Heater. . . . .again

[quixote]

Right lads, I need some advice. The heater in the Terrano has yet again stopped working :doh

Here's the run-down so far . . . .

All pipes flushed and clear
Coolant replaced
No leaks
No coolant loss
No overheating
No overcooling
No leaks from the water pump
No odd noises either

The heater was great following a coolant change a few weeks ago, but has gradually lost efficiency. The coolant entry pipe to the matrix is too warm to hold, but the exit pipe is only warm at best. So my thinking is that the circulation isn't up to forcing coolant throughout the whole system. The only thing I haven't looked at is the water pump. Do these have plastic, or metal blades, anyone know? I can only think that the pump isn't working as it should. I know this is pretty uncommon, but I've exhausted everything I can think of :nenau

Any other suggestions?

 

[solarman216]

most have metal blades from those that I have seen, are you sure it is not air locked? Rick

 

[quixote]

I'm not sure of anything as far as the bloody thing's concerned now, Rick :doh:lol:lol

It's driving me mad. The heater's gradually lost efficiency since the coolant change, but there are no leaks and no coolant loss so I'll be damned if I can figure it out. As of this morning, it's now blowing lukewarm again.

I've had a look online, and it seems that impeller blade erosion can be an issue at times. Truck's done about 85k and I'm guessing the pump is orginal. I've ordered a new one regardless. If that doesn't fix it I'm completely baffled

 

[Fez_uk]

have you tested or replaced the thermostat?

 

[quixote]

Brand new, Fez

 

[quixote]

If it is the water pump impeller, that would explain why it was such a pig to bleed . . . . .

The pump is the only thing that hasn't been looked at, and in any case a brand new one certainly won't do any harm as 85k is about time for a replacement anyway :thumb2

 

[Lazy-Ferret]

Just a guess, but have you checked the linkage to the valve that is opened and shut by the heater controls. I think there was a post on here somewhere about the clip that holds the outer sheath of the cable snapping and allowing it to slide.

Sent from my SM-T705 using Tapatalk

 

[quixote]

Yeah, I've checked all that mate. The blend door is fine, as is the rest of the system. The only thing left to check is the pump. Wish I'd thought to take it off when I had the radiator off, but I thought as the truck's not overheating it was unlikely to be the cause.

 

[firebobby]

It could be the pump, but would you not see the engine temp climbing higher than normal?
You could try to back flush the heater matrix, it' possible that some rust or muck has been dislodged when you did the change.

 

[Mobieus_uk]

from what you describe the matrix is blocked and the water is finding another path, pump is easy to check, disconnect a hose and start the engine, if coolant comes flying out the pump must be ok

 

[quixote]

Everything was flushed clean during the change. I suppose it's possible that something's clogging the matrix, but I'll be damned if I know what. As I'm changing the pump anyway now, I'll give everything another good flush through. The system was clean as a whistle though, so I'd be very surprised if it's clogged :nenau

As for the engine temps, we've been seeing temperatures of minus 2 here already. I've removed the air conditioning condenser so the radiator's square in the airflow . . . .I reckon the windchill factor will take the air passing through the core and over the engine to a good minus 10-15, so even with reduced coolant flow the engine sits within its range, maybe even too cool.

It's kicking my arse now :nenau

 

[jims-terrano]

My only thoughts are water pump or matrix, since you've ordered water pump do it and see what happens. If pump doesn't help then surely must be matrix, it'll be a pig to get to though I should think.

Been watching a webcam up there at Tayside and it does look cold with snow on the hills but looked nice n sunny today when I looked.

 

[quixote]

It was a lovely sunny day today. Quite pleasant in fact . . . .until the sun went down :lol

The water pump is really my last resort now. It's the only thing I haven't replaced, so finger's crossed!!! :thumb2

I don't even want to think about replacing the matrix!

 

[Mav96]

If the matrix is clogging up on the inlet side normal flushing wont help, you need to try hosing the matrix from the outlet as a seperate item, it sounds like there maybe something floating arround, which is why when you got it working before it worked ok for while & then the obstacle moved into its blocking position again.

 

[quixote]

That's entirely possible, Mav! The matrix was thoroughly-flushed in both directions when I changed the coolant, but that's not to say any obstruction couldn't re-occur (especially if it's perhaps debris from deteriorated impeller vanes, or a piece of scale or similar) First check tomorrow is going to be another matrix flush. I can do this without dropping all the coolant, so it makes sense to eliminate that as a potential cause. If it runs free, then my theory of reduced pump performance gains credence. The pump's getting changed regardless though.

I've eliminated the obvious, so it's now only the not-so-obvious that can be the cause of it :doh

We'll get there

 

[Mav96]

That's entirely possible, Mav! The matrix was thoroughly-flushed in both directions when I changed the coolant, but that's not to say any obstruction couldn't re-occur (especially if it's perhaps debris from deteriorated impeller vanes, or a piece of scale or similar) First check tomorrow is going to be another matrix flush. I can do this without dropping all the coolant, so it makes sense to eliminate that as a potential cause. If it runs free, then my theory of reduced pump performance gains credence. The pump's getting changed regardless though.

I've eliminated the obvious, so it's now only the not-so-obvious that can be the cause of it :doh

We'll get there

can you try gently flushing first into a clean bucket or something to see if there is any debris, I had similar problem on an old Ford (sorry for swearing) & that had what looked like pieces of plastic, never found where they came from.

 

[panelbeater]

have you tried taking off return heater pipe and see water coming out of end when hot,watch hands, then put back on,used to do this on a lot of cars.

 

[quixote]

Did that a few weeks ago, PB. I seem to remember the flow was a tad sluggish, but that could be selective memory

Mav? I hope to find something similar to what you describe . . . .my thinking is that the impeller vanes are either corroded away, or (if they're plastic) damaged, or that the impeller is pinning on the pump shaft and not being driven at its full speed.

If I find the matrix isn't blocked, and take the pump off to find it undamaged I will be seriously confused (Even more than usual :lol )

 

[firebobby]

As I said before, If the pump is the culprit, your engine temperature would be going up higher than normal, this looks like a blockage in the matrix.

 

[quixote]

I'm honestly not convinced, FB? Even with the radiator blanked with carpet the temperature gauge stayed bang in the middle. I'm down to my last two options though, before it goes into a garage to be sorted, and that's the matrix, and pump . . . . I can just feel it sucking the life out of me now :nenau :lol:lol