Oil smells like gas in our XJ?

[Bluesky4x4]

Just a quick baby jeep question, what's wrong if you check the dipstick and there is a gas smell coming from the oil? Engine also doesn't sound right, either exhaust leak at the manifold or something internal.

[bentpushrod]

Not sure if your jeep has a mechanical fuel pump. If it does, that'd be the first place I'd be looking.

[Serious Johnson]

Don't know what sort of carb (if any) your rig has, but a blown power valve on one of our FSJs with a Motorcraft 2100 can make the thing run very rich, not "sound right" and eventually contaminate the oil via "washdown" of unburnt fuel past the rings. By the time it's gone that far, the motor has likely endured severe wear.

It's also possible for a mechanical fuel pump with a leaky diaphram to pump gas into the crankcase. This usually results in a rapidly rising "oil" level, and strong underhood gas smell. It's not necessarily noticeable as a loss of performance, generally only breaks stuff if the motor is run hard, and does a fair job of flushing the motor of gunk.

Might be a good time to stop smoking.

:-

[Nobby]

Secound the above, comments.
You say it does'nt sound right to. Richness is a likely culprit.
Get it checked out like Serious J said excess fuel is not a good scenario and is a self compounding situation with regard to the bores.
If it is richness hence fuel getting past the rings do a compression check do see how things are.

Have no experience as to what kind of fuel pump you'd have.
Is your oil level magically increasing? Getting thinner? Is your tailpipe black and carbony.

Figuring on a 95 XJ that you have Fuel Injection so mechanical pump not an issue. Check into sensor issues.
Like I said not an XY guy.
Get it checked out should be able to hook up to Diagnostics Computer.

[The Anti-Chrysler]

How old is the oil?? You're talking about the '95 I assume, so we're not talking about car problems or fuel pumps.

We could be talking old, watery oil, bad injector(s), faulty fuel pressure regulator, worn ring(s), bad sensor(s) causing an over-rich condition...

[Bluesky4x4]

Thanks for the info guys. The oil did seem a bit high, since i know the engine had two leaks. It smelled like gas and was somewhat runny. I'm going to look harder to try and find an exhaust leak tonight and change the oil while I'm at it. Maybe run come injector cleaner through the system also. Ah yes, compression test too (haven't used that tool yet, whats the process?).

[Bluesky4x4]

Also, the cat convertor seems to be rattling lately when I turn off the Jeep. It's only dones this for about a week or so. Could a bad cat cause the engine to run rich?

[Don S]

..
Bluesky4x4 ...
... Some fuel additives or who knows what can cause a cat to partially plug up. This can severely restrict the exhaust flow and in some cases an engine will die half a minute after it is started up. The crud will usually be in the front part of the cat. Take the front pipe loose, move the cat out of the way and crank the engine then give it the gas. Grayish brown crud will come out of the header pipe. Don’t pick it up till in cools.

Good Luck ;) and CUL.. Don S..

[Bluesky4x4]

I worked on the XJ tonight. First step was the compression test. It came out good, first 3 cylinders were 145, last 3 were 147 (suppose to be between 125 and 150 with a max variance of 30). The plugs looked great, no carbon build up and no oil on them. After putting all the plugs back in, I found a nasty crack in the exhaust manifold at the Y. I welded that up as good as I could and the engine sounds better. Then I changed the oil. I ran the Jeep for a bit and the exhaust is kind of white, no real smell to it. I could hear the cat shield shaking a bit and took a look. I found that the joint between the cat and exhaust is leaking and the muffler has a hole in it (more of a 2in split). There was a lot of condensation coming out of the cracks (no smell and felt like water). The only other issue I noticed, was the air filter has quite a bit of oil in it. It's on the top, so it must be blow by from the valve cover. What do you make of the exhaust and blow by?

[andy d]

normal for a high mileage motor to collect oil in the aircleaner. it may be worsened by the gassy oil and a clogged pcv valve. does the f/i use a cold start valve? it also could be a bad coolant temp sensor or a thermo time switch if so equipped. this is stuff that a bosch f/i has , ive only had a carbed jeep. a bad diaphragm in the fuel pressure regulator will suck gas and cause rich mixture too. but im puzzled as to why the plugs arent black. i'll bet the condensation and white smoke (steam) is normal for a cold engine. did it go away in about 10 minutes or so? my curiosity is piqued, so please post your progress with this problem.

[heydave]

Check the plastic pcv line from the valvecover to the throttle body. These are known to plug up on XJs and cause excess crankcase pressure. This will cause oil in the filter and maybe your gas smell in the oil.

[Bluesky4x4]

Thanks Dave, I did read a post about that last night with some replacement part numbers. The goof engineers built the pcv into the valve cover for some odd reason. I'm going to check those lines tonight.

[heydave]

You usually need to just clean the lines and possibly remove the valvecover to clean underside. You shouldn't have to replace the lines.