Thermostat stuck open?

[MrPulldown]

My 02 EVC seems to take forever to warm up (190 on the gauge). Always thought that it was just a characteristic of the van. But now that winter is here and I have been driving the van consistently I am beginning to think that the thermostat is stuck OPEN. Is this common? I guess WAY better than stuck closed.

When I leave the ski area to drive home my engine starts to warm up and get to the 10 o'clock position on the gauge. The ski area is on top of the summit so driving home is downhill for the first several miles (except for the half mile or so leaving the actual resort). The engine temp will actually go down to dead cold while descending.

This can be another reason that I am getting bad gas mileage as the engine is stuck in cold start enrichment. This is also bad for catalytic converts and O2 sensors right.

Assume I should swap out a thermostat with a new factory unit. Based on my reading here this should be accompanied with an aluminum TS housing and a coolant temp sensor. GREAT... Having just fixed the leaking coolant fittings/connections with the brass and stainless ones, I thought I was free of coolant system wooos for a while. This might have to wait.
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2002 EVC

[Abscate]

More likely your coolant sensor is flaky. Are you getting good cabin heAt?
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.ssS!

[MrPulldown]

[Abscate]

[Stripped66]

[MrPulldown]

The temp gauge doesn't jump.
TS prevents coolant t from circulating. It shouldn't allow coolant to flow through the heater core unit it is open. What ever coolant is in the heater should be cold right?
The part that is the weirdest is that it will come close to being warm and the get colder as I am going downhill.
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2002 EVC

[Stripped66]

[YOGIVW]

[MrPulldown]

[Whridlsoncestood]

Where is this located? Is this on the underside of the van? Is that the afterrun pump right behind it? I have a little vac diverter in the coolant lines right next to my afterrun pump but no electrical connections to it like that.
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2001 EV MV

[MrPulldown]

[gesoffen]

Anyone have a functional description of this system? I'm having similar issues to the OP - temp at gauge and via scan tool never gets to normal operating temp when moving, heat in cabin is warm (not hot).

In troubleshooting the system, the vacuum valve functions and holds a vacuum. The solenoid seems to function as I can hear it clicking when bench testing with 12V power. It too holds a vacuum.

To further troubleshoot, I need to understand a couple of things:
1) what triggers the noid?
2) what should the vacuum be (psi)?
3) When should the vacuum valve be open or closed (with respect to engine temps)?

Thanks in advance!

[Whridlsoncestood]

Mines totally a stuck thermostat. Cold air moving over radiator keeps engine too cool. For the winter until I can get under this and change it I’ve put a piece of cardboard in front of radiotelephone behind the grille. Been keeping a nice steady 190.
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2001 EV MV

[TheOneTrueQuux]

[gesoffen]

[spacetiger]

If you ever replace your thermostat, take the old one and put it in a pot with water and bring the pot to boil. Watch to see how the thermostat operates - you need a thermometer.

It goes without saying, you can do this to the new one before you install it to verify its functionality.

[TheOneTrueQuux]

[gesoffen]

What's with everyone telling me what I don't want to hear !

j/k symptoms do point to a thermostat but the vacuum system interaction with the cooling system is something I don't understand so want to investigate that further.

Unfortunately, I tossed the old tstat (so confident in my diagnosis at the time, I was). Considering the ~$20 cost, I may order another just to play with it and do the swap if it passes the hot water test.

[wannabecamper]

For short nose vans, I think the OEM temperature was 89 degrees celsius. I ordered 89 degree thermostat before and was sent 82 degrees unit from rock auto. Had the same temperature issue that everyone was talking about. Ordered 87 degree unit from SD Euro and seems to be good. I am not sure why there are so many different temperature thermostat for these vans.

[gesoffen]

I have a new hypothesis on why I'm having issues reaching operating temperature in cold weather.

Background: During my December '21 cooling system refresh, I had also installed a GoWesty trans cooler kit. For those unfamiliar with the kit, it requires physical removal of the stock coolant/atf cooler and thus comes with a barbed splice to join the stock cooler's coolant in/out lines, creating a loop.

Normally I don't like to work on multiple systems at once (harder to trace problems that way) but since both required work inside the cooling system, it made sense to do it in this case. I did want to eliminate the loop altogether by replacing the Tees in the coolant system with appropriate replacement fittings. However, I didn't have them on hand so shelved that part of the project for the future.

Through various threads, here and on VW Vortex, I stumbled upon a good coolant system block diagram: http://www.rialtainfo.com/vw/vw_images/engine_repair_1997-2000%20EV%20Repair%20Manual.pdf.
While this is more focused on the 12V motors (mine's a '03 EVW/24V), this largely captures the various cooling system components sufficiently to aid in troubleshooting, see page 113 of the link.

Following that cooling system block diagram, I see that by eliminating the stock ATF cooler and splicing the coolant lines together essentially creates a path through the radiator that bypasses the thermostat.

My new hypothesis is that this ~1" diameter thermostat bypass loop is providing enough coolant flow through the radiator such that it does not reach operating temp in cold weather.

I will test this hypothesis by clamping off the loop to stop/severely restrict flow through that loop and see its impact on reaching operating temp.

If this hypothesis proves correct, I will look into the correct fittings to eliminate the loop. I vaguely recall another poster (here or elsewhere) that had a good list of fittings to replace NLA parts or eliminate stock plastic pieces. Failing find that, I'll just measure the stock fittings to find suitable replacements.

More to come.....