200 tdi - water pump failure?

[LandyManLuke]

Morning all,

On the way to work this morning, the heater was blowing stone cold, and the water temperature guage rose almost to normal running temperature, something it hasn't done for a few weeks.

On arrival, I've checked that the header tank isn't full of ice and that the pump pulley and belt are ok, which they are.

I believe that the heater is fed by the pipe from the thermostat housing, and that the return goes in to the back of the head, can anyone confirm this?

The heater pipes at the heater are cold, and there's a definite temperature gradient over about 6" of the long heater pipe running along the head, from hot at the thermostat to cold.

The heater pipe from the rear of the head is warm, but still has a gradient along it - it's much shorter though, so i'd expect it to be warmer?

My current hypothesis is that the blades on the water pump are currently not doing their job, either because they're not being driven, or because they're not there?! Externally, the water pump looks and sounds fine, no nasty noises at all.

At lunchtime, my plan is to pull the pipe off the thermostat housing and see if the pump is producing any flow. If it is, I'll be checking the pipe at the heater, if it isn't I guess that'll confirm it's the pump.

So, if anyone could confirm the flow round the heater circuit, that'd be much appreciated.

I'd appreciate any other thoughts or experiences too.

Cheers,

Luke

[muddy]

I usually find a cold heater a sign of low coolant level as more often than not the heater is the highest point, however if you have checked the level i guess this must be ok, although a quick squeeze of the heater pipes should let you know whether they have water in them or not.

I would remove one of the heater hoses insted/aswell, thatway you can determine whether any water is actully reaching the heater, if the level is two low i would expect one pipe (the feed) to have a slight warmth to it near the block/head getting colder towards the heater and the return to be clap cold.

Something tells me that the rearmost hose is the feed although thats probably a 50/50/90

Happy burfday btw

[LandyManLuke]

Happy burfday btw

Err, thanks, it's off to a great start

[Lars L]

"The heater core draws its hot coolant from the cylinder head and returns it to the pump -- so the heater works regardless of whether the thermostat is open or closed."

Your question got me to wonder so I asked Google, this is what I found on a US site...

[LandyManLuke]

Thanks for that.

I'm still not sure exactly which way it flows, I'm about to start investigating during my lunch hour, will pull a few hoses off and see what flow I have where!

[western]

from stub pipe on rear left of cylinder head to heater matrix rear connection = hot feed

from heater front connection to pipe along cylinder head = return

[LandyManLuke]

Thanks Western, and Will and Lars, all correct.

Testing over my lunch hour revealed good flow from the thermostat housing, and reasonable flow from the return pipe, increasing with throttle. After about 5 mins of 1k5 rpm the vents were starting to give warm air.

My conclusion for now is that this morning the matrix was frozen to the point where there was no flow, so the pump was just circulating coolant around the engine circuit, not the heater circuit, having sat in a warm engine bay for the morning the matrix has now defrosted.

I plan to replace the water lost during testing with neat antifreeze, which should up the ratio to something more suitable for the current climate.

[western]

check the operating cables/flaps are all set up correctly, then you should be toasty warm.

[LandyManLuke]

Yes I've never had a problem with the heater as such, once the (rubbish LR) gauge needle has made it on to the scale, the heater output it warm, once it's up to 12 O'clock ish, it's toasty.

The only issue really is the time it takes for the engine to warm up, to generate the heat in the first place.

[muddy]

You need to stop driving like a grandad then

[western]

Yes I've never had a problem with the heater as such, once the (rubbish LR) gauge needle has made it on to the scale, the heater output it warm, once it's up to 12 O'clock ish, it's toasty.

The only issue really is the time it takes for the engine to warm up, to generate the heat in the first place.

in the current weather, mine gets up to operating temp after about 2 miles of normal driving in 30mph limits, sounds like your coolant mix wasn't strong enough.