Oil in Coolant? Is this the forbidden cream?

[ruhroh]

I bought an used car - it has issues but this potential bad head/HG wasn't disclosed. Car is a 2017 Grand Cherokee 3.6 Pentastar with VVL/VVT @ 110K miles.

Is this what I think it is? It is on the inside walls of the coolant reservoir. The coolant itself doesn't have oil slicks so the previous owner must have been driving like this for awhile and adding coolant. I don't know the rate that it loses coolant because I don't want to drive it until I fix everything else.

I think a head removal is in my near future - I sometimes see white vapor out the exhaust. Do you think I should borrow a combustion gas detector to make sure?

I am planning to also take a look at the rockers. I notice a slight tick but I can't be sure if it's normal. Should I replace the exhaust rockers/lifters even if they're not bad? Those should cost about $140 for both banks. This car also has VVL, which means fancy expensive rockers on the intake - each rocker costs over $90. Do you guys know if an alternative or better manufacturer for those exist? Otherwise, I'll replace only those that are bad because over $1000 for just a set of new intake rockers is insane to me.

Also, what is the proper etiquette for sending heads off to a machine shop to check for flatness? Do I strip it down to the bare head or leave the valves? Do I leave on the cam caps? Is google the main way to find machine shops in the first place?

Thanks

 

[JRay’07]

Was a non-OEM coolant ever mixed in? Perform a pressure check of the cooling system before condemning the head gasket.

 

[Number_35]

Are there any other places where oil and coolant are proximate (besides a head gasket) such as an oil cooler?

 

[Gyro Gearloose]

Change the oil and send a sample for analysis. In the comments mention that you are suspicious of a coolant leak into the oil.

 

[ruhroh]

I changed the oil the first thing when I got it home, I didn't find any glitters and no visual evidence of water/antifreeze. The old oil was in service at least 2K miles so if there is mixing, it had plenty of time to leave some hints. There is a plastic oil cooler on this car that is a weak point - the alternative is an aluminum cooler but it's made by the big D and that makes me uneasy, hahah

 

[tiger862]

You could have a bad cooler under the intake. It will mix oil and water which will give you the milkshake.

 

[ruhroh]

You could have a bad cooler under the intake. It will mix oil and water which will give you the milkshake.

Thanks for that suggestion. Definitely possible, but there is sometimes some white smoke out the tailpipe that smells like fried wires, which shouldn't happen if it's mixing through the oil cooler and not in the combustion chamber. But then again, sometimes I see it, sometimes I don't and that's strange to me unless it's a minor slow leak into the cylinders somewhere.

 

[bullwinkle]

The “Big D” oil cooler/oil filter assembly is cast aluminum, the (weak) OEM one is plastic. People do swear by the Dorman one, but it’s possible to have the plastic one last, our spare ‘15 3.6 Dodge G.C. has 198K on the OEM one, it hasn’t failed yet. I would get a combustion gas leak detector from Auto Zone’s Loan-A-Tool program-that will tell you if your HG(s) have bought the farm or not, or God forbid, cracked a head or block.

 

[Mcbeem5]

Try pulling 1 valve cover, on Chevrolet 5.3 they had porous heads with pinhole coolant leaks.When valve cover was off there would be a peanut butter colored gel on the inside top of the valve cover,which was coolant mixed with motor oil -sludge!

 

[Kurtatron]

Make SURE it’s not condensate from short tripping cold starts. Short tripping condensate looks just like this. Change oil and avoid short trips and see if it comes back.

Edit: I didn’t see that your coolant reservoir has the goo. If it were the valve cover, my recommendation would apply.

 

[Exhaustgases]

If someone was selling a car with a coolant leak or head gasket issue, wouldn't they add a sealer to try to stop it?

 

[The Critic]

If you're going that far, I would just buy a long block. These engines are known to be a pandora's box.

 

[JimPghPA]

If someone was selling a car with a coolant leak or head gasket issue, wouldn't they add a sealer to try to stop it?

Depends who the someone is. There are people selling their cars who do not know what's under the hood, let alone knowing enough to try a quick fix mechanic in a can.

 

[ruhroh]

I ordered the block tester fluid and it should get here this weekend so I’ll go from there. Autozone had the tester loaner but didn’t stock the fluid to sell.

Trying to avoid changing the block because of cost. A head with valves from Mopar only costs $350 for the AA revision, likely priced lower to make room for AB. If it’s a HG or head issue, I’ll go that route instead of a machine shop. The AB revision head costs over $600.

 

[BMWTurboDzl]

I ordered the block tester fluid and it should get here this weekend so I’ll go from there. Autozone had the tester loaner but didn’t stock the fluid to sell.

Trying to avoid changing the block because of cost. A head with valves from Mopar only costs $350 for the AA revision, likely priced lower to make room for AB. If it’s a HG or head issue, I’ll go that route instead of a machine shop. The AB revision head costs over $600.

It's not oil if that's what you were thinking of.

 

[ruhroh]

Well,

As long as it's not a cracked block, it'll be good to give the engine a close inspection of its timing parts. Will have to take off the oil cooler assembly anyway to see if that needs replacement other than gaskets.

 

[The Critic]

Well,

As long as it's not a cracked block, it'll be good to give the engine a close inspection of its timing parts. Will have to take off the oil cooler assembly anyway to see if that needs replacement other than gaskets.

View attachment 238580

I wouldn't trust that test.

 

[ruhroh]

What else should I do? I see oily layer on the walls of the coolant reservoir, small amounts of white smoke out the exhaust, depleting coolant with no visible leaks. No misfires yet.

 

[John105]

If someone was selling a car with a coolant leak or head gasket issue, wouldn't they add a sealer to try to stop it?

That happened to me. Car failed day 2. Sued the seller and lost. He put the magic words on the bill of sale: As is.

I did manage to drive that car 1990-1998 but paid $900 for a used engine/tranny. Put into perspective that's like spending $2,300 for the repair, when I spent $4,900 (2024 dollars) on the car.

 

[The Critic]

What else should I do? I see oily layer on the walls of the coolant reservoir, small amounts of white smoke out the exhaust, depleting coolant with no visible leaks. No misfires yet.

Leakdown test and also inspection camera to check inside cylinder for moisture after keeping the cooling system pressurized overnight.