3406b Oil in Coolant

[H621]

Hey I need some help, this 3406b has oil in coolant. I removed oil cooler pressure tested @ 110psi in 170°f water bath and not a single bubble. So I went to the air conpressor and pressure tested the Coolant side to 50psi (accidentally, I only meant to go to 10 but whatever) it held just fine. I also vacuum tested the Coolant side of air compressor to 25"hg and that held just fine. So i checked radiator with sealed check valve tube for compression getting into radiator, again no bubbles even at operating temp. What am I missing? Theres no Coolant is in the oil pan. Is there a possibility of head gasket failure between oil and Coolant passage ? Any advice is appreciated

 

[Former Wrench]

With the oil drained and thermostat removed, pressure test the cooling system. (NAPA and others carry the tool,) If coolant is running into the pan, my guess would be bad head gasket or cracked head.

 

[Truck Shop]

Just by chance does this truck {if it is a truck} have a coolant type transmission cooler mounted on the
transmission? So we get that possibility out of the way. Is the oil in coolant black or brownish color?

 

[H621]

Just by chance does this truck {if it is a truck} have a coolant type transmission cooler mounted on the
transmission? So we get that possibility out of the way. Is the oil in coolant black or brownish color?

No it is only an air cooler on the transmission. Oil in radiator was black

 

[H621]

No other auxiliary comes either.

 

[Truck Shop]

This is where ruling large items out starts. IMO-others may disagree which is fine but If it were me
I would drop the pan pressurize the cooling system to 15 psi and look for leaks from the bottom up
with rocker covers removed.

 

[H621]

I may do that, but my thoughts are at 15psi it may not be leaking. It may only leak at 40psi+ and at operating temp. I don't want to give a false positive test. But my options are limited from my understanding at this point

 

[Truck Shop]

Well at operating rpm {idle} oil pressure would be 40 psi and 55 to 60 at 1700 rpm. So the oil pressure will
overcome the coolant psi of 10 psi at hot working. With engine off at 15 psi on the cooling system you may
have a chance finding it. On E models when injector sleeves leak it pushes fuel into radiator while running
and coolant into fuel when off till engine cools and radiator pressure drops.

 

[H621]

Well at operating rpm {idle} oil pressure would be 40 psi and 55 to 60 at 1700 rpm. So the oil pressure will
overcome the coolant psi of 10 psi at hot working. With engine off at 15 psi on the cooling system you may
have a chance finding it. On E models when injector sleeves leak it pushes fuel into radiator while running
and coolant into fuel when off till engine cools and radiator pressure drops.

Ok ill give it a shot. Thanks

 

[Truck Shop]

We don't want another B model thread like the last one without proper trouble shooting. IMO

 

[Simon C]

I did test a engine oil cooler like in first picture in green tub, and it had no leaks for 3 times of off engine in tub. But was putting oil into coolant when running. It was leaking only with vibration. It finally appeared in tub leaking but would not with 20 PSI.. Very hard to diagnose if only vibration will get it leaking. That is my experience.
Simon C

 

[Truck Shop]

Very hard to diagnose if only vibration will get it leaking. That is my experience.
Simon C

That's a good point, one thing on those coolers that needs to be checked is where the tubes are vulcanized
around each other and to the main housing. If the rubber between those tubes and body is coming apart
or deteriorating it's a bad sign.

 

[Nige]

one thing on those coolers that needs to be checked is where the tubes are vulcanized around each other and to the main housing. If the rubber between those tubes and body is coming apart or deteriorating it's a bad sign.

Do you have any photos of what the cooler end plates look like.?

 

[H621]

 

[Truck Shop]

Do you have any photos of what the cooler end plates look like.?

I don't Nige- but when those go bad it's easy to spot because the sides of some tubes are more exposed
than others plus the material sealing the tubes kind of turns to a goo.

 

[Shimmy1]

I don't know of anyone around here that even bothers testing an oil cooler when they have a radiator full of gravy. Not saying it's right, but when the black is getting into the water, a new oil cooler gets put on, system gets flushed, and back to work. I have never heard of anyone hunting for a leak anywhere else....

ESPECIALLY on a B-model. Never.
Cats and ISX seem to have oil cooler trouble the most.

 

[Truck Shop]

Need a end view of tubes please.

 

[Truck Shop]

I have never heard of anyone hunting for a leak anywhere else..

I don't know of anyone around here that even bothers testing an oil cooler when they have a radiator full of gravy. Not saying it's right, but when the black is getting into the water, a new oil cooler gets put on, system gets flushed, and back to work. I have never heard of anyone hunting for a leak anywhere else....

ESPECIALLY on a B-model. Never.

That where you are and yes there are other places to leak. Always.

 

[H621]

I'll have to get a better picture tomorrow off the ends

 

[Nige]

I don't Nige- but when those go bad it's easy to spot because the sides of some tubes are more exposed than others plus the material sealing the tubes kind of turns to a goo.

Sorry for the confusion Mike. My question was directed at the OP. Since he had the cooler off for testing I thought he might've taken some photos of it looking from the direction of the water bonnet rather than in through one of the oil ports.

EDIT: Is dem cracks that I sees..??