"Blowby"

[JohnQ]

Is this a bad idea to fix my "blowby" problem?

It seems to be working. :roll:

 

[87manche]

did you put a PCV valve in there john?

I was toying with that myself, as it would right the flow of the cv system, but I was worried that if I truly had cylinder blowby that it might cause too much crankcase pressure, and start popping seals and such.

 

What did that PCV valve come out of?

[HOrnbrod]

I did this CCV mod from MadXJ site (http://www.madxj.com/); '93 XJ to '00 XJ CCV Upgrade from the "Engine" section. It completely eliminated blowby on my old 91 HO engine. Not sure if it will work on the Renix engines, but it might.

[JohnQ]

did you put a PCV valve in there john?

I was toying with that myself, as it would right the flow of the cv system, but I was worried that if I truly had cylinder blowby that it might cause too much crankcase pressure, and start popping seals and such.

 

What did that PCV valve come out of?

 

I picked up the PCV valve from Oreilly's auto. I only have about 10 miles on her since I put it on, but so far no leaks and she's still running. :D

 

Would I be better off putting in a collection bottle like Pete's truck?

[mjcanoe]

Hopefully attaboybob got his problems resolved, but since this topic is still alive, here's some info. Back in 1991 oem TSB # 145191 which applied to 4.0L. mentioned replacing ccv w/ #4638360. The original problem w/ the "Renix" jjeep was that the metered orifice was the actual grommet that fit in the V/C, got soft, then plugged. Later 4.0 L. ccv changed that to a grommet in V/C & orifice(2.2mm) in the tube @ V/C end(white fitting) which is still available. There were a number of earlier 4.0 that due to above issue &/or lack of o/f changes did end up w/ "vent stacks" inside of V/C plug up solid w/sludge. These "stacks" are triangular & removable from V/C. When I was deling w/ a badly sludged motor, I would trim about 3/8" from bottom of "stack", kept it away from sludge. Not only does frt. vent allow air flow during running, but allows venting after key off. Hope this helps.

 

mjcanoe

[mjcanoe]

Sorry I forgot to mention that on later 4.0 that the brass fitting in I/M would also get resticted/plugged w/sludge. Use proper size drill bit & cleaner.

 

mjcanoe

[Pete M]

All I know is that if the gasses can't all go out the designated tube, they will find a new place to escape (usually the front "fresh air" tube). I've got so much blowby that the engine doesn't produce enough vacuum to suck it all out. :(

[mjcanoe]

Pete M, That's so true, considering the vent @ frt. is probably 3/8 to 7/16 th ID as opposed to 2.2mm @ccv. If you have high mileage, would be good to do comp./leakdown test. Snap-On also offered a blow-by dection tool, maybe someone in your local has one. It was simple & efficent to use.

 

mjcanoe

[Pete M]

Detection tool? :hmm: Interesting. Although I don't need one of those for my 88. :D You can see the puffs coming out of the hose. :mad:

[mjcanoe]

Pete M, Hey, I'm sorry, I've been a mechanic for 35 + years. I guess I like tools & get carried away @ times. They have always treated me well in return. But, like you said, some things are obvious, like a paisley print shirt. Take care,

 

mjcanoe