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Hi gang,
Wifes trusty 94 prizm has a new issue.
The heater output used to be quite good after the car hit op temp.
Now its only a tad warmer than ambient.The cable to the valve appears functional. (It moves the lever, and is hooked up correctly)
The valve (the part i can see without taking it apart) appears fine
Both hoses to the heater core are warm/hot, with the top one being a tad warmer.2 issues. Well 3,
The radiator has begun leaking where the aluminum meets the plastic on the top. But its full.
Coolaint overflow tank was empty but it was that way for years and car never overheated and heater was fine
Due to the rad leaking i left the rad cap loose to try and reduce losses.Currently, the overflow tank, which was filled to “full” 2 weeks ago has lost more than half, he is a little above the low line now.
When i did fill the system i put about a cup of coolaint before radiator was full.
On the other hand, my civic same size motor, was far lower on coolaint, probably a quart to fill the radiator and then the entire overflow tank, and his heat was never bad, just a bit worse than usual and hes great now — i used tap water in both, am i going to hell?
Sadly my ebay radiator for the civic is leaking less than 3 years after installation… so thats why it was 45 dollars…..
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Leaving the radiator cap loose is not a great idea. That doesn’t allow the system to build pressure, which might slow your leak some, but it also significantly reduces the boiling point of your coolant, which can cause your engine to overheat due to coolant boiling at normal operating temperatures. Fix your leak, then properly bleed all of the air out of your cooling system. When that is done, I would think that your heat will be working properly again.
copy on the cap.
new rad is a given…
why thermostat? the motor gets to and stays at op temp fairly quickly
I don’t see how either of those solves the heater problem though. All the hoses are warm, so the system is flowing.
please help me understand.
With the radiator cap loose, you ARE leaking coolant, no two ways about it. That also means that as the coolant cools back down after you shut the engine off, and contracts like all liquids do when they cool, instead of creating a vacuum in the cooling system, and drawing in coolant from the reservoir (overflow bottle), instead, it is drawing in air from the surrounding atmosphere, because the radiator cap is loose and isn’t allowing a vacuum to be created. There is every possibility that that air has trapped it’s self in your heater core and is keeping the heater core from getting a good flow of coolant.
This is why I said FIRST, fix the leak, THEN BLEED the system
There is every chance that sealing things up, allowing it to get to proper pressure so it can handle MORE heat than it does now, AND getting the air out so that coolant can flow properly through the entire system will fix your problem.
IF this doesn’t work, then we can look for additional issues from there, but in my experience, if you have a known problem, you deal with that first, and then if your symptoms persist, you look for other problems.
[quote=”Tomh” post=78006]IF this doesn’t work, then we can look for additional issues from there, but in my experience, if you have a known problem, you deal with that first, and then if your symptoms persist, you look for other problems.[/quote]
Agreed!
Fix all that other stuff then if it still doesn’t work I would try and unclog the heater core since it’s a fairly quick & easy procedure (Eric has a video on it). Even though both your hoses are warm there may still be a partial clog. Or maybe there is trapped air in your system affecting things and that video Tom posted is perfect for that.
Also, pretty much the first indication that your coolant level is low is usually that the heat suddenly doesn’t get very hot.
I suggest changing the thermostat as it’s usually a cheap and relatively easy thing to change, and if it’s more than 5 years old, it is likely to be a bit unresponsive. I just replaced mine and hey, now I have heat! The old one was about 1/3 open at room temperature. Way wrong.
With no radiator cap the fluid is probably low and/or boiling, which leads to air going into the heater core, and the air is not a good carrier of heat. You can even get the bizarre “air lock” which I don’t understand at all, but apparently air can block the flow. I can see if air gets into the pump, then it won’t pump, but in a hose or heater core?
Anyway, you need to fix everything, cap, leaks, radiator, the whole shebang. Nothing will be quite right until the system is sealed and full.
Turn off the fan in the car. Turn the heat selector to full heat.
Feel the inlet and outlet heater hoses. They should be hot. If not
check the heater control valve. You may need to flush the heater core
with a garden hose. I would start over with a new radiator,T-stat,
hoses,cap and flush of the cooling system. Refill with new coolant and
bleed the system.http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
http://www.ericthecarguy.com/faq/finding-and-fixing-fluid-leaks
[quote=”Tomh” post=78006]With the radiator cap loose, you ARE leaking coolant, no two ways about it. That also means that as the coolant cools back down after you shut the engine off, and contracts like all liquids do when they cool, instead of creating a vacuum in the cooling system, and drawing in coolant from the reservoir (overflow bottle), instead, it is drawing in air from the surrounding atmosphere, because the radiator cap is loose and isn’t allowing a vacuum to be created. There is every possibility that that air has trapped itself in your heater core and is keeping the heater core from getting a good flow of coolant.
This is why I said FIRST, fix the leak, THEN BLEED the system
[/quote]
Could have not said it better myself. As long as you have a leaks in the system (cap/rad), your cooling system will not function properly and that includes heat.
The cap wasn’t loosened until the leak was discovered. The leak was discovered 2 weeks AFTER the heater (mostly) stopped working.It may be the leak in the rad causing this but the cap is not the culprit.
I agree that fixing the radiator is a priority…. I still just don’t understand how thats the issue. My other car was far lower on coolant,– there was an inch of air in my radiator– and the heater was maybe 10% less than normal. Her car really wasn’t that low, I had to top off the radiator but that only took a cup or so of coolant. (OF course then again, after I filled the reservoir it only took 2 weeks to eat 3/4 of it so…. )
lovely, I get to be working on a cooling system in 40degree weather…
And can somebody still help me with the whole replace the thermostat idea, I always heard if the car warms up in a few minutes that little feller is just fine.
“I would start over with a new radiator,T-stat,
hoses,cap and flush of the cooling system. Refill with new coolant and
bleed the system.”You sir, are a more well-to-do man than I! (well what do I expect you did goto college.)
I’ll fix the broken stuff, the rest waits til it breaks!
[quote=”dosmastr” post=78160] I still just don’t understand how thats the issue. My other car was far lower on coolant,– [/quote]
Every car is different, I have seen some where a small amount of air will prevent the heater core from doing its job and some, where half the coolant could be gone and the heater will work perfectly.
Ever hear the saying penny wise, pound foolish?
Sometimes the $50 repair job you put off until it brakes winds up costing you $1500 instead.
Your cooling system is one of those beasts. It is a fine line between the coolant being a bit low, and the engine overheating and warping the cylinder head, which leads to a $1500 repair bill to pull the head, have it machined, and put everything back together with a new head gasket.
The point of the giant yellow funnel is NOT to keep you from spilling any. It is to allow a quantity of coolant to be held ABOVE the radiator neck, so that as air works it’s way out of the system, it bubbles up into the funnel, and coolant from the funnel enters the radiator to replace that air. The job can be done without the funnel, but the funnel just makes it easier, less time consuming, and keeps you from making a mess when your car decides to belch a bunch of fluid out with the air.
Finally, several of us have explained to you how and why the leaking radiator not only CAN be the issue, but likely IS the issue. If you don’t believe us, feel you know better than we do, what ever, feel free to figure it out on your own. Keep in mind, we are only trying to help because you came and asked for help.
[quote=”dosmastr” post=78160]The cap wasn’t loosened until the leak was discovered. The leak was discovered 2 weeks AFTER the heater (mostly) stopped working.It may be the leak in the rad causing this but the cap is not the culprit. [/quote]
Just possibly, could it be that you didn’t discover the leak until, oh, I don’t know, say two weeks AFTER it had leaked enough to screw up your heat?
I agree that fixing the radiator is a priority…. I still just don’t understand how thats the issue. My other car was far lower on coolant,– there was an inch of air in my radiator– and the heater was maybe 10% less than normal. Her car really wasn’t that low, I had to top off the radiator but that only took a cup or so of coolant. (OF course then again, after I filled the reservoir it only took 2 weeks to eat 3/4 of it so…. )
Just because you don’t understand it, doesn’t mean it isn’t so. It has been explained to you in great detail. It depends a lot on the relative positions of the engines cooling passages and the position of the heater core, and where the hoses leading to the heater core attach to the engine, and the relative position of the radiator to it all etc. etc. Some cars will have heat with almost no coolant left in the radiator, others will lose heat the moment they are a bit low on coolant.
lovely, I get to be working on a cooling system in 40degree weather…
Could be worse, at least it is above freezing
And can somebody still help me with the whole replace the thermostat idea, I always heard if the car warms up in a few minutes that little feller is just fine.
If the thermostat is stuck full closed, will the car not warm up quickly? Does that mean that the thermostat is not screwed up? How about if the thermostat is stuck part way open? When ever there is a problem with the cooling system, and the thermostat and radiator cap are old, it is generally not a bad idea to replace them. They are relatively inexpensive bits, and are very often the source of issues with the cooling system. Plus, if they fail, the results can be catastrophic, not to mention very expensive to repair. As a general rule of thumb, if I am having a problem with the cooling system, I will look for leaks in major components, and will replace the thermostat, radiator cap, and if they are not relatively new, the hoses. It is just cheap insurance against a failure down the road, and hoses are often neglected, so it is usually a safe bet that they are in need of being replaced.
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