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HI All,
My 1997 Ford F-150 w/ 4.2L Engine is being evaluated for repair or replacement. There is coolant in the oil. Since it doesn't blow a lot of smoke I suspect the head gasket is ok and the coolant is making its way into the oil via the water pump housing. There is at least one place oil runs thru the housing and if the gasket is breached the fluids will mix. Prior to this the heater would sometimes work and other times it would not, but right before it would start working again I would hear a swooshing sound. like pressure releasing. I suspect the heater core is plugged with "milkshake".
The question is whether the engine can be salvaged from the milkshake condition without completely tearing down and rebuilding. The rings and bearings, head gaskets, heads resurfaced at 130K, it's at 166K now. If you were to replace the engine, what engine would you replace it with. I use this truck periodically about 10-20 miles per month, so I don't need it to haul a trailer/boat. Suggestions?
Steve
Last edited by Steve Leitzke; Jun 20, 2025 at 06:31 PM.
Iirc It's in the timing cover directly behind the pump. On the 3.8's which is basically all the 4.2 is had a well known problem in that area of the engine, the 4.2's weren't as bad as the predecessor.
IF you’re gonna keep the truck I guess you could try a back flush and see if helps
not knowing how long it’s been run with a milkshake would lead me to toss the engine and grab another, If I were to do that, I’d grab a 4.9/300 and slap ‘er in modify some wiring exhaust etc and enjoy
You are correct. The timing cover is between the water pump and the block. The gasket at the block is gapped allowing coolant to combine with the oil. Thank you for correcting me. Whomever worked on the engine before probably re-used the gasket. It is very thin and should never be re-used.
HI All,
My 1997 Ford F-150 w/ 4.2L Engine is being evaluated for repair or replacement. There is coolant in the oil
I use this truck periodically about 10-20 miles per month, so I don't need it to haul a trailer/boat. Suggestions?
Steve
I would just fix the coolant/oil interface problem, run it the 10-20 miles per month and see if there's a major problem. Sounds like the only "problem" at this point is the fact that you found coolant in the oil. It still runs. Oil-water can still lubricate. Good luck.
You are correct. The timing cover is between the water pump and the block. The gasket at the block is gapped allowing coolant to combine with the oil. Thank you for correcting me. Whomever worked on the engine before probably re-used the gasket. It is very thin and should never be re-used.
Common problem as I mentioned, it's why they redesigned the V6 and came up with the bullet proof 3.7 V6 in 2011.
