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TBI Running Hot

I could be wrong but I don't think it is a internal engine problem either. I'm thinking air pocket, clutch fan, or something simple. Also check the hose to the overflow bottle and make sure it's not clogged. You would think before blowing the rad cap off it would blow out the overflow bottle.
 
Last time through it..Saturday..when i replaced the heater core, I broke the overflow reservoir taking the inner fender out. So currently it has no hose or tank to clog. Prior too that mishap the level did fluctuate hot/cold though so I think it was probably working.

On the clutch fan, I am fairly confident it is working because you can watch the gage drop out of sight one the thermostat opens. I'm absolutely positive it is not opening without the hole as I have seen the rad cap blow.... at idle, and the hose out of the thermostat neck to the top of the radiator was cold. That thermostat absolutely was not open.

My though was that there is a compression leak into the cooling system causing a buildup of pressure thereby limiting the thermostat from opening? An air pocket I presume woudl have similar effects as it would take for ever for the air to open the thermostat?
 
What happens if you leave the radiator cap off and let it get up to t-stat temp?
 
Initially, to get the air out of the system I left the cap off and let it run. Initially it drew the fluid down...the water pump is now running and then it did overflow about $20 worth of antifreeze before I shut it down. I don't remember the engine temp, and I should have checked the outlet hose temp. Just for conversations sake, I thought this was the proper way to bleed the system? I've done this many times in the past without any adverse results. Perhaps this method is incorrect? The truck was on level ground in the garage.
 
I don't do anything special...level ground, add antifreeze until the radiator stays full, start engine, add until full. Cap it, let it get to operating temp, shut it down, let it sit until cold, check fluid, top it off, then fill overflow to proper level and I'm done with it.

Losing a massive amount of coolant with a cap off I can't see. Obviously coolant expands, but not THAT much. Sure sounds like the block pressure is too high when it finally lets go. But theoretically that pump might be putting a lot more pressure into the block.

Which makes me wonder...were all the pumps you used higher performance, or were some stock? IIRC the stock thermostat opens AGAINST the flow, which I would imagine would be a problem if you are putting more than stock pressure/flow against it. You have no cooling problems with the t-stat out...

I assume you haven't talked with anyone like these guys?
http://www.stewartcomponents.com/Contact_Us.htm

They sell stuff, so I'd always be suspicious of what they have to say, but maybe they've run into this before, with their business being cooling and all...just hate to see you waste more time and money guessing at the problem. No one here has nailed it down obviously, and you've tested/swapped/reswapped about as much as I can think of!
 
I tested it with the original water pump that was on the motor before rebuild. That is not to say that that pump was in great shape (not new anyhow), but the motor did not have the cooling problems before. That test was a while ago..like a year ago. I was running the 160 deg stat and the problem was the same other than the gage did not bury (like it does with the 195 deg stat), it only went to 260deg or so which is still.... wayyyy too hot. I ended up swapping the pump back out because the belt was squeaking which I have since diagnosed and fixed as a bad PS steering pump bearing. I should make that clear too, this thing has been running a good year and a half (20k miles or so) like this without any significant change that you would expect with a bad head/gasket.
 
If it stays cool at idle with no thermostat, I feel comfortable saying the fan, radiator, and pump are all probably in good shape....otherwise you'd overheat.
 
Pondering this, I think that when I had the other water pump in there the heater core was leaking slightly. This of course could introduce air into the system? I think I might try swapping a stock pump back in with a 160 thermostat, bleed it correctly, and see what transpires. At this stage in the game I'd really like it to simply run correctly without cooling worries. I wouldn't normally run a 160 stat but that was the recommendation with the chip from TBI chips.
 
I would check the new water pump to make sure it is the correct rotation. If the impeller is going backwards it wont flow much and would get hot. you can pull the backing plate off to compare the two if you have to.
 
Certainly wouldn't hurt to check it to make sure. If all else fails I guess I'll have to get my *** in gear and finish building the 383.
 
X2 on the pump rotation. I didn't think there were any aftermarket pumps for the serpentine setup (reverse rotation). Even if the pump is supposed to be correct for the application, it could have ended up in the wrong box.
 
It's an Edelbrock 8881 series, reverse rotation without a doubt. Coolant flows (visibly through the cores) through the radiator without a thermostat installed. There are a few other companies that make them as well.
 
I'm no mechanic, but any motor I ever had that got to the overheat temps., then dropped to normal run temp, had a blown head gasket and more often than not, a cracked in the exhaust valve seat. Hope that's not it for you, but that has happened on no less than 4 motors with me. Good Luck! Hope I don't sound too much like an idiot!:dunno:
 
I've read all the latest since my late reply to you. The only question in my mind is if the wrong water pump ended up in the reverse rotation box but since you've just said you can see the flow with the t-stat out i would rule that out. The only other thing that comes to mind is if the engine was either bored .060" oversize or has alot of core shift in the block and has a thin cylinder wall which will give you the EXACT symptom you're having regardless of what the overbore size is.
 
There would certainly be some cause there...same block/jheads(?) as before (it sounds like) but problem now exists with old cooling components that worked fine previous, or are new.

I assume since it's Jasper, you got the thing as a long block?

I blew past that...if our resident machinist says it could be core shift, what kind of warranty, if any, does the motor have?
 
pseudomike said:
I wouldn't normally run a 160 stat but that was the recommendation with the chip from TBI chips.
Click to expand...

CHIP! CHECK CHIP! CHECK TIMING! just went through something similar (tbi chips chip) What is your timing with the ESC wire in bybass ? Now JUST HOW ADVANCED DOES YOUR TIMING GET WHEN YOU PLUG IT BACK IN?

I have not contacted Brian about the chip I got fro him, but it created SERIOUS heat (and related coolant system pressure) problems. Runs coool with the stock chip, and well enough for now...

My motor has also been bored, and My theory is that the advance curve on the chip is creating too much heat in a cylinder that is now much thinner than stock, and super heating the coolant...
160 degree thermostat or not, I don't like the idea that that much heat is being cranked out inside the cyl.
 
New water pump 160deg stat same problem.


I bought the motor from Jasper as a long block, they swap them out type of deal so not original heads/block and no clue on the tolerances. I had the motor in my Blazer for about 8 months in stock form. Never skipped a beat, no heat problems, nothing. Then I swapped the motor into my K2500 (probably a warranty no-no), with the cam, intake, bored out throttle body, and the chip. Definitely woke the motor up, but pretty much since has been running hot. I never suspected the chip, and I think the casting/machine work is good because I ran the motor before no problems. I don't know what the spark curve on the chip is other than it must be fairly aggressive. I think I'll try a stock chip to see what happens. Will probably run like **** with the cam etc but it may alleviate the problem.
 
Post up your results. (I know you will) I dropped timing in my motor something like 15* essentially across the board, and bumped idle timing up to 23*, and had no problems with heat (other than pinging) either way.
 
dyeager535 said:
Post up your results. (I know you will) I dropped timing in my motor something like 15* essentially across the board, and bumped idle timing up to 23*, and had no problems with heat (other than pinging) either way.
Click to expand...

I had to bump the dial on my timing light to 25-30 degrees before I could even see the timing mark on the balancer. It still wasn't on the timing marker.
Might have been a faulty chip burn, but ????????????

I would really like to see some results posted also...
 
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