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#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.
#584 of 631 Re: BIG HEADACHE!! [imidazol97]
Apr 06, 2010 (6:39 am)
OK You have helped alot. Just 2 questions, How hard is it to change head gasket?
How can you test the lower hose for integraty?
Very thankful for your input
#585 of 631 Re: BIG HEADACHE!! [rickysmyboy]
Apr 06, 2010 (6:57 am)
Feeling the hose is one technique. If uncertain, taking it off and looking at interior is best. By then it's cheap just to go ahead and replace it.
Does it overheat driving at speed along the highway or roads? Overheat sitting idling?
Head gasket requires careful diagnosis and checking pressure inside cylinder with compression tester to see if a particular cylinder doesn't maintain as high pressure as next one. It requires removing the intake manifold, valve covers, and then the head bolts. Head needs to be inspected for cracks, etc., that might cause leaking.
#586 of 631 Re: BIG HEADACHE!! [imidazol97]
Apr 06, 2010 (7:16 am)
Just went out and started truck for 2 minutes, let it get to operating range, no change in resistance on fan but let it run idle, not highway. It heats up at highway speeds, not on idle. Felt top and bottom hoses, top felt hot and bottom did not.
Suggestions on the "Cheaper" way to check for sure?
#587 of 631 Re: BIG HEADACHE!! [rickysmyboy]
by MrShift@Edmunds HOST
Apr 06, 2010 (8:45 am)
Okay, if it heats up at speed but not at idle you have a coolant circulation problem, not an air circulation problem.
By the way, a chemical flush of the radiator is a pretty lame procedure---you could still have a clogged radiator.
#588 of 631 Re: BIG HEADACHE!! [rickysmyboy]
Apr 06, 2010 (9:00 am)
Agree with shiftright. Now that you've said it's an overheat at higher speeds, it's back to the radiator and or lower radiator hose.
The cheapest is to take the radiator out yourself and take it to shop for proper cleaning.
#589 of 631 Re: BIG HEADACHE!! [Mr_Shiftright]
Apr 06, 2010 (9:03 am)
just ran it at speed for a few minutes (Actually went on highway for a few miles) The gauge never mooved but after coming back, I felt no resistance change in the fan, is that a correct way to see if the fan clutch is bad or going bad?
Any idea whats the best way to make sure radiator is not plugged? (No more LAME testings)
Thanks for your input.