the reason I took out the 2.8 in the first place was because the rear main seal was leaking so bad it ran out of oil on my brother and spun the #1 rod bearing. I rebuild the motor and made a few modifications.

I started the new motor for the first time today and it seemed to run ok but the rear main seal is leaking worse than ever now!

The previous owner was my grandmother, and my grandfather and uncle have worked on this car in the past. they told my brother that the rear main seal leaked a little (1qt per tank of gas) ok a lot!

Is there a part that a previous "mechanic" may have removed from the rear main seal area that is causing it to leak this bad? How does the rear main seal stay in the block? I just put it on the crank and tightened the main cap down on it, but what is to stop it from falling right out of the back? the flexplate is too far from the block to do that task, and I don;t see any holes where anything could be bolted or screwed in to keep the rear main seal in place.

 

It is as you mention, just pressed into place. The spring end goes toward the inside of the block, with the dust lip toward the back, or outside of the block.

The two other common areas for leaking is the cam rear cover and the distributor O-ring.

RBob.

 

yeah I'm pretty sure its the rear main seal and it popped out of the block and leaning on the flywheel. I put "the right stuff" gasket sealer on every thing but the RMS, so I'd bet thats the problem.

Thanks though

 

You can replace the rear main with the motor in the car, if so suspected. Take the oil pan off and use a small punch to push the upper half of the seal out....



Wait a minute, a 1988 rear main should be one piece, why would you need to use the cap to seat it?

 

With it popping back out I would look into something else being the issue. The FSM mentions oil on the inner surface and nothing else (such as sealer on the outer). The FSM even states to remove the old seal with a screwdriver. By carefully prying it out and not damaging the crank surface.

RBob.

 

I don't think I'll have to do much prying to get it out, so that will save me from messing up the crank... maybe I got some assembly lube on it?

My plan is to take the RMS out, clean everything, reinstall, and secure it by putting some permatex high-temp metal epoxy on the back of the block to ensure that it cannot back out anymore.

I guess I'll have to move the tranny back a few inches to get the flexplate off? Wouldn't it be sweet if all I had to do was unbolt the torque converter and push it into the tranny?

 

Are you putting it in backwards? You said you want to glue it to the block, not possible if its in the right way. When its on right, it should be flat with the block. Cupped end should be towards the engine. You should not be able to see the spring. The oil pressure goes into the seal, pushing the springed lip into the crank and seals it. More pressure, more sealing. I would not use glue. IMO. Just tap it in all the way.

 

I have the RMS installed in the correct direction. I pulled the flywheel cover today. I looked up at the RMS with a flashlight and it was not pushed out of the block as I suspected, and for the most part, was dry of oil. I'm leaning toward the "rear engine cover" as the problem. At least I hope that is the problem because I wouldn't know what else to do about the RMS. The only way to find out is to pull the tranny back and get in there. I do know that the oil is definitely coming out somewhere inside the bell housing.

I was just going to use the epoxy to make a "retainer" off the back of the block to keep the RMS from backing out in the future. I don't intend to get any epoxy on the crank itself, and very little if any on the RMS as well.

 

"rear engine cover"

what is that???

Try considering the intake manifold seal at the back, the cam seal, and the distributor.

My 2.8 would leak liek CRAZY, enough to dry the engine if you didnt refill, and it all came from the distributor O-ring which was all hard and old. When I put the 3.4 in, I didnt seat the dizzy right so I coudl time it and it leaked liek CRAZY. My mechanic said that there is no way in hell the O-ring could leak so much cause its in there and blocking the oil from coming up, but it did. Snug the dizzy down and that stopped the oil leak liek that.

I think bwecause there is a oil passage right near the tp of the distributo opening so if the O-ring is bad it leaks liek crazy.

 

I searched back there with a flashlight and a white lint-free cotton cloth (old tee-shirt)... its all clean and dry. the leak is from something in the bellhousing.

the rear engine cover is a plate that seals the rear-most cam journal on the back of the block... that would experience some oil pressure as well.

 

more then likley its the cam seal or on of the 2 oil galley plugs right aboce/nexto the cam seal.theres nothing else back there that could leak

 

If it was coming from the main seal you would see oil on the back of the flywheel like one of those spinny frisbee paint things.

 

It was the "rear engine cover." The cork gasket blew out, and was spraying oil all over the place. I'm going to eliminate the cork gasket and use "The Right Stuff Gasket Maker" which is the best stuff since sliced bread and JB weld.

 

Good deal! I've taken more than a couple 2.8's apart and found that gasket britle, but never broken. Glad it was something simple, now fix it!

 

Done. no more leaks anywhere that I can find. The next step is tuning and fabricating a tie bar to keep the throttle body coupler from blowing off!

this thing is really slow for a turbo 3.1L. We're only talking about 5-6 psi, but its a dog. I'm confident that the tune is so far off that it will pick up at least 30hp with a good dyno tune with a wideband sensor. When the motor gets broken in a little better, we'll crank the boost. I'd like to see a reliable 12-14psi.

 

Found other 3.1 turbos with a similar problem.. They had way to much base pressure from boost... If you have too much of that then the pressure has to go somewhere. Actually had mine leaking out top of the oil dipstick tube for a short period of time until I found a Vacuum Line that was a positive pressure line instead of neg pressure.. Glad to hear that you found your problem.

 

are you talking about blow-by? or did I neglect to do something with the vacuum lines? The only hose I changed was the breather hose that went from the pass side valve cover to the intake tube in front of the throttle body. I just have that vented to the atmosphere.

I tested the pcv valve and it totally seals shut when positive pressure is applied (1 psi or more). I think the IAC valve also ties in with the pcv valve on the back of the intake, but any boost in there just goes to the lower intake (not the crank case) right?

 

correct if its using a 2.8 tb/iac setup

as far as that coupler blowing off mount the bov on the intercooler to tb side of the charge pipes closer to the tb the better.

also swaping from an reg hose clamp to a t=bolt clamp will help. the best thing to do is weld 4 lil **** on the edge of the tb lip.

btw that t4 50 trim wont really come alive till around 10 psi possibly a bit more.but it will still make more power then the t3 u had on there even at low boost

 

^^ You changed turbos from the one you had on the origional 2.8?

 

I changed the compressor wheel and housing to a t04E 60 trim. I guess I need to make a way in the next month or so to get time on a dyno.

 

What we found was oil coming directly from the dipstick tube like a steady stream only where the engine rpm was above idle.

Initially we thought it was a PVC valve.. So we purchased a new one. Put it in the left valve cover and attached the line from the plenum assembly. Rev ed the engine and the problem was still there. So, I did a little experimenting. I removed the PVC and rev ed the engine and the problem stopped. I raised the RPM to around 5000 and there was no problems. I removed the PVC with engine running and checked for vacuum at that line where the PVC plugs into the plenum with had plenty.

As soon as I plugged the PVC back in and raised the rpm to around 1000+ the problem came back. Just out of dumb luck, I was looking at the left side of the engine and there was a line coming from the TB to the left valve cover to what appeared to be another PVC valve.. After taking it out of the left valve cover, It was just a plastic elbow. But, once that was taking out, The problem stopped again.

I checked for vacuum at that line. There was positive pressure, Not Negative pressure to help evacuate the pressure from the base.

I called a friend who is a tech from Garrett turbos. He simply explained it to me that once you use a turbo or S/C, all the air going into the engine is considered as positive pressure, as is all the air going through the throttle body, Your system no longer uses negative pressure from the engine to draw more air.

SOLUTION

We had to remove the line from the T/B and put a plug in the hole.

Problem solved.

 

I'm pretty sure thats the same as what I did, but instead of plugging the hole I just replaced the entire intake pipe. I checked the dipstick and all seemed fine. no oil leak, firmly seated.

I guess the low 8.5:1 compression hurts it pretty bad untill I crank the boost. I drove my older brother's '06 Cobalt (140hp) and noticed that it is considerably faster than this 3.1 turbo.

 

Finally got around to turning up the boost... its a noticable difference from 5psi to 7psi. thats how the car's been running for the past 5 months(7psi). The valve covers started leaking because I messed up the gasket installing them. While the mid and upper intakes were off to replace the gaskets, we installed some 37pph injectors, and I made the neccesary changes to the chip. We put 7 turns on the wastegate too. The power difference from 7psi to 15psi is very impressive. Even more impressive is that the stock MAF sensor seems to be reading that amount of airflow fairly accurately. Well into the 200g/s range. The stock tune is heavily modified at this point. I have a 165 ecm and V8 MAF tha I was going to put in place of the V6 stuff to handle the higher airflow, but that doesn;t seem neccesary just yet.

That all said... its still not very "fast"... maybe a high 14 1/4

 

High 14's on boosted iron heads is all anybody seems to get. From what I understand and read, professionally ported heads are still only going to get you in the low13's/high12's if lucky.

Boost is so much fun

 

Could possible be the rear cam seal. Or distributor o ring

 

Why not swap it in anyway and use the $32B mask? That's a neat little trick you mentioned in my other thread to get the stock maf up to 197 g/sec. How good is the resolution?

 

resolution... the off-idle tip-in has suffered a lot. My guess is that it's mostly due to the MAF sensor being so far upstream from the motor and low injector pulse widths, combined with a critical MAF signal. Small variations high or low can cause decent swings in the tune at idle, but seems fine everywhere else. the O2 sensor being pretty far from the motor doesn't help idle either. To take off fast just preload the motor a little with the brakes on.

The available $3A definition doesn't have any parameters for AE vs TPS... only load and CTS. I was told some time ago how to do a ROM dump to enable the programmer people to due a full ecm hack, but never really felt like figuring it out. it always seems easier to go $32b/$6E when ever I think about it.

 

What trick is that? I didn't see the other thread (can someone point me in that direction) but I'm trying to soak this maf stuff up. I'm not new to fuel injection, but I am new to proper tuning and maf all around.

So, you are turbo-ing a third gen V6 with a stock ecm and maf? Did I read that right?

 

the other thread is on the diy PROM board called "v6 owners check this out" (or some thing like that).

I am boosting an 88 v6 with stock 302 ecm and v6 MAF. The available parameters in the available definition ($3A) are far inferior to the $32B or $6E. However, if you plan on making enough power to make it worth the effort of fabrication and tuning... get something better. If I could start over, i'd swap a FWD top end and run some code $59 on 7730/7749 ecm.

 

Thanks much.