Q: Engine overheating replacing thermostat

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I own a 3500 express van with a 5.3 votex engine. I replaced the water pump a year ago and put in a new thermostat 2 times. 2 weeks ago my engine started to overheat again. So I replaced the thermostat, and it was OK for a few days. Then it started to overheat again. I checked the water and it was low, so I added some. The van drove OK for a few days, but now it’s overheating again. So I decided to completely take out the thermostat to see how the van would run without it. I drove down the road a few miles and ENGINE flashed on the screen display. This time it wasn’t boiling over, and it didn’t reduce the power like it did before. Is it OK to run the van like this without the thermostat? I don’t want to ruin my engine What are you thoughts and ideas? Thank you.

Hello. Let me start off by saying that it is just as bad, if not worse, to run an engine with no thermostat as it is to run it with a bad one. It will also cause engine damage. It sounds like there is a head gasket issue with the engine.

If it primarily overheats under load then it has combustion pressure getting into the cooling system which will ultimately causes this to occur. I usually look for bubbles in the cooling system when the engine is running and do a block test to verify this.

If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to you home or office to diagnose your overheating issue and repair this.

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