155K on ZJ and using oil=plenum gasket???

allenjp · 01-16-2009, 10:27 AM

OK so I have a '96 ZJ and it is using some oil.

It does have a small leak but not real significant I think it is burning some because I don't think it is leaking all the oil it is losing.

It has 155K on it, and the PO kept unbelieveably detailed records on the maintenance and reapirs he had done to it (the maintenance he did to it puts me to shame). I can't see anything saying that the intake plenum gasket was ever replaced.

I've read plenty about the plenum gasket issue in the numerous threads. It pings just a little when under a load, nothing I would normally worry about. Whaddya guys think? Should I gasket it or not???

wsar10 · 01-16-2009, 11:11 AM

don't know much about P. gaskets but my previous ZJ (94 ltd 5.2l) used and burned oil for well over 20,000 miles and it never concerned me and never cuased me a problem, I just kept an eye on the oil level, it was @ 145,000 mi on the clock and the new owner is a college kid that drives in start stop traffic every day and the ZJ still runs strong. I only sold it cuz i got a great deal on my current ZJ.

allenjp · 01-16-2009, 04:25 PM

Anyone got an opinion?

ddeadserious · 01-16-2009, 04:46 PM

Sounds like a plenum gasket. I haven't found any real good writeups on how to do it though.

Mine leaks a decent amount of oil, and I'm assuming it's burning it as well, since it went down a quart and half in a matter of 20 days.

Will fix all the seals and gaskets when A. I get money to have a shop do it, or B. when it gets warmer out.

allenjp · 01-16-2009, 06:06 PM

I have plenty warm weather so I guess I'm fresh out of excuses...I'll need to spend the weekend workin' on it...

But, please tell me...does anyone else agree with that assessment? Should I do the plenum gasket or just not worry about it???

Does anyone else think the plenum gasket is bad?

BigDaveZJ · 01-16-2009, 08:09 PM

Have a look down the throttle body and see for yourself. Clean = good. Dirty = bad.

There's plenty of writeups out there for the plenum gasket too. I used the factory service manual when we did it on our 98 though. The 95 doesn't quite need it yet.

zjay · 01-16-2009, 08:17 PM

To check for a leak at the gasket- disconnect the breather hose from the air cleaner, and pull the pcv valve from the valve cover. Fire it up, then plug the breather hose to the valve cover with one thumb, and the pcv hole in the other valve cover with your other thumb. Leave it there a few seconds.
If you feel a vacuum releasing when you unplug the pcv hole, it's leaking. There should be no vacuum with the pcv valve out, but a slight pressure. If you dont feel any suction, you might plug them a little longer, but if there is no vacuum after 10 seconds or so you're probably ok.
Mine uses oil and I have the gaskets, but so far looks like just a little blowby.

Greeeeenberg · 01-16-2009, 09:15 PM

With mileage you should expect that, id say try the test zjay said and if turns out to be nothing run it.

Upside · 01-17-2009, 12:39 AM

My ZJ was using a quart every 800 miles before fixing my plenum gasket. After the gasket it uses a quart every 3000 miles. The Jeep had 195K on it when I did the gasket.

It will damage or already has damaged your catalytic converter to be sucking oil through the engine.

allenjp · 01-17-2009, 10:40 AM

Thanks a lot guys!!

**Yardman Harry** · 01-17-2009, 10:55 AM

Quote:

Originally Posted by ddeadserious

Sounds like a plenum gasket. I haven't found any real good writeups on how to do it though.

Heres a good writeup... http://www.jeepforum.com/forum/f13/zj-wj-faqs-read-first-contact-mod-changes-additions-591821/
posts 2-5 or just use your chiltons, but Tim has a lot of good pointers and things to watch out for...

FAQs gotta use them...

Harry

allenjp · 01-17-2009, 11:43 AM

Yeah thanks...I saw that thread, but it doesn't say how to know if you need to do it or not. I'm not a noob when it comes to wrenchin' but I like to avoid long jobs if I can...

**newfieZJ** · 01-17-2009, 12:42 PM

http://dodgeram.info/tsb/2000/09-05-00.htm

allenjp · 01-17-2009, 12:54 PM

Sweet! Thanks!

**horatio102** · 01-17-2009, 01:55 PM

How can you tell if it's the plenum gasket? What someone said about the breathers, or pop the throttle body off and look inside. If there is oil pooling inside, the gasket is shot. If it's just misted, the gasket isn't gone (yet).

hughesengines.com

Specifically: http://hughesengines.com/Index/products.php?browse=category&level0=U21hbGwgQmxvY2 sgTWFnbnVtICgzLjkvNS4yLzUuOSk=&level1=R2Fza2V0cw== &level2=UGxlbnVtIFJlcGFpciBLaXRz&partid=22220

I don't know if that link will work, but there's a reason the plenum gasket fails, and replacing it with an OEM one will not fix that reason. Chrysler "fixed" the problem in 98ish, or so they say, but my 2002 5.9 Dakota had the plenum gasket fail. The dealer fixed it under warranty once, at about 60k, and it started going out again around 85k so I bought the Hughes kit and had it fixed when I did the timing chain, water pump, and some other goodies.

Get the Hughes fix and be done with it. Instead of a piece of stamped tin, it's a 1/4" thick aluminum plate that won't flex or bow under load. Remember that the intake bolts are designed to stretch once, and not get reused, so buy new bolts too.

01-16-2009, 08:17 PM	#7
zjay Registered User Join Date: Jul 2005 Location: Vermont Posts: 282 Profile Gallery Classifieds My Jeeps	To check for a leak at the gasket- disconnect the breather hose from the air cleaner, and pull the pcv valve from the valve cover. Fire it up, then plug the breather hose to the valve cover with one thumb, and the pcv hole in the other valve cover with your other thumb. Leave it there a few seconds. If you feel a vacuum releasing when you unplug the pcv hole, it's leaking. There should be no vacuum with the pcv valve out, but a slight pressure. If you dont feel any suction, you might plug them a little longer, but if there is no vacuum after 10 seconds or so you're probably ok. Mine uses oil and I have the gaskets, but so far looks like just a little blowby.

01-17-2009, 01:55 PM	#15
horatio102 Web Wheeler Join Date: Mar 2001 Location: bjjkb Posts: 1,430 Profile Gallery Classifieds My Jeeps	How can you tell if it's the plenum gasket? What someone said about the breathers, or pop the throttle body off and look inside. If there is oil pooling inside, the gasket is shot. If it's just misted, the gasket isn't gone (yet). hughesengines.com Specifically: http://hughesengines.com/Index/products.php?browse=category&level0=U21hbGwgQmxvY2 sgTWFnbnVtICgzLjkvNS4yLzUuOSk=&level1=R2Fza2V0cw== &level2=UGxlbnVtIFJlcGFpciBLaXRz&partid=22220 I don't know if that link will work, but there's a reason the plenum gasket fails, and replacing it with an OEM one will not fix that reason. Chrysler "fixed" the problem in 98ish, or so they say, but my 2002 5.9 Dakota had the plenum gasket fail. The dealer fixed it under warranty once, at about 60k, and it started going out again around 85k so I bought the Hughes kit and had it fixed when I did the timing chain, water pump, and some other goodies. Get the Hughes fix and be done with it. Instead of a piece of stamped tin, it's a 1/4" thick aluminum plate that won't flex or bow under load. Remember that the intake bolts are designed to stretch once, and not get reused, so buy new bolts too.