Temperature a bit low

jetta&golf · January 15th, 2019, 16:10

I’ve got two 2002 MKIV TDIs. Had them for years.

Just recently on the Jetta the engine temperature dash gauge is not reaching its normal vertical straight up position. It reads a bit low.

I’m in Canada. Got the VW winter front. I’m used to poor heat, slower warm up, and such.

Usually it reaches operating temperature but last night at -10 C even after a 100 km it was still half a bar low. If I turned on the heat it would drop temperature reading to about one full bar low.

Wondering if this is something I can investigate, or it needs to go to the shop or it’s just an getting old issue.

miningman · January 15th, 2019, 16:21

do yourself a favour, change the thermostat and coolant temperature sensor.... dont bother thinking anymore, anywhere in Manitoba is too cold for less than ideal heat output.

Vince Waldon · January 15th, 2019, 16:56

Given that the dash gauge is programmed to read "90" any temperature in the range of 75-95 or so your actual temperature is probably 70 or lower, which suggests your t-stat has worn enough that it's opening too soon. Could also be that something has jammed it partially open.

They can definitely wear out over time, and they do so gradually.

Either way, new t-stat (and housing) is the standard approach here before thinking about any further complexities... half-hour job and about 35 bucks in parts.

Just did mine, and wow... the heat on an Edmonton winter morning...

STDOUBT · January 15th, 2019, 18:40

Add to that 35 bucks the cost of replacing the giant puddles of coolant you'll lose when you pop the CTS and the thermostat.
Last time I did it, I used a collapsible "bucket" wadded up behind the head to catch the flow from the CTS (don't forget to dig out the gasket).
For the thermostat gush, I have not found a good way yet to catch every drop from that location. Next time for sure.

fouillard13 · January 15th, 2019, 23:25

I just had my thermostat replaced too and its a huge difference like Vince mentioned. the car gets up to operating temp WAY quicker now. its definitely noticeable. I love it. well worth the very little time and money it took.

steve6 · January 16th, 2019, 06:37

in for : THERMOSTAT CHANGE

Tdijarhead · January 16th, 2019, 10:22

My dash needle reaches vertical at *164 it stays at the vertical position till at least *215. I have not seen my car get hotter so I don't know how long it stays at the 190 mark. If your cars needle is less than vertical then it is less than 164 degrees.

Time to change the thermostat.

andreigbs · January 18th, 2019, 10:06

I concur: thermostat is the culprit most likely.

jetta&golf · January 18th, 2019, 16:57

Many thanks.
Happy to see the dash instruments back to normal.

Mongler98 · January 18th, 2019, 19:36

Quote:

Originally Posted by STDOUBT

Add to that 35 bucks the cost of replacing the giant puddles of coolant you'll lose when you pop the CTS and the thermostat.
Last time I did it, I used a collapsible "bucket" wadded up behind the head to catch the flow from the CTS (don't forget to dig out the gasket).
For the thermostat gush, I have not found a good way yet to catch every drop from that location. Next time for sure.

a $10 shopvac will suck up 100% of every drop as its leaving the hose, as long as the vac is CLEAN first, just reuse it!
It baffles me how many people try and do any coolant service with OUT a shopvac.
it can even be a cheep POS, as long as its like 2 gallons, 4 preferably.
I use my ridgid but i filter the coolant before i reuse it. A clean bath towel over a bucket will filter (slowly),