Uh oh, strange cooling problem with freshly built KA-T (I searched).

[MarkEmark]

Let me preface the post by saying that the engine is freshly rebuilt, has about 5 miles on it. Brand new thermostat, brand new water pump, brand new (last year) Koyo 2.1" thick aluminum radiator, fresh coolant at a 70/30 water/anti-freeze mix.

The engine was completely devoid of all fluids when I got it back from the shop, so I filled it up exactly like the FSM told me to...had the front end of the car a little higher than the rear, had the heater hose disconnected at the heater c*** after putting the heater dial in the car to hot, and had that little bolt in the intake manifold removed. I filled it up until coolant came out of that bolt hole, then I massaged the upper radiator hose so I could put in more coolant to make sure the system had the max amount of coolant (in the past, whenever I drain and refill coolant, theres never enough coolant and this causes the engine to overheat).

Anyway, I take the car out on its first ride (we'll skip all the problems I had initially starting the engine), and the temp gauge sky rockets, as expected. I don't like taking chances though, so I shut the car off at 230 degrees (I have a digital read out) and let it cool down, then eventually got home, but not before shutting the car off again once more to let it cool. By the way, the first ride was only 6 miles long....3 miles there, 3 miles back.

The weird thing is that right after I shut the car off when the temp gauge reads 230+ degrees, the upper radiator hose is boiling hot, and the lower radiator hose IS NOT HOT, AT ALL, and is as cold as it was before the engine was started, as if NO coolant is flowing through it. When I squeeze the lower radiator hose, there is definitely SOME coolant in it, however. I thought maybe I accidentally installed the thermostat incorrectly, so I took off the lower radiator hose/elbow and indeed, it was installed correctly. This is a brand new OEM thermostat, set to open at 76.5 degrees celsius. Every time I have started the car up, it has warmed up incredibly fast (75 degrees ambient temperature), and after I stop it, the same thing: the lower radiator hose is COLD. It's not just a *little*cooler than the upper hose, the way it should be...it's as cold as ambient temperature. Before the whole engine rebuild I would frequently check the upper/lower radiator hose after a long ride, and the upper hose would always be hot, and the lower radiator hose would be hot as well, although not AS hot.

The cooling system does NOT need more coolant, because after the engine completely cools down, the overflow tank has its level exactly where it should be: halfway between the "min" and "max" line. With the heater on in the car while the engine is running, it blows hot air.

Does this sound like theres still air in the system? I don't see how there could be, considering I filled the system up with coolant EXACTLY as described by the FSM.

I may go ahead and try to run the engine with no thermostat whatsoever to see if the thermostat is defective, but this seems highly unlikely because it is literally brand new. Also, I don't feel like spilling a gallon of coolant on my garage floor again when I disconnect the lower radiator hose/elbow.

Any ideas?!? Anything I can do without spilling coolant everywhere?

This is pretty frustrating because I finally got the engine installed and started (it's been out since mid-march), and now I can't even break it in safely.

Thanks

Marc

[:: orion ::]

Common problem with the KA after replacing a thermostat...air is caught behind the thermostat, so it will not open.

Get the front end as high as you can...

Start the car, let it idle. As it gets hot, shut it off. Try again. As the whole thing gets hot, the thermostat will eventually "pop" and coolant will flow...then you're set.

...

OR...pull the thermostat, and drill a small hole through it at 12 o'clock. Like a 1/16" hole, in the metal, half way between the edge of the themostat and the "plunger"...this should aid in flushing that trapped air out.

Good luck with it...I have spent HOURS bleeding KA cooling systems...sometimes it takes 20min, sometimes 2hrs.

I have yet to try the hole trick, but have heard it works well.

- Brian

[nismo521]

Yep, sounds like you've still got an air bubble on the thermostat. Throw a funnel and some AF mix in your car and drive it 'til it gets hot. Then put the heater on full (sucks in the summer), shut 'er down, pull over, and crack the bleed screw open. You will be surprised how much air escapes. Once all the air is out, take the screw completely out (may want some gloves, that little joker is HOT) open the rad. cap, and crank the car back up. Pour some more AF mix into the radiator until it starts coming out of the bleed hole, then look in the bleed hole for bubbles. If you've got 'em, pour more AF in there and massage the top hose again. Keep pouring and massaging until you don't see any bubbles coming out of the bleed hole, then replace the rad. cap and bleed screw IN THAT ORDER. Hop back in and drive and see if it gets hot again. If it does, you've still got air, pull over and do it again. It helps to lug the engine going up a hill while doing this, as long as it's cool before you hit the hill. Good luck man, the KA's cooling system is a biatch.

[MarkEmark]

Common problem with the KA after replacing a thermostat...air is caught behind the thermostat, so it will not open.

Get the front end as high as you can...

Start the car, let it idle. As it gets hot, shut it off. Try again. As the whole thing gets hot, the thermostat will eventually "pop" and coolant will flow...then you're set.

...

OR...pull the thermostat, and drill a small hole through it at 12 o'clock. Like a 1/16" hole, in the metal, half way between the edge of the themostat and the "plunger"...this should aid in flushing that trapped air out.

Good luck with it...I have spent HOURS bleeding KA cooling systems...sometimes it takes 20min, sometimes 2hrs.

I have yet to try the hole trick, but have heard it works well.

- Brian

I'm glad its a common problem, but still not that glad haha.

The problem with this is that it's a freshly built engine with only 6 miles on it. I do NOT want to let it sit and idle and warm up under no load...the only way I want to warm it up until it's fully broken in is to place it under load.

Also, it's strange that another 1/16" hole should need to be drilled in the thermostat...I thought that was the whole purpose of the jiggle valve at the top of the thermostat (right at 12 o clock)...to let air pass through when it's closed.

Nismo521....I might try your method becauase I don't feel like spilling coolant everywhere again...the problem with it is that it sucks having to do all this on an 85 degree day when everything's so damn hot!!!!

Damn the KA cooling system, DAMN IT!

[MarkEmark]

Yep, sounds like you've still got an air bubble on the thermostat. Throw a funnel and some AF mix in your car and drive it 'til it gets hot. Then put the heater on full (sucks in the summer), shut 'er down, pull over, and crack the bleed screw open. You will be surprised how much air escapes. Once all the air is out, take the screw completely out (may want some gloves, that little joker is HOT) open the rad. cap, and crank the car back up. Pour some more AF mix into the radiator until it starts coming out of the bleed hole, then look in the bleed hole for bubbles. If you've got 'em, pour more AF in there and massage the top hose again. Keep pouring and massaging until you don't see any bubbles coming out of the bleed hole, then replace the rad. cap and bleed screw IN THAT ORDER. Hop back in and drive and see if it gets hot again. If it does, you've still got air, pull over and do it again. It helps to lug the engine going up a hill while doing this, as long as it's cool before you hit the hill. Good luck man, the KA's cooling system is a biatch.

I used this method and it seems to have worked...at least I know the thermostat is fully functional now...

I just got back from a fairly long ride, and the temperature never climbed above 178 degrees F, with 70 deg. ambient temperature. But, the engine also never went past 3 psi nor 3000 rpm....so I'm sure once I really start boosting that temperature would be more like 200. I bet theres still *some* air in the system, because this is like a 75/25 water/AF mix with an all aluminum 2.1" koyo. I'll add some redline water wetter too.

[nismo521]

Cool, glad to hear it worked for you. To me, this seems to be the easiest way to bleed the system. You just have to be careful to keep an eye on the temp gauge, 'cause it will shoot straight up when an air bubble hits the thermostat.