Rear main & Head Gasket

dawerm · Feb 24, 2008

I just wanna get some opinions to make sure I'm on the right track.

I purchased a stock 95 XJ sport (I6 HO, NP231 J, AW4 I think, & 155,000 miles) for $800 yesterday. The fellow I bought it from had it at a mechanics shop and told me that the diagnosis was bad piston rings & a leaking tranny pump(?). He told me it was sitting for 1.5 years and when he started it it was fine but once it warmed up, alotta white smoke was pouring out of the exaust...:repair:

I've traveled about 50 miles in the XJ and kinda smells a lil rich, aside from that nothing outta the exaust. Major oil leak on the back side of the i6 (rear main I think) leaking onto the exaust. I checked the Filter and tightened the valve cover. Still leaking like a stuck pig.:repair:

Checked the oil stick and it had white funk on it (head gasket Probably...crack maybe). Drove it for a little more and the white went away and it had tiny bubbles on the stick with a tad foggy oil. :repair:

So, Ive bought the gasket sets and dropped the oil pan ready to change the rear seal.and plan to replace the head gasket. Oh and by the way This jeep runs and drives perfect. Tranny & I6 run and shift insainly well :shocked: and 4H & 4L work awsome with no unusual noises. In 2WD Ive got a loud clicking noise when I brake slightly hard coming from the driver side wheel area.:repair:

Sorry about the Novel, Any comments or suggestions would be greatly apreciated.. I'm a newb member but I have been lurking around these threads for a good while & I have a 91 Briarwood Budget trail rig that I've been wheeling and fixing for a couple years now, But this one will be the wife's DD and Kinda wanna double check myself, well and it runs so well i'd hate to do anything to screw that up.. Any Help would be greatly appreciated..

5-90 · Feb 24, 2008

dawerm said:
I just wanna get some opinions to make sure I'm on the right track.

I purchased a stock 95 XJ sport (I6 HO, NP231 J, AW4 I think, & 155,000 miles) for $800 yesterday. The fellow I bought it from had it at a mechanics shop and told me that the diagnosis was bad piston rings & a leaking tranny pump(?). He told me it was sitting for 1.5 years and when he started it it was fine but once it warmed up, alotta white smoke was pouring out of the exaust...:repair:

I've traveled about 50 miles in the XJ and kinda smells a lil rich, aside from that nothing outta the exaust. Major oil leak on the back side of the i6 (rear main I think) leaking onto the exaust. I checked the Filter and tightened the valve cover. Still leaking like a stuck pig.:repair:

Checked the oil stick and it had white funk on it (head gasket Probably...crack maybe). Drove it for a little more and the white went away and it had tiny bubbles on the stick with a tad foggy oil. :repair:

So, Ive bought the gasket sets and dropped the oil pan ready to change the rear seal.and plan to replace the head gasket. Oh and by the way This jeep runs and drives perfect. Tranny & I6 run and shift insainly well :shocked: and 4H & 4L work awsome with no unusual noises. In 2WD Ive got a loud clicking noise when I brake slightly hard coming from the driver side wheel area.:repair:

Sorry about the Novel, Any comments or suggestions would be greatly apreciated.. I'm a newb member but I have been lurking around these threads for a good while & I have a 91 Briarwood Budget trail rig that I've been wheeling and fixing for a couple years now, But this one will be the wife's DD and Kinda wanna double check myself, well and it runs so well i'd hate to do anything to screw that up.. Any Help would be greatly appreciated..

Bubbly, milkshake-looking oil usually indicates coolant is getting in there - and a head gasket is the usual suspect.

Oil dripping onto the exhaust manifold is not going to be the rear main - you'll actually fix that in the course of replacing the head gasket (since that's probably the valve cover gasket.) That's if the oil is dripping onto the manifold. If it's getting onto the downpipe, that could be the valve cover gasket, rear main seal, or oil filter adapter (you're taking care of tho of those three.)

Also, if it had been sitting for a while, you might want to think about new valve guide seals - since you're going to have the head off anyhow. They tend to dry out and shrink, and don't fully recover once they're thoroughly wet again. Since you're going to have the head off, invest in a valve spring compressor (about $25) and a set of valve guide seals (unless you got a head gasket "set" already - everything from the head gasket on up) and take the extra hour or so to head that one off from the go.

You've probably already bought your oil sump gasket - if not, get the later (1996-up) version, since it's one-piece moulded rubber (vice the four-piece cork & rubber.) It will fit - it fits all 4.0L blocks (I know - I've got one installed on my 88 from doing an oil sump and rear main a few years ago...)

88 Wagonman · Feb 24, 2008

X2, but I also recommend having the head checked for cracks (Magnafluxed) and checking to make sure the mating surface is flat.

Saudade · Feb 24, 2008

Well, certainly check your compression before you tear it apart. If the rings are bad, you already have the head and oil pan off. Getting to the rings is not that much more work.

MTBracer367 · Feb 24, 2008

if your gonna be doing all this work already if i were u i would just pull the motor and rebuild it completly u might even wan ahav eto block re-honed depending on how bed the rings were aloud to get it'll save u alot of future headaches if u do it all the first time and especially b/c it's gonna be your wifes dd u don't wnan have it breaking down on her i'm sure u'd never here the end of it

Ecomike · Feb 25, 2008

Saudade said:
Well, certainly check your compression before you tear it apart. If the rings are bad, you already have the head and oil pan off. Getting to the rings is not that much more work.

I would change the oil, add some MMO, and run the engine for a good 30 minutes before I checked the compression since water and any resulting sludge in the oil might affect the compression readings.

How is the oil pressure?

Rear main & Head Gasket

dawerm

NAXJA Forum User

5-90

NAXJA Forum User

88 Wagonman

NAXJA Forum User

Saudade

NAXJA Member

MTBracer367

NAXJA Forum User

Ecomike

NAXJA# 2091

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