S3 overheating when driving. Normal when idling

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
Sputnik01 said:
Some thoughts on this
1) Are you getting an air lock? I had a similar situation where it (109 2.25 petrol) ran at a decent temp then as soon as I started to climb a gradient the temp shot up. It was too quick a reaction to be the actual engine temp increase due to loading. Later when I pulled the cooling system apart to replace the thermostat due to other issues it disappeared. No reason why the thermostat would be affected by gradient
2) It's not the valve timing or what ever you have on diesels that make it go bang is it?
3) Head gasket.
Click to expand...
series engines favour the bypass unless thermostat is fully open which often old thermostats dont fully open, for hot countries and omn later engines ther bypass hole was reduced on series engines by a plate with a smaller hole fitted between bypass and thermostat housing and on later the hole in thermostat housing for bypass was cast smaller
 
I'm at a loss then. I have no reason to doubt the gauge. As soon as I let the engine idle the gauge reading goes down. I haven't tried. Leaving it sat stationary with higher revs for very long but stationary revving doesn't seem to make it rise

Only when actually driving
 
Stormintrooper said:
I'm at a loss then. I have no reason to doubt the gauge. As soon as I let the engine idle the gauge reading goes down. I haven't tried. Leaving it sat stationary with higher revs for very long but stationary revving doesn't seem to make it rise

Only when actually driving
Click to expand...
if gauge rises as revs do check alternator output at idle and when revved
 
Is there a way to test it?

Don't mean to question your knowledge I just want to avoid spending more money replacing things that aren't broken lol
 
Try checking the voltage at the temperature sender at tickover and revs , an analogue gauge is best. Temp sender should just be getting 10V same as fuel sender , as it is switched on and off by old type voltage regulator digital meter struggles to read the changes.
You can buy electronic versions of voltage regulator which give a smooth 10V
 
Its not right that the temp should drop when the engine idles....if the stat is working correctly it should stay the same...or raise after a while as its getting no cooling air passing through the rad.

Get an infra red thermometer off ebay £10 or less...point it at the thermostat housing and it will give you its temp...thats where the sender is.

Then you will know if your gauge is giving you correct info or not.
 
Sadly not. New job started just before December and I haven't had time to touch it yet. Plan for today however is to get the analogue meter on it and hope the one I bought isn't too cheap to get an accurate reading lol
 
The rad will go cold lower down...just doing its job...a laser thermometer is a very handy tool in the garage for checking things like this...very cheap on ebay.

I was going to say the voltage stabilizer for the instruments...that what at idle the gauge drops.
 
Tested with an analogue and digital multimeter. With engine off. Battery voltage about 12.2v

Lead to temp sensor and lead to fuel sender reading between 11.5 and 11.8 volts.

Is it weird that the digital meter had a clear reading with no jumping?
 
If some one has fitted an electronic voltage stabiliser the true reading will show on either meter. Sure the voltage to intruments should be 10V not 11.5V or 11.8V.
This voltage needs testing with the engine running as alternator will give out upto 14V.
 
Found a rusty voltage regulator behind dash. Figured it was knackered. Opened it up out of curiosity and it was pristine inside. Guess the part that contacts the case to earth itself had corroded too much. New one on order. Will see what difference it makes
 
Just had a Series 2 in complaining of intermittent overheating, wire from temp sender resting on exhaust manifold, burnt through insulation but not making good enough connection to manifold to give full scale deflection on gauge
 
UPDATE
Changed the stabiliser.
More accurate and responsive. Still reading high under revs. Normal at idle.

Next step is a new radiator I guess :(
 
New update.

New rad fitted. Another new (tested) thermostat . Still over heats but slightly less.

Still goes back to normal at idle and creeps up with revs whether stationary or moving.
Checked alternator output again. 12.6 idle and 13.6 at revs
 
You must log in or register to reply here.

Similar threads

Moorhouse2
Series 3 Gearshift Jammed in Neutral on S3
Replies
15
Views
1K
tottot
tottot
enjoi
P38A Going through radiators- not overheating
2 3 4
Replies
60
Views
4K
enjoi
enjoi
gold rover
L322 Barrel lock failure
2
Replies
27
Views
2K
Grrrrrr
Grrrrrr
E
Overheating, Defender 110.
Replies
7
Views
1K
currymunster
currymunster
bertone902
L405 2014 3.0 start stop not working wven after new battery
Replies
16
Views
2K
kds
K
Back
Top