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Unread 08-07-2013, 07:48 AM   #1
sconnell
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1995 YJ Wrangler 
 
Join Date: Aug 2010
Location: Hornell, NY
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Oil smell when I let off throttle

I am trying to figure out why I smell oil or burning oil when I am driving down the road and let off the throttle. Most of the time I smell it when I am ready to roll up on a stop sign. When I am driving I smell nothing. I cant see any signs of oil leaking from my valve cover or my oil pan that would cause it to drip onto anything hot. I dont leak or burn any oil but yet smell it? Hopefully someone can give me some insight on what the problem may be?

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Unread 08-07-2013, 10:04 AM   #2
superj
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it could be running down the back of the block and onto the top of the trans and running down on to the exhaust. you won't smell it driving because the wind takes the smell away
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Unread 08-07-2013, 10:38 AM   #3
sconnell
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Yeah I already looked all over the block from the valve cover down. I degreased the whole motor and dont see any wet spots.
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Unread 08-07-2013, 10:44 AM   #4
Xzero117
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your valve seals are most likely worn

oil gets by them when the engine goes into vacuum, such as when you let off the throttle or when you stop/ slow down by downshifting

ask someone to start the jeep for you while you keep a close eye on your tail pipe, if you see smoke which smells like oil on start up, it's the valve seals

on a 20 year old engine it's to be expected, if you're not gonna get the heads done just switch to heavier oil and hope it helps
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Unread 08-07-2013, 11:07 AM   #5
sconnell
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I have checked that also I dont see any smoke other than the normal when it has been 40* out in the morning and I dont smell any oil. I have that in my toyota tercel I do know that.
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Unread 08-07-2013, 11:52 AM   #6
Xzero117
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well if it ain't coming from the tail pipe then just clean your engine bay, and parts of the frame close to the engine, and then take a drive and look for oily spots

there has to be a leak somewhere which is making it's way to an exhaust pipe

you could also be sucking oil through your pcv valve, try replacing that, also check for engine blow by, does a lot of smoke come out when the engine is running and you remove the oil cap ?
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Unread 08-07-2013, 12:17 PM   #7
SoNova
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Just snow balling here, but could it be a worn T-case tail shaft seal that is slinging over to the exhaust pipe? Only leaking when driving and burning off so no drips? See if you have a greasy line beside the tail shaft
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Unread 08-07-2013, 01:07 PM   #8
sconnell
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Quote:
Originally Posted by SoNova View Post
Just snow balling here, but could it be a worn T-case tail shaft seal that is slinging over to the exhaust pipe? Only leaking when driving and burning off so no drips? See if you have a greasy line beside the tail shaft
I do have a leaking tail shaft seal, and I cleaned the muffler off and made a sheild so that it wouldn't get coverd again. I have parts on the way to replace the seal.

Quote:
Originally Posted by Xzero117 View Post
well if it ain't coming from the tail pipe then just clean your engine bay, and parts of the frame close to the engine, and then take a drive and look for oily spots

there has to be a leak somewhere which is making it's way to an exhaust pipe

you could also be sucking oil through your pcv valve, try replacing that, also check for engine blow by, does a lot of smoke come out when the engine is running and you remove the oil cap ?
I have degreased my engine and cant find any wet spots. I am gonna change the PCV valve and see if that helps.
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Unread 08-07-2013, 02:41 PM   #9
pasinbuy
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1994 YJ Wrangler 
 
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Are you one of those that cut the end of your hood cowl drain? If so that is why.
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Unread 08-07-2013, 04:18 PM   #10
sconnell
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Quote:
Originally Posted by pasinbuy View Post
Are you one of those that cut the end of your hood cowl drain? If so that is why.
Cut the hood cowl drain? Never heard of such a thing. What does that do or what does it affect and why would it cause an oil smell?
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Unread 08-07-2013, 04:29 PM   #11
sconnell
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Ok I just went out and looked at my drain tube. It is there and it is a rubber hose that goes down to almost the tranny bell housing. It is squished/crimped at the bottom with a slit in the bottom and up the side about half an inch. Is this what it is supposed to look like or is it not supposed to be cut?
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Unread 08-08-2013, 10:51 AM   #12
pasinbuy
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Sounds right. The hose is a drain for your cowl. It needs to be cleaned regularly of debris or you will get water overflow in the cab. Some will cut the tapered end to avoid having to keep it clean which can cause motor smells inside the cab.

The slit should be only on the bottom of the hose. If yours is larger that could be the problem for the odor.
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Unread 08-08-2013, 11:11 AM   #13
sconnell
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Location: Hornell, NY
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Ok sounds like mine is the way it should be then. I guess when I make it to the parts store I will pick up new pcv valve and try that next. After that I guess I deal with it unless I stumble upon something else.
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Unread 08-08-2013, 01:00 PM   #14
Xzero117
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Quote:
Originally Posted by sconnell View Post
Ok sounds like mine is the way it should be then. I guess when I make it to the parts store I will pick up new pcv valve and try that next. After that I guess I deal with it unless I stumble upon something else.
take off the oil cap with the engine running, check for blowby

a little is normal, if you're getting a lot it means the engine is showing it's age

I recommend a heavier oil if that's the case, 15w-40 is what you should be running in the straight 6 during the warm months
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Unread 08-08-2013, 03:18 PM   #15
sconnell
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Location: Hornell, NY
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I will go out and check for blowby. If I remember right I have done that also and have very little blowby. I did replace my pcv valve today and when I went to rattle the pcv valve there was no rattle. So I am hoping that my problem was with a bad pcv valve.
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