Better Air Cleaner=Oil Leak??

[joed]

Using Dr. Lee's Swanger air cleaner as a model, I recently made my own taller air cleaner assembly. I added about 2" so it now holds two 3"x14" air filters, made a better snorkel for it and ran a 4" hose to it.

It now has great air flow and more power, but...it now leaks oil like a sieve, seemingly from the rear main. I've read about the rear main going after turbo kits are installed, but from just changing the air cleaner assembly?

I replaced the CDR with a new one, but to no avail - still leaks. If I install the stock assembly with its water trap/silencer, it has virtually no leak - just an occaisional drop as it was before the modfication. I've also ran both with and without the EGR/EPR hooked up - doesn't seem to affect the oil leak rate with the more free-flowing air cleaner installed.

Since the truck is an 82, it could still have the original rope rear main which I understand are somewhat fragile. I guess this is proof the stock air cleaner setup is restrictive (i.e., helps creates vacuum).

Could there be something else in the CDR system plumbing I'm overlooking? It's just kind of hard to believe a better air cleaner could create such an oil gusher.

Thanks. Joe.

[BobND]

If your's is like the last rope-seal 6.2 leaker I repaired, all you'll find in the seal groove is some odd threads and fibers.... 99% of the rope was GONE, yet it didn't leak TOO bad.

[john8662]

Noticed a similar thing too.

I'll agree that the stock air cleaner assembly is pretty restrictive. Especially the 82, which has to be the smallest inlet into the aircleaner of them all. Anyways, you're doing good getting more air into the engine.

Unfortunatly, the seal isn't up to the task. It is odd that you're getting more crankcase pressure, which better air flow in theory shouldn't allow. Unless blow-by has increased substantically. I have also noted in the past that the more restrictive the airfilter, the more blowby comes out of the filler tube. But, just the opposite (contradicting myself) when you completly remove the air cleaner and start the engine and then open the oil filler cap, you REALLY get blowby coming out.

I guess the end result is you're gonna want to update the rear main seal. Was it leaking some anyways prior to the air cleaner upgrade?

[joed]

John,

It really wasn't leaking much before, maybe a couple drops in a week's time if you didn't drive it... I still need to verify if that's what actually leaking.

As for blowby, I've kind of noticed it seems to be increasing with the better air cleaner as well - it didn't seem to emit much from the oil filler cap before the mod.

Would EGR flow or having the stock exhaust instead of a more free flowing exhaust have any effect?

Thanks.

[john8662]

The stock exhaust on these rigs ain't bad (the mufflers are the restriction).

The non EGR intake manifold will help a bunch regardless which aircleaner setup you have on the engine.

OH, I just noticed, we have the SAME truck, '82 1/2 ton shortbed 2WD trucks, cool! I'll bet mine's uglier though...

[joed]

Well, I put the stock air cleaner setup back on - same results as before, virtually stopped the leak and virtually no blow by from the oil filler neck. (With the better flowing air cleaner, I was getting steady puffs of smoke out the neck).

In the end I guess I'm going to have to bite the bullet and replace the rear main, but...

This gets me to thinking, could a CDR from a 6.5 turbo be used in place of the stock CDR to help hold more vacuum or would this make it worse? I'm wondering if the stock 6.2 CDR setup isn't set up for higher air flow. It seems like a 6.5 one could be retrofitted...

I'm already missing the extra power from the better air flow!

Thanks. Joe.

[john8662]

The CDR system on the 6.5 is mainly plumed the way it is because of the turbo. It's less likely to suck the crankcase dry of oil in the location it's at. The spring inside the CDR is also stronger to keep the turbo vacuum from being able to pull oil and crankcase gasses un-necessarily.