Booster Heater Stays On When Engine Warm

[Steveenduro]

Since replacing glow plug and run-on pump, my booster heater has been working fine, but fails to turn off when the engine temp reached normal limits.

I've tried a search to see if anyone else has this problem, but can't find anything.

The coolant temp. sender was replaced years ago and seems to work ok.

Any ideas?

Thanks

[Scorpiorefugee]

Obvious question, but someone has to start. Are you sure that it has reached normal temp? I have both 110 and 115 models and the 115 heater is on a lot more than the 110. It can take up to 10 miles in this weather. It frequently comes on for several miles when the 110 doesn't come on at all. I am aware that the threshold air temperature is much higher for the 115 (some have quoted as high as 12C) but this doesn't explain the longer run time.

 

I've been intending to put a manual switch in the air temperature sensor cct. but there always seems to be something more important to do. :rolleyes:

Edited December 9, 2008 by Scorpiorefugee

[Steveenduro]

My morning journey is 30 motorway miles, and it seems to warm up in 5-7 mins, but the heater is still running 30min later.

A few years ago when I replaced the coolant temp sender, the retaining clip broke off, but if it were loose I think I would see problems with temp gauge - so probably red herring.

[richyrich]

I believe the heater stays on in the lower setting if the outside temp is very low. Mine does - not sure what it is but I'm sure somebody in the know will confirm

yes or no.

Rich

[big_kev]

The booster heater should cut out when the water temperature reaches 85 deg. approx.

[gregers]

i have noticed that the booster(mine)will cut out when i turn the interior heating off,but once it is turned on(high)it starts up again,dunno if this is right or wrong????

[chromedome]

Mine stops when normal temperature is reached, well sort of.

 

If you listen to mine very carefully it's sort off ticking over if that makes sense. Mine is one of the last Mk2's so may be a mod that's been done to stop it seizing up from lack of use. :wacko:

 

My aux heater was intermittent but changing the temperature sensor/switch has cured the problem.

[Scorpiorefugee]

Just looking back and a silly thought...

 

The tempeature sender on the 110 is a 2 part thing, one used for the engine management and the other as far as I can make out is only for the display, meaning that if on part fails, the dislay indicates that all is well but the engine management is getting rubbish information. One clue is that the Glow plug sequence can be affected. It is a commont fault on the AFN 110 engine but I have no knowledge on the 115.

 

As I said - asilly thought.