oil cooler Q's

[1992gen1_fan]

Hello. I think the oil cooler might have sprung a leak on my truck. Theres oil in the coolant. Does anyone here use an external oil cooler instead of the factory water/oil core?

[PToombs]

If the oil cooler is bad you'll need to replace it, not work around it. It's in the block behind the oil filter. You can't run with out it or the oil will really get into the coolant.

[1992gen1_fan]

Ok, thought that might be the case. I had heared of a kit that by-passes the stock cooler to a external air cooled, but I guess I'd have to fix the stock one first

I should be removing the cooler to test it this weekend. I hope its broke instead of the head gasket

[BobS]

Always use the correct replacement part.

The "oil cooler" is actually a "heat exchanger" It is calibrated by the number of heat exchanger plates it immerses in a constant thermostatically regulated coolant. Too few plates and the oil overheats and cooks. Too many plates and the oil sludges up.

A leak in the heat exchanger usually ends up with oil in the coolant and coolant in the oil. The oil pressure overcomes the coolant pressure and seeps oil into the coolant. After the engine shuts down the coolant pressure overcomes the zero oil pressure and transfers coolant into the oil. The transfer proportions are not equal. The oil transfer rate will generally be much higher than the coolant transfer rate and is why it is noticed first.

[1992gen1_fan]

The last oil test analysis I had done showed a small amount of coolant in the oil so I was expecting something to happen sooner or later. I plan to pressure test the oil cooler soon. Just looking at the oil coolers online looks like the 7 plate coolers are whats in the dodge trucks correct?

[BobS]

The last oil test analysis I had done showed a small amount of coolant in the oil so I was expecting something to happen sooner or later. I plan to pressure test the oil cooler soon. Just looking at the oil coolers online looks like the 7 plate coolers are whats in the dodge trucks correct?

Correct - 7 for a 6BT and 5 for a 4BT.

[1992gen1_fan]

The last oil test analysis I had done showed a small amount of coolant in the oil so I was expecting something to happen sooner or later. I plan to pressure test the oil cooler soon. Just looking at the oil coolers online looks like the 7 plate coolers are whats in the dodge trucks correct?

Correct - 7 for a 6BT and 5 for a 4BT.

Ok thats what I thought, thanks

[BC847]

While the engine's oil heat exchanger helps keep the engine oil at no more than the engine's coolant temperature, it also helps warm the engine oil after a cold start-up and cold weather in general.

[1992gen1_fan]

Good info

Well, did'nt get around to taking it appart today. I did loosen the oil drain and let just a little oil out to see of there was coolant at the bottom and there was'nt luckily. It don't even have a coolant smell to it.

[Deathrod]

Sure it's not head gasket?

[1992gen1_fan]

Sure it's not head gasket?

I'm not for sure yet, the head gasket is fairly new as I replaced it a couple years ago and had the head resurfaced and the valve seats done.

The upper rad hose does get kind of tight fairly quick after starting the engine sometimes. Its done that for a while, or as long as I can remember anyway. Are there any simple tests I can try for the HG?

[93-12smoke]

One way is to crank the truck and remove the radiator cap to watch for bubbles. If you get bubbles, you got a bad head gasket.

[1992gen1_fan]

Ok, so if I start the engine and see bubbles in the rad at idle, head gasket is bad? Easy enough, I'll give that a try

That test would tell me if there is cylinder pressure getting into the coolant system, but might not tell if theres a hole between the coolant and oil. I might need to rent a rad test kit to test this??

[1992gen1_fan]

I took the rad cap off and let the engine idle for over 5 minutes and there were no bubbles in the coolant at all.

[93-12smoke]

So then your hole is must likely between just an oil passage and water jacket. I think problems with the oil cooler are more rare than head gasket issues. I recently replaced both the hg and oil cooler at one time because i was in a time bind and couldn't do one then find out it was the other and need to order parts. My oil cooler was fine.