Hi -

I'm trying to help my daughter solve a problem with her 1991 F-150 4.9L w/air conditioning.

The serpentine belt is throwing off some sort of oil up near the power steering pump. The oil is so lightweight that I thought it was antifreeze at first.

Coming off the belt, the oil is a heavy mist or a very light spray; it's sort of like what you would expect from the nozzle of a spray bottle. It's getting all over the bottom of the hood and, with the help of the airstream from the fan, pretty much everywhere else.

The power steering pump was the first suspect because the oil is so light, and because it's flying off the belt at that location. However, the pump shaft and the inside lip of the pulley are dry and I don't see anything that looks like a PS fluid leak. I think it's flying off there just because the PS pulley is where the belt turns its sharpest "outside corner."

I'm trying to figure out where this oil is coming from. There's the air conditioning compressor, but with even a slow leak I would think it would be bone dry by now. There's the air pump -- but I've never known one of those to have any oil, much less spew it. Alternator? No, of course.

So, I'm pretty much talking myself into looking at the front crankshaft oil seal. That would surprise me for a couple of reasons. First, it doesn't look all that easy for oil from that location to get on the OUTside of the serpentine belt (to get thrown off). Second, the stuff on the bottom of the hood doesn't seem like engine oil to me. But then again, I'm "old school" and accustomed to 10W-40, not 5W-30. So maybe...

After all that, my question is: Does anyone have experience with solving this particular problem? Any advice (even a joke or two) would be appreciated.

Thanks in advance.

Mark W. in MI

 

If you have an automatic, it may be transmission fluid. There are transmission fluid lines that run into and out of the radiator on the drivers side. If those are leaking, it could be spraying fluid out. Another possibility is power steering fluid from one of the lines.
Has any fluid shown a drop in the level?

 

It's probably coolant coming out the weep hole on the water pump. Check the coolant level in the radiator (NOT while it's hot), and try warming up the engine while the cap is off. If the leak stops, it's probably because there's no pressure building up. The weep hole can be hard to see because the pulley bells over the front of the WP, but if you look up from below, you'll probably see a drop of coolant on the WP pulley.



All oil looks basically the same after sloshing around inside an engine, and that engine shouldn't have 5W unless you live in Alaska.



This thread describes how to post pics free on this & most other BBSs:
http://www.supermotors.net/forums/th...-and-or-videos

 

Thanks for the reply, Steve.

I remember what you're talking about from when I used to work on a occasional Chevy 350 many, many moons ago. In this case, though, no antifreeze dribble. Good suggestion, though, and thanks again!

 

I think you're on the right track, Kingfish.

I noticed a few weeks back that the A/T lines to the radiator were damp; now they're downright wet. And the transmission fluid level is down.

I immobilized the engine fan to stop that infernal wind and see if I could spot the leak. There does seem to be a mist coming from the area where the line connects to the radiator.

What still bugs me, though, is how it gets on the outside of the belt and how such a small mist turns into a pretty respectable amount of oil in such a short time. Maybe it's under more pressure and therefore leaks more when I first start the engine, as I can't see that area from the driver's seat...

Anyway, I'll try two new transmission lines and see what happens. (I wanted to get stainless, but not even LMC carries them for a '91.) :-(

So thanks very much. As I said, I strongly suspect you're right.

Mark W. in MI

 

Once the engine heats up, it is under some pressure as it is pumped through the radiator. With trannie fluid, it does not take much for it to spread all over the place.