Oil in Water but no Water in Oil

[marshoaksyukon]

I put rebuilt heads with all new gaskets on my 1999 Yukon about 1 1/2 years ago. I found oil in the water and a little water in the oil so I replaced the intake manifold again, thinking I must have done something wrong. It ran well and I didn't notice a problem until about three weeks ago when I checked the oil, noticed it was down a bit, checked the radiator and it had a lot of oil in it.

I put another intake manifold gasket on it after learning the 5.7 L vortecs are notorious for back intake manifolds. I put in the latest and greatest AC Delco made to compensate for the vortec problems of the past.

Well, everything was going sweet. It was running perfectly. I had flushed the cooling system to try and get all the old oil out so I could start fresh. A couple of days ago I noticed a little oil in the radiator. It, of course, floats to the top. It wasn't much so I sopped it up with a shop towel and assumed it was residual from the previous problem. I've been driving the vehicle short distances and checking the oil and water levels almost every day. It's been fine.

Today I take about a 130 mile round trip. The truck ran perfect. I went out just now to check the fluid levels. The oil had dropped just a little, but noticeable. I checked the radiator and it had what looks like a good bit of oil in the radiator. I am just sick about this. I am not a skilled mechanic, but can do a lot of things on my own.

Can anyone steer me in the right direction as to how to diagnose the problem. I'm thinking now that I wasted my time replacing the intake manifold gasket twice.

Vehicle has approx. 162K miles on it.

Thanks,


Ron

 

[rockenthebowtie]

If your oil cooler is integrated with the radiator you may have a bad radiator

 

[lesterl]

Disconnect the oil lines from the drivers side of the radiator (aluminum lines attached to the plastic tank), rent a radiator pressure tester and see if you get coolant to flow out of the lower port. If you do, you need a new radiator.

If replacing the LIM Gaskets, I prefer the Felpro PermaDry + gasket set as it is a total redesign, not just a steel slug in the same crappy plastic gasket. FP PD+ is a steel frame with rubber or some kinda silicone around it.... work good.