Unsure if I have a thermostat issue

[neil555]

Not sure if anyone can help with this, my Bongo temperature gauge varies from cold through to about 45% depend on driving conditions (constant 40-45% on motorway, varies from cold to 40% on other roads). The gauge seems to take a fair while to move off cold.

I had assumed my thermostat was stuck open or had been removed, but I have now been reading about modified temperature gauges. The heater has always blown nice and warm once the van warms up, no noticeable difference dependant on gauge.

No concerns regarding air locks etc. as recently replaced the pipes to rear matrix and filled and bled the system (I know, should have sorted everything else at the same time!) but I only got the Bongo last summer and have done a few thousand miles now, at first I was concerned the thermostat might have been removed due to overheating/head issues but after the mileage I've covered and fairly long journeys I've done I'm happy that isn't the case.

I currently have a slow seeping leak on my heater matrix so have ordered a matrix and thermostat to change. I'm just wondering if there is anything obvious I've missed or don't know about with the Bongo? Any obvious way to check the temperature gauge?

Any help gratefully received!

Thanks,

Neil

[g8dhe]

Normally the gauge is slow to move up to the 11 O'clock position but then stays there no matter what, going lower isn't a normal report we see, however you don't say what engine your running ?

[Sven]

Had similar on mine when i first got it (2.0 petrol). Thermostat was stuck open - new one sorted it. Guage now goes up to the 11 o’clock position within about 3 miles & doesn’t move from there.

[skeinpuppis]

Definitely a problem with the thermostat. Need to buy new one and replace it

[neil555]

Thanks for the replies. It's a 2.5TD, I was hoping to get the stat delivered for today to fit it but no such luck, as I've got a new front matrix to fit too, the old one is weeping. Should have done it last week when the metal pipe to the rear matrix burst a leak rather than pay for another bottle of coolant and another age bleeding it! Ah well.

[Northern Bongolow]

Thanks for the replies. It's a 2.5TD, I was hoping to get the stat delivered for today to fit it but no such luck, as I've got a new front matrix to fit too, the old one is weeping. Should have done it last week when the metal pipe to the rear matrix burst a leak rather than pay for another bottle of coolant and another age bleeding it! Ah well.

sounds like the stat you have in may have a hole drilled in it or be sticking open, or be a crappy copy not a gen mazda ones which are better made and last longer, or the gauge has been modified with a resister to read a slightly different range, this is done by fitting resistors across the rear of the temp gauge, sometimes peeeps fit different value resistors to make it read what ever they want the gauge to show them and how soon. have a look at the back of the gauge cluster and look for soldered on resistors. finally it could just be a low reading temp sender in the front driverside of the head, or it needs the terminal cleaning etc, the senders are known to get the top riveted terminal coming loose, this can affect the viewed reading on the gauge.