blowing smoke

[gregor]

I just got done rebuilding the 302 in my 1990 bronco and at first all that was wrong was the timing. So we fixed that and now when I start it the idle will not stay constant, it goes from about 300 (just about to stall) up to about 2500 and it keeps jumping back and forth, and now it is blowing a lot of smoke out of the back of the drivers side of the engine. I think it is coming out of the head but I am not sure. So I was wondering if it could be a freeze plug that had come out that could cause this. Any help would be appreciated.

 

[Seabronc]

I just got done rebuilding the 302 in my 1990 bronco and at first all that was wrong was the timing. So we fixed that and now when I start it the idle will not stay constant, it goes from about 300 (just about to stall) up to about 2500 and it keeps jumping back and forth, and now it is blowing a lot of smoke out of the back of the drivers side of the engine. I think it is coming out of the head but I am not sure. So I was wondering if it could be a freeze plug that had come out that could cause this. Any help would be appreciated.

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The idle jumping around may be the TPS, check to see if it is sticking or the connection may be bad.

Blowing smoke, did you torque the head down according to the shop manual pattern and proper torque setting? Did you check the heads to make sure they were not warped and in need of machining prior to re installing them? Did you check for oil leaking around the valve cover?

You should have changed freeze plugs as part of the rebuild. If one of them came out you would lose your coolant. However, if one is rusted thru it could be leaking and burning off as it hits the exhaust manafold. What does the smoke smell like, oil or coolant?

Good luck,

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[gregor]

I took the heads to a machine shop and had them resurfaced and new freeze plugs installed. The smoke doesn't smell like oil or coolant. Thats why this is so aggravating. I bolted the head the way the manual said, but I am going to check to make sure they are torqued properly this weekend. We are also going to get a mirror to check to make sure the freeze plugs are still there.

 

[Seabronc]

Some heads had a small hole, about 1/2 in. in diameter, in the fire wall end for thermactor air injection. If your's have that hole and the air pipe is not installed or the holes covered with a plate, that may be the source of your smoke. The pipe that I'm talking about is the white one at the top of the picture with a check valve in it.

Good luck,

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[gregor]

Seabronc that is what it is, somehow during the reassemble that was not put in. Thanks for the help