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Re: coolant heating system troubleshoot
First of all you have to get a flush "tee" and have the engine cool drain the old stuff put the flush tee in the hose going to the engine block but before you do this get some prestone 10min flush and fill with water and let it run and then drain hook up garden hose and run water until it is clear and then replace antifreeze
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Re: coolant heating system troubleshoot
The old fashion way it to take the heater hoses off the engine but let them remain on the heater core connections. Take a garden hose and blast the water in one side and then the other. If it's clogged a bunch rusty goo comes out. You could blow compressed air in but the water usually does the job. Be sure though you don't have a control valve on one of the heater hoses. Sometimes they fail and block water to the core. (helps the air conditioner in the summer) Take it out and see if it's stuck closed. A simple test is to put a flushing tee in place of the valve and see if you get heat. Good luck.
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I had a 91 GMC 4.3 do the same thing. Liked to froze to ***** one winter. Found I had a air bubble (air lock) in the engine block and heater. It was a bear to get out. Finally installed back flush kit in the heater hose between engine and heater. Took cap off flush kit, pour coolant in through outlet till coolant ran through back to radiator. Replaced cap and started engine. Repeated again. Heater works as good as new. It's using the same principle as priming a gas powered water pump.
Sounds like low flow issue. Flush and clean system, PROPERLY! Buy a flush kit, drain system, blow compressed air through, fill with cleaner/water mix, run for 30 min with heat on, drain system, blow out with compressed air, fill with water, run for 30 min, drain, blow out with compressed air, fill with 60% coolant mix.
drain coolant system locate heater cores hoses going through firewall you need to buy the radiator flush kit at any auto parts stores. remove heater cores hoses from one end or buy extra long heater hoses same size as heater core hoses in vechicle at auto parts store use the flush kit when you flush through one of the heater core hoses let the other hose drain in a drain pan when you use home garden hose use low water pressure dont use garden hose to the max or you will rupture heater core. your best bet let radiator shop flush whole coolant system. because heater cores hoses are in a tight spot.make sure engine off if you just going to flush out heater core only .after flushing heater core good time to replace heater core hoses.if job too hard or complicated let radiator shop flush out radiator the engine block and heater core because if radiator stopped up or engine block stopped up the gunk and rust will reenter plug up heater core.if you tight on money you can flush out your own radiator.drain out radiator using large drain pan. remove top radiator hose and remove bottom radiator hoses connect to water pump.use garden hose with flush kit part with water pressure not too high put garden hose to top radiator hose run water until clear water run out bottom radiator hose in drain pan,the flush out engine block remove thermostat.if you had another spare thermostat housing with RTV SILICONE SEALANT THAT HAS SET UP INSTALL THERMOSTAT HOUSING BACK TO ENGINE WITHOUT THERMOSTAT FLUSH OUT THE ENGINE BLOCK, WHEN DONE INSTALL NEW THERMOSTAT THEN INSTALL ORIGINAL THERMOSTAT HOUSING WITH NEW ORING WHICH YOU BUY AT DEALERSHIP.IF ALL SOUND COMPLICATED LET RADIATOR SHOP FLUSH OUT COOLANT SYSTEM.
Thermostat.? if you haven't? Do it first then try it. While the car is running for a while touch the heater hoses that lead to the firewall. if one is cold and one is hot? You have a blocked Heater core. Follow the hoses back to the engine. Unconnect them both. By using a garden hose flush out the heater core do one side and then reverse by doing the other hose Lots of junk will come out so be care ful. Mistake people make is "Flushing the system" That doesn't mean your flushing the heater core. Seeing that you have done everything else it could be the thermostat which you didn't list or the heater core being clogged. When you finished installing the thermostat and flushing the heater core out. Replenish the coolant system . If you have a bleeder on the thermostat housing? use it . loosen it and top off the fluid until you see fluid comeout of the bleeder. The system being air bound would cause no heat..
Read all of these instructions before starting this job. First test your heater core for flow by disconnecting both heater core hoses from motor and forcing air from an air compressor into one of them watching for flow from the other. If you have no flow then you may need to backflush your heater core - it is possible you have blockage in it. Your local auto parts store has a backflush kit you can buy that will have a backflush valve ( to be added to your supply heater core hose ) and an additive to put in your coolant system. The kit will not include new coolant so you will need to get that too. Install valve and connect a garden hose.Run motor specified time in the kit. Remove lower hose from your radiator and turn on the water from the hose full blast. Watch the coolant coming out from your radiator to see if any chunky stuff comes out - also watch for the color of the flow. Run water until it comes out clear, then shut off water and disconnect garden hose. Allow system to drain, reconnect radiator hose and cap flush valve. Refill coolant system, turn heat on high and run motor until it is warm. Top off coolant in radiator ( be careful - the pressure may cause coolant to spray out when you remove cap - put a rag over the cap before you remove slowly). If you do not have warm air at this point you may have a bubble in the heater core and may need to block rear wheels then raise the front of the vehicle until the radiator cap is higher than the heater core. Restart vehicle and turn heater on high . Check coolant level in radiator and top off, then cap radiator and shut off motor. Lower vehicle and start again with heater on high. If you still have no heat then your heater core may be plugged. To check, remove both heater hoses from motor and force air from an air compressor into one of the hoses, watching for flow from the other hose - if no flow then core is plugged and needs to be replaced, but if you have flow then you still have an air bubble in the system and need to purge using the above steps until you have heat. Hope this helps and please rate my solution - good luck!!
Did you mean the only time it blows hot air is under acceleration?
First thing check the coolant level in the radiator. If coolant is low the first hing to stop working is the heat.
If the coolant level is fine but the coolant is muddy I woulds suspect a plugged heater core. You can try back flushing it by removing both heater hoses (engine cold) and then use a garden hose to flush clean water through the heater core. Do this on both pipes going into the heater core. Keep flushing until the water runs clear. Re attache the the hoses, remove the radiator cap, start the engine, let the engine come up to temp and top off the radiator with straight coolant (to comp for the water in the heater core). You may have to repeat this process several times over several days but you should be able to get it cleared enough to get sufficient heat without having to replace it.
At the radiator, drain and then flush with water then add 1 gallon of new antifreeze and top off with cool water. Now the cooling system will work.
If you have not performed routine maintenance on your cooling system - it will clog the heater in 10 years or less. Sometimes a bottle of radiator flush (purchased at any walmart or kmart) can clear the heater core - but you will have to run it with the heater on full heat setting for a few hours of driving.
The heater in your car depends upon a flow of hot coolant going through the heater core in order to get hot air into the car. If the heater core is partially plugged, it will restrict the flow. If you have a head gasket that is putting exhaust into the cooling system, it will eventually get into the heater core. When this happens there is no coolant in the heater core to make the air warm. If the water pump vanes have corroded away the result will be very poor coolant circulation causing the heater to not blow hot air. If your car is equipped with a heater control valve that is not functioning properly, the coolant flow will be restricted. One or a combination of these factors is likely the culprit in your case.
Since you state the 2 things you ruled out, that leaves only the water pump. Is the car running hot? The thermostat may be sticking as well... but im leaning toward the pump.
There are known problems with this vehicle's heater core not getting enough coolant flowing through it to blow hot air.
1) Even if the coolant looks good, there are problems with the heater
core plugging up. One solution is to use a heavy duty cleaner (CLR pipe
cleaner) to back flush the heater core. To know if the heater core is
plugged up, disconnect the 2 heater hoses at the heater core and
somehow connect a hose to one end of the core. Try to flow water
through, it doesn't have to be high pressure, and there should be a
steady stream. If not, try to get the cleaner directly into the heater
core and let it soak. Then back flush it and a lot of scale should be
seen coming out.
2) The other problem is that since the heater core is the highest point
in the cooling system air tends to get trapped in it. This should only
happen if the coolant goes low or someone has opened the system to
service it. There are a number of ways to bleed the system (vacuum
bleed, pressure bleed). One of the hoses should have a small hole in it
for bleeding air, pull that hose back just enough so the hole allows
coolant to flow out of it. Then accelerate the engine and get a good
flow coming out, when no more air bubbles are present, there should be
3)I've heard of bad water pumps with low flow causing issues as well as
an aux. water pump not fuctioning correctly leading to poor heat output
from the heater core. Someone should confirm this as I cannot get much
information on the aux water pump(electronic pump by the alternator
that is supposed to run after the car is shut off).