Oil/Ventilation Problem on 87 4.0 Renix. Ideas?

I just got through replacing the head gasket on the 87 4.0 in the shop's comanche. I went wheeling in it last weekend with no problems at all, however, I drove it home about 35 miles last night on the interstate, and i've noticed a slight problem.

It's leaking oil from the rear main (naturally), but the engine is dumping a milky/ chocolate colored oil from the breather tube coming from the valve cover to the airbox. The oil in the crankcase is a clean as new (it's only got 100 miles on it), but I can't for the life of me figure out why the oil blowing out of the tube is chocolatey colored. It's dumping into the airbox and running down the inner fenderwell.

I've compared the two oil samples and the stuff coming from the tube is a totally different color...

Anyway, the tube oil is covering the front diff, and blowing down the length of the truck onto the exhaust. There's a puddle of the chocolatey stuff about 5-6" in diameter under the truck already, and I've only been at work about 25 minutes.

Could there be condensation building up from the heat of the engine that's collecting in that tube or in the valve cover? Could there be some residual water left in the engine oiling system somewhere? It's not used any water, the res. is full. I pulled the dipstck on the engine and see no signs of any water entering the system at all. I pulled the tube off the airbox, tapped it a few times and a good bit of water came out, along with a few chunks of some white film.

I've got a 4.6 stroker sitting on the stand ready to go in, but i'd like to get as much out of this old engine as possible, since I've already put too much into it (headgasket and new exh manifold)

Thanks for any help.

Conn

Sounds like condensation to me, also the tubes might be slightly plugged, this can cause an increase in internal pressure which will then force oil out of the next path of least resistance which in your case might be the rear seal.

The first and easiest thing to do is to take the line off the rear of the valve cover and clean it out. Put some carb cleaner in it and let it sit then blow it out with air. Also stick a small screwdriver in the orifice at the back of the VC and make sure it is clear. This will drop the pressure that is building up in the engine. This probably did not cause the Rear Main leak but certainly does not help it. If that does not work You might consider taking off the VC and cleaning the snorkels out.

Good luck
K

katarn444 said:

The first and easiest thing to do is to take the line off the rear of the valve cover and clean it out. Put some carb cleaner in it and let it sit then blow it out with air. Also stick a small screwdriver in the orifice at the back of the VC and make sure it is clear. This will drop the pressure that is building up in the engine. This probably did not cause the Rear Main leak but certainly does not help it. If that does not work You might consider taking off the VC and cleaning the snorkels out.

Good luck
K

Click to expand...

If you have alot of sludge buildup in there around the spring area of the head that canslow down the oil return to the pan too as well as 'lift the oil up' to where it can reach that vent. Some have cut that vent down a 1/8-1/4 inch to get it up higher too so it's not sitting in the oil, specailly if you have been off road with a lot of angles and dangles going on.