Guys, I got something weird going on. Last night after a short drive home from a cruise, I was idling in the driveway while I opened the garage and moved stuff. My car started smoking pretty noticeable out of the right side pipe. Couldn't tell the color but it looked pretty light. It would just smoke more and more, if I would rev it, it would puff, then clear up for a few seconds, then it would start smoking again. It has done this a couple of times. It seems like extended idling causes it. It doesn't smoke on WOT runs but it has always VERY SLIGHTLY smoked on cold start up after a few days rest, I instantly assumed it was just old valve seals...no problem, I can live with that.

BUT now I can start it up and let it idle for 30 mins in my driveway and it won't smoke. It kind of intermitten but when it starts smoking it, it fogs up pretty good. It doesn't necessarily smell like oil burning. I just changed the oil last weekend with 20/50 so I know its not the oil itself. I am kinda thinking its burning coolant intermittenly. Maybe a headgasket is blowing by after extended idling etc? Either way I am not pulling this motor down, I am just curious as to what it could be. The carb is a new Q-jet and the car runs really well for what it is.

I can also believe its the valve seals and I might slap a set of seals in it just because. What you guys think it is??

 

BTW, The car runs 160-180* all the time, never gets over 205* no matter how long it idles.

 

Alan,
You're probably right. I think it's valve seals from what you describe. Did the car sit for any length of time? This is usually when the seal will get hard and not do their job any more.

The '75 I just bought had been sitting in the previous owner's garage for 2 years. GM crate motor with only 15,000 miles on it. I changed all the fluids, started the car up and drove it for about a week. Same situation as you describe. I pulled the valve covers and put new umbrella seals on, problem solved. The old "O" ring type seals were hard as rock.

Replace the seals. It's cheap, easy and pretty quick.
Greg

 

Greg, I am not sure if the car actually sat but the motor was rebuilt way back in '88 so...The seals are 18 yrs old with about 40k miles. Whats weird is that it is so intermitten. I mean if the car sits a few days and I start it cold, it BARELY smokes any on start up and you can tell its oil smoke. THis is only about the third time I have noticed it smoking like this at idle when warm within about 800 miles.. Gonna watch it today but its really got to be the seals because I made 6 passes at the strip two weeks ago and it never smoked once at WOT. I can slap some seals in it easy and see if that helps. Hell it can't hurt anyway. Its gonna be about a year before I can do my good motor so I am trying to keep this ole pig running for a while. It runs suprisingly well to considering the guy that rebuilt the motor mainly just installed rings/bearings/oil pump, gaskets a a valve job.. Plain jane $500 rebuild.


WHen I changed the plugs a few weeks ago there was no REAL evidence of oil burning that I could tell.

 

If your car is an auto check modulator hose for fluid.As far as the valve seals they usually are noticable after sitting--they might be bad but I would guess thats not that intermitant problem.Do you have a rad. pressure tester if so pump it up and let it sit and watch gauge.

 

since your car runs so cool you might not have any press. on system some of the time and when the rad. cap closes it builds pres. and forces coolant into cyl.---smoke

 

What color smoke is it? White or blue? White normally means coolant and blue means oil.
Bernie

 

Does the smoke dissapate quickly or hang around?

 

Well, I just started it and watched it again. Its not the heavy blue smoke you normally see at cold start up when its oil seals.. After it idles for about 2-3 mins, you can see the right pipe continually huffing a very light smoke. Can not tell the color but its definetly not blue or black. ITs kind of colorless if you can believe that. You can see it when the smoke blows infront of something, like my other car or something besides it. Its got to be a greyish color. Kind of like if you drove across a dusty parking lot and the smoke comes up. It does it continuously though. I never noticed it before. You have to really watch for it but if are standing by the car when its running, you will start to choke on it. Its only on the right side though..



Valve seals? Carbuerator? Its a new q-jet that runs perfect and does not miss or anything. Almost like its really rich on one side of the motor but not so rich that it smokes black, maybe greyish black...Maybe I need to play with the idle air bleed on the carb on that side of the motor. Maybe its just rich as sh*t at idle. I never even touched the idle screws because they were supposedly preset and sealed.

 

if flows away relatively quickly I guess but its constant out the right side. Gonna see if I can get a picture of the smoke.

 

What you think guys? Its more noticeable in the garage. IF I took pics outside, couldn't really even see it.


OIL SEALS?

 

Its not REAL heavy like major oil consumption but it does linger around the driveway as you can see. I can't believe I have not noticed this. I saw it last weekend when I was setting the valves but just assumed it was smoke off the headers and exhaust pipes.


I can go down the road and stop and its fine, but eventually within a minute or so, it will start huffing. Wide open throttle, no noticeable smoke that I can tell.

 

You could pull you right bank plugs but I have to believe it is oil. If it were coolant it should smoke from both pipes. You could have a bad seal on one or more of the right bank of valves and lifters. Just my thought.
Bernie

 

IF it had blown a head gasket, on the right side, it would only smoke from the right. My exhaust pipes do not connect(H-pipe) anywhere.

I think its got to be oil seals also but...to me the color doesn't really look blue. Keep in mind that on the other side of the smoke sits a blue car and a blue motorcycle behind it. Makes the smoke kinda look blue I guess. Not sure but I am about to take the vette on trip here in a few mins and its gonna get about 150 miles on it atleast. Guess I will try putting seals in it next week and see if it helps. I can't believe if it was idling rich it would actually smoke, especially only on one side. I just did the tune up about 2-3 wks ago to.

 

I know that cars will do this that don't get driven a lot and for just short distances. You are right it would only smoke on the side with your situation. It could be running rich, does it smell like unburnt gas? I guess I'm grasping at straws for you right now. Is your coolant level low?
Bernie

 

I did add a tad of water to the radiator since about 2-3 weeks ago.. Maybe half a pint. Didn't think much of it.


It does have a lot of exhaust fumes like it could be running rich but I can't imagine it would run so rich that it would smoke like that. I might try to lean that side of the carb out some on the idle bleed and see if it helps.

 

Alright, I just played with the idle mix screws, they were both about 5- full turns out from all in. I tried leaning the right bank out some..definetly not the problem. I kept backing the screws out evenly until I got the fastest idle speed. If I turn it off. let it sit a minute or two and start it back up, it blows a really good puff out the right side, it looks more blueish grey after a restart so its GOT to be the oil seals. I will slap a set in tomorrow and see what it does.

 

From the pics it looks steamy--does it have an anti-freeze smell?If you release the rad.cap and it goes away after awhile chances are its coolant.did you say if its an automatic or 4 speed?

 

Compression check time.

 

Car is an auto. I just made it back from 150 mile trip. It was actually smoking when going down the freeway at 3000rpms. If I backed off of it some to say 2000rpms, it would stop smoking. But when I start it up after its been shut off, it definetly puffs some smoke that appears to be blueish. Definetly think its an oil problem...Oil seals or rings, I am not sure. It doesn't smoke at WOT, only at steady cruise at higher rpms(3k) and at idle if its been idling for 2-3 mins. Gonna try to change the oil seals first...if it still smokes, I guess I will have to pull it out for a re-ring/bearing it. I don't want to spend a lot of money on this motor since I will be building a good motor in the next year or so but I need this one to cruise on until then so....


This pisses me off.