Jeep Wrangler Chevy Conversion Overheating Issues

6:10 PM 0 Comments A + a -

Below is a transcript between a customer that installed a 1682-3C and our parts technician.  We sell Jeep engine conversion radiators on in 3, 3HD and 4 Row versions.  Many customers often ask whether to go with the standard 3 row (which we do sell the most of) or to get into our HD cores and 4 cores.  This information is meant to give some conversion enthusiasts knowledge of questions and situations to be aware of when performing an engine conversion.  We hope that it may help you with your radiator choices.


1. The 350 is modified, bored, cam, full roller motor…

2. Flex fan is on it now, I have tried electric fans as well

3. I am not 100% sure of the CFM rating

4. Yes I have had a shroud made, and have run it both with and without

5. I had a 160 degree thermostat in it and have since removed it and it runs cooler, but still way above normal range

6. It has got a 15psi radiator cap on it

7. At idle, the temp will sky rocket quickly

8. The temp will rise at any speed

9. Temp will hold steady at higher speeds, but will not cool down much at all. The longer you have run it the less effect any variable has on the temperature, it just gets hot and stays that way.

After reading the specs that this 350 is modified I would have gone to a thicker radiator like the 1682-3CHD, 1682-4CHD. It is higher horsepower and higher compression so he really should have gone to more radiator in my opinion.

The radiator is a small part of the issue but there are other things going on. I would have gone to a 185 degree thermostat. A 160 is opening to soon and will not control the higher temps and no thermostat at all is asking for trouble.

The radiator does not generate heat. It get it from the engine. Even with this smaller core there should be some consistency in temps and I don't see any. The symptoms that are listed here point to lack of coolant flow or lack of air flow. The customer needs to get some temp readings using a thermal temp gun. Starting with the thermostat housing, then the top radiator hose connection and then the bottom hose connection. This will tell is what temps are coming off of the engine and going into the radiator and what is happening when the coolant leaves the radiator. With the thermal gun also look at cylinder temps to see if the cylinders are close in temp to make sure of circulation through the engine. The engine is holding a lot of heat and generating is quickly. Where is it coming from? Its not coming from the radiator so is the rear of the engine running considerably hotter than the rest?

This engine needs at least 2600cfm coming from the fan. It is also important to check the rotation of the fan. We also need to make certain that the coolant is flowing all the way through the system and by the description of what is going on one of the two if not both is part of this puzzle. A good starting point is the temp readings I mentioned. This will give a good baseline for comparison and start pointing out places to look for problems.