I'm chasing down a high rpm with low load overheating issue. Almost seems like the water pump is cavitating. 3500 rpm high load all day, no problem. 4k-4500 cruise on the highway in 60 degree temps... Overheats. Switch gear to 7th, after 1 second it immediately drops like a rock to appropriate temps. (took about 3-4 seconds to go from the computer shutting off the ac system to 209 degrees)


this will also happen at high load as well (temp goes up slightly faster, but its not dramatically different)


I have heard that the 15 has a different water pump, but i haven't found any information on that. I've ordered a lower temp thermostat and a Dewitt radiator to ensure that i have enough cooling power, but considering it happened at high rpm in 2nd gear on the highway at 60 degrees, and immediately dropped like a rock after switching to 7th.. I'm not thinking it's a lack of cooling.

 

Any chance you have a water hose collapsing under suction at high RPM?

 

I looked for it when i had the car on the dyno, but I'm not 100% convinced that this is not the issue. That low pressure side of the radiator is a rather long hose and doesn't seem to have the spring in it that they used to have. Not sure what the appropriate fix for it would be, perhaps a new hose, but it doesn't seem like a terribly good design as it is pretty easy to squeeze that hose.

 

Good luck resolving the issue but it was curious, 4-4500rpm is hardly a cruising rpm?? Don

 

I have also heard of cases where the inside of a hose had de-laminated and would restrict flow under vacuum so it may not even be obvious from the outside. Since the hose is less invasive than replacing a pump I would rule it out first.

Good luck!

 

Would be good if you provided more specifics regarding the coolant and engine oil temperatures during the various scenarios.

A few days ago I did a high rpm, low load experiements, mostly in 2nd and 3rd gears when I was stuck behind other cars in a continuously moving traffic. Stayed in 2nd and 3rd gears, averaging about 4500rpms over twisty roads. In about 5 miles my coolant temps were 230F but, the engine oil was already at 290F. Dropping the rpms by shifting into higher gears moved the temps back down to normal, around 200-220F for both. The ambient temps were 94F and I had the air conditioner on.

Yesterday, I did a high rpm, high load experiment over my local winding roads with the AC turned OFF. Still mostly 2nd and 3rd gears with the rpms averaging 5K. Ambient temps were at 77-80 degrees, as indicated by the display. After about 10 minutes of hammering, the coolant was at 233 degrees while the oil just touched 290F. Given the fact that I was running under temps that were at least 15 degrees cooler, I am not impressed with the cooling.

I still think that the greatest improvement could come from an external oil cooler, which could drop the oil temps at least 30 degrees, which in turn, should drop the coolant temps by enough to possibly cancel the need for a new water radiator. Wonder what is taking so long for the aftermarket to come out with an oil cooler?

 

Tx2k15, chillin on the highway in the appropriate gear, just in case

Also, i repeat this process to test to see if i resolved the issue or not

 

oil temps are always lower than the water temp in these conditions. over 2-3 miles under those same conditions my coolant temps are FAR FAR higher than what you experienced as well.

 

Never mind misunderstood thread.

 

rolling the stock thermostat..

 

http://www.hotrod.com/events/coverag...power-squeeze/