new engine for the old girl

[JayTheCPA]

You have an issue if you have 195 thermostats and it never gets over 170 on a decently long drive.

Definitely not disputing. At the same time am seeing similar observations from others whom just cleaned their cooling stacks, updated the fan & clutch, and switched to waterless coolant. ECT (as reported by the ECM) quickly gets to 170* F and eventually creeps over 170* F, but it takes a while. At first I was tempted to pull the thermostats out for a boil test in a pot, but then observed that warm-up temps were pretty much normal (specifically, the coolant quickly comes up to temp), so decided to leave them alone for now.

For a more robust picture, the Burb's ECM did show ~195* F when outside temps were ~100* F with the A/C 'On' (not towing).

Interesting observation is that the dash gauge will indicate ~180* F while the ECM reports ~170* F. With the 599 block, the sending units were typically within 5* F of each other during warm-up and then nearly equal when warm. With the P-400 and other mods, I am getting a consistently wider gap which does not close.

Presuming both temperature sending units are working normally, am curious as to whether the Burb's current cooling setup is simply that much better than OE and how much of a role the P-400 plays into the equation.

 

[great white]

Definitely not disputing. At the same time am seeing similar observations from others whom just cleaned their cooling stacks, updated the fan & clutch, and switched to waterless coolant. ECT (as reported by the ECM) quickly gets to 170* F and eventually creeps over 170* F, but it takes a while. At first I was tempted to pull the thermostats out for a boil test in a pot, but then observed that warm-up temps were pretty much normal (specifically, the coolant quickly comes up to temp), so decided to leave them alone for now.

For a more robust picture, the Burb's ECM did show ~195* F when outside temps were ~100* F with the A/C 'On' (not towing).

Interesting observation is that the dash gauge will indicate ~180* F while the ECM reports ~170* F. With the 599 block, the sending units were typically within 5* F of each other during warm-up and then nearly equal when warm. With the P-400 and other mods, I am getting a consistently wider gap which does not close.

Presuming both temperature sending units are working normally, am curious as to whether the Burb's current cooling setup is simply that much better than OE and how much of a role the P-400 plays into the equation.

Well, thermostats are not an on or off type of thing. They creep open in a range. I suppose it's possible yours are just starting the opening cycle a tad early.

Mine is running the dual stat housing, optimizer block (same heads as a p400) and dexcool. I run the stock steel 9 blade (I think it's 9 blade, been a while) and a "tweaked" oem clutch.

It jumps to 180 on fast idle warm ups after about 5 mins, then makes it's way to 195. Once there though, it cycles around it with about a 10 degree margin.

My stats are AC delco iirc.....

 

[WarWagon]

Under "low to no" power the heater core can flow enough coolant to keep the engine cold. Perhaps you are missing the factory restriction in the heater hose usually part of the nipple on the t-stat crossover. The engine oil cooler can also add to the cooling.

No power conditions on a downhill grade can completely cool the engine off from airflow through the engine.

 

[turbovanman]

8 blade fans are ok, as long as you use 2 of them, right?

Nah, just use one.

Edit, might have the blade count wrong but I have the metal "good" one, lol.

 

[JayTheCPA]

Perhaps you are missing the factory restriction in the heater hose usually part of the nipple on the t-stat crossover.

This might explain running cool. Fortunately I have a valve inline with the heat exchanger hoses and can manually control the amount of coolant that flows to the cab. Will play around with the amount of flow to the cab and come back with observations.