Howdy,

I've got a 1991 5.7 liter with no oil pressure. I checked it with a gauge, so I know it's not the sending unit. The engine's been sitting for three years, and there was a lot of solids/sludge in the oil when I changed it.

Can an oil cooler be so plugged up with sludge, just from sitting, that it can't push any oil through? I mean I'm getting ZERO pressure. It's a major hassle getting to that oil cooler.

Thoughts anyone?

pull the distributor and take a look down the hole to see whats going on. you could also try priming it with a drill to see if you get pressure on the gauge

Yeah that was going to be my next move. Buying a primer tool tomorrow.

When I put the distrib back in... is it keyed so it's lined up properly for timing? Or is it slotted or splined or something so that it's possible to totally screw up the timing when I put it back in?

I would suggest that you get somebody that knows what their doing to put the distributor back in and reset the timing . It's real easy to f@ck this up if you do not know what your doing.

Does the engine start and run? You could always just remove all the plugs and spin it over. Using a primer tool won't be any different. Restricting the oil flow is what makes pressure so a clogged cooler wouldn't have anything to do with it.

This has happen to me a couple of times where the oil pump seems to have lost its prime or suction ability after the engine has sat idle for an extended period of time. Certainly the best way is to prime the engine thru the distributor, but I really don't like messing with the distributor. What I do is pressurize the oil system thru the oil pressure sensor fitting, standard pre-lube approach (but with a temporary connection). This has a dual benefit, it pre-lubes the oil system and it also backs oil into the oil pump. I think that you will find once the oil pump has some fresh oil in it that your system will pressurize like it should. I purchased a master lube and just use it as a portable unit, although I probably should mount it permanently. If the system doesn’t pressurize instantly, shut down because something else could be wrong. A bad example would be that the draw tube has broken off the oil pump. If I haven’t ran an engine for a while, I will go ahead and pre-lube it before I will even crank in.

Hope this helps,

Andy

Yes the engine starts right up, but dies after about 5 seconds, like it's starving for fuel. I thought that the ECU might be detecting a no oil pressure condition and shutting off fuel flow (it's fuel injected). I guess if the oil pump picks up from the pan and then it goes to the cooler, that wouldn't prevent pressure from building, so that makes sense.

Since it was sitting for three years, I started out by lubing the cylinders and barring over with plugs out. Then I spun it with plugs out. It never builds any pressure up. I initially thought it was the sending unit, but then I put a mechanical gauge on it and saw that there's no pressure. Tomorrow I'll try pulling the gauge and just putting my finger over the hole to see if any oil is flowing. I suppose I could pull the oil filter and blow pressurized air through the system as well.

Yeah, that's a great idea. Thanks Andy. I'll definitely try that. I found an post that has an inexpensive pre-oiler a guy built out of a soda keg. I'll probably do that, since I've got the other engine coming back from the machine shop soon and it'll be dry.

I ain't scared , besides, you can't learn to swim if you don't get in the water.