Hey guys, got a serious problem here. I just brought my 84 T/A home from the shop after getting the new 355 put in and the exhaust in it and man it's fun to drive! Only got one problem...it's not cooling properly. ON the highway it heats up at higher RPM. I'm running a Becool radiator with Jet-fan switch that turns on at 185*. The mechanic said that when he test drove it around town for 20 miles to make sure the engine was good and there was no leaks that it ran right at 195* ...perfect for a stock motor. However when I was drivin home it was running at the tick-mark after the 220 mark at 70mph in overdrive at 2600rpm. When I got into the construction zone I slowed down to 55 and since the motor is still new, I shifted down to 3rd gear to give it some RPMs (I like the train of thought that you break in a new motor the way you intend to drive it...so as my friend says "Drive it like you stole it!") anyway... and the gauge shot practically right to the red line within minutes. I shifted back to OD and it went back down to just above the 3rd tick mark. The radiator is a year old, the fan switch is new, the air dam is in good shape and the fan is operating correctly. The hoses are re-used but were swapped when the radiator went in so they're only a year old. I'm stumped. Will the 355 run that much hotter? That Becool radiator is pretty serious but what looks to be a 70* jump in temp? Any advice would be greatly appreciated!

 

what kind of fan are you running? is the fan shroud in good shape?

 

The fan is the stock single electric fan with a jet fan switch that is supposed to turn on at 185*. I had to modify the bottom of the shroud a bit, actually cutting out about a 4-6" space because of how it fits with the new radiator. And the fan works as it's supposed to.

 

What size thermostat are you running? Also I would have the fan come on earlier.

 

I am currently running a 195 thermostat. I should probably drop down to a 180 or so. The fan switch is new, stock turn on is 220*. I'm going to have to double check the one I bought to make sure they didn't send me the wrong one.

 

I would agree with the fan, but that should be at low speeds.
At highway speeds you should have enought air flow going through the radiator to keep the engine cool.
I wouldn't think that the radiator would be plugged after a year.
The passages in the engine should be good too.
I would go more with air flow to the radiator.
So long as it good like you said, make sure the engine is running right.
Double check the timing.

 

What pressure cap are you running?

 

Stock...what is that, 16psi? I replaced it when I got the new radiator.

If I am running too lean, could that cause it to run hot like that? I thought I remember reading that running lean can cause the engine to run hotter than normal.

 

I did the same thing when I replaced my radiator. Switch to a 13 pounder and see what happens. Bigger isn't always better i guess. Nothing else made sense and everything was brand new, so I thought "There's no way it makes a difference but what the heck I'll try a 5 dollar fix." Threw the 16 pounder in the trash and put on a 13 psi(only size left at the hardware store, i'm lucky not smart) and it's never been over 200* since.

 

Well, ran up the engine with the cap off, (15lb cap by the way), got it up to temp and I could definitely see flow. Also, the coolant level dropped by at least 2" inside the radiator when the thermastat opened..that normal? Could that much loss/low of a level alone cause my overheating issues? I'm also going to check to see if my hose is bent the same as an "88" hose because of the bracket that holds the hose over the alternator belt, it looks like it might be pinching my hose just a little so that it could possibly restrict flow some.

 

A good rule of thumb seems to be if the heater blows hot then theres technically enough coolant to keep the motor cool. 2" drop shouldn't cause that big of a deal. I know it sounds stupid and repetitive, but I really think you should try going down a few PSI on the cap. If the thermostat gets kept open too long the coolant won't stay in the radiator long enough to be cooled properly.

 

what?!?! um no... the higher the pressure of the cap the higher the boiling point of water so why would u want to lower the pressure? now run the motor till the level drops again and top it off...have the heater on full blast too..fill the radiator... see what happens....make sure your timing is correct and mixture is righ too...

 

With the heater on I was getting good heat out of it when I was purging it. I'm going to let it heat up again, then fill it while it's at it's "low" point, then see if it "burps" again.