X300 ; No heat.

[8Ace]

Bit chilly this morning, but despite putting the climate control up to thermonuclear level, all I received was an icy blast from the vents.

Having, as I do, the mechanical knowledge of a croissant, I know nothing about the potential severity of this. All I know is that the heat comes from the engine, and a broken engine is bad.

I realise this may be too great a leap, but do you feel this is is something I should feel worried about, or is it likely to be an inexpensive fix? Any thoughts to help settle my mind will be gratefully received.

Many thanks in advance.

Edited by 8Ace on Monday 27th July 16:37

[a8hex]

What does the temperature gauge say?
If that is also at freezing cold then your thermostat has probably gone.
Mine went last year. I replaced my own, it didn't take long and the part wasn't expensive.

[Jaguar steve]

Check the coolant level (when cold) before you use the car again.

If the engine takes a long time to heat up from cold and the temperature guage consistently reads low - it should be roughly in the middle of the scale after a few miles driving - then chances are the thermostsat has failed in the open position.

If the engine heats up reasonably quickly and the guage reads normal, then with the engine hot and running try cycling the temperature selector from Hi to Lo several times and feel to see if the outlet temp changes from below ambient to well above.

If you can get chilled air when the Lo temp is selected but not heated air when on Hi then have a look under the bonnet. At the rear of the engine compartment on the left hand side you'll see a small black rectangular pump with one visible hose going into the front of it. With the engine running and hot air selected hold the pump and see if you can feel a faint vibration. Then, still holding the pump get an assistant to turn the air right down to Lo, wait for a few seconds then get her (it'll be the Mrs dragged into nursing an old Jaguar back to life won't it ) to turn off the engine.
If at some stage the pump stops vibrating then it's working and time to get help.

[8Ace]

Gents,

Thanks for the replies. It isn't the thermostat as the engine gets nicely warm in a few miles and the temp gauge rises accordingly. It is simply that no heat comes out when the climate control is set to above ambient. The aircon still works fine.

I will have a look for the appropriate pump. I assume that if no vibration at all is felt, it means it is knackered and should be replaced. Is this a simple task?

Otherwise, and if it seems to be working, I think I'll get it checked out.

[BigNige]

Dim question, but it isn't something as simple as an air hose that's become disconnected somewhere is it?

[8Ace]

BigNige said:

Dim Excellent question, but it isn't something as simple as an air hose that's become disconnected somewhere is it?

A very good point. Will have a look.

[Jaguar steve]

8Ace said:

Gents,

Thanks for the replies. It isn't the thermostat as the engine gets nicely warm in a few miles and the temp gauge rises accordingly. It is simply that no heat comes out when the climate control is set to above ambient. The aircon still works fine.

I will have a look for the appropriate pump. I assume that if no vibration at all is felt, it means it is knackered and should be replaced. Is this a simple task?

Otherwise, and if it seems to be working, I think I'll get it checked out.

You might feel a faint vibration from the coolant hydraulicking (that's not a proper word BTW, PH pedants) in the pipe and pump with the engine running even if the pump is not. My point about vibration was to feel for a change. The coolant pump has a fair buzz about it rather like a fish tank aeration pump when it's running.

While you have got the bonnet open you might have sucess by reminding the pump of it's obligations to you with a smart tap from a hammer - it could have just become too stiff from lack of use to enable it to self start. If not, sounds like a job for your local indy, both for diagnosis and repair.

[BigNige]

Jaguar steve said:

- it could have just become too stiff from lack of use to enable it to self start.

I know that feeling

[8Ace]

Jaguar steve said:

8Ace said:

Gents,

Thanks for the replies. It isn't the thermostat as the engine gets nicely warm in a few miles and the temp gauge rises accordingly. It is simply that no heat comes out when the climate control is set to above ambient. The aircon still works fine.

I will have a look for the appropriate pump. I assume that if no vibration at all is felt, it means it is knackered and should be replaced. Is this a simple task?

Otherwise, and if it seems to be working, I think I'll get it checked out.

You might feel a faint vibration from the coolant hydraulicking (that's not a proper word BTW, PH pedants) in the pipe and pump with the engine running even if the pump is not. My point about vibration was to feel for a change. The coolant pump has a fair buzz about it rather like a fish tank aeration pump when it's running.

While you have got the bonnet open you might have sucess by reminding the pump of it's obligations to you with a smart tap from a hammer - it could have just become too stiff from lack of use to enable it to self start. If not, sounds like a job for your local indy, both for diagnosis and repair.

Gents, an update.

It's been a little while since I've been arsed to do anything about it, mainly as the weather has been quite nice so it's not been needed.

Anyway, I have identified the pump in question, a little bigger than I expected but I know the one I need, and there is no vibrations when you cycle between hot and cold settings on the climate unit, even after careful percussive maintenance. Anyway, I have identified a replacement(used)part for £25, so all going well, this will be ordered and installed.

As this only has 2 connections, I should be able to replace this without making a pigs ear of it. However, before I do so, I have a couple of questions. Firstly, I assume that this will need to be replaced without letting in lots of air, as large air bubbles would cause havoc in the cooling system. Does this matter, and if so, what's the best way top go about this please?

Secondly, how exactly does this work? The pump in question is horizontal, has 2 hoses attached but no electrical connectors to tell it to go or stop. However, it is in series with another unit, a vertical cylinder roughly 4cm in diameter and 5-6 cm high. This has connectors attached and I assume that this controls the pump. Do I need to replace both bits? Is it controlled by pressure in the system?

As ever, thanks for any advice and expertise.