smoke from the dipstick tube. what is going on.

dastang2 · Sep 15, 2006

i may have a problem here. i got smoke coming from the dipstick tube when i floor the car hard. i can see smoke coming from the cowl hood and in the mirror i see smoke behind me but it is NOT coming from the tailpipes. i have a working pcv valve. when i take off the oil fill cap there is no smoke but when i disconnect the pcv valve, there is smoke at idle. the cylinders were very clean and had no ridges in them when i put the new heads on. i have not checked the compression yet but i am assuming the rings are good since the cylinders are. also i noticed that i am blowing oil out from the rear of the intake and i did not use the cork end gaskets. what do you think is going on.

stang8urimport · Sep 15, 2006

It's called Blow-by. The compression is getting past the rings and into the crackcase, and coming out of the dipstick. Time for a rebuild.

millhouse · Sep 15, 2006

Looking through your sig it appears that you have a carb conversion. Now when you did so did you keep the line that goes from the valve cover to the throttle body or did you remove it. If the latter is true you'll need to hook up the said tube which allows vacuum to be applied to the crankcase.

If it's all hooked up properly then you have some serious ring issues which need to be adressed.

dastang2 · Sep 15, 2006

i drilled a hole in the valve cover and put a pcv valve in it and hooked it to the intake.

millhouse · Sep 15, 2006

dastang2 said:
i drilled a hole in the valve cover and put a pcv valve in it and hooked it to the intake.

Hmmm....blowby it is then. Sorry man....a compression or leakdown test should confirm this before you go tearing into the engine, but it is the most likely explination.

foxstang9050 · Sep 15, 2006

sounds to me like maybe the dipstick tube isnt in all the way or is cracked... when you hit the gas hard... pressure builds and spits oil onto your exhaust... same thing happened to me... easy fix so check that before tearin apart your motor

alludethis · Sep 16, 2006

foxstang9050 said:
sounds to me like maybe the dipstick tube isnt in all the way or is cracked... when you hit the gas hard... pressure builds and spits oil onto your exhaust... same thing happened to me... easy fix so check that before tearin apart your motor

Def get under there and check to see if the dipstick is in all the way along with the tube that goes in. On both stangs i had i had a problem with it pulling out. It is possible that under WOT or hard driving it could be throwing oil onto your headers.

dastang2 · Sep 16, 2006

foxstang9050 said:
sounds to me like maybe the dipstick tube isnt in all the way or is cracked... when you hit the gas hard... pressure builds and spits oil onto your exhaust... same thing happened to me... easy fix so check that before tearin apart your motor

actually i lost the tube and i am in the process of looking for it. i thought that might be it the other day but i am not sure. when i unhook my pcv valve i get a little vapors out of the valve covers at idle but i heard it is normal. i am warming the car up now for a compression test.

dastang2 · Sep 16, 2006

well i got these numbers. all of them were 150 except for 2 cylinders. one had 160 psi and #6 had 135 psi. these numbers look ok to me. i had somebody rev it up high while i watched the tail pipes and absolutely no smoke. what do you think of these compression numbers. i believe all the smoke i see pouring out from the hood is mainly from the back of the intake. there is oil everywhere but also i notice that is blew the silicone out in front of the intake.

vristang · Sep 16, 2006

With #6 being a little low, that could be the problem.

Blowing the seals/gaskets out means that your crankcase pressure is not being vented.

For some engines, the single pcv is not sufficient. An addition of a second pcv on a valve cover, could help.
It certainly helped my 408w.

Still, #6 is lower than I would want it.

jason

HISSIN50 · Sep 16, 2006

It's too bad no one on this thread has 'been there and done that' with experiments for crankcase ventillation.

Haha - Jason is the first guy I think of when it comes to this stuff.

I gotta say that were it me and I suspected excessive crankcase build-up (blowing out the RMS, etc) and I had a carb, I'd consider a couple hog breathers. This would just let you see how things are when you KNOW you have adequate ventillation. I'm old school and didnt really like PCV's on carbed stuff anyhow (closed breathers were more my style).

I like the plan to clean up the back of the intake and go from there.

Good luck.

dastang2 · Sep 16, 2006

i rechecked #6 and it was 140 and not 135 if that means anything. what do you mean by the filters anyway. i was thinking i could put 2 pcv valve on it also or at least hook vacuum to the nipple on the filler tube.

millhouse · Sep 16, 2006

dastang2 said:
actually i lost the tube and i am in the process of looking for it. i thought that might be it the other day but i am not sure. when i unhook my pcv valve i get a little vapors out of the valve covers at idle but i heard it is normal. i am warming the car up now for a compression test.

There is your problem right there.

dastang2 · Sep 16, 2006

i hope it is. i had to use 2 intake gaskets sets to make the intake seal and i use the blue rtv. since i used 2 sets i think the rtv was not enough to seal the big gap i have now at the ends of the intake and thus making oil blow out. does this sound about right. is there such a thing as an in line pcv valve that i could hook up to the nipple on the valve cover filler tube and leave the other one at the rear of the drivers side cover.

HISSIN50 · Sep 16, 2006

I'm lost at this point (with what's been done, the intake gasket situation, and so-on). All I can say is to remember (as you plan things out) that PCV flow is bi-directional. In OEM form, there's a secondary line (from the oil filler to the TB) that flows both ways. Its primary purpose is to let air back into the crankcase (because your PCV valve on the primary line obviously only flows one way).

I still think your compression numbers are decent and close enough to consider being ok for the purposes of figuring out this issue. I'd bet things level out amongst them when wet, which can be more indicative of the real environment in which the rings seal.

Good luck.

foxstang9050 · Sep 16, 2006

millhouse said:
There is your problem right there.

word... gurantee you thats the problem... put a tube in before you bother doing anything else... its not worth the headaches

dastang2 · Sep 17, 2006

ok i found the tube,put it in there and went for a drive. got on it a little and so far so good, no smoke. thanks.

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