So if you saw my last post you know that I'm shopping for an 89 or 90 4cyl manual Dakota. I found a 2WD one near me at a below market price buuuuut the seller says that there's coolant in the oil. I've done a bunch of research and come to the conclusion that it could only be a head gasket, warped head or block (though more likely to be the head), and/or a cracked head or block (again the head is more likely). I dont mind pulling the head and doing some work on it, or worst case buying a new head, but before I do that I wanted to fact check my conclusion.

On the 89 Dakota, is there anywhere else for coolant to contaminate the oil? No on-block or in-radiator oil cooler? Or maybe an oil cooler attached to the filter mount?

And finally, is there a consensus on what head gasket material is best? I saw on minimopar.net that mopar makes a pretty good head gasket for the Chrysler 2.5L but it comes in 4 different flavors and I don't know which one I'd need. If not the Mopar one, Oreilly's also has a bunch of MLS and composite options, and RockAuto has a bunch of fiber re-enforced and graphite ones.

 

Seems like a cracked block is also possible source of coolant in oil. I have no other info.
Well I have this link. https://precisionengine.com/chrysler-engines/
There are a couple 2.5's there.

 

On my 95, Don’t see any oil cooling that uses coolant. So, the head or the block are about it.

About 4 mos ago I got oil in the coolant and coolant in the oil. I also had billowing white smoke out the exhaust. I had a blown right head gasket, and both heads were cracked. I got new heads and used a Felpro gasket kit that the machine shop recommended. Be sure to use new head bolts.

 

I don’t recall you updated us. Last I recall you were weighing your options.

 

Working on wiring harness finally cured the problem that started 7 mos ago. While working on it, the head gasket blew, so I replaced the heads. Runs great now.

Except, it overheats when it idles for 20-15 min in our 103 degree heat. I thought about putting an electric fan in it but I need a break. I replaced the fan clutch and the thermostat. No luck. Today I am replacing the radiator. When I was trying to get the oil out of the coolant, after the head gasket blew, I searched the web for the best way to get all the oil out. Just flushing with water wasn’t doing it. One suggestion was to add about a cup of liquid dishwasher detergent, let it run for a while, then flush. That did get almost all the oil out, but I have a hunch that the dishwashing detergent plugged the radiator. It was thick, blue and gel-like. I’ll know this afternoon if the problem is the radiator. I would strongly suggest not using dishwasher detergent to clean your cooling system. Maybe Simple Green would work better.

Ah, live and learn.

 

A new radiator isn’t all that expensive.

 

I've heard some crazy ideas before but ...OK I was told ot use citric acid. I ended up using powdered TSP. 1lb box into a gallon distilled water. Of course you have to dump some water out. Then drain the system, pour in teh water/TSP and fill it with distilled water. Run it until warm let it cool and repeat.I did it a few times on my little truck with the over heat problem and ever drove it a bit. When I drained it and flushed it many times and finally filled it with coolant I had a working heater for the first time since I owned it!. The motor also cooled a lot better. If your heater works it might be the thermostat. I have the 180 degree thermostat in my Dak not the OE 195. I see RA has a 160 T as well for my year. You might consider it.
Ooops I see I am hijacking here sorry OP.

 

I’ve always been reluctant to run anything in the cooling system other than anti freeze and the prestone chemical flush. I’m not smart enough to know how other cleaners will react with the various metals in the radiator, heater core, water pump, and engine block. I’m just too chicken to try. I wouldn’t mind changing out a radiator or even a water pump but I don’t want to change out a heater core or (worse) an engine or head gasket.

 

Prestone flush is Sodium Citrate and water. Sodium Citrate is the Trisodium salt of citric acid.
TSP is the same thing with phosphorous which is a rust converter.
Prestone max flush has a third ingredient that they identify as proprietary nonionic surfactant. From what I remember of how Ospho (phosphorous based rust converter) feels it is probably something phosphoric.It is pretty harmless since they use phosphoric acid in dentistry on your teeth as prep to glue something on.