Blowing Smoke up your......

Alright, first things first....I just bought my Jeep about 5 months ago. It has 234,000 miles on the odometer, but we aren't sure on the exact mileage (it was towed behind a motorhome for along time). Well the other day I noticed I was blowing a blue colored smoke out the back of the Jeep as I was driving down the road. I have also, started noticing, anytime I pull up to a stoplight smoke comes out the front of the Jeep (from underneath, not up top). Well I thought it might be a Valve Cover issue. So last Friday, I decided to change the valve cover gasket. I changed my valve cover gasket, but messed the gasket up when putting the cover back on. Well, I drove down the street and it was blowing more smoke out the rear (it is actually coming out of the exhaust pipe) and it was idleing really weird (wasn't doing this before). Well Monday comes around and I recieved the rest of my Lift kit parts that I had been waiting for. So, Monday I get started on installing my lift kit (@ 6pm). I firgured since I am working on the Jeep, might as well pull the VC gasket out and put it in correctly. Well, as of Tuesday at 6pm the Jeep is done. Well I am driving to work today and it is just billowing out smoke. When I am driving the smoke is blowing out the end of my exhaust. When I come to a stop, the smoke is blowing out the bottom of the engine. Has anyone had this problem? It is freaking annoying. The idle is weird and makes the power in the Jeep surge (all the lights will dim and then light back up). The RPM's jump between 250-500 at idle. I am completely confused.....PLEASE HELP!!!

I've had my 87' blow smoke before. It was caused by oil leaking from the rear seal and then dropping onto the exhaust pipe. The leaking oil also caused the CPS to fail, which might explain the rough idle. Check the rear seal for oil, and also look at the exhaust pipe for any signs of burnt oil.

Yeah, I know the Rear Main Seal is leaking, but this is way too much smoke for that. The Main Seal leaks like 3 drops of oil when it is parked and they are small, so it's not leaking tons or enough to cause that much smoke. Also, it wouldn't be coming from the inside of my exhuast pipe.

What is a "CPS"? and where do I find it?

Thanks for your help!!

Smoke from your exhaust pipe and and from below the engine.... looks like your piston rings are worn.
Run a compression test and see if you get no less than 135PSI in every cylinder with no more than a 10-15 PSI variation among them.

How do I do a compression test?

First off, get/borrow/rent a compression tester. This is a gauge that attaches with a hose to the sparkplug hole and reads pressure in PSI.
Remove all sparkplugs.
Do something (remove relay or whatever, I don't know for your model year) ***(can somebody help on this?)*** to disable the injectors so that they don't spray fuel. Otherwise, make sure you're not smoking.
For each cylinder in turn, screw the gauge's hose in the sparkplug hole and crank your engine 3-4 turns. The gauge will now show you the pressure that your cylinder developed when in the compression stroke.
Once you've tested all 6 cylinders, compare the readings.
That's it. Put your plugs back where they belong.

sounds like you may have mulitple problems. If the smoke is blowing out the tailpipe when driving I would agree with doing a compression test (sounds like blow by).seeing smoke come out from under the engine too? This may be either your rear main seal leaking oil onto the exhaust or oil from your screwed up valve cover leaking down onto the exhaust which would also run right over the top of the CPS causing your idle problem. I have an 87' with 247k on it and until I replaced the engine last year it leaked oil from many places and I had smoke rolling from many diferent directions at the same time (depending on which way the wind was blowing).either that or you have a hole in you exhaust near the motor and it is anly noticable when sitting still. good luck.

Thanks for all the help!!

Another question...I was going to clean the inside of my valve cover to see if that will unclog and help a little bit. What do I use to clean the inside? Thanks in advance!!

If all you want to do is clean the inside of your valve cover just use a good degreaser or even carb cleaner. When done just wipe everything dry before reassembly.

Just got done with VC gasket replacing I used a degreaser an TB cleaner with a wire bush. I have 220000 miles on mine an it was CAKED UP with carbon so yes clean out your valve cover. While your replaceing the gasket get some new CCV tubes if you havent already. Like jldiaz said it sounds like worn rings run a compression test.

TORX

To prevent fuel from being injected, you can jus pull the fuel pump relay out. It's in your Power Distribution Center (PDC, the black box behind the battery).

jldiaz said:

First off, get/borrow/rent a compression tester. This is a gauge that attaches with a hose to the sparkplug hole and reads pressure in PSI.
Remove all sparkplugs.
Do something (remove relay or whatever, I don't know for your model year) ***(can somebody help on this?)*** to disable the injectors so that they don't spray fuel. Otherwise, make sure you're not smoking.
For each cylinder in turn, screw the gauge's hose in the sparkplug hole and crank your engine 3-4 turns. The gauge will now show you the pressure that your cylinder developed when in the compression stroke.
Once you've tested all 6 cylinders, compare the readings.
That's it. Put your plugs back where they belong.

Click to expand...

Before you do this however you want the engine at OPERATING tempature. Doing it cold will give you false readings that WILL NOT be as high. I'd hate to see you do extra work becuase the test wasen't done properly.

Thanks guys!! Ya'll have been great help.

As for the degreaser for the inside of my valve cover...I have engine cleaner? would that work? It cleaned the top of the valve cover pretty good. Isn't there a screen inside the valve cover that I'm supposed to watch out for?

My_Little_Pony said:

Thanks guys!! Ya'll have been great help.

As for the degreaser for the inside of my valve cover...I have engine cleaner? would that work? It cleaned the top of the valve cover pretty good. Isn't there a screen inside the valve cover that I'm supposed to watch out for?

Click to expand...

When i cleaned mine i think there were a couple of baffles. Cant remember. Just get it clean, and get all the residue out by drying it. You don't want degreaser in the ENGINE.

Inside your valve cover theres two baffles or snorkels what ever you want to call them. When i cleaned mine i took them apart theres the baffle an a gasket clean em up an put a thin coat of rtv on the baffle gasket an assemble them be sure to let em cure for awhile. The baffles are what your ccv tubes connect to so get them clean as pssible to reduce blow-by

TORX

Also keep in mind the PCV orifice in the valve cover maybe clogged causing the notorious blow by problem. This will cause smoke from the tailpipe.

Mike

MK96XJ said:

Also keep in mind the PCV orifice in the valve cover maybe clogged causing the notorious blow by problem. This will cause smoke from the tailpipe.

Mike

Click to expand...

Mine is doing the same thing, blue smoke is coming out of the top of the pcv outlet on the valve cover...I will work on it
when I get it more drivable.

Thanks guys!! I am pretty sure my smoking and idle problem have to do with the Valve cover. Also, I know that my rear main seal needs to be replaced for sure. I figure if I get the valve cover all cleaned up and unclogged, it will slow the leaking on the rear main seal down.

Thanks again!!

Lets zero in on the smoke issue a bit. Does it smoke after it sits idling for a while, but not when running down the road? The classic test is to sit in a drive through at McDonalds. Check for a blue cloud when you first pull up, and then when you get your food. If it gets worse, and its not smoke from oil hitting the exhaust, then you have valve guide/seal problems. If the wierd idle was not there before the VC swap, I would tend to think of the vacuum hose on the MAP or the MAP disconnected.

As for cleaning the VC, Castrol Super Clean will do the best job of cutting the crud. Pull the little vent castings from the VC and clean everything well before reassembly.

Rear main has nothing to do with idle. I guess enough crud could pile up on the cps to cause a problem, but I have never seen it.

No, my point with the rear main seal....The Rear Main Seal is the weakest of your seals. If you start building up pressure in your oil system (due to clogged hoses or what not), it's going to force oil out of the weakest seal in the engine...first. My point was, I already have a bad rear main seal, so, with the valve cover being clogged, it's causing even more oil then if it werent clogged to come out of the main seal.

It smokes all the time. The more gas I give it the more it seems to smoke.