Loss of oil pressure

[Keith]

Engine was driven about a mile after it lost all the oil (hole in pan), had Mobil One oil in unit.  Engine now will start and run with minor knocking, when it gets hot, oil pressure drops to zero at idle, picks back up when accelerated.  Bearing problem?  Or engine destroyed?

[HOrnbrod]

What engine? What year?

[Eagle]

The pan has to come off anyway (if it hasn't already). I would replace the bearings (rods and mains), button it up, and hope for the best. The fact that it will start and run is a good sign.

 

When you open it up, before ordering the new bearings, examine all the bearing journals. If they aren't scored, I think you're safe to proceed. If they are slightly scored, you may be able to polish them up enough using crocus cloth.

 

There's a bearing size code stamped into the side of the engine near the distributor. Check that before ordering. Don't assume that everything is standard. They probably are -- but don't bet the farm.

 

While it's open, think about replacing the oil pump.

[Jeep Driver]

One mile with no oil/pressure?

 

You've spun a cam bearing anyway. 

 

You're pulling the engine. Regardless of what you can or cannot do with the bottom end. 

[Keith]

Eagle, thanks for the response, I will follow your suggestions and keep my fingers crossed.

[Jeep Driver]

1 hour ago, Keith said:

Eagle, thanks for the response, I will follow your suggestions and keep my fingers crossed.

You're not dealing with common knock

You ran it dry

Bearings oil pump front and rear seal oil gaskets Etc will run you about $300

It will take you about 14 hours worth of work assuming you know what you're doing and assuming that you can use standard bearings and you don't have to plastigage each bearing

You can find the Rod that knocks the worst by pulling your spark plug wires one at a time while the engine is running

Pull that Rod cap take a photograph it would be interesting to see that bearing Journal

Any foreign material in your oil passageway will come back to haunt you

It's your time and money just know that whatever you invest now you'll have to throw away because it will become contaminated referring particularly to your new oil pump

Post your results but I don't believe your cam bearings survived anyway and just because it runs now doesn't mean it will run a month from now

[Eagle]

An expedient field repair is generally worth a try before just assuming the engine is toast and tossing it.

 

In the famous book The Grapes of Wrath, the Hudson pickup truck the Okie family was driving west lost a piston ring. The repaired it on the side of the road by dropping the pan, lowering the bad piston, installing a new ring, and (since they didn't have a ring compressor, and that wouldn't have worked from the bottom anyway) using a length of fine thread or soft copper wire (don't remember which) to compress the rings while they pushed the piston back up. Once the engine started, the thread or wire released from the heat and the ring seated.

 

Yes, a work of fiction, but I don't think Steinbeck would have written that in such detail if he hadn't heard about the method from someone who had done it.

 

I number of years ago I picked up a 6-cylinder Javelin with a frozen engine. I removed the head, soaked the pistons with oil, and knocked them loose with a mallet and a block of wood. I reamed off the carbon rings, honed the cylinders with the pistons in place, blew and wiped out the gook as well as possible and put it together. I drove it as a commuter car for about two years when I worked in a neighborhood where I didn't want to take a decent vehicle.

 

More recently (about 6 weeks ago) a friend lost a piston in a '99 Wrangler with the 2.5L engine. Apparently that's a common ailment with the newer 2.5 liters. After driving it 15 miles with a broken piston, he pulled the head and pan, shoved the pistons and rods up through the bores, had new pistons put on the rods, and reassembled with new rod bearings. He didn't hone the cylinders, didn't even loosen the main bearing caps. It fired up and he said it runs stronger now than it did before the piston grenaded.

 

The point is -- yes, if you're building an engine for a NASCAR cup racer, you do everything "right." But in the real world, when you don't have anything to lose by trying a field expediant, why not do it?

[Jeep Driver]

1 hour ago, Eagle said:

An expedient field repair is generally worth a try before just assuming the engine is toast and tossing it.

 

In the famous book The Grapes of Wrath, the Hudson pickup truck the Okie family was driving west lost a piston ring. The repaired it on the side of the road by dropping the pan, lowering the bad piston, installing a new ring, and (since they didn't have a ring compressor, and that wouldn't have worked from the bottom anyway) using a length of fine thread or soft copper wire (don't remember which) to compress the rings while they pushed the piston back up. Once the engine started, the thread or wire released from the heat and the ring seated.

 

Yes, a work of fiction, but I don't think Steinbeck would have written that in such detail if he hadn't heard about the method from someone who had done it.

 

I number of years ago I picked up a 6-cylinder Javelin with a frozen engine. I removed the head, soaked the pistons with oil, and knocked them loose with a mallet and a block of wood. I reamed off the carbon rings, honed the cylinders with the pistons in place, blew and wiped out the gook as well as possible and put it together. I drove it as a commuter car for about two years when I worked in a neighborhood where I didn't want to take a decent vehicle.

 

More recently (about 6 weeks ago) a friend lost a piston in a '99 Wrangler with the 2.5L engine. Apparently that's a common ailment with the newer 2.5 liters. After driving it 15 miles with a broken piston, he pulled the head and pan, shoved the pistons and rods up through the bores, had new pistons put on the rods, and reassembled with new rod bearings. He didn't hone the cylinders, didn't even loosen the main bearing caps. It fired up and he said it runs stronger now than it did before the piston grenaded.

 

The point is -- yes, if you're building an engine for a NASCAR cup racer, you do everything "right." But in the real world, when you don't have anything to lose by trying a field expediant, why not do it?

Ever hear the phrase?- Don't ask a question you don't already know the answer to.

 

If you have to ask, you really don't know. Advise accordingly. 

 

 

Until people learn to use a camera and post pics of what you've got.....ie..........the rod and main journals............

Everyone is just pissing in the breeze. 

 

OP,  post some pics. 

[HOrnbrod]

3 hours ago, Eagle said:

An expedient field repair is generally worth a try before just assuming the engine is toast and tossing it.

 

Of course it is, and a viable option for the OP should choose to take it. No further explanation for this course of action is needed to anyone except the OP if he needs more details.

[Pete M]

It doesn't sound good.   but there's no way to know for sure until you tear into it.  

[Eagle]

5 hours ago, Jeep Driver said:

Until people learn to use a camera and post pics of what you've got.....ie..........the rod and main journals............

Everyone is just pissing in the breeze. 

 

OP,  post some pics. 

 

He can see what the rods and mains look like without any help from us. Your concern was the cam bearings, and if he's going to tear it down far enough to check those he's well into doing a rebuild.

 

The OP asked for opinions. I offered my thoughts. Your thoughts are different from mine. That's life. If it runs now but has low (zero) oil pressure just at idle, I think it's worth throwing a set of bearings at it. If that doesn't work, he can still use those new bearings for a rebuild. Once he drops the pan, if the bearing journals are badly scored, then he'll know it's time for a rebuild, or a different engine.