Properly flushing a cooling system

[UnderPrssureDSM]

Pertinents:
Honolulu-based so temps run 75-90* 365 days of the year
1997 GSX daily driver with 108k on the clock
Water pump changed at 68k
Hahn Racecraft FMIC
PTE SCM34
Stock fan on driver side, slim fan on pass side to clear turbo
Fluidyne radiator
Water and redline water wetter only
New thermostat
New upper and lower hoses

I'm having an overheating problem, 8 miles one way to work and the stock temp gauge hits 3/4 to the top. Overflow tank is bubbling when I park and when it's cool enough to check under the radiator cap, it's takes about 12 ounces to refill.

I do the whole "massage the upper and lower hoses" thing to burp any air out.

I'm not looking to get into the whole "it's your headgasket/compression/lack of air dams/etc." discussion. Rather, I just want to flush my cooling system.

I've tried just opening the drain on the radiator while running the garden hose into the radiator cap.

I've flushed it twice doing this and now I'm considering using one of those Prestone Flush'n'Fill kits from the parts store because I don't think I'm flushing out the system all the way.

Only problem is that I'm not sure which is the heater inlet hose so that I can tee into it to back flush the system.

Anyone got a VFAQ on that?

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Mahalo in advance.

 

[gofer]

That is the heater inlet hose in the picture you posted above, however I don't think flushing the system is going to fix your overheating problem. I too live in a climate that often sees 70 to 85* temps year round and also had a HRC front mount, I couldn't get coolant temps below 210* no matter what I did. It sucks but the only way I could get rid of my overheating issue was to remove my A/C condensor to get more air hitting the radiator directly.

Its really up to you though, whats more important you staying cool or your car? Recently I've switched interooler setups and my coolant temps dropped considerably. I think a lot of it is the HRC front mount design, its a good one but it doesn't let air pass through it as well as the others.

You should really add a mixture of antifreeze in the coolant system as well. Ethylene Glycol (antifreeze) has a boiling point of 198*C, where your water has a boiling point of just 100*C so it evaporates faster. Adding antifreeze to your coolant system does infact COOL better than water, it doesn't just keep the water from freezing in cold climates.

If you flush the system and add a 50/50 mix of coolant/h2o and you still overheat and you don't want to remove your A/C, try this... MISHIMOTO | 95-99 DSM | 143° RACING THERMOSTAT I'll warn you though, your car doesn't enter closed loop operation until the ECU sees a 180* from the coolant temp sensor so it might run to cold.

 

[UnderPrssureDSM]

I've had the HRC FMIC installed for almost 4 years now, so I doubt that the overheating problem would wait until this time to rear it's ugly head. Especially considering that I had the car when I lived in New Orleans, it's a lot cooler in Honolulu.

That said, I refuse to give up creature comforts to have a vehicle work properly. The a/c stays.

 

[95g-s-x]

Have you changed your thermostat yet? It is probably stuck closed. If it just started overheating one day out of the blue, i'd bet thats your issue.

 

[1997_GSX]

Well I tried all the stuff you mentioned too when my car was overheating, only under boost and the overflow bottle was pushing coolant or bubbling, wasted all the money on the new thermostat, rad cap, already had brand new gates hoses, and heater core hoses.

Compression test turned out fine 210 across the board.

The head gasket was indeed bad, took a few hours replaced it and my car is always around 195 degrees even on 95 degree days with a 4" thick fmic.

I had wasted $50 in antifreeze, did the flush 2x with the prestonet kit added water wetter, that crap was a joke.

 

[UnderPrssureDSM]

Have you changed your thermostat yet? It is probably stuck closed. If it just started overheating one day out of the blue, i'd bet thats your issue.

Nope, as per my first post, changed the t'stat last month.