[JWC]

I've got a 96 4bt with a P pump in an 81 Bronco. The problem I'm having is it is losing oil as I'm driving down the road, and in 20-25 miles at 60 mph it will have a film on the tailgate and back glass that with the dust you can't see through it clearly. In 50 miles it will have spit out 4-5 quarts of oil.
The tailpipe is black but "chalky", in other words it's not oil wet. The turbo tube from the turbo to the inter-cooler has no oil or oil film in it. The oil fill on the #1 cylinder doesn't have hardly any pressure coming out of the fill hole and the oil fill on the timing gear cover is the same. The crank case vent tube feels like it has about 1-2 lbs of pressure at idle and looks like it has been spitting out oil onto the front drive shaft. If you put your thumb over the tube hole for about 5 seconds it will build pressure and come out stronger for a few seconds until it levels back out.
When looking at the passenger side of the head on #3 & 4 exhaust ports it looks like it has oil around the top of the exhaust port but you can tell that it's not coming from the valve cover gaskets (dry around the gaskets).
Has anyone else ran into this? Is there a common problem that causes this? Any help would be greatly appreciated!!! Thanks in advance!

 

[Dougal]

Unless it's a crank seal it's going to be the breather. Put a catch can on it and see how much it collects.

Ultimately blow-by means worn rings. Might be worth a compression test.

 

[JWC]

Unless it's a crank seal it's going to be the breather. Put a catch can on it and see how much it collects.

Ultimately blow-by means worn rings. Might be worth a compression test.

I put a new front seal in a couple of months ago and checked the rear one yesterday, both looked good. When you say the breather what all does that consist of? Is there a baffle behind the tappet cover?

 

[Blackduck596]

How long has this been happening?
With that loss there should be very visible oil leaks on the engine unless it is burning it. Any oil on the ground where you park it?
When you lose that much oil is it still showing on the dipstick? An overfilled oil pan can cause losses.

 

[JWC]

How long has this been happening?
With that loss there should be very visible oil leaks on the engine unless it is burning it. Any oil on the ground where you park it?
When you lose that much oil is it still showing on the dipstick? An overfilled oil pan can cause losses.

A few weeks now, it mostly gets driven around town short distances. There's some oil on the ground at where the back of the engine is. It holds about 10 quarts but I've been filling it before it's not showing on the dip stick. The engine has been in this truck since 2013 so I fill it to where I always did (same mark on dipstick). From looking at the front drive shaft I'm thinking it's coming from the crank case vent tube. It starts right up, a second or 2 at the most (if it's cold out) and doesn't feel "down" on power.

 

[char1355]

Another possible place for loss would be a bad seals in the turbo. Oil could be going out the exhaust pipe on a bad rear seal. Also, check the front of the turbo as well. Oil can go past that seal and end up in the intercooler and eventually into the intake. Bad valve oil seals can be another point of loss.

 

[Dougal]

Another possible place for loss would be a bad seals in the turbo. Oil could be going out the exhaust pipe on a bad rear seal. Also, check the front of the turbo as well. Oil can go past that seal and end up in the intercooler and eventually into the intake. Bad valve oil seals can be another point of loss.

If you've got high crankcase pressure it'll push oil past turbo labyrinth seals on compressor and turbine. Blue smoke is one symptom of that and oil in the turbo exit is another. Stripping down a turbo makes it obvious.

 

[Death Row Dave]

Vacuum pump will pressurize the crank case also , is my understanding

 

[JWC]

If you've got high crankcase pressure it'll push oil past turbo labyrinth seals on compressor and turbine. Blue smoke is one symptom of that and oil in the turbo exit is another. Stripping down a turbo makes it obvious.