just what you said, I could not figure out where else the oil was coming from, especially being on the starter. I'm sure it is the area you describe on the back of the passenger head/intake. I am just learning about the cars but have done most all of the work, and did not realize that was a leak area.

 

[Gokou]

I love how things work... I put the car all back together to drive it, only to find out that it really IS the rear main. I came home after driving, and voila, soaked starter and crossover pipe. I stuffed a rag at the back of the manifold, and it came out spotless. Drat! So, I put the car on the lift and watched as someone rev'd it up, and once the motor was over 3000rpm, off the back of the pan rail came a steady "drip-drip-drip" of oil, some of which landed right on the crossover pipe, and the others hit the ring gear and slung a nice stripe of oil on my t-shirt

I couldn't tell if it was from the rear of the pan gasket or from the main and then dripping down, but either way since I have to pull the pan the main is getting changed anyways.

What sealant should I use on the top of the cap/block interface? RTV wouldn't work there because air can't get there, so I'd need an anerobic sealant. Suggestion?

Now, to fill the sides of the cap with RTV only, or use RTV and the side seals... I get recommendations both ways. I can't make up my mind!

Tomorrow morning, work will resume... hopefully I can finish it up tomorrow, get the car back on the ground and give the RTV a few days to cure.

 

[KWIKR 1]

Gokou , check out

www.gnttype.org/techarea/engine/rearmain.html .

 

[rc1626]

I just recently did mine. I used Permatex anerobic sealent on the cap to block mating surface and the side seals that came in the Felpro kit and not a drip. Make sure you use an anerobic sealant. It will save you headaches later on. The first time I did the seal I used rtv and it leaked. I pulled the cap a week later to redo and the rtv was still not dry through out.

 

[Gokou]

rc1626-- did you put the side seals in without any sealant, or did you smear RTV or the anerobic sealant on them before sliding them in?

It's really hard to tell on the instructions for the side seals, but does the little wire/pin/nail slide into the groove in the seal?

Thanks again...

 

[rc1626]

Gokou,
All I did was lubricate each side seal with oil, slid them in and drove the pin in. One pin per side. My kit came with four, only use two. The pin goes in on the inside of the seal pushing the seal against the block. Along with putting anerobic sealant on the cap to block mating surface I also put some on both sides of the cap next to where the seal goes but not on the seal itself. Don't forget that when you put your rear main seal in to offset it about a 1/4 inch on the block side and cap side so that the seams of the seal don't line up directly with the seam made by the cap and block. Also instead of lubricating the seal with oil I lubricated it with high temp. grease. Doubt that would have any profound diff. but just thought I'd add it in. Hope this helps.
Rob

 

[rc1626]

Oh Yea, one other thing. If you haven't gotten the anerobic sealant yet, don't fall over when you see how much it is. I paid $15 for a small tube.