I know that this has been discused the past few weeks but despite all of the advice, I still can't figure my truck out.

78 F-150
400 V8 with around 250 miles on fresh build
around 300 hp
Flowkooler high flow water pump
New Fan, fan clutch, shroud, hoses, t-stat, electric fan mounted in front of rad.

I can't drive more than 5 miles without it overheating!
The timing is set at 12 deg. The temp outside is around 70 F.
I pulled the new t-stat to see if that was the culprit. I ran it without the t-stat and it did not help at all.
Any other ideas on what it could be?

thanks

 

I had a similar problem with mine...a couple of suggestions that helped me...make sure all your vacuum hoses are open and not plugged in any way (i.e. make sure no old t's are in the lines, etc.), where is your temp. sending unit screwed in on the engine?, do you have a fan shroud and what kind of fan?, lastly, I went with a performance 180 degree thermostat...no problems since...

 

how is your radiator? new? old? if old was it cleaned and flushed? i am just wondering if maybe your h.v. water pump is circulating the coolant to fast. no time to dissipate the heat through the radiator.just a thought.
mattb

 

A couple of things I failed to mention. I flushed my radiator when I pulled the engine. It seems ok, no leaks and all the fins are real straight.

## Is there any other way to test the radiator? It worked fine before my new engine.

One other thing. I am using Sierra Antifreeze in this truck. They claim it is less toxic for pets.

## Has anyone used this type of Coolant? Results?

Thanks
Nik

 

Hey Nickolaus, i'm not sure if i responded to your post before, but lets see.Does your truck boil over or does your gauge just read hot? If no boil over, maybe you have a bad gauge. Is your electric fan in front of your radiator a pusher or a puller? I have a 1978 bronco with a 400 C.I. motor with about 30,000 on a rebuild. When i fisrt installed the motor, it run hot for a few weeks. It never boild over just run about on the L on normal. The chilton book told me to run 12 degrees with a auto tranny, which i have, and 6 degrees with a manual tranny. I adjusted the timing to 6 degrees and it never run as hot again. My motor is bored 60 over, how about yours? I expect my motor to run hotter than most others that are bored under 60. These motors already have thin cylinder walls, so the bigger you bore them the hotter they'll run. Also, are you running a 180 degree thermostat? I've found this stat to run the coolest. When my motor idles through stop and go traffic, it starts to run on the hot side, and when it starts to get moving it will cool right down. It sounds to me you've done almost everything possible to cool it down, might just need some fine tuning. Keep us posted and hang in there, you'll get it. Rob