hi everyone, my truck is an 86 f250 with unknown mileage that has a junkyard engine in it that the guy said has "ohh about 100k". In other words unknown mileage as well. I put that engine in about 10 years ago. Its from an 85 econoline. Its a 351w HO carbed.
The other day I checked my engine dipstick while it was cold and got nothing but water on the dipstick. No wonder it always screeches loudly for a couple seconds when I start it cold. It runs just fine otherwise. I don't know how the water is getting in but I know there's a big pool of coolant on top of the timing cover on the drivers side and it looks like the timing cover is leaking. I also want to take a look at the valves on cylinder 8 bc so much oil leaks into that cylinder, I've had to run a hotter plug or else it won't fire. I figure now is a good time to take the head off and replace whatever is leaking for cylinder 8. I also understand that the water leak could be through the intake manifold gasket so I want to replace that as well.
So I want to change the timing cover gasket and timing set while I'm in there, water pump, intake manifold gasket, thermostat, head gaskets and whatever work the heads need. Should I try to do all this with with the engine in the truck or just pull it out and do the work on an engine stand? Should I take more diagnostic measures to pinpoint my leak then deal with the oil leak into cylinder 8 separately? I'm thinking that a cooling system pressure test won't show me where internal leaks exist between water and oil. Am I wrong about this?
what would you do if it was your engine? Money is tight so that is a big concern. This is not my primary vehicle and only drive it 1000 miles a year. I've put a new rear main seal, oil pan gasket and valve cover gaskets on this engine since it's been in the truck and it's a strong engine with plenty of power.
Sorry if that was too long and all over the place. Thank you for your time if you read it and I look forward to hearing what you think.

 

I would pull it and go through it this way you can check main & rod bearing also.
Dave ----

 

If you are setup to easily pull it, then that is an option. Exhaust manifold pipes can be a pain to get loose. It is cheaper to get a complete engine rebuild gasket set, even if you do not use the head gaskets. Before you pull it, I think I would get a compression tester and check #8 cylinder to see how serious it is.

Some people have no means to easily pull a heavy engine out, so that is a consideration.

 

Given the opportunity to spend your time and money, I'd suggest running some basic diagnostics before anything else.

Are you losing coolant from the cooling system? Does the level keep dropping? Or are just finding water (not coolant?) in the crankcase? Who knows, maybe you've got neighbor kids playing gas station, and topping off the engine with water. I'd run a pressure test to make sure the cooling system is intact. You are correct a pressure test won't pinpoint the location of an internal leak. But it will confirm if you have a leak or not. And if you do have a leak, I'd lean towards the timing cover. If the leak was into a cylinder, I think you'd see it in the exhaust and the liquid in the crankcase would probably be frothy.

For the one unhappy cylinder, a compression test will provide more info. Could be a broken oil ring or valve seal, who knows. Start with a cranking compression test, and then if out of limits, do a cylinder leakdown to pinpoint the problem.

 

The coolant level does go down over time. I did do a compression test on cylinder 8 when I found the oil fouling problem. That was 10 years ago and have been running with the hotter plug ever since. I remember the compression was good enough to keep running it that way. When I pulled the dipstick out with the engine cold, there was no oil on it, just water. I changed the oil 6 months ago so I know there should be oil in there.
I'm leaning toward pulling the engine so what else should I do while the engine is out?

Also, I don't see any frothyness to the oil and there is no water coming from the exhaust

 

You might as well pull the heads. You can then see how much ridge is in the top of the cylinders and also investigate cylinder 8. Definitely change the timing chain and gears if it looks loose. The only way it would not be loose is if someone had changed it before.

If there is a lot of ridge in the top of the cylinders you are going to have to think about what to do next. A lot of ridge means a lot of wear in the engine.

 

I am planning on pulling the heads. Good advice about the potential ridges. If they're deep, I'll make some hard choices. This picture shows some of the leak I was talking about but not the pooling on the timing cover. Also, I can't tell if this shows a leak from the head or not. What do you all think?

 

Hard to tell the source of the leak. The fan and the air going by when you are moving can blow it all over. Best thing to do is to clean it up with brake cleaner and rags, and then drive it while keeping a close eye on it. On the cylinder wear, the ridge thing is a rough measurement to see if you do have wear. If you do have some ridge, you can take the block in and have it measured. If it has more than .006 inch wear they will need to bore it and put oversized pistons in it. Anything less and you can get by with just cutting the ridge off and putting new standard rings in it.