Why is my fresh rebuild smoking

[Erniemcwrench]

My 86 c10. just had my 350 built less than 500 miles ago was/is running good parked overnight. Started the next day around noon and she belched smoke out the Exhaust. No noise or leaks were found. I'm baffled as to what happened/ is happening. If anybody has experience like this. Please Help!

 

[fast 99]

Do you mean it smoked on startup and quit or continued to smoke. Is it coolant or oil?

Startup smoke [oil] is indicative of valve or guide issues. If automatic check modulator.

 

[Erniemcwrench]

Very white smoke, no loss of coolant or oil. Smoked the entire time I ran it shut down after a few minutes not wanting to do damage after so much work already done. Did not check the Transmission Fluid actually didn't think of it. I have not experienced transmission making the engine smoke. What's the best way to check the Modulator?

 

[Ricko1966]

1986,if it's a 700r4 there is no modulator. Turbo 400 Turbo 350, pull the rubber vacuum connection off of the modulator,see if there's transmission fluid in it. Should not be any.

 

[SirRobyn0]

Well if it's coming out the tailpipe like that I'd pull the spark plugs out. I'd probably run the truck for 5 mins or so, then shut it off and pull the plugs. If it's oil the cylinder with the problem will have oil all over the plug and likely be black. If it's coolant then, the plug will most likely look clean and there will be a coolant film on it.

 

[TotalyHucked]

Sounds kinda like head gaskets if the smoke is white. I'd pull a plug before you run it anymore and see if the plug is wet

 

[Ricko1966]

Very white smoke, no loss of coolant or oil. Smoked the entire time I ran it shut down after a few minutes not wanting to do damage after so much work already done. Did not check the Transmission Fluid actually didn't think of it. I have not experienced transmission making the engine smoke. What's the best way to check the Modulator?

How long did you run it? What was your over night temp and morning temp? Colder than usual?

 

[fast 99]

Coolant and tranny fluid both may appear white. Smell's sweet coolant.

 

[Radiohead]

Coolant and tranny fluid both may appear white. Smell's sweet coolant.

I've not had the pleasure of discovering yet, but do the new coolants with the bittering agent still smell sweet like coolant of old?

 

[fast 99]

I've not had the pleasure of discovering yet, but do the new coolants with the bittering agent still smell sweet like coolant of old?

Not a coolant sommelier. Given the year assume it has regular green. May be that assumption is wrong. To answer the question don't know.

 

[CountKrunk]

Where is the modulator to check it? Pls and ty

 

[Erniemcwrench]

Thank you all for your input. It turns out that I had two problems going on at the same time. Transmission is TH400 and the Modulator was bad, replaced it, and found that it still smoked not as bad as before an changed to a more blue color pulled valve covers and found a couple of leaves that we obviously missed when replaced the valve covers(the old MT aluminum ones cracked). That resulted in oil not draining back properly. She is doing fine now. Again thanks for everybody's input. The Modulator leaking into the vacuum line is a new one on me.

 

[Ricko1966]

Where is the modulator to check it? Pls and ty

Turbo 400 it's on the passenger side of the transmission near the cooling lines with a short vacuum line,turbo 350 it's on the passenger side near the u joint with a short vacuum line. If it's a 700r4 it's in the box at the parts store that's been returned 900 times because the 700r4s don't have one.

 

[SirRobyn0]

I've not had the pleasure of discovering yet, but do the new coolants with the bittering agent still smell sweet like coolant of old?

I'll give my opinion on it. Yes it does but not the same. I'd say it is less sweet smelling when burned. I'm not really sure about like the german and asian blue. But global and dexcool do smell sweet when burned, it's just different.

 

[Ricko1966]

And how come LEDs only light in one direction? Didn't we cover this yesterday? I'm more concerned with why did he have leaves,under the valve cover on a fresh rebuild