oil in radiator

[1987ss]

I have a 1999 suburban I got about 8 months ago when i got it it had a miss #6 plug porcelain was gone around electroid, mis fire returned to #6 agin about 2 months ago changed #6 it was gone this time porcelain was just cracked, now I just noticed oil in coolant I drained oil n didn't see any water in it.. has anyone ever herd of oil tank in radiator leaking? Or what else could cause this? By the way it hasnt over heated.. temp does fluctuate between 160-210 thanks! Forgot to add that what made me notice it was cap was leaking coolant changed cap gonna look at it tomorrow again

[rhandwor]

Originally Posted by 1987ss

I have a 1999 suburban I got about 8 months ago when i got it it had a miss #6 plug porcelain was gone around electroid, mis fire returned to #6 agin about 2 months ago changed #6 it was gone this time porcelain was just cracked, now I just noticed oil in coolant I drained oil n didn't see any water in it.. has anyone ever herd of oil tank in radiator leaking? Or what else could cause this? By the way it hasnt over heated.. temp does fluctuate between 160-210 thanks! Forgot to add that what made me notice it was cap was leaking coolant changed cap gonna look at it tomorrow again

If the tank in the radiator is leaking you should have transmission fluid in the radiator.
Napa sells a test for combustion gasses in the anti freeze,this or an oil analysis will test for anti freeze in the oil.
Get a loaner radiator pressure tester at Auto Zone or Advance pump up to 14psi and run engine if the pressure gage pulsates you have a blown head gasket.

[1987ss]

My buddy pumped up cooling system to 14psi needle held at 14 but u could see coolant building up were the plastic tank is crimped on drivers side by the oil cooler line. But the gauge didnt move was left on for about 5 minutes this was done engine off

[Tech II]

If you see coolant at the crimp, it's a leak......

[1987ss]

Thanks I do understand it shouldn't be leaking but even so with a leaky radiator it shouldn't have oil in coolant

[maxwedge]

Correct, if it trans oil the cooler is the rad. is leaking, motor oil, another issue. This can be caused by an internal engine issue. Are you loosing oil.

[1987ss]

It was about a quart low on oil yesterday when I changed it but not to bad. I checked it just now its full still but only has 100 miles on it gonna pay close attention. Is oil cooler in radiator under pressure?

[rhandwor]

Originally Posted by 1987ss

My buddy pumped up cooling system to 14psi needle held at 14 but u could see coolant building up were the plastic tank is crimped on drivers side by the oil cooler line. But the gauge didnt move was left on for about 5 minutes this was done engine off

This should be done engine running to check if gage pulsates.

[1987ss]

Originally Posted by rhandwor

This should be done engine running to check if gage pulsates.

I will try to do it tomorrow n post results

[lonerider909]

1999 Suburban, 160,000 miles. Owned it for 90,000 miles. I have always had some oil in the cooling system. It is black oil like it is from the engine. Not bad if you change cooler each year. It consumes 1 qtr of oil per 1,000 miles on a regular pattern. Drive 10,000 per year. No water in oil. I know what this looks like. Also, I think it has the intake gasket leak. It uses some coolant. Not bad. 1 gal per year.

Is the radiator leaking oil in or is the intake problem a one way into the cooling systems?

Thoughts??

[jyount]

That oil consumption isn't terrible by any means, but it is alot by these engine series. Check your head casting numbers. The intake gaskets leak air, not eat water. That sounds like a leak, or porous castings. GM put out a bulletin about a few heads that did that. As for oil in the coolant, yes check it for hydrocarbons. Engine = HC, transmission = no HC. Yes the trans cooler in the radiator is under pressure. If there is water in the oil one of two things happens, either the intake is leaking alot, or the headgaskets are going. Diesels do this because they often have "wet" cylinder sleeves, (they are o-ringed into the block and surrounded by water). This isn't a wet engine, so check that off. To be honest IMHO it would be more cost effective to get a low mile scrapyard engine and swap the whole thing, but I do my own wrenching so an engine swap would net zero hours labor for me... For hire shops may do a complete engine, but alot of times won't warranty a scrapyard part's labor....