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Discussion Starter · #1 ·
The temp on my truck continues to climb. My gauge will go well above 210 if idling but drive down the road and temp starts to come down again into expectable range. The first thing I did as pull thermostat, still climbs. Next changed radiator because it was really old, still climbs. Replaced clutch fan, still climbs. Tested gases in radiator to see if exhaust gas was present, test was good. I also have no fluid in oil and no smoke out exhaust. I have done compression test on engine and radiator, all pass. I have also verified temp sensor, it is accurate. The thing that really bothers me is why its so high with no thermostat. If I look in radiator water seems to be following well. I am completely lost on this one, any help would be appreciated.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,536 Posts
put a scan tool on it and see if your gauge is reading correctly- ps an cheap IR gun can verify things also.Could be as simple as bad hoses or a failing water pump.
 

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Engineer
2003 S10 4.3L 4wd Crew Cab
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96 Posts
I'd check your water pump. Could also be your heater core is clogged.
 

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276 Posts
Did you test or replace your radiator cap? It's often overlooked but it serves a very important purpose, If the system can't build pressure then it can't increase the boiling point of the coolant/water.
 

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Premium Member
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52 Posts
Discussion Starter · #5 ·
Thanks guys for responses. I had already replaced radiator cap, flushed system and heater core. I also had verified temp of sensor and its dead nuts. Could a water pump work partially??? If I am sitting in driveway and rev the engine the temp will go down, I assume because pump is moving more water.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,536 Posts
the impeller can rot away- so higher rpm would move more water.
 
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Engineer
2003 S10 4.3L 4wd Crew Cab
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96 Posts
fan clutch
That was done already. Only thing left out of the equation is the water pump.

Thanks guys for responses. I had already replaced radiator cap, flushed system and heater core. I also had verified temp of sensor and its dead nuts. Could a water pump work partially??? If I am sitting in driveway and rev the engine the temp will go down, I assume because pump is moving more water.
Since you have all the latest and greatest new components for cooling, you should throw in the high performance water pump if you replace it. The part number is 130-1820P
 

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Awww..you ain't got shit!
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3,551 Posts
Bad water pump. Impeller on inside has turned to dust. You e replaced everything and know it doesn’t have a head gasket issue. Bad pump. My best educated guess.
 

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Premium Member
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Discussion Starter · #11 ·
Replaced water pump and clutch fan and still climbing. The only thing I can think of is blocked cooling port/ports?
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,536 Posts
Have you changed the hoses? they can collapse if old and cause issues.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,536 Posts
?? what did you use for coolant ?
 

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Awww..you ain't got shit!
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3,551 Posts
Put a pump on it. Be careful though removing it. You should consider bracing the pump since some of the bolts pass through the front cover too. If you break that seal pulling on the pump you’re gonna have a bad day. If you don’t know what I’m talking about, the Haynes manual explains it. But if it were me? Hell, pull the front cover and put a new timing set on it while you’re in there. Those chains stretch like crazy.
 

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434 Posts
Sounds like a steam pocket somewhere. Have you parked it with the front a good bit higher than the rear and burped the cooling system?
 

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Premium Member
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52 Posts
Discussion Starter · #17 ·
This may sound stupid but is it possible I have the wrong head gaskets? I was looking at new heads and I have a 3.4 out of a 95 camaro, the company I went to order from asked me the stamp code because people tend to get the wrong heads. After digging into it I have heads with stamp 884, if I look at the pic of bottom of heads they are very different from the ones I almost ordered. I have reached out to the company to see if there are different head gaskets because the ports on the 884 seem bigger. I will let you know what I find out.
 

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94 4x4,01 Blazer
2001 Blazer 4dr 4wd LT
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1,536 Posts
not stupid- quite possible- as you never mentioned you had you mill open, no one thought about that.There are some differences in the gaskets that can cause that type of heat rise.
 

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Premium Member
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Discussion Starter · #19 ·
Company who sells heads tell me the head gaskets are the same.
 

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B4U Task Force Admin
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29,524 Posts
Company who sells heads tell me the head gaskets are the same.
Have you gone to the parts store to compare gaskets? Don't accept what they say at face value...verify.
 
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