Joined: 22 Apr 2007 Posts: 4010 Location: Perth, WA
Posted: Sat Aug 25, 2007 1:28 pm Post subject:
thats kinda wat i was thinking.. if it's hot at the top and cold at the bottom then the rad is doing it's job well.
Why it would get so hot though... either the engine is a nuclear furnace (unlikely), or you're just not getting enough flow through so what does go through gets super hot real quick.
To me this could either be the water pump, or perhaps something electronic controlling coolant flow? I have nfi how much control the ecu has over this? _________________
1994 Black JZS147 Aristo - RIP. Went swimming
New 1992 Aristo Project
just an idea mate, since your thermostat is designed with the complete standard cooling system in mind its flow rate is compatible with that.
if you pull out the thermosat completly and experiment with different size restrictors or even a tap like the ones used for spa`s or pools and put it in the top rad hose so its easy to control. as sometimes when your coolant flow is too fast the coolant doesn`t have long enough time in the rad to cool down. it`s just an idea, seen it happen a few times with custom cooling systems.
Another idea is maybe you need to bleed the air out of you system, if you`ve got an air lock in there the coolant wont circulate properly and you`ll create a hot spot. the classic DIY mechanic job that ends up being a huge culprit of causing the head gasket to go.
let us know how you go mate
will post pics when mines done.
Usually hot water comes out of the top of the engine, into the top tank, cooled water out the bottom hose.
This issue didn't exist until you put the new radiator in correct? So it is doubtful that your pump all of a sudden died. However you could do a flow test, pull on of the heater hoses off or something, check how much water it pumps into a bucket, although you will need a baseline to compare to.
You could run it without a thermostat to test that if you wanted, the car should over-cool when driving, just increasing consumption a bit.
Ive ripped the guts out of an old thermstat and threw it in. Surprise surprise it now runs at around 82Ž°. Cold start doesnt last long, about 2 minutes, then the coolant temp is up to 40Ž°, go for a casual drive for 5 minutes and its up to 72Ž°. Start giving it a bit, stop and then idle and the highest it got to was 90Ž° then it came back down to 82Ž° very quickly. Ive let it idle for 10 minutes and it stayed right at 82Ž°. Drove at 70kph and it was 76Ž° and stayed there. 100kph it dropped to 72Ž°.
So from the anaylsis its simple. The thermostat i had was set to open too late in the temp range. I need to either find another low temp thermostat, 70Ž° or similar, or leave the current set-up in place (which id rather not).
Anyway, im off to jamboree!
Big thanks to all that helped.
Ben
PS - Dazwaaah, its strange that yours is still working fine. Who knows, maybe you have a lower temp thermostat, or my one i tested still isnt up to scratch _________________
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I think i know why yours is running as per normal (albeit colder). You have the auto cooler in the bottom tank, so its going to heat the coolant up no matter how good the radiator is. Im assuming it would heat it up past the stock thermostat temp range therefore allowing you to have a properly working set-up.
Me being stupid? decided to not bother with the tranny cooler in the radiator which worked out to be a bad decision.
Ohh well. We live to die tomorrow
Cheers guys!
Ben _________________
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River City Compliance
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installed a new 77Ž° thermostat. Still overheats. I think it might be the radiator cap. The stock style just doesnt fit right. Off to supercheap for me _________________
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Well its the radiator cap. They didnt tell me the cap needed to change from the stock type to a new size. Since the stocka fit pretty good, i thought nothing of it. Little did i realise that the valve inside the stock type cap is 0.5cm too shallow. Went to superheap and bought a new one for $10 with a depth of 1.5cm and now she's perfect! Runs 85 degrees all day long. Went for a good 10minute thrash and it only ever got up to 90degrees.
Heres a pic showing the different depths, stock on the right:
Heres the new cap installed:
I'll write up a thread on how to replace the thermostat for a new one in the how to section.
Cheers!
Ben _________________
Your local Brisbane Compliance Contact
Shogun Car Company
River City Compliance
RCN Compliance Centre
East Coast Compliance
It might be worth getting some adhesive backed foam from Bunnings and run it between the top tank of the radiator and the front bonnet support rail, that should stop air escaping out through that gap and force it through the radiator instead. _________________
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