Videlicet

I was driving my car after replacing the transmission, then I parked it for a few minutes leaving the engine running. To my surprise smoke suddenly started coming out of the hood. I quickly turned it off, the temperature gauge had very quickly skyrocketed. Right after that, a plastic connector between two hoses broke, and sprayed out coolant everywhere.

The connector was old and probably gave out under the heat, but the car had overheated before that happened. I replaced that piece but of course the car continued to overheat.

Now usually overheating is something simple like the water pump, or thermostat. My car does not have a thermostat, so the coolant should run freely through there, and I just changed the water pump yesterday, and it still overheats. Today I checked all the hoses and the radiator for clogs. Any ideas on what this might be?

My car is a 240sx S13 1991, with a KA24DE, it's more or less stock aside from an exhaust, a cold air intake, and a CX Racing radiator. The previous owner of the car must have removed the thermostat, and also he seems to have wired the radiator fan to continuously run regardless of oil temp. It's always run cold before, but now it overheats within minutes of driving.

SupaDoopa

Those radiators are generally shit. Honestly if the water pump was done and you didn't overload gasket maker to where it spewed into the cavity, you probably have a moot radiator. Pictures would be helpful for us to see what you got going on there.

Is there adequate airflow to the radiator? Are you running straight water or a mix?

S14rebuild

Did u bleed the coolant system properly? Since the connector broke there will be air trapped in the system. I beleve there is a bleed screw on the upper coolant neck


Mods move to tech section please***

mav1178

when's the last time you changed your radiator cap?

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Videlicet

It could be the radiator. The only thing is, the radiator itself stays cool, if it weren't working wouldn't it heat up? The airflow should be fine, its never had issues with this before. I'm running a standard premixed coolant.

Videlicet

Here is some photos, sorry if they aren't helpful

first one is where the connector broke
https://imgur.com/TnAp2cO

https://imgur.com/g5kASok

https://imgur.com/21XS5Ol

S14rebuild

Again. Did u bleed the cooling system properly?

NukeKS14

This x 100. How did you bleed your coolant when you filled it? KAs can be a real PITA to get all of the air out.

Kingtal0n

There should be a bleeder on the upper radiator hose? SR have it, KA might?

Make sure you remove that bleeder when filling coolant/water.

next, only use distilled water 100% during diagnosis, so you can spill it anywhere.
When finished and problem is solved, use only distilled water + antifreeze. Never use tap water.

Okay now, diagnostics. Do a compression test because its quick and easy. make sure you got no blown head gasket.
Take the rad cap off and run the engine from cold start, since there is no thermostat you should be able to see water flowing constantly and getting warm pretty fast. make sure it doesn't have a bunch of bubbles forming which could indicate a blown head gasket. I put my finger in the water to feel it heating up but be careful if you do that. The top of the rad should be hot or be getting hot as the engine runs. If the water up there stays cool and there is no evidence of flow then obviously the water pump isn't moving water. The system is very simple, water pump moves water and rad cools it. ez

and here is a warning about hot coolant. That shit will burn you, the skin right red off. So ALWAYS gently squeeze the radiator hose before you remove a cap to see if there is pressure in the system, and ALWAYS be aware that at any second the system could violently erupt, a hose could pop, a fitting could burst, etc... and hot water will boil you alive. IMO wear extra protection around a unknown cooling system, a face protection, eye protection, arm and hand protection, treat it like fire.

finally you really need a thermostat and a controller for the fan. Run an engine cold and it will eat engine bearings and cyl wall up. Oil needs to be 200*F to 220*F and the coolant needs to be at LEAST 170*F IMO (168* to 210*F is fine)

Videlicet

I've been testing it. The coolant doesn't seem to be circulating. I've blown air through the hoses, the water is able to go through everything like it should; it almost seems like the water pump simply isn't doing its job. I ran the car with the hose going to the radiator disconnected, and the water does not flow out of the hose.

zombiewolf513

That "test" isnt going to work bc thermostat. Btw, is your thermostat siezed?

Edit. I see you dont have one.

brndck

so. . . . . if the water pump isn't doing its job . . . . .

replace it?

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S14rebuild

Hows the water pump go bad from a broken plastic heater hose connector? Uhhhhhh

NukeKS14

He said he JUST changed the water pump in original post. Op, I'd recommend taking this to a qualified mechanic to look at for you dude....

Not trying to be rude, just realistic, but you may be in over your head here.

S14rebuild

Didnt know it was this hard to bleed a coolant system.

- jack the frontend of the car up hight(1ft off the ground)
-remove bleeder screw from upper waterneck
-add 50/50 mixture of coolant or water to radiator
-fill till coolant/water comes out bleed screw hole
-reinstall bleeder
-start car and turn heater on
-top off coolant/water constantly for 10mins(ac is off)
-lower car
-put rad cap on and drive for 10mins(watch temp guage)
-park car and let it cool off
-open radiator cap when radiator is cool to the touch and upper hose is soft.
-top off radiator with coolant/water
-fill over flow tank half way
-reinstall cap

*if the car truly has no thermostat this should be a very easy process


Done


Anything eles?

mav1178

I'm gonna ask again:

when's the last time the radiator cap was changed?

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S14rebuild

Why would u be so concerned with the radiator cap when the op has posted he has coolant flow/air in the system causing over heating



If the cap was bad 2 things- it wont hold pressre and constantly cause coolant to overflow the the overflow tank(op hasnt described that issue)

Or

The cap wont relieve pressure and when parked the upper rad hose will be sucked shut(op hasnt described this situation either)


So sure throw a new cap on the radiator and see what happens

Videlicet

After bleeding it again, the overheating seems to have stopped. However the hose going to the radiator split today and spilled coolant everywhere. I replaced the hose and refilled the coolant. I had to bleed it again. Hopefully that is the end of it. I'm not sure why the hose broke, it might have been weakened from the overheat

S14rebuild

At this point, sounds like your better off just replacing all the hoses u can.

brndck

if its old enough to be damaged by 230*, you better look into replacing every single other coolant line as well.

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mav1178

I'm gonna quote OP's post for reference.

I asked about the radiator cap because something caused excessive pressure buildup in the coolant system. An old/reused/bad radiator cap could be the cause of this and is often overlooked, not to mention I have personal experience from this 20 years ago.

He specifically said "the car had overheated before that happened " (the connector broke) and never ruled out the radiator cap. A bad radiator cap can also cause air pockets to boil over and cause overheating, especially at idle.

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Distributor for Nismo, ORC, and discontinued genuine Nissan parts.

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