Cylinders #5 and #6 strike again - Head Gasket #3

[Tony D]

The only caveat with letting the electric pump cool down the block after it's run hard is the possibility of cooling it too fast and with cast pistons actually locking them in the block till the temperatures equalize. Lance was yelling at Jeff on the dyno for doing this. Technically correct...but geeze, let it post cool to some degree!

 

Our compressors circulate oil and coolant for 30 minutes minimum after a hot shutdown. When in R&D it was interesting to watch instrumented bearings show the temperature spiking to levels nobody thought possible from a simple normal shutdown. Temperature goes into the bearings for quite some time after shutdown. From what I saw, it seemed much more important to keep oil flowing (and let it's sump capacity act as a reservoir for the heat it takes out of the bearings) than circulation of water after shutdown.

 

And a standalone oil pump wouldn't cool your block before the pistons...making Lance happy! (even with those cool SR20 style oil squirters for cooling the pistons...you'ld cool the pistons more than the block, increasing clearances circulating oil after shutdown!)

 

There I go again, 'thinking'! LOL

[jc052685]

I have seen 'plenty' of people with a loopped heater core. And in EVERY case when I block it off properly, overheating problems go away.

 

You can get away with a LOT on the cooling system, especially in the cooler, more temperate regions of the USA and Canada. But you try that stuff in the Desert Southwest, and you will be milling overheated heads on a regular basis!

 

That someone 'has done it that way' does not mean it's correct. Think about it logically, and you realize the system is designed for ONLY 'cooled' water to go in the water pump inlet, save for ONE small 8 to 10mm internal boring on the block.

 

Other than the later ZX 'poppet' valve which was added for extreme circumstances, nothing is flowing through that 15mm line on the side of the block, and nothing comes through the external bypass line that has not been somewhat, if not totally cooled. The bypass line usually heats the TB, and AAR valve, and the 15mm line goes through the heater core to be cooled before re-entering the coolant pump.

 

You use that line, you have a direct shunt---you may not see a temperature increase on the outlet...but what you have a DRAMATICALLY reduced internal block pressure due to the greatly increased flow. Add a slight heat increase in inlet temperature to a decreased pressure system and you have a recipe for nucleate boiling, and cavitation in the pump or the block perpindicular to the wrist pin...

 

That line being blocked off completely is NOT detrimental to the engine whatsoever.

 

Letting it recirculate uncooled---it's bad. just how bad will be determined by the condition of the rest of your system and operating environment. Lots of aerosol blocking UV and a 90 degree day in NH is better operating conditions than a 65 degree clear and sunny day in SoCal---road temperatures at the radiator will be likely 10-15 degrees higher (in the area of 104F) in SoCal, while NH will be maybe 95F.

 

so I have been dealing with overheating since I added my front mount and I just figured that i was blocking most of the air the the radiator. only gets hot under high load or high rev. I basicaly replaced the heater core with a turbo, so it my be contributing to my problem, you think? Where should I tap for coolant if not there?

[Tony D]

so I have been dealing with overheating since I added my front mount and I just figured that i was blocking most of the air the the radiator. only gets hot under high load or high rev. I basicaly replaced the heater core with a turbo, so it my be contributing to my problem, you think? Where should I tap for coolant if not there?

 

PM answered.

[jc052685]

PM answered.

 

thanks