Smoking Under Hood

So I was driving my XJ today to school, and began to notice a smell somewhat resembling diesel fuel exhaust. I didn't think anything of it, but when I got on the freeway, I saw smoke coming back at the windshield through my drivers side hood louver. Not pouring out, just enough to notice it and make my cabin smell bad. I got out and inspected and didn't find anything out of place and continued to school. I figured maybe it would magically fix itself, but alas, when I left to go home, it was still doing, but smoke was only visible at highway speeds. It's idling fine, and when I'm not moving, there's no visible smoke, even with the hood up...

It's a 4.0 HO from a 94 ZJ in my 93 XJ. The only thing I've done in the engine bay lately(yesterday) was recharge(clean & oil) my K&N filter. And put a mini Autozone ricer filter on the end of the elbow toward the front of the valve cover(don't remember the name) and taped off the hole in the intake tube for it.

So any ideas what this could be? I'm going to go buy some new tube and just hook it up the way it was, but I don't see why it would change anything.

was it overheating? was it smoke or steam? black or white?

Could your valve covers be leaking?

It was grey smoke only coming through the drivers side hood louver.

andddd my thermometer sensor is stuck in the the block with the wire broken off, so I can't keep track of temperature.

andddd my valve cover is leaking, on the side of the injectors, but I can't get a wrench in there to tighten the bolts up.

I replaced all the hoses and took off the stupid air filter, hopefully this fixes everything.

ddeadserious said:

andddd my valve cover is leaking, on the side of the injectors, but I can't get a wrench in there to tighten the bolts up.

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Bingo.....

ddeadserious said:

andddd my thermometer sensor is stuck in the the block with the wire broken off, so I can't keep track of temperature.

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yikes! I don't think i'd run with it like that for too long. The idea of not knowing what temperature i'm running at just doesn't sound appealing to me...

ddeadserious said:

It was grey smoke only coming through the drivers side hood louver.

andddd my thermometer sensor is stuck in the the block with the wire broken off, so I can't keep track of temperature.

andddd my valve cover is leaking, on the side of the injectors, but I can't get a wrench in there to tighten the bolts up.

I replaced all the hoses and took off the stupid air filter, hopefully this fixes everything.

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I'm with 99XJSPORT06 I wouldn't drive it with out fix it unless you want to chance a blown head gasket or even worse and cracked head. with out the gauge you will not know............... until it's to late.
Just some friendly advice.


when you drive down the road the oil is dripping on the header(Hot exhaust manifold) and causing the smoke that you are seeing.....It would be vary difficult the make the oil ignite or take fire BUT.........if it ever did turn to flame:flame: By By XJ


Flash

Lots of good stud advice here so I will say IT. DON'T smoke under the hood. It's bad for the engine.

The smoking is gone now that I replaced the hoses. I'm going to try my best to tighten the rest of the valve cover bolts tonight.

On another forum, someone suggested that something was venting from the little air filter. That seems somewhat logical.

Oh, and it wasn't my thermostat is stuck in the block with the wire disconnected, it's the sensor that goes to the dashboard to tell me the temperature. I don't believe that would affect anything other than my knowing how warm or cool I'm running.

ddeadserious said:

Oh, and it wasn't my thermostat is stuck in the block with the wire disconnected, it's the sensor that goes to the dashboard to tell me the temperature. I don't believe that would affect anything other than my knowing how warm or cool I'm running.

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It's always good to know your engine coolant temp while you are driving. I just replaced that sensor, and it's very easy. A socket wrench with a deep socket fits over it perfectly. It's also very cheap ... about $23.00 from the dealership: http://allchryslerparts.com/

About your smoke ... if your motor was in good shape it wouldn't be blowing smoke out of the FRONT hose of your valve cover. Either your rear vacuum hoses are blocked (the hose going from the rear of your valve cover to your intake manifold), and/or you have excessive blow-by at your piston rings or valve seals. The front hose is to actually allow fresh air INTO your valve cover as the rear vacuum hose sucks out the fumes.

Good luck with all of it.

montanaman said:

It's always good to know your engine coolant temp while you are driving. I just replaced that sensor, and it's very easy. A socket wrench with a deep socket fits over it perfectly. It's also very cheap ... about $23.00 from the dealership: http://allchryslerparts.com/

About your smoke ... if your motor was in good shape it wouldn't be blowing smoke out of the FRONT hose of your valve cover. Either your rear vacuum hoses are blocked (the hose going from the rear of your valve cover to your intake manifold), and/or you have excessive blow-by at your piston rings or valve seals. The front hose is to actually allow fresh air INTO your valve cover as the rear vacuum hose sucks out the fumes.

Good luck with all of it.

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I tried to replace the part a few months ago, but the end is stripped and I can't get it out. I'm going to find somewhere else to tap the sensor into as I would like to know what temp I'm running at.

I don't have excessive blowby, I only have to recharge my K&N every 4 or 5 months. There's just enough to notice it. I'll check the vacuum hoses and see if they're blocked. Thanks alot.

ddeadserious said:

I tried to replace the part a few months ago, but the end is stripped and I can't get it out.

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I haven't had the pleasure, but a couple things to try might be a plumber's basin wrench (looks like pipe wrench jaws on the end of a T handle), or a drill and easy-out. No matter how bad you have to destroy the sensor, since it is brass it should come out without ruining the theads in the head with a little care. It could be difficult finding another place to put it.

rpyne said:

No matter how bad you have to destroy the sensor, since it is brass it should come out without ruining the theads in the head with a little care. It could be difficult finding another place to put it.

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Yeah ... and I don't think it's really a good idea to be tapping new holes in the head anyway. Getting the old one out is definitely doable, it's just one of those jobs that you can't really know what will work until you get started and try lots of different things. rpyne's idea of that special plumbing wrench sounds like it could work. You might have to move the plastic bracket that holds the FI wiring ... that helps you get better access to the sensor.