Alright guys, I've had 2 runs on the motor since I rebuilt it and now 2 blown rear seals. I think it's related to the mustang valve covers I have on it. They are solid one one side and the other has the breather. Is there something special I need to run to get the Mustang valve covers to work?

I would have posted this on the ford site but I know a lot of you guys are running these motors in your Heeps and such so :flipoff2:.

Thanks.

-Jack

Do you have a PCV valve in the rig?
Or, a "Pan Evac" system?
At higher revs you need some way of reducing pressure in the crankcase or seals MAY (not will) blow.
Chev engines will loose the intake seal in this senario...

This might be the reason...

Cory

There's a PCV valve in the back of the lower intake. It has 3 lines going off of it. One is to the upper intake (which provides it vacuum), the other is to the power brake booster and the last is to the fuel pressure regulator.

The oil neck on the valve cover has a stem coming off of it which I ran to the air intake tube. I'll check all of the above lines tomorrow again and make sure they are on there and take the one from the oil neck off and see how that works.

Getting tired of changing this damned thing out!!!! Thanks.

-Jack

Not trying to offend you, are you putting the seal in the right way? This happens, I got a rebuilt 390 once with the seal in backwards.

Does the seal have a small spring around the inside edge?

If so, try packing it with grease to hold the spring in place when installing.

Rich

No spring. The seal is one of those 2 piece jobs. In fact when I removed the other one it looked fine. No grooves or anything.

And I'm sure that I didn't put it in backwards. I drove it around quite a bit but it wasn't until I took it on a couple of hour drive that it started leaking. I think the crank pressure just gradually rose on it and caused the leak. Any chance that the seal is still okay and I just need to fix my problem? Or is it that once it starts leadking its bad.

Thanks all for the information.

-Jack

Does it leak with the motor not running?? If not, then the seal is prolly OK. Sounds to me like you´ve got somthing plugged and pressure´s building up inside the engine.

Might sound silly and simple, but try driving around a bit with the oil filler cap loose and/or the dipstick removed. You should then find out if it´s pressure build-up...

Never had to try this myself, but it would seem to work. Let us know...

:beer: :beer:

Originally posted by IronBenderII
There's a PCV valve in the back of the lower intake. It has 3 lines going off of it. One is to the upper intake (which provides it vacuum), the other is to the power brake booster and the last is to the fuel pressure regulator.



-Jack

Your PCV needs it own vaccum, I am sure it does not have any, the boster is robbing it all
Find a different post on the mainfold for the PCV only

Originally posted by welndmn


Your PCV needs it own vaccum, I am sure it does not have any, the boster is robbing it all
Find a different post on the mainfold for the PCV only

I agree... I think you've got the PCV hooked up in the wrong spot. On a carbed motor, the PCV typically goes in the base of the carb, but since you've done a SEFI conversion I can't tell you where is should be.

The idea is to burn the crank case gasses by sucking them out one valve cover, in turn pulling clean air in the other valve cover...... so if you were to remove the filter from the clean air valve cover and a place a piece of paper or plastic bag over the opening, there should be a slight vacuum. If it blows the paper away, then you may have excessive crank case pressure.

I'm not familiar with how the SEFI PCV systems are routed. But I think it's the source of your problem.

I guess it's also possible your rings didn't seat, or haven't seated and you are getting excessive blow-by

Thanks for all of the great information guys, I'm stuck in Chico and appreciate your help!!!!

I checked and there are seperate lines running to the PCV and the fuel pressure regulator/power brakes.

It doesn't leak when not running. I just started it up and ran it for a bit and gave it a few RPM's and it had a few drops come out, but I thin that was just left over from when it was draining and shook loose with the flywheel moving.

I'll try taking the dipstick out and see how that works.

If anybody has any more ideas, let 'em flow!!!!!!

-Jack

Check compression in all cylinders. My kid rebuilt his 5.0 and had a problem with one piston. Between him and his buddy, somehow they managed to leave some of the rings off so he was getting so much blow-by, it would blow the pcv valve out when power was applied and blow oil all over the place. If he had checked compression, it would have been obvious there was a problem with that one cylinder. :rolleyes: But No, dumbass kept driving it till it finally blew up and broke the crank in half. :eek: Next time, he had someone else build his motor. :D:D:D

:flipoff2:

All right damn it, now I'm pissed...

I started it up many times in the driveway after it sat for a day and no leak. I reved it in the driveway. No leak. I head home from Chico today and stop after an hour of freeway driving. No leak. I stop again about 20 miles out of Sacramento, leak.

I ran with no dip stick and took the like off of the oil filler neck off. WTF??????

Are you 100% sure it's coming from the main?? When I first put in my tranny I got a bad "rear main" leak, and after the third seal I discovered it was coming out the front of the tranny. Ya, I'm kinda slow!

Sorry I never got back to you last week about helping replace the seal, It was that or take my wife to the ER for emegency gallbladder romoval. :( :(

Well, it's certainly motor oil, not gear oil. And it is coming from the inside of the bellhousing. This really has me puzzled.

So to recap, I have the mustang valve covers. The PCV valve in the rear is running to a main line on the bottom of the upper plenum. The line on the oil neck was going to the air intake hose, which didn't work. So I left it open, which didn't work. I also tried running without a dipstick and that didn't work. It takes over an hour of freeway speeds to start leaking.

I give up!

Hmm,
The line off the filler hose, is the breather, Take the valve cover off and clean that hole with some carb clean, it could be plugged.
also just replace your PCV, it could be plugged as well, don't clean the PCV, just replace it.
Also that breather, just put a little K&N thing on it, it needs something.

DO you have an good oil PSI gauge? what do you run at?

How fast can you change a rear seal? mine drips a little, and i don't want to fix it :D

The rear seal was easy. I run a 5 1/2" lift so that helped. I had to take the tie rod (which brought with it the drag link) off of the passenger side knuckle and then I could slide my oil pan out (tight fit).

Took off the bearin cap, used a screw driver/pliers to get the top 1/2 of the seal out (it's a 2 piece). Put the new one it and put it back together. I have air tools which helps with all the damned oil pan bolts. Probably a 45 minute job all together.

I'll change out the PCV valve and make sure the breather isn't clogged. You'd think that running without the dip stick would relieve any pressure in there. Guess not...

It might make a differance, but i dought it.

Wanna change mine? i have the one peice seal :(
It would be something new and fun for you :D
LOL, mine will just leak until i smoke my clutch

That's an awful tempting offer there Mark but I think I'll have to pass. As soon as you got to the part about having to drop the tranny and such you lost me. Or my support anyway. Oil is to cheap to go through that much work!

Keep the help coming guys, I need it!!!!!!

-Jack

PCV valve backwards? Pull the vac hose and suck on it - can you get some flow?

It has a different connector on each side. I gave it a suck and got some oil. Doesn't taste very good... I'm gonna replace it for shits and giggles anyways.

-Jack

Here's my two cents. Maybe you need to suck it a little harder!:rainbow: You think anyone was gonna leave that alone?
JC

man, always bustin my balls...

:flipoff2: