EP4 - heating issues

Joseph80

New Member
Hello everybody!

I'm new to Honda absolutely, just bought my Civic 1.7 CTDI a month ago.
From the very first time I had heating issues so I started looking for the root cause.

The symptom: when engine is idle no warm air blowed. As soon as I start revving and it goes above 2000/min the air is warming up and heating works like charm. Then I lower the speed or stop and heating is gone very soon.

What I did so far: brand new quality thermostat installed, checked if heating valve was working, washed the heater core 2 times (reverse as well), descaled the heater core with citric acid put into warm water, checked if the hoses are not bulged, made sure no air bubble left in the system

Result: zero

I've read through several comments in forums but in most case the idea was to change the T-stat, unclog the heater core, remove air bubbles.
Been there done that.

I'm wondering if this could be the result of a faulty water pump? Theoretically if this is failing somehow maybe the circulation of the coolant would be poor. With revving also the rev of the pump rises. But maybe I'm wrong.

The question is if there is any other element of the heating system could be failing here? Maybe some electric component? I'm really out of ideas. Would be thankful for every new advice.
 
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Ep3po

Respected
Isn't that a Diesel engine? They don't sell those in the states. I don't know much about diesel but I do have a friend with a diesel truck and if he is in park with the motor running in the winter the temp gauge falls far below operating temperature. This is normal operation. And it won't get to operating temperature without driving it. He also has a blanket that came with the truck from the manufacturer that snaps on the front of the truck over the grill for sub zero temps or it never gets to operating temp in extreme cold weather
 


Joseph80

New Member
It's a diesel engine.
I know these need more time to warm up and indeed when idling the engine (coolant) temperature falls after a while. But definitely not within 10 seconds as the engine won't cool down that rapidly. And I not only get this issue when the engine is idling but when driving slower (rev. under 2000).
The blanket you mentioned is familiar to me. I had some thick cardboard placed in front of the radiator. No difference.
 

Ep3po

Respected
My next guess would be the water pump has corroded fins and isn't moving enough fluid when your at an idle. You have covered everything else thermostat and flush etc. maybe the new thermostat is defective?
 


Joseph80

New Member
It seems everything else checked but the water pump.
As the engine itself is heating up normally and gets the operating temperature after some minutes of driving I would say the new thermostat is working fine.
I hope there is no other component stays hidden causing this issue. It's equipped with a manual AC so there should be no problem with some kind of electronic stuff I don't know about.
 

Ep3po

Respected
I would take a look at the water pump and take it from there. Are both the upper and lower radiator hoses the same temp when motor is warm?or is one hotter that the other.
 

Joseph80

New Member
This is what's gonna happen next. But this I cannot do myself at home. Better to have it replaced by a professional at a garage.
Already bought a brand new Japanparts made water pump.
Both hoses are the same warm so I guess the heater core is ok. Especially after having it descaled.
 

Joseph80

New Member
Of course. Once I have the old water pump in my hand I'll check and share you some photos in case of this is the source of my heating issues.
Anyway thank you for the advices!
 

Joseph80

New Member
Long time no check in.
I thought of adding the outcome of this issue.
Worst case scenario happened. Blown head gasket. :(
I got the cylinder head fixed. So the heating issue is gone.
But.
Since they put back the repaired cylinder head the engine has a very very bad noise.
It's like the valves are clapping. 3 times louder then before.
They said it's because the head is lower than original and the combustion chamber reduced - resulting in a knocking engine.
However I can't just believe it. Had another cars with the same issue before but none of them got even the same like symptoms.
I'm wondering what went wrong here.
 


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