Oil in the coolant

[Dpas1973]

I can really use some help I have a 6.5 na rebuild by meltons is 09 if the odometer was t changed only has 6k miles I noticed oil in the coolant 9 months ago no coolant in oil. Was told head gaskets my mechanic has the heads off and say they look fine and the gaskets that he don’t see how oil in the coolant can be head gasket or a crack in a head he’s saying he thinks the motor is cracked and is saying there is test that he can do to confirm. But he’s never seen no oil in coolant/no overheating and it be a head gasket. Can someone please advise me.

 

[Mogman]

The GM 6.5 was bad about having cracked cylinder walls, it is said the tooling that machined the piston coolers nicked the bottom of the cylinders of blocks that had a significant core shift, (this would lead to a crack in that cylinder wall) many were the #8 cylinder, so it could be diesel instead of oil in the coolant which would look the same.
Have him do a combustion gas in coolant test or buy one off of fleabay and test it yourself.

Also unfortunately Melton rebuilds do not have a good reputation.

EDIT, if it failed the test after having the head gaskets replaced I would just drive it if it is not overheating while I looked for a good GEP takeout.

 

[Dpas1973]

The GM 6.5 was bad about having cracked cylinder walls, it is said the tooling that machined the piston coolers nicked the bottom of the cylinders of blocks that had a significant core shift, (this would lead to a crack in that cylinder wall) many were the #8 cylinder, so it could be diesel instead of oil in the coolant which would look the same.
Have him do a combustion gas in coolant test or buy one off of fleabay and test it yourself.

Also unfortunately Melton rebuilds do not have a good reputation.

EDIT, if it failed the test after having the head gaskets replaced I would just drive it if it is not overheating while I looked for a good GEP takeout.

When I drained the coolant it came out like mayonnaise that yellowish color like tar. He has the heads off now. I wondering if that’s why I been getting like 6-7 mpg and everyone else on the forums claim 10-12 mpg. I also have to add a half court oil every 3 months.

 

[Dpas1973]

The GM 6.5 was bad about having cracked cylinder walls, it is said the tooling that machined the piston coolers nicked the bottom of the cylinders of blocks that had a significant core shift, (this would lead to a crack in that cylinder wall) many were the #8 cylinder, so it could be diesel instead of oil in the coolant which would look the same.
Have him do a combustion gas in coolant test or buy one off of fleabay and test it yourself.

Also unfortunately Melton rebuilds do not have a good reputation.

EDIT, if it failed the test after having the head gaskets replaced I would just drive it if it is not overheating while I looked for a good GEP takeout.

So you think it’s a waste of time and money to have the heads tested?

 

[Mogman]

Maybe someone else has had this experience, all I can suggest is have him inspect the cylinders very carefully, have the heads magnifluxed for cracks and have the head gasket surfaces checked to see if they are true, if nothing is found then have him reassemble it and see, not all head gasket defects are easy to find.

There are certainly other defects that would allow oil to get into the coolant, some would be very hard to find.

But the coarse you are on, you are already into the project for almost half of the labor so giving up now would be a tough decision.

 

[Dpas1973]

So you think it’s a waste of time and money to have the heads tested?

Im stuck he said he has no way to confirm 100% it’s a crack and if I want the heads tested I would have to pick them up and pay and find someone to test them. Or he can put it back together for the 3k labor he charges for head gaskets and I leave. Or I can buy a new motor for him to put in

 

[Mogman]

Does he see what he thinks is a crack? if so where?

 

[Dpas1973]

Does he see what he thinks is a crack? if so where?

No he said visually he sees nothing wrong with heads or head gaskets and don’t see how oil and coolant can mix in the heads. He said it has to be a crack in the cooling jacket somewhere that’s it says he don’t see it.

 

[Mogman]

He is correct that the normal failure of a head gasket generally has coolant getting into the oil or both, but combustion gasses can get into the coolant from a head gasket failure, I don't think it could contaminate the coolant as much as you describe without being obvious, did you ever look for bubbles in the coolant tank, or did he test for combustion gasses before dismantling it?

As to when to give up that is a tough one and I can not advise, do you have a line on another, hopefully GEP engine?

 

[Dpas1973]

He is correct that the normal failure of a head gasket generally has coolant getting into the oil or both, but combustion gasses can get into the coolant from a head gasket failure, I don't think it could contaminate the coolant as much as you describe without being obvious, did you ever look for bubbles in the coolant tank, or did he test for combustion gasses before dismantling it?

As to when to give up that is a tough one and I can not advise, do you have a line on another, hopefully GEP engine?

He didn’t check anything first he went on my saying it’s prob head gaskets. I have no line on a motor you know anyone that’s selling one? I have idled the truck with the cap off the overflow and didn’t see any bubbles

 

[NotThatGuy]

I can really use some help I have a 6.5 na rebuild by meltons is 09 if the odometer was t changed only has 6k miles I noticed oil in the coolant 9 months ago no coolant in oil. Was told head gaskets my mechanic has the heads off and say they look fine and the gaskets that he don’t see how oil in the coolant can be head gasket or a crack in a head he’s saying he thinks the motor is cracked and is saying there is test that he can do to confirm. But he’s never seen no oil in coolant/no overheating and it be a head gasket. Can someone please advise me.

I'd check the trans cooler portion of the Radiator. I've seen them fail inside of the Radiator and cause Tranny Fluid to contaminate the Coolant.

Btw, You're Mechanic skipped a few diagnostic steps before assuming and pulling the heads off.

 

[Dpas1973]

I'd check the trans cooler portion of the Radiator. I've seen them fail inside of the Radiator and cause Tranny Fluid to contaminate the Coolant.

Btw, You're Mechanic skipped a few diagnostic steps before assuming and pulling the heads off.

The mechanic said I have an air cooled trans cooler no coolant runs through it. I have the dual oil/trans cooler how can coolant get in there?

 

[Mogman]

The mechanic said I have an air cooled trans cooler no coolant runs through it. I have the dual oil/trans cooler how can coolant get in there?

It can't

 

[Mogman]

He didn’t check anything first he went on my saying it’s prob head gaskets. I have no line on a motor you know anyone that’s selling one? I have idled the truck with the cap off the overflow and didn’t see any bubbles

If I ever taught a "customer 101" course the very first thing I would say is never tell the mechanic what the problem is unless you are willing to take the consequences, the only thing the customer should do is describe the symptoms and let the mechanic do the diagnostics.

 

[Dpas1973]

If I ever taught a "customer 101" course the very first thing I would say is never tell the mechanic what the problem is unless you are willing to take the consequences, the only thing the customer should do is describe the symptoms and let the mechanic do the diagnostics.

I was told by people on the Humvee forums and I told that to this mechanic I have never used before and he said ok 3k to change head gaskets.

 

[Milcommoguy]

Sign of the times......

Your wallet IF YOU ARE ON A FORUM. LOL

Inflation hits the HumV hobby, CAMO

 

[Mogman]

I was told by people on the Humvee forums and I told that to this mechanic I have never used before and he said ok 3k to change head gaskets.

That is unfortunate as you took full responsibility for diagnosing the issue.

 

[NDT]

Wow $3000 for 8 hours work, I am in the wrong business