odd Coolant system symptoms

grimreaper

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Jul 2, 2008
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Ive been watching my coolant res. closely to try and gauge a "norm" but its not adding up to my limited knowledge.

The res. level never rises much when i drive "normally" which is only a few psi when accelerating, ac on, stop and go traffic, cruising on the highway. basically anything except beat on it or racing it. The level might get up to an inch or so above the max line but that takes 30 minutes or so in hotter weather.

Over night it returns to the max full line like id expect.

When i beat on it with extended boost runs the res. is usually between half and 3/4 of the way full (this is usually a good 20 minutes of boost). When it cools down it USUALLY sucks it all back in. However Ive noticed it is leaving a 1/4 of an inch in the res. over the full line and the radiator level is a bit low (few oz.'s at most). I notice that there are tiny BB sized bubbles coming from the overflow tube under the cap if you watch it after a hard run. Never has been over 200F and under all the abuse of hard driving rarely tops 190 unless i jump of the freeway and hit a light (expected temp rise though)

Block tested it a week ago with negative results. Nothing is leaking, all new coolant hoses and basically nothing out of the norm besides the sustained higher then expected level in the overflow bottle when i run it hard.

Is this normal? I have a new cap on the way and new overflow hose (the one under the cap) that ill be putting in this week. However the upper coolant hose has not sucked closed like id expect from a bad cap.

My thoughts are the hg (hks stopper) is leaking under high loads/boost or for some reason my coolant system isnt creating enough vac to pull all the coolant back in from the overflow/res. Ill let the level in the system go for now and see if it corrects it self like i understand it should. In the past (noticed this after hard runs since november when i really started paying attention) i always topped the radiator back off.

any input?
 

GrimJack

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Replace the hose inside the overflow. And the one from the radiator to the overflow as well, although it's substantially less likely to be causing this problem.

What happens is that this hose cracks. Then when the engine is hot, it still pushes coolant out just fine. However, when it cools, it sucks in air through the crack instead of pulling up coolant from the bottom of the overflow tank. Same reason a straw with a crack in it is useless.
 

grimreaper

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Jul 2, 2008
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alright well the hose leading from the overflow cap (inside tube) was loose fitting. Replaced all the lines and the rad cap. No more bubbles in the overflow tank however my overflow level still rises to about 2/3-3/4 of the canisters capacity after some heavy boosting and half hour of stop and go traffic with the ac blasting. Highest temp ive seen is 202 F after 20 minutes of idling in traffic with ac blasting. Drops instantly to 195F once i get moving again.

What level do you guys normally see in your overflow tanks?

What does exhaust do to the coolant color? Will it change its color at all? G05 is already yellow so im not sure if its getting contaminated or not. Looks like gatorade or pee :)

Maybe im just being picky?
 

GrimJack

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Exhaust doesn't change the color. It will change it's acidity, eventually, but even that doesn't really change the color. Until it eats most of your head, anyway.

As long as the overflow isn't pushing coolant out, it's fine. Mine usually sits at the low level when cold, and the full level when hot. Not exactly a good comparison, mind you, my cooling system holds a LOT more coolant than stock.
 

grimreaper

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i dont know how thick or big a stock one is but my fluidyne is of decent size. The level rise you see is what i normaly see just tooling around the block. Ill just keep an eye on it.
 

grimreaper

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* UPDATE * Replaced the radiator cap and all of those small overflow lines and zip tied them as well. Old cap wouldnt hold pressure past 7-8psi. New one is solid until 15psi. Overflow doesnt rise even an inch now and pulls it all back in like it should. ill keep an eye on it over the next few weeks (fingers crossed)

thanks for the pointers grimjack