I'm not expert on cooling at all. But isn't it weird that the 160 tstat runs hotter than the 180?

Anyhow, I would probably just keep the thermostat out for the rest of the summer.


Also, for your radiator - do you have a shroud to direct the flow of air to the fan?

I imagine that at higher speeds/ higher rpms, that the electric fan might actually be a restriction for the air being pulled by the mechanical fan.


I don't follow your reasoning of why you suspect a cracked head from the fact that coolant flows fast... (Or do you mean that coolant is exiting the system and moving to the environment, which yeah, would be a bit of a problem, lol.) Is there white steam coming out of the exhaust? Or is there foamy oil on the dipstick? Those are the symptoms I know about that indicate a cracked head.


I'm guessing that if you have a methanol injection system, you probably already know a lot more than I do about this stuff, but those are my suggestions.




Quote Originally Posted by skullzaflare View Post
i know it has been 100f in my area recently so it is to be somewhat expected, however, i am fighting a cooling problem.

175k~ supposedly headgasket was replaced at 150k

91 4d56
td04 15t 30-40PSI
good aluminum 3 core radiator, clutch fan running and electric that kicks on at 190

Current tests, 160 tstat runs hotter, 180t runs hot but better, no stat runs cooler overall and cools down better
this is mostly flat ground, slight slope, gearing at 50mph is 1400rpm or so and 0-3psi. 70mph is 7-10psi at 2400rpm
runs cooler at 50mph, in OD at 1400, with OD off at 2200rpm it gets warmer..

I have a new water pump, have not installed it, with stat out you can see coolant flowing fast.
Im thinking maybe cracked head?

Oh, EGT at 50 is 0-400 depending on load
EGT at 70 400-800 depending on load
EGT is AFTER turbo about 2"

Meth injection running washer fluid, does not help at all no matter the settings