Heater Lukewarm - Tried Everything!

[matt1356]

The story so far:

I inherited a Rover 75 CDTi from my father about two years ago. Ever since I have owned the car I've been unhappy with the heater, it just doesn't feel 'toastie' like the other cars I have owned. My 1992 Ford Escort 1.8 gets much hotter for example. About a year ago I put it into the garage to have it checked over, mentioning the common blocked heater matrix fault. They replaced the original thermostat and flushed out the system but could find nothing wrong. When I got the car back it still wasn't toastie like I'd expect. I therefore decided that the only economical way to get to the bottom of the issue was to take a look at it myself:

1) I bought an aftermarket replacement matrix off eBay from a popular seller. After several hours of fiddling with the poorly designed pipe connections I modded it to use the popular rubber hose pipe solution. Matrix back in car, coolant topped up, ran the car for 20 mins with radiator cap off to get any air out. Put cap back on, took car for 30 min drive, no difference. Heater lukewarm, warmer on drivers side than passenger side. Car back on the driveway, checked pipes leading to, from matrix, very hot!!! Ran car in diagnostic mode and noticed that engine temperature was running at 84c.

2) Decided to fit an inline thermostat from DMGRS, checked diagnostics, engine now running at a steady 87c. Heater still the same, again ran with radiator cap off to remove air, replaced cap, ran with air bleed valve open just to be sure.

Heater is still the same, it does get warm, just not toastie. It is also still very slightly warmer on the drivers side than the passengers. All heater controls such as the one which mixes with the outside air seem to work as expected. Is there anything else I can try or am I just being fussy, is this just the way these cars are? Looking at the design of the heating system I can understand why there is a difference in heat between the passenger/driver side but I still expect the overall temp to be higher!!!

I've lost all motivation to do anymore work on this at the moment but would still like some suggestions for when my motivation returns

P.S. The car has a/c but no climate control.

[T-Cut]

I don't think a coolant temperature of 87C will provide enough heat from the matrix to get anything like 'toasty'. You should try to get the temperature up into the 90s.

TC

[matt1356]

Thanks, what do you suggest? I've fitted the recommended inline thermostat mod, the car doesn't lose any coolant....I'm stuck.

[T-Cut]

Originally Posted by matt1356

It is also still very slightly warmer on the drivers side than the passengers. - - - - Looking at the design of the heating system I can understand why there is a difference in heat between the passenger/driver side but I still expect the overall temp to be higher

The temperature on each side of the matix should be similar. The coolant doesn't preferentially heat one side. It sounds like an air lock or sedimentation. But the underlying it all is running temperature.

You can get 89C Renault in-line stats, but anything higher means fitting the very expensive housing. This should accept one of the American units that go into the 90s. You could try blanking off the upper radiator.

TC

[matt1356]

I was thinking about blanking off the radiator option, what's the best material to use for blanking, anyone done it on a 75 before?

[T-Cut]

Just try it with a piece of cardboard as a starter. Wedge it tight to the face of the radiator. If that helps, use something more durable. Don't cover the lower half or the aircon and intercooler will be compromised. Diesels are cool running, but you have to watch the OBD temperature. It will overheat if worked hard enough.

TC

[kaiser]

I don't understand how anyone can say that 87 degrees is not enough to make a heater toasty.
Of course it is. The litmus test for electrical equipment was about 60 degrees, which is about all you can put you hand to. If you had to remove your hand, it was more than 60 and not right, if you could (barely) keep you hand, the motor was OK.
87 degrees will burn the skin clean of your hand, if you are foolish enough to try!!!

So 87 degrees C IS definitely enough to get your heater toasty! No two ways about it!!!

So if it does not, it is one of the following!
1. The flow of water in the heater is too low.
2. The flow of air over the radiator is too low
3. The flow is directed wrongly or mixed with cold air.

So no 1 requires a flush of the radiator in the heating system, and the rest is a matter of flaps, fresh air intake and fan.

But if the 87 degrees is correct, you have enough heat at source to heat your car.

[COLVERT]

The heater air mixer flaps are Not working.

When closed they should shut off All cold air input.

Your's obviously don't.-----

[matt1356]

The heater mixer flaps certainly work to some extent because when I move the dial to the left the cold air dissipates, perhaps the flaps are not closing 100% How would I get at them for inspection, do I need to take the dash to pieces?

[SD1too]

Originally Posted by matt1356

... perhaps the flaps are not closing 100% How would I get at them for inspection, do I need to take the dash to pieces?

No; check the control cable initially by removing the panel. But wait ...

Originally Posted by matt1356

... ran the car for 20 mins with radiator cap off to get any air out ... ran with air bleed valve open just to be sure.

This is not the correct way to bleed the cooling system. The bleed valve is for use during filling only, before you run the engine. Here are MG Rover's official instructions which you should follow before doing anything else.

Simon