My 1978 F150 351M has recently begun billowing out a pure white smoke when started. The smoking lasts a few seconds and then dissipates. Although I dont notice any more smoke when I am driving, sometimes it smells a little like engine oil smoke when I stop. Any suggestions/ideas? Thanks, Andrew

 

White smoke usually means it's burning coolant/water. Oil burning causes blue smoke, and too much gas burnt is black. Sounds like a head gasket problem.

 

As the above post states white smoke usually means antifreeze is leaking into the conbustion chamber. But some oils can burn as a white smoke also. There are a couple of test you can do yourself to see what is happening. Before you start the engine have someone hold a clear piece of plastic warp over the exhuast pipe. Start the truck and let it breath for a few seconds into the plastic. If its antifreze you'll see a rather large amount of water on the plastic. If not and you see an oil flim it could be a couple of things. If you can't tell then you can try one of these other test.

To avoid the possibilities of having hot antifreeze blow in your face do this with a cold engine. Remove the radiator cap and start your truck. If the head is bad it will be blowing pressure into the cooling system. Look inside the radiator and watch for bubbles forming around the filler neck. You might even see it foaming up. Both are good signs a head gasket is shoot.

You can also have the system pressure tested. An sealed system will hold pressure for a long time. One with a gasket leak will fold perrty fast. Almost any place that does radiator flushes can pressure test the system for you.

If you seen an oil flim on the plastic wrap the oil could be coming form a couple of sources (some synthetics will burn white and not blue). One is the valve guides or the oil seals. This would seem to be the case because you state its there when you first start up. This happens when oil leaks past the guides and seals as the engine sits and puddles in the chamber.

Automatic transmissions can also be a sourse of burning oil. Mercon, Ford Type F and Dextron all burn white if they make it into the fuel misture. The way this can happen is if the vacuum modulator on the transmission has a pin hole leak in it. The engine will suck the oil from the pin hole in up into the intake. To see if it is the modulator unplug the vacuum hose from the intake and look for tranny fluid in the hose. If you see any signs of oil in the hose replace the valve. I've seen a shop put 2500 into completely rebuilding an engine only to find out later it was smoking because of a bad modulator. The guy took the shop to court and walked out only paying for the modulator valve.

welp theres a little list you can look at and few ways to test for things that could be wrong. Hope this helps.

 

Rus,
You are describing worn valve seals. I have a 78 F150 351M. Its also puffs blueish/white smoke on startup. I have worn valve seals. They are a bitch to replace but the heads do not have to be removed.
1. Remove valve covers.
2. Remove rocker arms/retainer/spring.
3. Remove old seal replace with new seal.
4. Reassemble valve train.
It is not that simple, to say the least.
You will need to pressurize the combustion chamber with air and use a fulcrum to remove the retainer. I have done it before and it would take me the better part of a day to do it again. Each Valve has one seal.
My Way is the Highway,
KingFisher
P.S. There is not a doubt in my mind, this is what you are describing.