Hey guys i just got my bottom end rebuilt and it runs great but sometimes when i give the engine a lot of load at low speeds (going up a hill doing 35 in 5th gear) my temp gauge will rise to about half and then come right back down again after about a mile of driving with little to no load at all. There are no leaks and both a/c and radiator fans work. I do have a mugen fan switch in the car so the fans turn on at 185 and not 210ish. The only thing i can think of is that i have a bad thermostat because the lower radiator hose never seems to get nearly as warm as the upper radiator hose so i don't think the thermo is opening. I don't know i'm kinda lost it's not a big problem and like i said it only does it if there is a lot of load at a low rpm/speed. I think it's my thermo but i was looking for other input. Yes it does blow hot and cold air.
Thanks,
Dan

 

bump for an answer

 

you shouldnt put so much stress on your motor. 5 gear 35 mph and up hill just down shift.

 

i understand that but it shouldn't be doing it in the first place...i know that is considered excessive load but it shouldn't overheat because of it..before the motor was rebuilt it never did it so something has changed. I know fresh motors run hotter until they are broken in but i don't think it should be fluctuating in temp that much. Can i have a technical response??
Thanks

 

answers please?? Opinions??

 

As a general rule of thumb, if you question the thermostat at all, replace it. It's $4 worth of insurance, and one less thing to worry about.

I would think the temperature fluctuation is relatively normal, on highway on-ramps in my car when I really hot-foot it, the temp rises a bit [~1/2 the gauge], but settles right back down to normal [~1/3 the gauge]. Keep in mind though, I've got a B20VTEC with stock LS cooling components, so I'd expect it to get a bit hotter than normal when on the go-pedal.

 

flush coolant and check your hoses? just a guess.

 

You shouldn't put a colder fan switch in with the stock thermo. There's a good change that it will never reach the proper temp to open.

Like above....when in doubt, change it. It's cheap