Running a bit hot.

Hi guys.

I know this has been mentioned so many times, but given my circumstances I'm kind of praying I can't be far off sorting it.

Basically the Jetta is running a bit hot, I did have a photo of how hot but my phone has got dementia and has forgotten the photo.

It's pretty much 3/4 all the time, the fan does kick in (most times, I have it on a switch too) and its only on for 10 seconds or so, but it never gets it down to 1/2 like it should be. The bottom rad pipe heats up like it should, and they both go rock hard.

I've had a new head gasket, new rad, new water pump, coolant, thermostat and temp sender, the cambelt was done in Jan so the timing is ok on that as far as I know, and the ignition timing is spot on.

The car has always sat on 3/4.

However, in the last two weeks its gone past that and twice now the red light has flashed, luckily its been when I've been parking up. The one time it happened the fan didn't even kick in, even though it does usually, its never boiled through the cap either.

The only thing I can think of now is a dodgy gauge, is there anything else I could check.

Thanks.

is it a 2 speed fan (how many wires) and does it sit at 3/4 when you're moving at speed, or only after you're sat for a bit

rubjonny said

is it a 2 speed fan (how many wires) and does it sit at 3/4 when you're moving at speed, or only after you're sat for a bit

There are two wires coming off the connector on the back of the fan if that helps? a red/black wire and a brown wire so I'm guessing its just power and earth.

The fan doesn't come on often though, there are no signs that say it's overheating other than the 30 year old gauge lol.

Its at 3/4 constantly once warmed up mate.

Thanks.

ok couple things it could be, faulty thermostat, the radiator is clogged, water pump is weak or maybe dash gauge is over-reading.

even if rad fan was bust it wouldnt be a problem while you are driving along, just when you pull up and sit for a bit.

have a read:
http://www.vwgolfmk2.co.uk/viewtopic.php?f=37&t=14913

Ok thanks John, will have a read!

Just had a look mate,

The fan kicks in when the gauge goes over 3/4, by then the stat has opened and the bottom pipe has started to warm.

Best way to explain it is 3/4 on my gauge is the same behaviour wise as 1/2 on everyone else's. when it gets to the point where the radiator kicks in, it has passed the 3/4 mark dot.

Gauge issue then do you think?

i would be leaning that way aye, the sender is the small black one in the flange on the head, with red/yellow wire, first off check connections are clean and it is actually black! then make sure any earths to the head are good as these can effect the gauge display. you could run a wire from the main body (the brass bit with spanner flats) of sensor to battery -ve see if that improves anything, if it does the engine earth to battery is poor

You sir are a legend.

Something to try!
 
Thanks, will check and post up my findings!

Good luck Spilz mate. Hope you get to the bottom of it

smudger1980 said

Good luck Spilz mate. Hope you get to the bottom of it

Cheers dude, me too, the car is really close to running spot on. Just this to sort really then she's all good for this year hopefully!

Bit of a thread revival haha, the joys of owning your own business, no time!

Not managed to check the earth thing yet in all honesty.

I have had a breakthrough with the car though, on the way back from a meet it was getting dark so I put my lights on, and the temp gauge went from 3/4 to nearly maximum, I turned them off again and it went back to 3/4.

I'm baffled lol. Any ideas?

Sounds to me like youve got a short in the track on the back of the binicle mate. Had this with a Fuel gauge on one car before. When i switched the lights on i had a fith of a tank more fuel compared to when they were off  

Chris

could be poor earths behind the dash, so when you switch your lights on something is earthing via the cluster rather than where it should be

Gordonthegolfer said

Sounds to me like youve got a short in the track on the back of the binicle mate. Had this with a Fuel gauge on one car before. When i switched the lights on i had a fith of a tank more fuel compared to when they were off  

Chris

Ah right ok, by Binicle do you mean the circuits behind the cluster?

rubjonny said

could be poor earths behind the dash, so when you switch your lights on something is earthing via the cluster rather than where it should be

Yea I thought it might be the earths that go into that earthing ring by the fusebox, but I re-did those when I had dash out, and it made no difference.

This is going to bug me forever lol.

Yeah sounds like poor wiring/connections. So, no actual temperature issue with the engine. It might be worth fitting an oil temp gauge as peace of mind.

the engine needs to be well earthed too, the temp sensor for the cluster needs to earth via the engine block so have a look at that too

I know this is probably alright, but have you checked how well the coolant system is bled?

I had a similar issue on my Golf, and after replacing almost everything I tried bleeding the system again and 18 cubic bumloads of air came out of it, runs alright now!

Just gotta put a remote fan switch on it now.

paul_c said

Yeah sounds like poor wiring/connections. So, no actual temperature issue with the engine. It might be worth fitting an oil temp gauge as peace of mind.

Ah ok cool, will look into this as it doesn't sound easy! haha. I've got the spaces in my centre console for gauges!

rubjonny said

the engine needs to be well earthed too, the temp sensor for the cluster needs to earth via the engine block so have a look at that too

Any ideas where I'm looking for that earth?

X said

I know this is probably alright, but have you checked how well the coolant system is bled?

I had a similar issue on my Golf, and after replacing almost everything I tried bleeding the system again and 18 cubic bumloads of air came out of it, runs alright now!

Just gotta put a remote fan switch on it now.

Well when my mate did my head gasket (january) he let it get to temp and loosened one of the jubilee clips to force the air out (silly mechanic haha). I've done the "cap off till it warms up" trick countless times aswell, so I'm 99% sure it's not that. Cheers though!