TD5 - Lack of constant heat.

The heater in my 51' Td5 works only when it wants to, any ideas why??
It doesn't matter whether the AC is on or off or whether auto or manual temp select is selected.

It works a little better when moving and the fan speed is low. When i'm stationary just forget it!!

It does work sometimes and gets lovely and warm so something is working!

Please help!!

Does the engine temperature vary with the heater, or does it stay constant and the heater temperature goes up and down?

It's a constant flow heater by memory, same as the V8, so it should be hot as long as the engine is.

You could check the controls for the heater flaps and mixer vents, one of those might be loose and flapping around.

There is also what is described as a 'servo' to operate the heater moving flaps, but I can't quickly find out what that is powered by.

Peter

Try flushing the whole water system. The matrix could well be full of crap and causing a blockage so a thorough flush won't do it any harm.

sticky thermostat possibly, if temp gauge reads cold

Put some coolant in the engine and you might get some heat - this is a very common complaint from DII Td5 owners.Often the inside of the header tank is stained and looks full - its often nearly empty.

Thanks for the suggestions/ideas.

I've just come back from an hours drive, the engine temp gauge is working fine and remains at the halfway mark, i've checked the coolant level and that's also fine but for the entire journey......NO HEAT, the fan is just circulating cold air.

Normally there is a noise from the vents when the air is re-directed from the windscreen to the floor etc but no noise this time. It is almost like the heater system isn't connected to the engine to draw heat!!??

Further advice needed!!

I was just on the M5, the car juddered, lost a little power (hesitated and wouldn't pull in 5th anymore) and the heater started working! any ideas??

The engine temp gauge then dropped to the bottom and the red light came on, I pulled over turned the ignition off and on and all seemed ok but no heat again. What is going on???

Have you tried filling and or bleeding the coolant system? If not that might help.

As far as the loss of power and temperature fluctuating; check the coolant level and make sure you haven't got a leak - look on the right hand side of the engine where the water pump is, also check that the top hose isn't getting rock hard due to too much pressure.

Hopefully someone with a bit more knowledge than me will be along in a bit!

The coolant level was very low (none in the reservoir) so i've just topped it up. As for spotting a leak, it's dark and water/slush/snow everywhere so i'll wait till morning and see if any of the snow has been stained with coolant.

One thing I did notice is when I started it up after topping up the coolant, the fan started and kept going. In this temp that can't be right? The temp gauge was in the middle so no need for it to be on really.

Many thanks.

broadoakboy said:

Thanks for the suggestions/ideas.

I've just come back from an hours drive, the engine temp gauge is working fine and remains at the halfway mark, i've checked the coolant level and that's also fine but for the entire journey......NO HEAT, the fan is just circulating cold air.

Normally there is a noise from the vents when the air is re-directed from the windscreen to the floor etc but no noise this time. It is almost like the heater system isn't connected to the engine to draw heat!!??

Click to expand...

are you sure it was when you checked it?

See what I mean ?

Eightinavee, you are right - now I have topped up the coolant, the heater works!!! However that must mean coolant leak somewhere, great!

Not sure how I check for a leak though, there's water all over the floor because of melting snow and cant see anything dripping!!

And the fan wont stop, it's on all the time right from cold but isn't that ECM controlled so it might just need a reset??!!

Thanks for the continued help!

Dont want to alarm you, but like headtester said i would feel the top hose if it is rock hard then it could be the head gasked. Mine went not so long ago and the simptoms sound the same, good luck

No the top pipe isn't rock hard, if anything there is too little pressure in the system as it is always quite soft, even after 20 minutes on the motorway, which just confirms a leak somewhere.

I 've just had the engine cover, rad cover and anything else plastic off and I cant see a leak/dripping anywhere. But there must be one because when I checked the coolant level it's dropped again to just a couple of inches in the bottle.

One other point, is the small covered fan in front of the small rad (just behind the front grill) the engine fan or the AC fan? That is the one that will not turn off. The only way of stopping it is to take the fuse out!

At least the heater is working now!!!

I'm fairly certain the little fan you are referring to is the AC fan - does it switch off if you turn the heater control panel off?

The gurt big fan is to cool the radiator - has the original viscous fan been relpaced with an electric one? If not the viscous one doesn't turn off - do a search for viscous fan to read hundreds of posts about removing or replacing it

wouldnt worry overmuch, give the cooling system a good flush and refill with coolant, I just did my bosses, he had the same problems - no heat and steady engine temp. I added 51/2 litres of anti freeze and spent a very chilly hour f*****g about trying to clear airlocks in the system. check the hoses at the back of the engine going through the bulkhead, if you can lift up the front of the car (sounds daft but works) and run the engine for a good long time and vary the throttle and this should disperse any airlocks

From what you are describing it sounds like you may be losing pressure and coolant through a failed expansion cap. without pressure the bypass valve on the thermostat won't allow the coolant to circulate properly.

Its not the viscous fan, it is the smaller one. Funny thing is, it doesn't run if just the ignition is switched on, the engine has to be running and I cant switch it off via the dash, it doesn't respond.

I'm thinking of simply disconnecting the battery for a couple of minutes to see if the ECM resets, that might do it!!??

As for the airlock, i'll top it up and leave it running with the cap off for a bit, i've been told that helps clear air from the system. It looked liked a little coolant had dripped from the overflow earlier so perhaps air has made the level rise and that's where the 'leak' is but that wouldn't explain the soft pipes though.

Thanks for the continued help.

broadoakboy said:

Its not the viscous fan, it is the smaller one. Funny thing is, it doesn't run if just the ignition is switched on, the engine has to be running and I cant switch it off via the dash, it doesn't respond.

I'm thinking of simply disconnecting the battery for a couple of minutes to see if the ECM resets, that might do it!!??

As for the airlock, i'll top it up and leave it running with the cap off for a bit, i've been told that helps clear air from the system. It looked liked a little coolant had dripped from the overflow earlier so perhaps air has made the level rise and that's where the 'leak' is but that wouldn't explain the soft pipes though.

Thanks for the continued help.

Click to expand...

Have you tried the Econ button on the AC control panel - that turns off the AC and should stop the fan (does on mine anyway)

As far as filling is concerned have you read the instructions in Rave? It tells you to unclip the expansion tank and raise it when filling. As far as pipes are concerned not being rock hard is a good sign that the cooling system is not over pressurising. Do you get a constant flow from the small retun pipe in the top of the expansion tank? - this is supposed to happen, the other thing to look for is excessive bubbles in the exapnasion tank.

Suddenly.....NO LEAK!!!

I topped up the coolant level, left the engine running with the cap left off the coolant reservoir to see if it would clear any air and it seems to have worked. The level has remained constant for 24 hours after doing 150 miles, now so fingers crossed.

I think the engine must have been running with very little coolant for a while and the AC fan kicked in as an emergency measure. The problem is, now it wont stop running, the ECM must think the engine is still too hot even though the temp gauge is working and registering normally.

I think the current very low ambient temp is the only thing that has been cooling my engine for the last 7 days, lets hope I get away with that!!!!

I've taken the fuse out to stop the AC fan as it's draining power and fuel!! I reckon I need the ECM reset properly as disconnecting the battery for 30 mins didn't work. The ECON button has no affect (it did used to).

In answer to your question, yes there is a steady stream of coolant returning to the reservoir.