Thermostat stuck open?

Hey folks,

I noticed last winter that my Hiace would never reach the mid engine temp mark in the cold. I'm in Vancouver so it wouldn't go below freezing often but still struggled to make it over 3-4 of the digital bars on the dash engine temp indicator. Wasn't getting much heat out of the vents.

Anyone experienced this? The same condition is starting again this winter. Seems like my thermostat is stuck open or something

yep, when I first got my van it was very slow to reach temperature and would often loose engine temperature easily.

Replaced the thermostat and it has warmed quickly and been stable in the middle of the gauge (old style gauge) ever since.

Thermostat looked okay but I never bothered to test it, guess spring was weak and it was opening too easily.

Yeah replace thermostat, and throw the old one away.

TwentyOneThirtyFive wrote:

Thermostat looked okay but I never bothered to test it, guess spring was weak and it was opening too easily.

I never understood testing thermostats unless to verify a diagnosis, after all the effort of getting the old one out only a new one is ever going back in for me too

@GPW, in general I agree, but sometimes you cannot reproduce the issue at the time of replacement.
Lets say your back in the UK, wanting to replace the thermostat because somewhere in Spain it was getting hot on a steep mountain. Than it could be useful to see if it was the thermostat.

But typically speaking, you have some kind of issue that is easy to reproduce. Like the topic starter. The van isn't getting warm, replace thermostat and go for a drive to know it is resolved.

Hiace4wd wrote:

Than it could be useful to see if it was the thermostat.

Yes I'd test for diagnosis, but I'd never put it back in unless I was stuck without a new one and the old one was not jammed shut

Yes I agree.

By the way, if you are on the road (holiday roadtrip) having problems and you can't get a thermostat, then you can simply run without a thermostat. On a summer holiday, this will be fine.
In colder winter times, you could put some cardboard in front the radiator (partially at first), but you have to be careful as it can overheat quite quickly.

Have looked at my thermostat houseing a couple of times with a view to changeing it as matter of prevention (its 21 years old and probably original) mine is a 3ltr turbo and its no easy job, it will have to wait till I pluck up courage to dive in.

JT69 wrote:

Have looked at my thermostat houseing a couple of times with a view to changeing it as matter of prevention (its 21 years old and probably original) mine is a 3ltr turbo and its no easy job, it will have to wait till I pluck up courage to dive in.

I'll probably wait until the timing belt and then change the belt, water pump, coolant and thermostat all at the same time.
BTW don't lets cats near any coolant, it's lethal for them.