Engine running hot help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**yellowblazer1969** · 03-18-2009, 10:41 AM

Here we go again, the engine is running hot in the blazer now and i just wanted to ask a few questions, how do i know what the cause is, any signs that would lead me to the thermostat, water pump or radiator, also what is the best way to flush the block and radiator.

Thanks again ,

chris

maddog1331 · 03-18-2009, 11:04 AM

Don't know if this will help you any, but mine started running hot awhile back, so I put a new thermostat in it. Shortly thereafter I was driving along, and it ran hot again...really hot, I did not notice it until it was starting to spew out (funny how that gets your attention). I replaced the thermostat again and it was fine.

The truck had sat a good while before I bought it, so I think maybe there was some crud in the system that might have blocked both the old and the new thermostat...seems to be good now.

I don't think the new thermostat that failed was completely closed, but was enough so that it overheated on me. You can check if it is thermostat by squeezing the hose that goes from the radiator to the top of the engine where the thermostat is. When you start up it should be a bit hard to squeeze, once the engine warms up and the thermostat opens up it will be easier to squeeze. If the engine is hot and that hose is still hard to squeeze, the thermostat is not opening up.

I think I explained that right....hope it helps man

cdowns · 03-18-2009, 11:07 AM

hot running? first thing i do is check the actual temp of the coolant with an accurate thermometer to make sure its hot and not a gauge problem

**yellowblazer1969** · 03-18-2009, 11:13 AM

Noticed the spewing like maddog said, yeah a real attention getter. Seems to be having trouble at the upper hose on the radiator side thats where it was spewing, ill try the thermostat and see if its opening.

maddog1331 · 03-18-2009, 11:51 AM

If you are going to the trouble of taking the old one out, if it were me I would buy a brand new one and put it in. Thermostats are cheap, thankfully

When you get one, I think there are a few temperature ranges....I have a 350 in mine, there were 2 temp ranges available for mine in stock at the local O'Rileys, I got the one that wouldn't open up until the higher temp was reached ( 190?? can't remember). I don't think there is any problem getting either temp, I got the higher temp one so the cab would warm up more quickly.

03-18-2009, 10:41 AM	#1
yellowblazer1969 Registered User Join Date: Jul 2004 Location: columbia sc Posts: 387	Engine running hot help Here we go again, the engine is running hot in the blazer now and i just wanted to ask a few questions, how do i know what the cause is, any signs that would lead me to the thermostat, water pump or radiator, also what is the best way to flush the block and radiator. Thanks again , chris

03-18-2009, 11:04 AM	#2
maddog1331 Registered User Join Date: Feb 2009 Location: Somerset, KY Posts: 398	Re: Engine running hot help Don't know if this will help you any, but mine started running hot awhile back, so I put a new thermostat in it. Shortly thereafter I was driving along, and it ran hot again...really hot, I did not notice it until it was starting to spew out (funny how that gets your attention). I replaced the thermostat again and it was fine. The truck had sat a good while before I bought it, so I think maybe there was some crud in the system that might have blocked both the old and the new thermostat...seems to be good now. I don't think the new thermostat that failed was completely closed, but was enough so that it overheated on me. You can check if it is thermostat by squeezing the hose that goes from the radiator to the top of the engine where the thermostat is. When you start up it should be a bit hard to squeeze, once the engine warms up and the thermostat opens up it will be easier to squeeze. If the engine is hot and that hose is still hard to squeeze, the thermostat is not opening up. I think I explained that right....hope it helps man

03-18-2009, 11:07 AM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Engine running hot help hot running? first thing i do is check the actual temp of the coolant with an accurate thermometer to make sure its hot and not a gauge problem __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

03-18-2009, 11:13 AM	#4
yellowblazer1969 Registered User Join Date: Jul 2004 Location: columbia sc Posts: 387	Re: Engine running hot help Noticed the spewing like maddog said, yeah a real attention getter. Seems to be having trouble at the upper hose on the radiator side thats where it was spewing, ill try the thermostat and see if its opening.

03-18-2009, 11:51 AM	#5
maddog1331 Registered User Join Date: Feb 2009 Location: Somerset, KY Posts: 398	Re: Engine running hot help If you are going to the trouble of taking the old one out, if it were me I would buy a brand new one and put it in. Thermostats are cheap, thankfully When you get one, I think there are a few temperature ranges....I have a 350 in mine, there were 2 temp ranges available for mine in stock at the local O'Rileys, I got the one that wouldn't open up until the higher temp was reached ( 190?? can't remember). I don't think there is any problem getting either temp, I got the higher temp one so the cab would warm up more quickly.



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