89 SC smoke pouring from dipstick hole

89 Super Coupe

Registered User
:confused:
So my friend has an 89 SC with about 250,000 miles on it.

The problem(s): Strange disappearing brake fluid. It will sputter and stall, the RPM is all over the place. It sounds like there is a misfire, it also sounds like the air/fuel ratio is off. Im fairly sure there is a vacuum leak, and It will hesitate when you rev it.Also! There is smoke (what i suspect to be blowby) pouring from the dipstick hole. Which could be a PCV failure or worn out rings. When it starts it will start at 3,000 rpm, and then drop and go between 800 and 2,000. Then when you try and rev it the tach will quickly drop to zero and then back up to about 2,500 or so. Then it started backfiring!
{[Now the car wont even start at all}]

What we have replaced so far:
Idle air control valve
Coil Pack
Ignition control module.

Mods:
intake ducting. pod air filter. catalytic converters removed.

Heres a video of it running.
http://www.youtube.com/watch?v=QpPY9Nt6C3Q
 
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Smoke/air from dipstick is pretty normal. Any open hole crankcase pressure will come out. Now if the pressure blows the dipstick out then you have excess blowby or the pcv system isn't flowing enough.
 
It behaving like it's a bad IAC valve (stuck open bypassing too much air), but I see that you already replaced that. I noticed the vacuum was really low when rpms dropped to about 1000 so there may be something holding the throttle from closing all the way. Pull the air pipe off and take a look at the throttle plate to see if it's closed. I would worry about the smoke coming from the dipstick tube.

David
 
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Looks like you have a bad vacuum leak. I would pull the engine codes. Ignition module could be going bad judging by the tach dropping when you rev, but I'm not big on the older cars.how long has the double intercooler been on there? Check those pipes for proper seal and the big nut at the blower top.
 
It behaving like it's a bad IAC valve (stuck open bypassing too much air), but I see that you already replaced that. I noticed the vacuum was really low when rpms dropped to about 1000 so there may be something holding the throttle from closing all the way. Pull the air pipe off and take a look at the throttle plate to see if it's closed. I would worry about the smoke coming from the dipstick tube.

David

That too......
 
I am 99.99% sure it sounds like a vacuum leak. You can find it with a smoke test or rev test with an unlit propane torch. (Search for details.)

Did you hook the black plastic PCV tube up to the bottom of your cold air intake? It's the tube that runs across the engine, under the blower, behind the AC compressor, and connects to the bottom of the stock rubber intake tube.

The SC looks pretty nice overall. Is that rust free? Hard to find.

Also, I think the blower rotor pack bearings are getting a little worn out, just guessing from the clacking sound I heard under the hood. Doesn't mean you need to replace it right now, but be aware that it might need attention sometime.
 
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I've probably had more smoke pouring out of the dipstick tube of my white XR7 that anybody else every had. I never found the complete cause of the problem, but I think it was vacuum hose related because it didn't smoke until I changed the return plenum.

Anyway, I also discovered that the rubber seal in the dipstick handle had folded over. Once I found that problem and straightened out the rubber seal, the smoking was reduced.
 
I know these cars will run like crap if the firing order is incorrect. Many of the repair manuals are incorrect on the firing order diagrams for these cars. Strangely enough the computer will figure out how to get it to idle but no great.

Check to make sure the firing order is correct.

http://www.sccoa.com/forums/showthread.php?t=68255


On top of checking that you defintiely have a vacuum related issue.
 
I know these cars will run like crap if the firing order is incorrect. Many of the repair manuals are incorrect on the firing order diagrams for these cars. Strangely enough the computer will figure out how to get it to idle but no great.

Check to make sure the firing order is correct.

http://www.sccoa.com/forums/showthread.php?t=68255


On top of checking that you defintiely have a vacuum related issue.

I was thinking that too, but I would expect some popping in the exhaust if that was the case. Worth checking the plug order at least.
 
It behaving like it's a bad IAC valve (stuck open bypassing too much air), but I see that you already replaced that. I noticed the vacuum was really low when rpms dropped to about 1000 so there may be something holding the throttle from closing all the way. Pull the air pipe off and take a look at the throttle plate to see if it's closed. I would worry about the smoke coming from the dipstick tube.

David

Im fairly certain the throttle plate isnt moving while its running. Ill be sure to check next time though.
Thank You for the help!
 
I am 99.99% sure it sounds like a vacuum leak. You can find it with a smoke test or rev test with an unlit propane torch. (Search for details.)

Did you hook the black plastic PCV tube up to the bottom of your cold air intake? It's the tube that runs across the engine, under the blower, behind the AC compressor, and connects to the bottom of the stock rubber intake tube.

The SC looks pretty nice overall. Is that rust free? Hard to find.

Also, I think the blower rotor pack bearings are getting a little worn out, just guessing from the clacking sound I heard under the hood. Doesn't mean you need to replace it right now, but be aware that it might need attention sometime.

I do believe it is rust free, and thanks! Actually yes, we found the hose just cut open and laying disconnected. We're in the process of connecting that hose back into the intake pipe. As for the rotors, its kinda on the tail end of the list right now. And i agree with you on the vacuum leak.
Thanks for the reply!
 
Looks like you have a bad vacuum leak. I would pull the engine codes. Ignition module could be going bad judging by the tach dropping when you rev, but I'm not big on the older cars.how long has the double intercooler been on there? Check those pipes for proper seal and the big nut at the blower top.

Well, we tried to pull codes just with the engine off and no matter what we did we couldnt get the check engine light to flash at all. Im not sure how long its been since the intercooler was modified. Could be several years.

Thanks for the advice!
 
Vac was at 10....so yeah Vac leak and I noticed his bypass valve isn't closing
I would check the plastic line going to that also..

Tom
 
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