Yet another No Heat topic '00 Merc Mounty V8

[JimMadsen]

Few weeks ago wife complained of no heat. I checked and her overflow was very low. Brought it up to the cold fill line and got heat at all temp settings. Granted it was the same full blast heat at low and high, but will look at that when it is warmer out.

Never did see where the coolant went to and was going to just keep an eye on the levels. This morning I take it to work and I get barely luke warm heat from vents panel floor defrost etc. Temp set at 90 degrees on high. This was during and after highway driving of 15 miles. Temp gauge has been right where I expect it throughout. Just under half way which is normal position for me and it seems others. I am able to transition between all of the position settings.

Got to work and checked the overflow. About half full. Realizing this may not mean much, I will check it and the rad cap once engine is cold.

History of work: Last Jan replaced rad cap (with one of those fancy safety release red handle ones from autozone), water pump & gasket, water pump outlet hose, tstat, coolant flush, heater core flush.

I have not seen any puddles under the car or green spots in the snow. When I can, I will use a head gasket sniffer that I just picked up to test my car which has a LIMG leak (at the least), any tips on using it? Got this one: http://www.amazon.com/gp/product/B004FELK6A/ref=oh_details_o00_s00_i02?ie=UTF8&psc=1

Thanks all!

 

[MAS Tequila]

Mine had been doing the same thing for about 2 months. Then last Saturday night the gauge went up almost to hot.

And like yours the heat wasn't working. After it cooled I filled the rad and the reservoir, and voila...heat.

It ended up being the thermostat housing was cracked. You couldn't see it unless the engine was at operating temp, and only then right before the tstat opened.

A new housing, gasket, and stat (may as well while it's apart) and all is well.

The dripping coolant wasn't making it to the ground. It was burning off.

MT

 

[JimMadsen]

Well car is cold, coolant level filled at rad cap and overflow tank is right at cold fill line where I put it a few weeks ago. So I am doubtful I am leaking any.

 

[RomeovilleIL]

Do the standard tests: check temps of hoses under the hood with engine warm first. If everything is good (ie both heater hoses hot and same temp), then check in the cabin. Go step by step.

 

[JimMadsen]

Got it on the heater core hoses. Can you elaborate on the cabin checks please?

 

[radman]

Exhaust Gas Tester Question

Few weeks ago wife complained of no heat. I checked and her overflow was very low. Brought it up to the cold fill line and got heat at all temp settings. Granted it was the same full blast heat at low and high, but will look at that when it is warmer out.

Never did see where the coolant went to and was going to just keep an eye on the levels. This morning I take it to work and I get barely luke warm heat from vents panel floor defrost etc. Temp set at 90 degrees on high. This was during and after highway driving of 15 miles. Temp gauge has been right where I expect it throughout. Just under half way which is normal position for me and it seems others. I am able to transition between all of the position settings.

Got to work and checked the overflow. About half full. Realizing this may not mean much, I will check it and the rad cap once engine is cold.

History of work: Last Jan replaced rad cap (with one of those fancy safety release red handle ones from autozone), water pump & gasket, water pump outlet hose, tstat, coolant flush, heater core flush.

I have not seen any puddles under the car or green spots in the snow. When I can, I will use a head gasket sniffer that I just picked up to test my car which has a LIMG leak (at the least), any tips on using it? Got this one: http://www.amazon.com/gp/product/B004FELK6A/ref=oh_details_o00_s00_i02?ie=UTF8&psc=1

Thanks all!

Jim,
That tester works great but the fluid will turn green if gases are present so be careful if your radiator coolant level is high as you may suck up coolant which will also turn the test fluid green from the antifreeze. Make sure you only suction up the air above the coolant.
Mike

 

[JimMadsen]

Jim,
That tester works great but the fluid will turn green if gases are present so be careful if your radiator coolant level is high as you may suck up coolant which will also turn the test fluid green from the antifreeze. Make sure you only suction up the air above the coolant.
Mike

Yes, you are totally correct on that, except the time I did it, it turned orange with dexcool. Supposed to have the level be 2 inches below the cap, I thought it was!

Thanks

 

[JimMadsen]

Passenger side hose piping hot, driver side not as much. All the paths work inside the car. Fan speeds work ok, no change with idle or acceleration.

Should we flush it again said my dad in october, no I said. It's working fine I said. Silly me.

 

[radman]

Infrared Heat Gun

Jim,
Use an infrared temperature gun to get the exact temps. in the system. At the thermostat housing, heater control valve, both heater hoses, and the air temp. coming out of the vent closest to the heater core. You say there is a slight temp. difference between the heater hoses at the firewall, that would point to the heater core pulling some heat out of the coolant as it should. It could also mean that there may be an internal failure in the core not directing the coolant fully thru the core. Without exact temperature readings it is difficult to pin point where the issues might be.

You might try the old technique of running some DrainO into the core and allowing it to soak for about 20 minuets then flush it out. Sometimes it can help and sometimes on old heater cores it can cause them to start leaking.
Mike

 

[JimMadsen]

FINALLY!!!! A good reason to justify getting this:

http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465-8905.html

I would skip the draino. I will get the readings on Saturday and probably plan on flushing the core out on Sunday. I made a nice little bypass so I can flush it out without waiting for the engine to cool down or anything. Going to have to take it either to a car wash or my parents with their hose hookup. Would prefer my parents so I am not putting coolant into a drain at the car wash.

 

[lobo411]

FINALLY!!!! A good reason to justify getting this:

http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465-8905.html

It's way cheaper at Amazon. Just get any generic brand--they're all made by the same prisoners at the same factory in China.

 

[JimMadsen]

It's way cheaper at Amazon. Just get any generic brand--they're all made by the same prisoners at the same factory in China.

Good call. 18.66 shipped. Should have it on Sat. I love Amazon Prime. We need to make sure we give those prisoners something to do, right?

 

[lobo411]

Good call. 18.66 shipped. Should have it on Sat. I love Amazon Prime. We need to make sure we give those prisoners something to do, right?

Keeps em off the internet. Nothing but sin there!

 

[JimMadsen]

Engine nice and warm, water pump 174* driver side hose 77*, passenger side hose 66*.

Which is inlet, outlet?

Really strange, heat seems to come and go. Wife said earlier that heat was so hot she had to turn it down, now back to luke warm. Even stranger, the pipe I thought was piping hot was the passenger at the bend. Had the wife check these temps when she got to work. I will recheck these readings tomorrow afternoon.

 

[radman]

Not enough temperture

Jim if your 77*/66* are heater hose temperatures you are not getting coolant to or through the heater core. Normal should be 145*/ 130* in/out. Check your heater control valve, take it out and run the hoses directly to the heater core and see what you get. If it does not change the readings then you either have a stopped up core or an internally collapsed hose. Since it comes and goes it could be either.
The hot side (inlet) hose on my 99 Eddie is on the passenger side just the opposite of what you posted.
Mike

 

[JimMadsen]

got it.

Makes some sense as I grabbed the hose prior this valve and it was hot but the heater core hose on the other side was not as much. I will just go ahead and replace it, it will either work or it will not.

I assume it controls the fluid flow through the core itself and if it is stuck in any particular closed position, that would diminish the amount of hot coolant flowing through. However the flow arrow points towards the engine, or points towards where I felt the hot hose. Could that be back flow of coolant that was hot compared to cool coolant coming through the valve from the core?

thanks

 

[JimMadsen]

Pulled the valve and ran water through it. Open and water went right on through it, closed and water slowed down noticeably.

Heater controls opened and closed via vacuum control.

Gonna flush it

 

[JimMadsen]

Temp readings at the vent itself was pumping out at 130* with the engine nice and warmed up. Think the flush got it going.


I did note that there was no temp change at the vent when I decreased the temp setting down to 75* from 90*. Would this be normal, or would this be a bad blend door. If it is a bad door, I will have to get that fixed prior warmer weather coming around.

 

[koda2000]

you should notice a big increase in vent temp between 75 and 90. my trucks will just about run you out of the truck when set to 90.

 

[JimMadsen]

Nope, same temp at vent if control set at 75 or 90. Temp varies between 120* and 135* depending on engine temp. Either way, when fan is on high, I want to roll down the windows!