HI, I just joined the Diesel Bombers. I am going crazy I bought a 93 cummins in January, I recently started to over heat. I flushed it and changed the thermostat. Still hot next i installed a aftermarket gauge by the thermostat housing. Then water pump then had the radiator rodded, the man at the shop said it wasn`t to bad. Changed out the fan clutch. It shows 280ish on the aftermarket gauge. i checked it w a digital thermometor 140. I took the gaude back it shill is showing its running hot. Any help would be great thanks in advance.

 

are you saying you get a reading of 140 from a thermometer? then getting around 280 on the guage? you may need a head gasket had same problem and in the process of doing my head gasket, studs, and glass beating/painting half of my engine

 

If he's not loosing or gaining coolant it won't be a head gasket causing it.

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When it's running and hot can you grab the top rad hose n squeeze it n hold it hold it squeezed? I'm thinking you may have an air bubble somewhere after changing 1 of the things you changed like water pump. I'd try letting it idle for a while with the rad cap on but loose till it hits full temp n see what happens. I changed the rad in my 90 n it ran hot on me for a while even after letting the system bleed any air out or so I though as there was still a pocket or two of air left.

 

it doesnt loose coolant. I can hold on to the hose when it it showing a high reading on the gauge. I`ll try running it with with the cap on but loose. I bought a non cummins thermostat would that be an issue also. I`ve been reading of possible causes anywhere i can look

 

my 93 i had would slowly creep up to over heating temps on the gauge but then would fall back down shortly after

 

Weak fan clutch can do it, make sure the heat is on high while you're warming up too. Sometimes you can "burp" the engine by tapping the throttle rhythmically, just enough for the engine to rock a lil. Either that or jack the front of the truck up to see if you can move the air bubble to the front. Might want to remove a gallon or two of coolant and then re-add it slowly. There's a number of little "tricks" that can remove a bubble. Squeezing the bottom radiator hose can move a pocket around too. I wouldn't run it around too much if it's getting hot... Just for giggles; are you sure you installed the thermostat in the correct direction? If its reading "hot" and you can HANG onto the top radiator hose then it isn't as hot as it should be, which means thermostat isn't opening.


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I`ve got some ramps i can drive it onto. I`ll check the thermostat also. I may have put it in backwards. I`m open to try anything at this point. Thanks for all the help will report back later

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I was told autozone fan clutches were not the best. It was only a few days old but I put on one from napa. Checked the thermostat it was in correctly. Did I mention I just installed a new aftermarket temp gauge. I thought the old one was bad it was only a few weeks old. Its still showing about 260ish. My next door neighbor had a brand new temp gun. The waterpump upper hose both show about 178ish. The temp gauge is an electric one could that be my problem. Thanks

 

Sounds more like a gage issue than a mechanical one. If the digital thermometer says 140° - 178°ish and you can hold your hand on the hose, I would say the gage is wrong. They probably gave you the wrong probe for the after market gage. On your original gage, replace the temp probe.

 

You were right I bought a mechanical and it worked fine. I guess maybe carquest packaged them wrong. Thanks everyone for the help.