Oil in coolant
 

Hello. After running on a road course where I saw very high coolant temps at times I noticed that I had very small traces of oil in my coolant resevior. I also noticed oil sludge build up on the cap itself. There are no signs of coolant in the oil. I imagine if I can see it in the resevior it is throughout the coolant. I have a Z51 with stock rad with EOC and Trans cooler. Can one of the lines be leaking? Clogged? What should I be looking at and should I be concerned? Or just do a flush? Would imagine this isn't helping with cooling. Thanks

Head gasket. If it was a small leak it may have resealed itself but I'd be getn the heads pulled and the cooling system drained

Not what I wanted to hear but was afraid of that. I think the high temps and pushing it as hard. Think I will start with a full flush. Will drain and then run straight distilled through it and flush again.

flush it out with straight tap water. run a chemical flush agent that u can buy from auto pro etc. they make the oil crystalize n breaks it up so it isnt goey n stick to everything. run it for a day then flush it out again. flush it via a heater hose or similar to get behind the thermostat n into the motor not just the radiator. wtvr u do not run a head gasket sealer as that can block up everything incthe radiator in ur cooling system

I had a friend with a similar issue, there was a crack somewhere inside the radiator allowing fluids to swap

So did a leak test and no issues. Well I only tested one cylinder on each side as its a PIA to find TDC on each one with covers on. Also did compression test on each and lowest was 160 and highest 175, all good there too.

I flushed the coolant and poured in a bottle of prestone flush and cleaner with distilled water, ran it FO a few hours and draining again now. I plan on adding another bottle and refill with distilled again and run it like that at the track Monday as there is no fear of freezing.

I wonder if it was residual from when I changed the heads, etc or a leaking EOC line. Who knows. Odd thing is I was also loosing boost but that could have been due to the hi temps causing a lot of timing reduction. Also notice the plugs look lean so going to add some fuel and see how that goes.

You could use this (link below) which will check for combustion gasses in the cooling system.. probably not going to find anything since you've flushed it already, but worth a shot if it happens again

Maybe you are lifting heads? They studded or bolted?

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That is what I am afraid of. Studs.

I lifted heads with studs. It was only because someone swapped the heads before i bought it, and did not torque them correctly. That lead to a whole bunch of problems for me.

I ran autocross again and pushed the car. Temps ran as high as 140's even with just distilled water. There is no visual oil in the coolant. The water is murky but would expect that with straight water and flushing agent. I will perform another leak test on all cylinders. Anyone know of a good piston stop tool to determine TDC? Or just pull the valve covers?

Ok so an uodate after messing with this thing. I no longer think I am lifting the heads. I ad no oil in the coolant and the water that I just drained came out clean. There are no signs of coolant in the oil. I believe the oil I saw before was from the engine rebuild where I replaced heads and had the rad out.

What I do have is
1. A stuck BOV. I saw that a line was pinched, I reroute the line but when I connected it and started the engine there is air flowing out of the BOV the entire time. I believe these are serviceable? I run the big red from procharger, anyone know how to service them or is it self explanatory?
2. A leaking valve cover. I noticed an oil drip on the pass exhaust and there is oil residual around the valve cover and one bolt. I have the nasty performance valve covers. I also have my oil fill cap routed to my catch can, maybe it's full, will check tomorrow. Will also remove that valve cover and check the seal, the other side is clean as a whistle.

How did you test the BOV? From what I remember, they should be open at idle. If you unplug the vacuum line, it should close. It wouldn't be the first time I've heard of one of those things sticking, though.

Well maybe I'm wrong. I didn't think it should be open at idle but makes sense it should open under vacuum and close under boost. Guess I can use a compressor and a shoot air down the line, if it operating properly it should be sealed...right?

The best way to test it would be with something like a hand vacuum pump. It doesn't care about boost, though. It's likely sprung closed, and pulled open by vacuum. As soon as the vacuum gets low enough, the spring pressure overcomes it and it closes.

I'm not sure about the Procharger BOV, but the Turbosmart BOV I had was adjustable. Some BOVs have springs that need to be swapped for that. Where it needs to be set has a lot to do with how much vacuum your engine makes.

The easiest test would be to just run the engine at idle, and (if the valve is open) then simply disconnect the vacuum line going to it. It should shut when the vacuum supply goes away. That would be a simple test.

What is your compression ratio? Most of us don't come close to Raising Heads especially in AX.

I do have access to a hand pump but I will try the simple trick first. But even if it was slightly open it will create a loss in boost. I will call PC tech tomorrow.

Compression is low, 9.5.

What else besides bad BOV and belt slip can cause a loss of boost? Well guess a lot of things but just want to hear what others have experienced.

You know, I could be wrong about whether the BOV is supposed to be open at idle or not. I just looked at Turbosmart's adjustment instructions, and they say it should be closed at idle. I think that would be dependent on the spring stiffness/adjustment of the BOV and how much vacuum your engine makes at idle. Then again, there would be no reason for it to be open at idle on a turbo engine.

When I said that your BOV doesn't care about boost before, I guess that's really not totally accurate now that I think about it. BOVs work based on differential pressure vs. spring pressure. The spring is trying to keep it shut. Vacuum is trying to pull it open. Boost would want to try to push it open, but since there is boost on the vacuum side as well, that = 0 differential pressure, and the spring keeps it shut. So the difference between the pressure/vacuum in the manifold and what's in the charge pipe are really what matter. Then it's just a matter of whether or not that pressure difference can overcome the spring.

But either way, it should spring shut when you pull the vacuum line from it. And a hand vacuum pump is still a good way to make sure it moves freely.

Well it is def open at idle and I don't remember it that way before. But even if that is correct it should close under boost and reopen. I'm also not hearing the loud whoosh any more.

spoke to PC and yes it should be open during idle, they also say there are very few issues with these (of course). So I will still test it and also check all connections, maybe there is a loose one somewhere.