Overheating

[brum]

Hi all, I've just finished building my s14a with a blacktop SR in. I've got a very annoying problem with the temp gauge rising when it's being driven or revved a bit.

First noticed it when on the motorway, I had to be somewhere so I put the heaters on full and it kept it from overheating somehow (although it did get close). On the return journey i did have to turn the car off and pull over because it just got too hot.

SO I've changed out the thermostat and bled+flushed the coolant system multiple times with multiple methods now to no joy. It's got a standard rad, nismo 1.1 bar cap, standard viscous fan minus the cowling.

Things to note;
No mayo under the oil cap
Bottom hose never gets hot with either new or old thermostat in
Heaters get and stay hot
Pump has been off and checked, all good
85% of the rad is cold, just the top closest to the top hose gets hot

Please help!

[JuicyCarbonFX]

I would either buy a cowling (cheapest fix) or pay out for a thicker aluminum rad with twin fans in a alloy shroud which is what I've done.

[green_rs13]

if your bottom and top hose are different temperatures then you have problems.

[brum]

I would either buy a cowling (cheapest fix) or pay out for a thicker aluminum rad with twin fans in a alloy shroud which is what I've done.

What makes you think it's the rad though? Because like i said my rad is pretty much always cold

[Chriscooke]

Is it a standard radiator? Would be worth pulling the top and bottom hoses off and run a hose pipe through it to check it’s not blocked.

How did you bleed the air out of the system? Bleed nipple on the top water neck by the cas?

[brum]

Is it a standard radiator? Would be worth pulling the top and bottom hoses off and run a hose pipe through it to check it’s not blocked.

How did you bleed the air out of the system? Bleed nipple on the top water neck by the cas?

Yup standard rad and I should've done that to be fair, I'll do it tomorrow but surely even if it's blocked the bottom hose would still get hot when the stats open?

I've bled it a few different ways, always with heaters on full and squeezing rad hoses and heater hoses. Used the rad cap off method, bleed screw method, front end in the air and flat. Revving it off and on. I've even tried emptying the system then re filling it with as much coolant as I could before starting it by filling up hoses, filling engine first ect...

[green_rs13]

I would run it up to temperature then check to see the top and bottom hoses are the same temperature and that the whole surface of the radiator is an even temperature. if its not then you have a blocked rad. taking if off and reverse flushing it with a hose or prying back all of the tabs and separating the end tanks should fix it, or just buy an ebay special replacement for £100 odd.

to fill them I I get a 2L fizzy pop bottle cut the bottom off and wrap some electrical tape around the screw thread until it forms a tight fit in the top of the radiator. block off the feed hose to the expansion bottle by clamping it or kinking it over.

[tricky890]

I had this issue on mine , fitted a japspeed. Rad , still had the cowling aswell, it never overheated butvthe bottom rad hose was always freezing cold, I changed out the thermostat and now it’s perfect . Pull the stat and test it in some boiling water . I’ve known even new ones to not work.

Also is your coolant temp sensor good ? That can cause havoc




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[arry]

As above I'd start with the obvious first. Just because thermostat is new doesn't mean it's working. Check that, and go from there.

[Chriscooke]

Fair point about the stat. I was chasing an overheating issue in another car for a while and even fitted two non Oem stats. Both were faulty.

[brum]

Sorted it! It was the temp sensor for the gauge. Because the engine was from an S13 it must've had a CA sensor in so it read wrong! Thanks for your suggestions!