I paid $500 for this project. It was a company truck that received regular maintenance at a Ford dealer. It sounds great at startup and has plenty of power. After warming up, it makes crazy tapping and knocking when I drive it. It also occasionally stalls and/or runs rough. I first thought it was rod bearings but after some research, I thought it was the timing chain tensioner/guide/phaser problem. I decided to check oil pressure before I tore into the front just to be sure there weren't other problems. I used a GlowShift adapter, which meant replacing the filter and catching some oil in the drain pan. Pressure at idle is 60 psi at startup in 75 degree weather, using 5w-20 which I had just changed. Pressure at idle drops to 40 when hot. I thought both readings were great, especially for an engine with 250k. I do have a P022 code so maybe it is a timing-related problem.

Unfortunately, when I went to empty the drain pan and the oil in the filter, I saw brown oil, like mud. What I was hoping was a timing chain issue is now head gaskets, or worse.

My current analysis: head gasket(s) gone but rod bearings not necessarily destroyed since pressure hot is 40 psi. Knock could still be timing chain issue, or maybe it's probably timing related since I have the P022, but it could also be rod bearing(s).

So, I'll do a compression test first, but not until we fix a bad torque converter or pump shaft on our 2000 Windstar. And rethread a spark plug hole on a 2000 Taurus since it threw a plug last weekend.

Any other suggestions to narrow down the problems? Are head gaskets a common issue on 5.4s?

 

No the 2 most common problems are the cam phasers, and the 2 piece plugs breaking of when trying to remove them. But if it has been maintained by the ford dealer it should have had the plugs changed twice now and they updated to a one piece plug that doesn't break. The cam phasers will make knocking sound when going bad obviously I can't say for sure that's your problem but I'd also be looking into that. For 500 bucks I'd still say you got a deal even if you have to put a motor in it.

 

Hate to say it, but I think it's engine time. Coolant contamination does lots of nasty things to your oiling system:

The Effects of Glycol Contamination in Engine Oils

Your oil pressure readings aren't accurate because your coolant is thickening up your oil. I think it's likely your bearings are trashed from the contamination. Mike may have something with the cam phaser suggestion because they are oil pressure actuated. I'd change the oil and take it for a drive to see if the problem goes away with the contaminated oil. If it acts the same once you start driving it I'd be sourcing a used engine.

 

Another scenario and some other info. Truck has been sitting for a year. I've only been running the engine long enough to move it in/out of the drive way. So maybe the coloring is due to combustion byproduct (moisture) that's not getting "boiled off" since the oil never gets hot. I've read of this before both as a cause of gunk on the oil filler cap and as a source of other problems (exhaust system corrosion, etc). I haven't been monitoring the coolant level but it's still above min level in reservoir tank, which admittedly is not exactly scientific.

The oil filler cap shows gunk from moisture. The reservoir tank shows no sign of oil floating on the water. See pics.

Coolant system pressure test holds pressure at 12 psi 30 minutes after pumping up to 16 psi. Don't know what the drop means.

I'm gonna send a sample to Blackstone Labs and see if they find water or antifreeze in it. I'll also change oil but will try to catch the first few ounces separately in hopes of catching any water present (water will settle below oil).

I read somewhere that it takes very little water to turn oil cloudy/milky so I'm hoping the chocolate milkshake oil is from running the engine for short periods. I also plan on adding drops of water to oil in a glass jar to see how much water is actually needed to turn the solution brown. Will repeat with antifreeze.

 

While I'm waiting for the kit from Blackstone labs to arrive, I decided to change the oil and check oil pressure at startup before any water/antifreeze has a chance to contaminate the oil. Pressure was 60 psi at startup so my previous reading of 60 was not because of water mixed in oil.

I drove the truck a bit, engine ran for 15 minutes. Oil pressure gradually dropped and noises got worse. Pressure was about 10 psi as I pulled into driveway and increasing engine RPMs did not increase pressure. I let engine sit for 2 minutes, started it and oil pressure was 40 at idle.

So, something is intermittently causing these variations in oil pressure. I can't see how bad rod bearings could cause this. I can imagine bad timing chain tensioners causing this.

Sound reasonable?