Hi all.

I am indesperate need of some help here. I recently rebuilt a 351W and installed it into my 85 F-150. I replaced everything except the bottom end, i.e. pistons, rings and crank. The motor runs great, but I am having a problem where oil is blowing out of the dipstick tube. I had a carb problem originally, and it dumped a lot of gas into the lower end. Since I fixed the carb (new one), I noticed excessive pressure in the oil pan. The oils is milky/bubbly, but not white. It seems to be airrated to some degree.

Could this bee bad rings or cylinder? I also am wondering about a bad catalytic converter that may be causing backpressure? I will do a compression check this weekend, but other than that I am stumped. I have driven the truck, and it seems like it has power but steady throttle is required to go down the road.

Thanks!

 

I'm not sure I understand if you done the rings.
If so did you stager the rings properly?
Crank case pressure is from combustion via blowby or a head gasket not sealing, Pcv not working etc.
The milky oil seems to sugest water in the oil.
A coolant system pressure test is in order.
Good luck, my crystal ball just shut off!

 

I did not replace the pistons or rings. The motor ran fine, and was from a donor truck. I replaced the easy items including intake, oil pump etc. The heads had the valves lapped and new seals by a machine shop. The PCV seems to be working fine. I am beginning to wonder about the head gaskets. The engine does not overheat, but when it gets up to temp, there is almost steam (more than normal) coming out of both pipes.

 

I'm no engine builder but I would definitely be thinking about the head gaskets.

 

Almost for sure your head gasket.

I wouldn't drive this puppy - until repaired as they don't lubricate very well on Anti-Freeze.

 

I did a compression check on all cylinders today. Most averaged at about 95psi, with number 1 and 2 cylinders at 110psi. Still no sign of water in the oil whatsoever. My last check is with the Cats. I'm running dual exhaust, with two seperate Cats and mufflers. When I installed this motor last month, I had a arb that was bad and it FILLED the oil pan with gas. I am not sure what this would do to the cylinders, but it may have deystroyed the Cats? My big problem is that there is alot of pressure in the oil pan for some reason???

Thanks!

 

The pressure has to come form compression.

I would pressurize the cooling system and see what you have. I don't think you're going to find anything here though. Since you stated you don't have milky oil or such.

If you have pressure in the crankcase that will blow the dip stick out, well that's alot. Has to come by the rings.

Did you remove the pistons and ring and then reinstall them??

Pump air into the spark plug holes and see where it comes out. Do a leak down test.

Good luck

Happy New Year !!!

 

You didn't overfill it with oil? If so the oil may be foaming due to aerating from the crank. it should only take 5 quarts.