New Build Overheating
 

OK, here's the setup:

98GT, Teksid block (coolant passage drilled in driver side deck), dry sleeve 3.700 bore, PI Heads and Intake, VT StageII NA cams, 160 Hypertech t-stat, stock cooling system.

The fan is definitely working, the t-stat is definitely working, the heater works, heads / gaskets are OK, motor sounds great, no smoke.

I tapped the top of the t-stat housing for the coolant temp sensor. In my stock block I had the sensor in the driver side of the block. Unfortunately the freeze plug in this Teksid block was a little stubborn so I decided to leave it in place and tap the t-stat housing instead. What's weirding me out now is that after the initial warmup the the temp needle is right where I expect to see it, between the R and M in NORMAL. Then, a few minutes later, it will take off to the right then I can see the coolant start to force its way out of the cap.

Is it possible that the stock radiator and fan just simply doesn't have the capacity to cool this motor?

hmmm, after our fone call a couple of other things come to mind;
1 is the coolant fan, it has a high and a low speed, so do you hear both?
on the temp sensors, there are 2 and they serve different functions, even though they look alike and use the same connection, getting them mixxed-up could cause an over-heat

Hmmmm... The fan speed is questionable, I'm not sure I've seen both speeds but I feel certain that the speed I've seen is the higher of the 2. The temp sensors are definitely correct.

More info...

I ran it with no t-stat tonight. It still got hot and forced an overflow but it definitely took a lot longer to go from normal operating temp to too-damn-high operating temp. I'm still leaning toward the idea that the stock system just flat won't cut it so I ordered a Fluidyne rad that will be here Friday. I'll be thrashing on it over the weekend and hopefully that'll be the end of my overheating issue.

Update time...

Put the new Fluidyne rad in Friday night, fired it up Saturday afternoon and got the same result. Ran normal temp for a few minutes after initial warmup, then overheats. Yesterday I pulled everything back apart and re-installed my stock damper in order to return the accessories back to normal speed, particularly the water pump. Fired it up and it worked perfectly! Took the car out for a 30 minute cruise and the temp stayed absolutely normal!

So, PI Headswap 2V dry sleeve big bore motors with VT Stage II Cams and Ferrea 1mm oversize valves, FRPP shorties, Bassani O/R exhaust in Bright Atlantic Blue 98 GT's don't like having a March underdriven damper.

WOW, never would have thought that:eek:
glad to hear it's fixxed:cool: