Ok this is my first time on here Got a 92 jimmy with the 4.3 vortec runs great starts just fine one of the smoothest running vortec motors I have had.(after the tune up and me fixing the spyder the previous owner put in wrong, forgot the o rings on the fuel lines that feed the spyder) But the thing keeps overheating. Put a new t-stat in it and still it won't open thought at first it was just the digital dash messing up but when it flashes you can smell it no water in oil so I am stuck. going to pull the t-stat in the morning to see if that stops it but winter will be back again and I will need heat so that will only be a temporary fix. You can hear the seal release on the radiator cap when you open it hot. The previous owner said it sat in his neighbors feild for close to 5yrs and never moved untill he bought it. What am I missing??? Could it be water pump???

 

ok new to this see some have viewed my posts but yet to comment, thats ok someone will come along on hereto help me out. I talked to a guy at the auto store about the truck while I was getting a new water pump. Didn't look like it was circulating to good in the radiator and figured what could the 20 bucks hurt. Now I it flows real good to the point where it looks like a garden hose is on when you give it gas. Theguy at the store says it will run hot without the t-stat because its circulating to fast to cool down in the radiator. Anyone else ever heard this? After the new pump it took almost an hr to get t the flashing point on my dash. Also how can you tell if a head gasket is blown? Other than water in oil, water or smoke from exhaust or running rough cause it does none o the above. I reallywant to drive the thing but don't want to have to pull over to letit cool down every half hr or so.

 

Ok I have this thing were it will run great but cannot figure out why it still overheats. I have had a 93 jimmy and 2 94 blazers all with the 4.3 vortec. But this 92 is getting on my nerves. I have done everything short of pulling the heads and putting new gaskets in the top half. That will be the next step I guess. I changed the water pump earlier and it helped alittle, just came in from the garage it's 12:30 in the morning put a t-stat back in it and still the same the hoses stay soft they don't get firm like there is pressure in the system will that cause the t-stat to fail? And is that a sign of a blown gasket be it intake or head? still no water in oil or exhaust no smoke either and she stills runs smooth as can be. Any advice???

 

*Combining 3 separate threads on the same subject* Please stick to one thread on a given topic and try not to post consecutively within 24 hours, rather use the edit function if you need to include additional information in that time span. 'Bumping' of a post is permitted if you have not received a response after waiting 24 hours.

Yes, it is true that having no thermostat can cause over heating as the coolant doesn't have enough time to cool down in the radiator. This is generally the case with high heat loads and low airflow through the radiator though.

One rather quick way to check head gasket integrity is to look for bubbles in a completely full radiator. Another is to run a compression check. A blown head gasket will show up on a compression test.

 

So I am out by the street with the hood up and a drunk guy walking by that i have never met before asks what wrong with the truck. I tell him I changed water pump and put a new t-stat in it and still it overheats. The stranger then tells me to fire it up I crank it and when I come back up front he is standing there holding the fan still with his hand. Says hay look it's the clutch. Changed the fan out with one I had in the garage and now she holds at 210-215. guess I'm glad I live down the street from a bar I never would have thought about the fan clutch since it wase't makin any noise. Thank you anheiser bush

 

That would do it. As stated in other threads on this topic, the clutch should have very little resistance when cold and should almost lock up when hot. There is a thermo-viscous material inside the clutch that reacts to the temperature of the air exiting the radiator.

 

if your not getting pressure in the system you might have a bad radiator cap