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#574 of 631 Re: Can't trace coolant leak [georgiaman]
Feb 22, 2010 (7:05 am)
Coolant leaks typically could be (in no particular order):
- heater core inside car, typically you might smell antifreeze in cabin, passenger carpet wet, or windows fog up
- engine head gasket, allows coolant to leak into cylinder, get's burned up when car start and comes out as vapor out the exhaust. Can ruin cat converter, and of course water in engine is not good.
- water pump, could drip around shaft
- any and all hose connections, as previously mentioned
- radiator core, sometimes obvious, sometimes pin holes will drop so little that the air flow vaporizes and hard to find. Could also leak internal into transmission cooler section, disaster for transmission.
- cracked overflow container, or hose to the container.
#575 of 631 Re: Can't trace coolant leak [kiawah]
Feb 22, 2010 (9:03 am)
Thanks for your detailed reply!
From your list, I think I shall check the overflow container and the water pump first.
If it is a leaking water pump, approximately how much should it cost to replace?
#576 of 631 98 markII overheat
Apr 05, 2010 (4:26 am)
I've been having a slight problem with my 1998 toyota mark II - 1G-FE 1988cc engine.
Here it goes: whenever I pressure the car (drive real hard) or use the ac the temperature gauge rises and will continue to rise to even red zone if I dont ease up. When this happens the radiator loses no coolant nor does it boil, it just seem to be cool and normal and i never have to top it up...ever.
The radiator have been removed, flushed and rod out, cap has been changed, clutch for fan replaced and also the thermostat has been replaced but still the problem remains.
I am now suspecting that the problem is stemming from either a faulty coolant temperature sensor or temperature switch, however, i've looked for a temperature switch where I know they are normally located (at the exit or inlet goose-neck where the hoses are connected) but cant seem to locate it.
Can anyone offer some input on this problem or help me locate the temp. switch or temp. control unit on this car?????
#577 of 631 Re: 98 markII overheat [fullerru]
by MrShift@Edmunds HOST
Apr 05, 2010 (7:41 am)
You mean, by "switch" the fan sensor as opposed to the gauge sensor?
If your fan turns on during this "overheat" then no sense chasing the fan switch/sensor or the relay.
I'm sorry but we don't see this engine in the USA, so I can't locate the part---unless you know of some older US model that might have used it.
Apr 06, 2010 (5:02 am)
I hope someone can help me out. I have a 99 Chevy silverado, 5.3, 4 weel drive. Started overheating so flushed out radiator and changed thermostat. Next day, still over heating, replaced water pump and verified fans are working. STILL overheating, The BIG question, WHAT'S LEFT??? Any one know what steps I am missing? Any help would be great.
Thanks to ya all
#579 of 631 Re: BIG HEADACHE!! [rickysmyboy]
Apr 06, 2010 (5:09 am)
How do you know it was overheating?
Is the temperature gauge reading high?
Is the coolant bubbling?
Is the engine actually above the permitted range?
Temperature gauge reading wrong due to gauge or sensor bad?
Head gasket leaking?
Pressure cap not sealing and holding proper pressure allowing the engine to go above the boiling point of the pressurized coolant giving boiling?
Infrared heat thermometer to see if thermostat area/upper radiator hose are actually above the 230 or so it might reach under pressure in a hot environment.
Check coolant with a test strip or sensor to see if hydrocarbons are in it from leaking head.
Clean pressure cap. Check pressure if a cap check device is available. Is upper hose becoming very solid because of pressure--that might indicate the cap is working. I do not recommend opening cap when car might be under pressure warm because of danger from coolant spewing out.
#580 of 631 Re: BIG HEADACHE!! [imidazol97]
Apr 06, 2010 (5:54 am)
Well, have pressure on upper hose, gauge is reading hot, no "Bubbling" in over flow to indicate overheating, replaced thermostat, water pump, chemically flushed radiator, put in fresh antifreeze, new radiator cap. Checking clutch fan to make sure it is working properly.
I read there is a sending sensor for this year? Is that correct?
Think the sensor could be bad since there are no other obvious indicators?
THANKS for any help
#581 of 631 Re: BIG HEADACHE!! [rickysmyboy]
Apr 06, 2010 (5:59 am)
Is there a time or type of driving when it overheats? That might indicate inadequate flow through radiator.
Have you used a chemical test strip or the sniffer type sensor to check for hydrocarbons in coolant as a worse case possibility?
Has interior of lower hose collapsed restricting flow to water pump when it sucks the coolant through the hose?
#582 of 631 Re: BIG HEADACHE!! [imidazol97]
Apr 06, 2010 (6:11 am)
I am not familiar with that kind of testing. Actually called chevy shop and for $49.95 they can run diagnostic.
The "Worse case" possibility is what? I have exhausted my knowledge at this point. Granted, I am no mechanic either.
#583 of 631 Re: BIG HEADACHE!! [rickysmyboy]
Apr 06, 2010 (6:33 am)
Shops use a tailpipe type sniffer that senses hydrocarbons coming from the coolant. That indicates a combustion leak into the coolant, typically a head gasket. There also are test strips that can be dipped into the coolant to sense hydrocarbs that I've heard mentioned on car repair programs on radio.
Radiator shops do a flow test on radiators to see if enough coolant can flow through the radiator.
If the lower radiator hose is somewhat soft after years, it might have the inner layer pulling away from the outer part and partially blocking the flow of coolant from the radiator.