Cab Heater Airlocked ?

KiotiKevin · Dec 6, 2009

Hi folks, I'm looking for a little help here.
I installed a heater I got with my cab from Simms. Last January someone thought they would do a dirty deed (a young mechanic who thought I wouldn't know the difference - can't prove it) and pull off both my hoses connected to the heater and then reconnect so I would have air in my system and everyone knows how hard it is to get those things to circulate hence the reason why he did it. It is mounted below my windshield but above the motor. I laid it down on the floor and let the motor run at full rpms, both hoses got hot but when I put it back up in the bracket they cool off. Just wondering if anyone had any suggestions ? Thanks

Kevin

EddieWalker · Dec 6, 2009

I'm no expert, but I never heard of a heater that had an airlock. I didn't even know that it was possible to stop water under pressure from going through the heater core with air. I would think that the water would go right through the radiator and flush out the air in seconds.

Have you checked to make sure the hoses are not pluged up? Or the heater core? I'd pull the hoses off and shoot air through them to make sure they are free of obstructions. If you feel that somebody is messing around with you, then capping or plugging the line is what they would have to do to stop it from working. Just removing and draining the water out of the heater core wouldn't do anything, since the water pump would just fill the heater core back up again.

Since the water lines get hot, it sounds like you have enough water in the system. Is it safe to assume that they engine temp runs normal and you're not overheating? If the thermostat or water pump are not working, then that would stop the heater from working, but it would also cause the engine to overheat.

If the air hose blows though the lines and the heater core, then I'd loosen the return line that comes out of the heater to see if water is coming out.

Is the fan working? A hot heater core wont do anything if the fan isn't blowing the air through it. Is there a shroud with an ajustable opening? Some older cars that I've messed with had this, and if the cable comes off, the air doesn't come out and there's no heat. This was on the defrost, but it might be similar on your tractor?

Good luck,
Eddie

massey driver · Dec 6, 2009

I agree with what Eddie has said about everything.As long as the water pump is pumping the water[antifreeze] through the system you should still get heat from the heater.I've changed many heater cores on cars and trucks and have never had one not work due to air in the system.A tractor is the same thing.What I will say is check to make sure one of your heater hoses is comming from either your water pump or right in that area otherwise if there both comming from somewhere off of the engine block then something isn't and wasn't installed properly.As always Larry

KiotiKevin · Dec 6, 2009

Hi Guys
Thanks for the info. I guess I am at a loss (realizing a 3 cylinder deisel takes a long time to build up pressure) for when I lay the heater on the floor the hoses are hot but when I pick it up and put it back in the bracket they cool off. The hoses and heater are clear for circulation. When I first installed it, it took a long time to get heat to it. I guess I'll just have to keep fiddling with it. I appreciate the responses. Thanks again.

Kevin

EddieWalker · Dec 7, 2009

That's very odd. Are you sure the water pump is working properly? It should be circulation water through your engine, your radiator and through your heater core. It should be under pressure. It should be under so much pressure, that it you take a hose off, water will shoot out like a garden hose. Gravity should not matter to this at all.

If the hoses cool off when you lift the heater up higher, then there is something VERY WRONG with your water pump, or water circulation.

As soon as the engine starts, the water heater is pumping water. It doesn't build up pressure, it doesn't take time, it's instant. The only delay would be for the thermostat to open up, but if your hoses are hot, then the thermostat is open.

Are the belts tight? Is the fan spinning? The fan is usually attached to the water pump, but not always. If the fan isn't attached to the water pump, there is a pully on it that is being turned by a belt.

If it's cold enough outside, the engine can run all day long without a water pump to cool the engine. Truckers do this all the time by blocking off their radiators with a cover to keep the air from going through the grill while driving in really cold weather.

The other thing to remember is that the heater is a very simple loop. Hose from the water pump to the heater, and then a hose from the heater, back to the engine. The heater is just a small radiator. Water goes right through it, and while it passes throug, it heats up the fins. Then a fan blows air over the fins, which warms the cab.

If the water pump is putting out water, under pressure, then there is an obstruction in the hoses or heater itself. It might take a bit for the heater to warm up, especially if you have a big radiator on the engine, but once the engine is up to operating temps, the cab heater should be just as hot, since it's getting the exact same water.

Good luck,
Eddie

kenstrac · Dec 7, 2009

It was a common problem in older cars and they sold a bleed valve at automotive stores for that purpose, check Auto Zone or similar type stores it will take awhile to get the air out of the lines because you heater is higher than the engine and any air in the system will go to the highest point.
In some instances I have removed the radiator cap an run the engine and kept the radiator full, you can see it burp.
Also make sure the the overflow tank is at the level where it belongs and the pickup hose is in good shape and below the liquid level.

RickB · Dec 7, 2009

Heaters that are mounted high such as yours can and do become airlocked at installation. But once properly bled by lowering to the ground (as you have done) or loosening a connection while the unit is mounted, the unit should blow heat. Either you are not getting all the air out of the heater circuit, or you are not refilling the radiator after the heater is purged. It is also possible that the connections to the engine are such that the coolant is not flowing to the heater properly. Analagies to replacing vehicle heater cores are meaningless because your car's heater core is not 2 to 3 feet above the rest of the cooling system. Curtis Cab for sure and probably Sims sell a coolant pump that can be used as a last resort.

jim_n_nh · Dec 7, 2009

Could it be that heated water is not being diverted through the cab heater? When you raise the heater there is more resistance than going through the regular loop and it is cold, when you lower it it is on the same plane and will heat up.

Maybe you need a diverter valve.

Jim

DEON · Dec 7, 2009

I have a CK25 with a heater mounted on the roof of my home made cab. I just connected the hoses with all clamps screwed tight. I started the engine and with the rad cap off I began adding water/antifreeze as it started circulating. In less than 15 minutes all hoses and heater was hot and rad was full. I screwed on the cap and everything has worked perfectly since. The heater was fastened to the roof when I first set it up. Did not need to drop it to the floor to bleed it.
I don't know what to tell you except it may be incorrectly connected.
Good luck.