Prelude overheating after fans turn on.

[Cris]

Hey, I have a 1994 Prelude with a JDM swap that I did a month ago. Earlier today I went to work and when I got there I noticed the temp went up, I also noticed the temp rises about 2 or 3 seconds after the fans turn on, a few seconds later I hear the fans turn off, the gauge would stay reading hot then return to normal and it overheats again until the fans cycle on again. This same exact thing happened to my old engine I had in there, reason why I swapped it in the first place because it was always overheating after everything was replaced, including the head gasket, which even then 2 weeks after the HG replacement it started to do the same symptoms above. This engine ran great temp wise until today. I had a new water pump in and a honda thermostat when I did the swap, radiator is less than a year old. I noticed I’m losing coolant, it wasn’t low low, but It wasn’t up to the radiator neck, when I squeezed the top hose there was coolant in there. When I was driving home it was all good, when I stopped at my house I let the fans cycle about 4 times and on the 4th time the temp rose after the fans turned on, is it really overheating? I broke the thermoswitch on the head during the swap, got a new one and put it on. There is another one on the thermostat housing, I have a OEM one that came with the new engine but I didn’t use it cause I thought that one is good, but I’m not sure what exactly what that sensor does. The sender for the gauge is also new, was replaced last year with a honda one. I’m gonna fix the leak when I find it and hopefully it was just air trapped, but the same thing happened to the old engine I thought was bad so maybe it’s something else. Any ideas? thanks

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[Andrew Phillips]

It does sound like air in the system. If the coolant bottle ran empty the hot radiator could have sucked in some air somewhere along the line. Also, the cap may not be working properly.

[Cris]

I’m gonna pressure test the system on Sunday and see where the coolant is being lost from. Once I fix the leak I’m gonna bleed the air again and see what happens. I’m gonna see tomorrow morning how low the coolant got. It seems I have to add some every few days. No visible leaks but I do smell coolant when I open the hood, not alot but it’s there.

[Ingvar]

Every few days? She’s a fast leaker then. Any white smokes from under the hood? Contrast dye will do you much help.

[Author]

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