FORD - debug help

[lizzyhermit]

my son's f100 302 equipped PU is blowing whiffs of white exhaust. it smells like uncombusted fuel but we can't figger it out. changed the distributor, all new spark plugs and wires and it appears the wires are good based on the timing light.

haven't done a compression test yet but that's our only hope to indicate a stuck/broke valve/spring.

any other ideas out there?

 

[B.G. Smith]

Smoky

If it is blowing smoke on startup then clears up, it is probably the valve stem seals. If it is blowing smoke while idling after warmup it could be the modulator on the trans. if auto. You can check the modulator for leak by pulling the hose off at the trans. and checking for trans. fluid. If it is newer truck, may not have modulator. The valve stem seals can be replaced without pulling the heads. bg

 

[lizzyhermit]

boy's truck is a stnd trans with a 4 bl carb on a 302 gasoline fueled engine. the smoke appears on start up and continues while the beast is running... ...

 

[B.G. Smith]

Smoke

You say puffs of smoke like maybe it is just one cylinder, how many miles and how much oil does it use between chages? Did any of the plugs have oil on them? If it is like a broken ring it should show up when you do the compression test. Also look at the PCV system, oil drainback holes have been known to get plugged causing the PCV system to pull oil out of the top end. bg

 

[Motorhead]

Is it losing coolant? He could have a leaking or blown head gasket into a water passage. My old Diesel VW did that. A small leak in the head gasket caused coolant to enter the combustion chamber.

There is a test for this, It involves a blue fluid that goes into a clear plastic tube and you put it over the radiator filler neck with the cap off. It has a small suction bulb at the top and it "sniffs" the coolant for carbon monoxide. If the gas is present, the fluid turns green or yellow. This indicates a combustion leak in the cooling system.