Low Coolant and Heat

[beachrog]

Alright, up until now, I've just accepted this, but now I'd like to know why.

Why is it that if you are low on coolant, the heat does not work as well?

[J-Ri]

Usually there is a very thin line where the heat doesn't work as well. Most of the time it works just fine until it doesn't work at all. That is because the coolant isn't circulating as fast because the water pump has to wait for water to come through the radiator/heater core before it can pump it through the engine. Normally there is plenty waiting in the radiator. When the coolant is flowing through the heater core slower, the incoming air is able to take more heat out of the coolant than is available.

[beachrog]

Thanks for the explanation, that is helpful.

My situation specifically goes like this.

Bought the truck in Apr. '07. When I bought it the guy said that he had flushed the radiator numerous times and could not get the "rusty" stuff out. I replaced the Termostat a few weeks ago and it was covered with rusty dusty stuff. The hose from the reservoir tank was completely plugged with the same stuff. We cleaned that out and figured this spring we'd need to replace the heater core and radiator. I never thought about the water pump. My concern is that when we opened the pitcock, literally a trickle came out it was so plugged with that stuff. I'm assuming when we open the drain plugs on the block we'll run into the same problem. When something is that built up, can I ever hope to get it all cleaned out? I'm not getting much heat and figure it is probably because the heater core is plugged to some extent based on how plugged that hose was to the reservoir. When we replaced the thermostat we tried to flush the system the best we could, but since the pitcock was plugged we just unhooked hoses and tried to get as much out as possible. When we filled it, we put three gallons of anti-freeze in and it was full. I'm worried because it should hold 5.5 or so I believe, I realize we didn't get it all out based on how we went about it. I just picture a block plugged solid with crud...

Any thoughts would be appreciated...

[inafogg]

hello unless you drain completely which we seldom do you will only get 2-3 gallons out.by draining rad & draining the engine(remove drains from block)you get more but still not everything.if you remove rad petcock & flush rad then remove block drains & thermostat flush by putting hose in thermo. housing.do this until water is clean then flush heater core in both dirrections then entire system using a flush cemical you should get it pretty clean.hope this helps good luck

[beachrog]

We've actually talked about back flushing the heater core just to see if we can improve the heat situation temporarily until we can take some time to replace the radiator and heater core. I'm afraid that all that rusty crusty stuff is actually plugging some holes in the heater core and if we back flush it now, I'll have to replace the heater core now before I'm ready.

It got all the way to 31.8 degrees in the cab this morning.

Brrrrrr, man, brrrrrr.

[J-Ri]

Something to try temporarily is to leave the blower motor on a lower setting. That will let the air get warmer as it passes through the heater core slower, of course then it may not be able to keep up with the heat loss through the glass...

Don't ya love dex-cool?

I think you'd be safe flushing the heater core now. The stuff that forms from dexcool breaking down stays soft in the coolant, not all crusty like in the cap and reservoir, so I doubt it's plugging any holes. Be sure you backflush it first, or you'll just be packing it in the core tighter. Remove both heater hoses. Some years have a plastic fitting on the upper intake, BE CAREFUL, they like to break and are a PITA to get out. You may want to remove the hose from the heater core side for the "hot" hose, but then there's a chance you'll break the heater core. Start on the "warm" side that goes to the water pump first. Gently spray water from a garden hose through the hose. After the water runs out clear, carefully spray short bursts of compressed air through in the same direction. Spray more water, more air, etc., until the water is clean. After it's clean, reverse directions and spray through the "hot" hose, altering water/air spray. Once the water is clean, go back to the "warm" hose and spray until it always come out clean. Keep going back and forth until you get only clean water in both directions.

To flush the entire cooling system without a machine: Recover and recycle as much coolant as possible. Remove both radiator hoses at the radiator. Put a running garden hose in the lower radiator hose. Start the engine and turn on the heater. It takes a while and goes in short spurts (could remove thermostat to speed up), but it gets every last drop of old coolant out. To fill, just let as much water drain as possible and reconnect the hoses. Add 1/2 the total capacity of antifreeze, and top the system off with water.

[j cAT]

Originally Posted by beachrog

Alright, up until now, I've just accepted this, but now I'd like to know why.

Why is it that if you are low on coolant, the heat does not work as well?

i find this question funny! water pumps only pump water not air. if you were very low in coolant you would have no heat but your engine would be smoking hot! when cleaning out plugged/sludged coolant system all componets must be drained this should amount to 4gallons .......when flushing do not have thermostat installed .use all drain locations not just radiator make sure engine is drained also. when flushing use chemicals to clean out rust. rust will damage water pump seal and plug up heater core. use garden hose to back/fwd flush heater core. then if possible blow out with air. when filling fill engine at thermostat then install thermostat and then continue to fill the rest of system. leave cap off run engine cap off do not rev engine add coolant as required. when flushing and thermostat is not in , no need to get engine hot and damage to engine is nill.......

[beachrog]

Well, we backflushed the heater core today, there wasn't a damn thing funny about it. This truck has so much corrosion in it, it's almost unbelievable. At any rate, I thank the Lord that my stepdad is a mechanic or I'd have been so lost. Essentially, he works for a bus garage and we went over there to have good access to what we needed including a floor with a drain.

When we got there, we were feeling the heater hoses and all he did was attempt to feel the hose that enters the manifold to see if it was hot. It snapped right off right at the manifold. Needless to say, backflushing the heater core went smoothly and the truck gets pretty hot now. But watching him get that broken piece out made me appreciate his knowledge and skills. The easyout wouldn't grab it as it was all corroded. He tried taking a hack saw and cut slits on each of the four sides and then bust the pieces out with a chisel but that didn't work either. He ended up using a grinding tool and then rethreading the hole.

I'm thankful for his help, but feel pretty bad, but then again, that's why I started this thread. Seeing the amount of the corrosion that was in there when we first flushed the radiator made me think something was going to go horribly wrong and sure enough it did. But backflushing the heater core worked fabulous for getting the heat going again. Got to 90 degrees in the cab on the way back. The crap that came out of the heater core when he flushed it was quite disgusting, and when he first put the hose to it, it didn't even come out.

[j cAT]

Originally Posted by beachrog

Well, we backflushed the heater core today, there wasn't a damn thing funny about it. This truck has so much corrosion in it, it's almost unbelievable. At any rate, I thank the Lord that my stepdad is a mechanic or I'd have been so lost. Essentially, he works for a bus garage and we went over there to have good access to what we needed including a floor with a drain.

When we got there, we were feeling the heater hoses and all he did was attempt to feel the hose that enters the manifold to see if it was hot. It snapped right off right at the manifold. Needless to say, backflushing the heater core went smoothly and the truck gets pretty hot now. But watching him get that broken piece out made me appreciate his knowledge and skills. The easyout wouldn't grab it as it was all corroded. He tried taking a hack saw and cut slits on each of the four sides and then bust the pieces out with a chisel but that didn't work either. He ended up using a grinding tool and then rethreading the hole.

I'm thankful for his help, but feel pretty bad, but then again, that's why I started this thread. Seeing the amount of the corrosion that was in there when we first flushed the radiator made me think something was going to go horribly wrong and sure enough it did. But backflushing the heater core worked fabulous for getting the heat going again. Got to 90 degrees in the cab on the way back. The crap that came out of the heater core when he flushed it was quite disgusting, and when he first put the hose to it, it didn't even come out.

that guy is a true mechanic not just a part replacer like the dealerships employ. i hope you took good care of him, for that great repair he made.........

[inafogg]

hello beach,glad to hear all is well you might want to reflush come spring time and yea take care of your friend...atleast a case of.......?

[beachrog]

I've been trying to figure out something to do for him or to get for him. Can't get him a tool as he has everything under the sun. But I'll figure something out.

We plan on reflushing come spring, I can't wait to do that, I just want to take the time to really clean the system out good.

We were still puzzled by something though. The heat gets REAL hot, to the point where you almost don't want to put your hand up by the vent. But when we turned on the defroster it COOLED right down. Granted it isn't recycling the internal air like it was on heat and it's pulling in fresh air, but we thought it should get warmer than it did.

Any thoughts?

[j cAT]

Originally Posted by beachrog

I've been trying to figure out something to do for him or to get for him. Can't get him a tool as he has everything under the sun. But I'll figure something out.

We plan on reflushing come spring, I can't wait to do that, I just want to take the time to really clean the system out good.

We were still puzzled by something though. The heat gets REAL hot, to the point where you almost don't want to put your hand up by the vent. But when we turned on the defroster it COOLED right down. Granted it isn't recycling the internal air like it was on heat and it's pulling in fresh air, but we thought it should get warmer than it did.

Any thoughts?

because your coolant system was very dirty scale and mineral deposits will require a chemical flush this i believe is an acid mixture. after running this with thermostat removed drain and flush out and add a neutralizer baking soda to get PH of water/engine back to neutral. this should all be explained in the flush kit. i used this many years ago and it cleaned out my 307 olds engine/radiator it looked like new inside. your heater core will rapidly fill up with contaimination from the engine goo left behind also. for some reason it just gets trapped in there first................

[jonnik]

When you put the control to defrost, the A/C compressor is engaged. This is done to dry the air going to the inside of the windshield and preventing condensation on the cold glass.