Deathevn

iTrader: (5)

So I've been reading through the various overheating threads on here the past couple of weeks, but haven't seen anything that is quite what I'm looking for.

I was running a stock 8 turbo, stock exhaust manifold, EPM o2 dump on e85@27psi. Never had any issues with overheating. Using 50/50 mix.

I upgraded to a JMF manifold, BBK Full, Shearer o2 housing, still on e85@28psi. All of those are coated. Using distilled water with water wetter. The car only overheats on the track after a couple of hard laps. Doing cooldown laps doesn't bring the temperature down either. Now if I take it easy from the start, it takes awhile before it starts overheating, but it will eventually get there before the end of a 15 min run. After each session I would have to add another 1/4 gallon to top off the radiator since it was steaming out of the overflow. It never overheats in traffic, stop and go, or single pulls like merging onto the interstate.

Compression checks came out ~150psi on all cylinders.
Boost leak check is good.
Used a CO2 tester on the radiator - good until it sat there awhile, then foam started getting into the tester causing it to change to green. It never turned yellow to indicate CO2 in the coolant.
Oil looks good, no milkiness.
Don't see any oil in the coolant.

Possible causes -
Lifting the head on boost. I thought it might be this at first, but looking through the threads, it seems I would overheat even on a single pull. I tried to rev the car up with the CO2 tester on there, but it just shot coolant up into the tester turning the liquid green. It still didn't turn yellow to show CO2. Can't really build boost in my garage, I'm sure the neighbors just loved the revving to begin with. Currently running APR headstuds, torqued down to 100ft-lbs.

Stock radiator can't handle it? I'm wondering if the new manifold/turbo is putting out too much heat that close to the radiator. I couldn't find any threads which said the stock radiator is the cause of overheating. I'm not sure if that is because everyone upgrades the radiator earlier, or if the stock radiator is good enough to handle the extra heat from a tubular manifold.

I don't think it is the thermostat since it controls just fine in every situation except at the track. The water pump is another possible failure, but I'm not sure how to troubleshoot that out of the equation. Already replaced the radiator cap.

So I'm just seeing what everyone else thinks. Upgrade to L19 headstuds? Get a new radiator?

heavens turbo

it may be a head gasket. it may leak under boost. does the coolant smell like combustion? the oil doesn't always look milky if the leak is small enough to let in some combustion and pressurize that cooling system. does the temp go down when you turn on the heater? fans coming on? could be other things too. good luck.

1d10t

iTrader: (19)

^agree
Also check your radiator cap. If the seal is torn, or it is stuck open, when the coolant heats up, it expands and may be seeping by the cap seal and overfilling the reservoir.

Deathevn

iTrader: (5)

I put a new radiator cap on there already.
Also verified that the fans are running.
I had the heater running full blast when it started overheating, didn't really help.
I didn't notice any odd smells from the coolant. The coolant is foamy though, almost like fine soap suds. Not sure if that is something getting in there, a by product of the water wetter(DEI radiator relief), or just left over antifreeze.

TommiM

iTrader: (19)

could be a headgasket. Oil doesnt have to always be in the coolant, could just be enough to pressurize the coolant system. Open your overflow and rev it up and see if coolant starts blowing out of there. Maybe water pump could also be starting to go out and is cavitating because its worn or whatever. Do you have any leaks?