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Coolant in oil

brielly

NAXJA Forum User
Location
nj
I just dropped the oil pan to do the rear main seal (again) and you guessed it......coolant in the oil. The last time I dropped the pan a few weeks ago there was no sign of coolant. I had suspected a cracked head because i was losing coolant for quite some time but I never saw anything in the oil and I even went as far as doing a block test which came up good. I'm guessing coolant may have been burning off in the exhaust or combustion chamber but now the leak crack has gotten worse. I'm a bit concerned about dropping a new head on an engine that has 140k but the rear main bearing did look to be in good condition, the oil pressure is good and there's no strange noises coming from the engine. Should I just go for it? Which would be best, the new casting from clearwater or a rebuilt tupy? Thanks!
 
I wouldn't put a new head on a high mileage bottom end, but that's just me!
 
Well the if the oil pressure and compression are good, even with that mileage, a new head maybe ok. specially if you dont pay labor and have the time. My buddy did that with I think simular mileage, and we have been jeeping for the last two year with it.

Id at least first check the oil pressure, and compression to see how the engine is, if within wear limits by a reasonable margin, then go for a head if you want. you may get who knows 40,000 maybe 60,000 more miles out of that motor bottom end.

Of course confirm the crack if you can, before buying a new head. Maybe you get lucky and find no crack, only a messed up leaky head gasket! How sweet that would be!

You will also get a peak at the bores with the head off, and can check for excessive wear, even measure it. Also ask was she burning oil?, or making excessive engine noise?, or passing smog test? and such as an additional check before deciding if it makes sense to replace head or the whole motor.
 
Thanks! Being that this head is prone to crack there's no way I'm putting it back on. I'm leaning toward the new casting from Clearwater. This is no longer my daily driver so hopefully I can get it back up and running for a few more years.
 
You can also get a newer head off a grand cherokee that is a tupy head , that's what i did . Just checked it out reseated the valves and changed the valve seals . It only cost me about $75 from a pick an pull .
 
I have redone heads on high mileage engines before without any issues. My 2001 XJ had its head rebuilt at 180,000 and replaced with a TUPY at 314,000. It now has 396,000 and still runs fine... I have another one that I had the head rebuilt at 186,000 and it now has 267,000 and still runs fine... If the engine isn't burning a lot of oil I see no reason to replace the bottom end.
 
The new cylinder head from clearwater is on and it's running well. Looking at the old gasket, it appears that it rusted through in one spot. There was rust everywhere the gasket came in contact with the water jacket. This is not surprising since the po clearly neglected the cooling system and probably used regular water instead of distilled. The coolant looked awful when I first bought the truck an only after several flushes is it now nice and clear. If there's a lesson to be learned here its change your coolant!
 
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