Topic: 2004 EL - Heater not blowing hot when idling

[wing0]

Around 156000 km or almost 100k miles

Car does not blow hot air until it is driven, once I come to a red light for extended period of time with fan at full speed, air temperature will start to decrease until it becomes cold and this repeats.

I know most people would say this is low coolant problem.
I checked the overfill tank. It's beyond the full mark and up to the top of the filler neck. ie. I can see the coolant when taking the cover off the filler.

After warming up the car and having the fan blow at max. The fan blower in front of the engine do not turn on. I felt the coolant return line that goes from the top of engine back to the engine(I think that's the flow) did not get warm at all.

I have a few questions before I take it upon myself to fix it or take it to my mechanic.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?
2. Can bad thermostat cause this?
3. The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.
4. What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.
5. Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Any other suggestions of what to check would be great. Thanks all.

[rrocket]

If you have a headgasket problem, you're likely to find coolant in the oil.  And yes, a thermostat could cause such a problem.

[wing0]

If you have a headgasket problem, you're likely to find coolant in the oil.  And yes, a thermostat could cause such a problem.

Thanks for the quick reply.
Would the thermostat also cause the coolant to not flow regularly and cause an excess in the overfill tank? Wouldn't the restriction cause the engine to overheat then?

One more question, could it be the waterpump?

[rrocket]

If you have a headgasket problem, you're likely to find coolant in the oil.  And yes, a thermostat could cause such a problem.

Thanks for the quick reply.
Would the thermostat also cause the coolant to not flow regularly and cause an excess in the overfill tank? Wouldn't the restriction cause the engine to overheat then?

One more question, could it be the waterpump?

A thermostat could cause what you describe.  Sometimes the thermostat just isn't opening/closing as it should.  But yea, in a complete failure you could have an overheat.

Have you changed the waterpump??

[rrocket]

You know....you might have an air pocket in the coolant system...

[wing0]

If you have a headgasket problem, you're likely to find coolant in the oil.  And yes, a thermostat could cause such a problem.

Thanks for the quick reply.
Would the thermostat also cause the coolant to not flow regularly and cause an excess in the overfill tank? Wouldn't the restriction cause the engine to overheat then?

One more question, could it be the waterpump?

A thermostat could cause what you describe.  Sometimes the thermostat just isn't opening/closing as it should.  But yea, in a complete failure you could have an overheat.

Have you changed the waterpump??

No, the waterpump has not been changed yet. What would be the symptoms for a seized waterpump?

I tried running the car without the radiator cap to see if I can get air pocket out but it didn't seem to help at all.

[rrocket]

I really, really think your system needs to be purged.  It sounds like an air pocket.

Your water pump should be fine...was just wondering if it had been changed per maintenance schedule.

Do you know how to purge the coolant system of air bubbles?

[wing0]

I really, really think your system needs to be purged.  It sounds like an air pocket.

Your water pump should be fine...was just wondering if it had been changed per maintenance schedule.

Do you know how to purge the coolant system of air bubbles?

Open the radiator cap, start the car, put on defroster. temperature set to hot? Wait for it to get hot?
Unless you're suggesting I try putting some coolant in and let that push out the air pocket.

[articsteve]

Around 156000 km or almost 100k miles

Car does not blow hot air until it is driven, once I come to a red light for extended period of time with fan at full speed, air temperature will start to decrease until it becomes cold and this repeats.

I know most people would say this is low coolant problem.
I checked the overfill tank. It's beyond the full mark and up to the top of the filler neck. ie. I can see the coolant when taking the cover off the filler.

After warming up the car and having the fan blow at max. The fan blower in front of the engine do not turn on. I felt the coolant return line that goes from the top of engine back to the engine(I think that's the flow) did not get warm at all.

I have a few questions before I take it upon myself to fix it or take it to my mechanic.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?
2. Can bad thermostat cause this?
3. The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.
4. What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.
5. Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Any other suggestions of what to check would be great. Thanks all.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?

Did you ever see the fluid level at the normal mark?  That is one hard design to read I gotta say.  When the motor is cold I would remove the excess coolant to get it down to the "max" level.  Siphon I guess.  Did someone fill it up to the top with windshied washer fluid?

 Can bad thermostat cause this?

Just at idle?  

The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.

The coolant is good for 5 years so they say.  In reality it is shot after 4 years in any vehicle.  "5 year" coolant is an EPA thing.

What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.

Pink

Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Not really.  If the head gasket leak is on the exhaust side then yes the coolant will go out the exhaust.  Otherwise it will mix with your oil.  Is your oil milky in colour?

You have not talked about the engine temp gauge.  What is that doing when you come to an idle?

Could be weak water pump.  However, you are at the point of a timing belt change.  If you plan on keeping the car I would get it done asap.  At which point you get a new rebuild water pump and of course a total coolant change along with a new thermostat.

You could try changing out the thermostat.  That would be the easiest and cheapest thing to do right away.  But I think you need a water pump so it's part of a T belt job.

[rrocket]

It's air bubble.  I know it.  When air enters the system, the coolant gets pushed back into the overflow....That's why his overflow is filled.  IMO.

[rrocket]

I really, really think your system needs to be purged.  It sounds like an air pocket.

Your water pump should be fine...was just wondering if it had been changed per maintenance schedule.

Do you know how to purge the coolant system of air bubbles?

Open the radiator cap, start the car, put on defroster. temperature set to hot? Wait for it to get hot?
Unless you're suggesting I try putting some coolant in and let that push out the air pocket.

1) Refill the cooling system and raise the right front corner of the automobile with
a suitable jack.
2) Set the heater temperature selector to maximum and leave the blower fan off.
3) With the radiator cap off, start the engine.
4) When the engine reaches normal operating temperatures, open the air bleed
screw until coolant flows in a steady stream. Wear protective gloves to
prevent burns from hot coolant.
5) Lower the car and fill the radiator and the coolant reservoir. Close the cooling
system and verify that the cooling fan works on schedule.

[articsteve]

What would be the symptoms for a seized waterpump?

Timing belt jumps and you destroy your valves.

[bridgecity]

Around 156000 km or almost 100k miles

Car does not blow hot air until it is driven, once I come to a red light for extended period of time with fan at full speed, air temperature will start to decrease until it becomes cold and this repeats.

I know most people would say this is low coolant problem.
I checked the overfill tank. It's beyond the full mark and up to the top of the filler neck. ie. I can see the coolant when taking the cover off the filler.

After warming up the car and having the fan blow at max. The fan blower in front of the engine do not turn on. I felt the coolant return line that goes from the top of engine back to the engine(I think that's the flow) did not get warm at all.

I have a few questions before I take it upon myself to fix it or take it to my mechanic.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?
2. Can bad thermostat cause this?
3. The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.
4. What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.
5. Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Any other suggestions of what to check would be great. Thanks all.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?

Did you ever see the fluid level at the normal mark?  That is one hard design to read I gotta say.  When the motor is cold I would remove the excess coolant to get it down to the "max" level.  Siphon I guess.  Did someone fill it up to the top with windshied washer fluid?

 Can bad thermostat cause this?

Just at idle?  

The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.

The coolant is good for 5 years so they say.  In reality it is shot after 4 years in any vehicle.  "5 year" coolant is an EPA thing.

What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.

Pink

Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Not really.  If the head gasket leak is on the exhaust side then yes the coolant will go out the exhaust.  Otherwise it will mix with your oil.  Is your oil milky in colour?

You have not talked about the engine temp gauge.  What is that doing when you come to an idle?

Could be weak water pump.  However, you are at the point of a timing belt change.  If you plan on keeping the car I would get it done asap.  At which point you get a new rebuild water pump and of course a total coolant change along with a new thermostat.

You could try changing out the thermostat.  That would be the easiest and cheapest thing to do right away.  But I think you need a water pump so it's part of a T belt job.

If your coolant is original it should be green, not pink.  Honda calls for 192K km interval changes for coolant, or 10 years, whichever comes first

[wing0]

Around 156000 km or almost 100k miles

Car does not blow hot air until it is driven, once I come to a red light for extended period of time with fan at full speed, air temperature will start to decrease until it becomes cold and this repeats.

I know most people would say this is low coolant problem.
I checked the overfill tank. It's beyond the full mark and up to the top of the filler neck. ie. I can see the coolant when taking the cover off the filler.

After warming up the car and having the fan blow at max. The fan blower in front of the engine do not turn on. I felt the coolant return line that goes from the top of engine back to the engine(I think that's the flow) did not get warm at all.

I have a few questions before I take it upon myself to fix it or take it to my mechanic.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?
2. Can bad thermostat cause this?
3. The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.
4. What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.
5. Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Any other suggestions of what to check would be great. Thanks all.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?

Did you ever see the fluid level at the normal mark?  That is one hard design to read I gotta say.  When the motor is cold I would remove the excess coolant to get it down to the "max" level.  Siphon I guess.  Did someone fill it up to the top with windshied washer fluid?

 Can bad thermostat cause this?

Just at idle?  

The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.

The coolant is good for 5 years so they say.  In reality it is shot after 4 years in any vehicle.  "5 year" coolant is an EPA thing.

What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.

Pink

Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Not really.  If the head gasket leak is on the exhaust side then yes the coolant will go out the exhaust.  Otherwise it will mix with your oil.  Is your oil milky in colour?

You have not talked about the engine temp gauge.  What is that doing when you come to an idle?

Could be weak water pump.  However, you are at the point of a timing belt change.  If you plan on keeping the car I would get it done asap.  At which point you get a new rebuild water pump and of course a total coolant change along with a new thermostat.

You could try changing out the thermostat.  That would be the easiest and cheapest thing to do right away.  But I think you need a water pump so it's part of a T belt job.

I actually have not seen the coolant level at the right level before, but this car was maintained at Acura during warranty period and then my mechanic afterwards. The windshield reservoir is quite noticeable on the side that it's kind of hard to miss for any mechanic. It's only been me, Acura or my mechanic touching this car.

Basically the car starts to blow cold air if the car comes to a stand still. Once I start driving, the hot air will gradually come back. Next time I'll try keeping a constant rev while in a standstill to see if that will produce hot air.

Somebody from a Honda forum says the coolant should be green/blue for Honda and not pink. I have a toyota too and that has pink/red coolant.

The engine temp gauge goes to the right level, ie. a bit below the half way mark of Hot and Cold.

[wing0]

Around 156000 km or almost 100k miles

Car does not blow hot air until it is driven, once I come to a red light for extended period of time with fan at full speed, air temperature will start to decrease until it becomes cold and this repeats.

I know most people would say this is low coolant problem.
I checked the overfill tank. It's beyond the full mark and up to the top of the filler neck. ie. I can see the coolant when taking the cover off the filler.

After warming up the car and having the fan blow at max. The fan blower in front of the engine do not turn on. I felt the coolant return line that goes from the top of engine back to the engine(I think that's the flow) did not get warm at all.

I have a few questions before I take it upon myself to fix it or take it to my mechanic.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?
2. Can bad thermostat cause this?
3. The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.
4. What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.
5. Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Any other suggestions of what to check would be great. Thanks all.

1. Is the fact that the coolant is up to the filler neck an indication of a clog?

Did you ever see the fluid level at the normal mark?  That is one hard design to read I gotta say.  When the motor is cold I would remove the excess coolant to get it down to the "max" level.  Siphon I guess.  Did someone fill it up to the top with windshied washer fluid?

 Can bad thermostat cause this?

Just at idle?  

The coolant has not been replaced before and from the manual, it says doesn't need replacement till 192000km.

The coolant is good for 5 years so they say.  In reality it is shot after 4 years in any vehicle.  "5 year" coolant is an EPA thing.

What colour is the coolant supposed to be? I know toyota's is red, but not too sure about honda.

Pink

Should there be a burnt smell in the coolant? If I have a headgasket problem, shouldn't there be no coolant in the overfill tank?

Not really.  If the head gasket leak is on the exhaust side then yes the coolant will go out the exhaust.  Otherwise it will mix with your oil.  Is your oil milky in colour?

You have not talked about the engine temp gauge.  What is that doing when you come to an idle?

Could be weak water pump.  However, you are at the point of a timing belt change.  If you plan on keeping the car I would get it done asap.  At which point you get a new rebuild water pump and of course a total coolant change along with a new thermostat.

You could try changing out the thermostat.  That would be the easiest and cheapest thing to do right away.  But I think you need a water pump so it's part of a T belt job.

If your coolant is original it should be green, not pink.  Honda calls for 192K km interval changes for coolant, or 10 years, whichever comes first

Hi, thanks for the reply. I can verify my coolant is green from looking at the overflow tank.

[articsteve]

Honda calls for 192K km interval changes for coolant, or 10 years, whichever comes first

Well there you go.  Companies will tell potential owners anything to get them to buy their vehicle.  Ten year old anti freeze will be beyond corrosive.  The  "alkalinity" will be zero.

Hi, thanks for the reply. I can verify my coolant is green from looking at the overflow tank.

Well thats not good because obviously the factory did not fill that side reservoir to the top.  From the max level to the top cap is a lot of volume.  If it's green it could be the 2 year stuff added in by someone.  Regardless you need a change out.

So it's either a water pump impeller that is not gripping, a thermostat sticking open, (but sounds unlikely if the temp gage shows normal),  or a heater core restriction because your antifreeze has gone acidic.  I'd take this as a potential water pump problem. 

Now after thinking about this further it might be a vacuum loss at idle issue possibly effecting a heater core control valve.

[Minou]

Did you try running the car with the blower fan in its lowest speed?

These small aluminum motors don't produce a lot of heat and will lose temperature when you ask more than the heat they can produce in cold weather by turning the blower to max speed.  Especially when idling after a cold start.  A mistake too many people make in the winter thinking that the cabin will warm up faster.  Actually, it's the contrary.

Next, with the overflow tank above the full max line, you have more coolant to warm up so it may compound your problem.

I've seen what you describe in a few cars I had in the past.  Idling in windy and very cold temperature with the blower at speed no 2 or 3 and seeing the temp needle go down or not going up as the engine can't produce the heat it's being asked for.

[wing0]

Did you try running the car with the blower fan in its lowest speed?

These small aluminum motors don't produce a lot of heat and will lose temperature when you ask more than the heat they can produce in cold weather by turning the blower to max speed.  Especially when idling after a cold start.  A mistake too many people make in the winter thinking that the cabin will warm up faster.  Actually, it's the contrary.

Next, with the overflow tank above the full max line, you have more coolant to warm up so it may compound your problem.

I've seen what you describe in a few cars I had in the past.  Idling in windy and very cold temperature with the blower at speed no 2 or 3 and seeing the temp needle go down or not going up as the engine can't produce the heat it's being asked for.

Even when I put it down to speed 1 or 2 instead of max, it would still blow cold.
The engine temperature does not dip down at all, it just goes to the right position as prior to me noticing this problem.

[bridgecity]

Honda calls for 192K km interval changes for coolant, or 10 years, whichever comes first

Well there you go.  Companies will tell potential owners anything to get them to buy their vehicle.  Ten year old anti freeze will be beyond corrosive.  The  "alkalinity" will be zero.

Interesting comment Steve.  So are you saying that Honda is risking their reputation for building good engines just to stretch coolant intervals?

I currently have two Hondas, both with coolant that is over 4 years old.  Actually one has coolant that is 7 years old.  What am I risking here?  I'm not trying to be a smartass, I am truly interested to know.  I've spent quite a bit of time on a Honda Pilot forum and their has never been a mention that coolant should be changed out earlier than Honda recommends.

[slybry]

I suspect a bad thermostat is the problem.

At 156,000 kms you are overdue for having timing belt replaced. If you have not done so yet I would suggest it be done.

Routinely .... pump change and coolant flush should be done at same time as Timing belt replacement. This along with changing your thermostat should address all your concerns.