smoke out of tail pipe

[recordsj]

1500 mg midget
A little over a year ago I rebuilt the engine (new pistons, rings, bearings, etc).
Last summer while driving the car it was overheating a bit (getting to about 210F).
This winter I have replaced the radiator with a new one (the old one had a lot of deposits in it). The car has set without coolant for about 3 months.
After getting the car running again this weekend with putting new coolant in it, I am getting a lot of smoke out of the tailpipe (it appears white maybe a littel grey or blue). Also the cylinder 3 & 4 spark plugs are black with soot, 1 & 2 are clean. The smoke does have a smell of fuel.

Before I did the work on the car, I wasn't having this issue. I also did check the plugs recently last summer after the overheating and they were clean.

The only thing that has changed is a new radiator & coolant, car sitting since last September.

My thought is that with the car sitting with out coolant for about 3 months something happened to the head gasket, but that wouldn't explain why 3 & 4 spark plugs have black soot on them. I have done a compression test on 3 & 4 and had about 140 psi on both cylinders. I plan to do a leak down test on all the cylinders soon.

Any thoughts?

 

[JPSmit]

what are you using for carbs? If twin SU's the rear one is too rich. In terms of the smoke, I suspect head gasket - as mentioned, not a difficult fix.

 

[Boink]

what are you using for carbs? If twin SU's the rear one is too rich. In terms of the smoke, I suspect head gasket - as mentioned, not a difficult fix.

That's where I would start in this case, too. Are both carbs correctly set?

 

[recordsj]

I have a Weber DGV. I haven't touched the carb since I did tuning on it over a year ago after I rebuilt the engine.
It just makes me currious on why after putting in a new radiator that this would be happening (the combination of 3 & 4 cylinder spark plugs covered with soot and smoke/vapor with fuel smell coming out exhaust).

 

[JPSmit]

It may actually be that the weber is running rich - and that the vapour has cleaned plugs one and two.

 

[recordsj]

It may actually be that the weber is running rich - and that the vapour has cleaned plugs one and two.

True, but why would the carb all of a sudden run rich? The only thing that has changed is: car sitting since Sept, removed the old radiator in Dec and installed new radiator this weekend. But with the smell of fuel in the exhaust would make sense though if the carb is running rich.

 

[recordsj]

It may actually be that the weber is running rich - and that the vapour has cleaned plugs one and two.

If it is running rich, wouldn't the smoke be black? The smoke/vapor is whitish.

 

[JPSmit]

I have certainly had mine run rich without the exhaust being noticeably different in colour. I just went and re-read your initial post and if I were to hazard a guess, I think you have two separate issues.

#1 head gasket. The clue is you noting that the car was overheating in the summer. It may have heated a bit too much. Did you re-torque the head after the first 500? miles?

#2 Carb issues. Not exactly sure how or why except to say that I know other things on my car had to be re-set after a few months/ few hundred miles - maybe?

 

[Boink]

One can also get a LOT of smoke with oil into the intake... and I mean a LOT of smoke (sort of gray stuff that won't necessarily be blue until it dilutes). I state this because: a) I've seen the finding top-dead-center trick using oil in the cylinder, and b) in my own case, my PCV valve allowed the intake manifold to briefly suck some oil into the engine and wow was there a lot of smoke that took several minutes to burn out. I think "white" smoke is either coolant or oil in large amounts. In the case of coolant, one would normally expect that to linger as it dissipates very slowly as a quasi-vapor-trail.

 

[recordsj]

I have certainly had mine run rich without the exhaust being noticeably different in colour. I just went and re-read your initial post and if I were to hazard a guess, I think you have two separate issues.

#1 head gasket. The clue is you noting that the car was overheating in the summer. It may have heated a bit too much. Did you re-torque the head after the first 500? miles?

#2 Carb issues. Not exactly sure how or why except to say that I know other things on my car had to be re-set after a few months/ few hundred miles - maybe?

I did retorque at around 500 miles, but I could check torque again. I agree that I may be dealing with two issues, but for the soot covered spark plugs, I just checked the plugs in Sept before I stopped driving the car. I guess I will retorque head and do a complete pressure test and leakdown test on the cylindereds

 

[recordsj]

I have certainly had mine run rich without the exhaust being noticeably different in colour. I just went and re-read your initial post and if I were to hazard a guess, I think you have two separate issues.

#1 head gasket. The clue is you noting that the car was overheating in the summer. It may have heated a bit too much. Did you re-torque the head after the first 500? miles?

#2 Carb issues. Not exactly sure how or why except to say that I know other things on my car had to be re-set after a few months/ few hundred miles - maybe?

checked the torque on the head with a torque wrench, all bolts are torqued down (none of them moved when torqued with the torque wrench set @ 46 ft-# which is the setting for 1500 head)

 

[recordsj]

I did a leak down test and everything tested out fine.
So I gues I could be the carb running rich or lean?
I do smell fuel in the exhaust. The exhaust coming out is whitish (still see it coming out even after the engine is warmed up) and hangs around a bit.
All 4 spark plugs are black and have a dry soot on them and smell of fuel.

I thought if it is running rich, the exhaust would be black?

 

[bobhustead]

Black smoke is gasoline. White smoke is steam. Blue smoke is oil. Steam depletes water in the cooling system. Frequently, steam will be less if you remove the radiator cap. How is compression in 1 and 2? do you have photos of the plugs?
Bob

 

[recordsj]

I did a leak down test and it was close to 100% leak free on all cylinders.
Smoke is whitish.

 

[Guest]

Old fuel possibly. if you have a difference b/w front and rear plugs check your intake torque.

 

[recordsj]

leak down test results: 20 to 25% leakage rate on the 4 cylinders, test done on a cold engine (feel air coming out of dipstick tube and valve cover)
plant to retest on warmed up engine since I would expect the cylinders to seal better warm.

 

[recordsj]

leak down test results: 20 to 25% leakage rate on the 4 cylinders, test done on a cold engine (feel air coming out of dipstick tube and valve cover)
plant to retest on warmed up engine since I would expect the cylinders to seal better warm.

last time I filled up was in Sept last year. after I last ran the car I poured some fuel stabilizer in it. tank is about 1/3 full.

 

[bobhustead]

As I posted above, white smoke is steam. Seems like you have a leak between the cooling system and a cylinder. Most shops should have a "sniffer" that will detect combustion gasses in the cooling water.
Bob

 

[Boink]

It might be steam... but I'll also add again, white smoke (though not bright white) isn't always steam. Steam will linger for a long time in the air when mixed with exhaust. "White" smoke is often a very light grey smoke and can be due to a LOT of oil (and it won't be blue until it becomes dilute). I've seen this on my own 1275 when the PCV valve gulped a relatively small amount of oil directly into the intake manifold... and it took several minutes to burn off. That was very smoky and it wasn't black at all; in fact, it looked rather white.

See if a shop can verify combustion gases in the coolant. Combining that with the leak-down test (and the fact that you're not losing any coolant), and I might turn to something else. BTW, does the oil look normal?

 

[AN5Sprite]

My .02

If you've already done a leak-down, why not do a compression test as well? If you do have coolant getting into a cylinder a compression test will show you. You'll have a much higher reading on the offending cylinder, and probably water in you compression tester. If that winds up to be the case with a little light you'll probably be able to see coolant sitting on top of a piston too. If none of that happens I would think you could rule the head gasket out.

Also, if you're not sure what's coming out of the tailpipe, hold a piece of paper up to it. If it's H20 you'll know quickly.