KA24DE Coolant Disappearing and Overheating

Information on the naturally-aspirated KA24E and KA24DE engines.
Gokussj5okazu
Posts: 8
Joined: Sat Nov 20, 2010 3:08 pm

Post

I've got a bit of a head scratcher here, I'm about to say screw this engine and sell the whole car.

I rebuilt this KA early last year, but didn't end up driving it until December or so. It ran fine, temp stayed right in the middle of the gauge. However, my heat would come and go randomly, with no particular pattern.

About 2 weeks ago we had a very cold night, around 3*. Unfortunately I was running straight water and no antifreeze. Went out the next morning for work and the car started fine. Had no heat at all 1/2 the way to work, but it did finally start. At about 3/4 the way, or 40 miles, the temp gauge started creeping up and my heat disappeared. Finally made it to work, but it was overheating.

Before I left work that day I topped off the coolant. It took probably 1/2 a gallon. Started on my drive home, and after about 10 miles it started overheating. I made it home but had to stop every 5-10 minutes and add more coolant.

Thinking the radiator was cracked, I replaced it. Then I discovered the water pump was leaking from the weep hole, so I replaced it as well.

Drove it to work 2 more days and it wouldn't heat up at all until I was on the highway over 3k rpm for a while. So I replaced the thermostat, and found the old one was stuck partially open.

Got it all back together 2 days ago, and have been fighting it since. I made sure to jack the front end up as high as possible, pulled the bleeder screw, and can say 100% for certain there are no air bubbles.

I can let it idle literally forever and the thermostat never opens. The top hose gets warm, bottom stays ice cold. However if I hold the throttle open at about 3k for 2-3 minutes, the bottom hose slowly starts getting warmer but the gauge never goes above 1/2. So no overheating. Also, I get no bubbles up in the radiator while it's idling, even with the thermostat open. So head gasket's good?

Now here's where it gets weird. I have tested this 3 times now. I can drive it town about 12 miles, gauge stays at half, and I have fantastic heat. I can beat on it as hard as I can, hell I can even run it at 4k there the whole way, no problems.

BUT, as soon as I get to town and slow down it starts overheating. Gauge jumps to the dot before the H, and I start getting coolant bubbling from the overflow. Also, my heat stops completely. Ice cold. Check the coolant, and I'll be about a quart low. EVERY TIME. Fill it up, rinse and repeat.

SO what's going on? I'm thinking head gasket, but I have no symptoms at all except for disappearing coolant.


IAMTheRuckus
Posts: 90
Joined: Wed Oct 05, 2011 9:59 pm
Car: 1990 Nissan 240sx

Post

If you were to be loosing coolant to a head gasket there would also be coolant in your oil more than likely. There may be different offerings on thermostats so make sure you got the right one for your temp range you need. Are you running electric fans or clutch fan? Check the heater core too, as it may be stopped up or the lines running to it may be (had a vehicle like that at work that had me stumped for a while). Your clutch fan (if you have one) could be slipping and not allowing it to cool properly at idle.
I found this nice article about clutch fans you can check out, very informative and possible applicable to your situation.
http://www.aa1car.com/library/cooling_fan_clutch.htm

Russel
Posts: 1
Joined: Sun Feb 07, 2016 10:22 am

Post

Get yourself a cooling system pressure tester and pressurize the system (cold) to find any leaks. If the thermostat is opening and the water pump is pumping, the heat should be transferring to the radiator. If the radiator is getting hot and the fans are not working, it will overheat at idle or low speed operation.
A couple of common mistakes made in DIY are routing the belt wrong, so the pump is turning backwards, and putting the thermostat in backwards.


Return to “KA24E / KA24DE Forum”