1990 Other Chevrolet Models Occasional overheating

Tiny
MATDYER
  • MEMBER
  • 1990 CHEVROLET
  • V8
  • 2WD
  • AUTOMATIC
  • 112,000 MILES
My older G30 van sprung a leak in the radiator, had it replaced. Ran well for a month(January in PA), then began overheating badly. I replaced the termostat, had the serpentine belt and tensioner replaced. Now runs about 150 deg. On highway but creeps up in stop and go traffic, occasionally red lining for 15 seconds then dropping back, sooner if I can get moving. Was advised to check fan clutch with engine off, if spun half a revolution freely then stopped. No apparent leaks except for under muffler on humid days. Am loosing a gallon or so of coolant per day however.
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Thursday, April 22nd, 2010 AT 5:49 PM

3 Replies

Tiny
HMAC300
  • EXPERT
Due to you saying you lose a gallon or more of coolant you still have a serious leak. Have a pro pressure check your system to see if there are any visible leaks. If not then you may have a head gasket or intake gasket blown. It could possibly be a heater core as well or even a water pump. But a pressure check should give you a very good indication
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Saturday, April 24th, 2010 AT 10:42 AM
Tiny
MATDYER
  • MEMBER
No visible water leaks even after vehicle sits, nothing on the ground except below muffler on humid days. Heater blows heat, am suspecting head gasket. Will have to change intake gasket also to work the head. Will a compression test identify which head gasket is faulty? Or in for a penny in for a pound and have to do both, plus intake and valve cover gaskets?
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Friday, May 7th, 2010 AT 8:34 PM
Tiny
HMAC300
  • EXPERT
First let's get teh muffler thing. The water you see there is probably from the a/c drain that is in the heater area. It is normal for this to happen. It doesit whenever you have the a/c on. Humid days you would see it more. As far as the compression test, if you pull all the spark plugs out and the gasket is blown between the cylinders then it would show up on a compression test. But a pressure check would show a drop in pressure indicating a leak. Which if there is nothing external it would mean internal. If you drain the oil and get water from the oil, then that would be either something cracked or an intake leak. If not it would be a head gasket or soemthing cracked. By the way if you continue to drive and it continues to overheat then it may have something cracked as well. Also if you do one head gasket you may as well do both just as a precaution. One other thing, check the lifter valley on both sides for a crack. Some of these were cast thin in those areas and have cracked there. It would be about an inch down from where the head mates to the block.
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Saturday, May 8th, 2010 AT 8:45 AM

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