Advice on replacing a thermostat?

[Windysurfer]

Hi all,
I new to the forum and all this mechanical stuff but hoping to get a few tips on changing out the thermostat (thereby saving some pennies to spend on beer this weekend!). Van running fine but recently temp dropped to bottom end of the scale. Under normal 'easy' driving the temperature isn't even registering but up some steep hills it start to rise. I haven't yet found a hill big enought to get it back up to the normal 11 O'clock position it always sat at in the past as Somerset is pretty flat!

From reading all sorts of posts about coolant issues I think it must be the thermostat jammed open and causing the over cooling. It's not losing any coolant and and the fact the temp gauge still registers under load makes be think the temp sensor and wires are still intact and functioning.

So.... I think I've narrowed down where it is and got the new thermostat ready to drop in but how to access it? The two bolts are head down so I pressume I'd be better coming at it from underneath? I've got a basic socket set and a few spanners but will I need anything else? Will I need to loosen/move anything else to get at it? I'm gonna try the see-saw method to refill the coolant and bleed and it looks doable for an amateur....
I've got to try and get it sorted tomorrow night so we can take the van down to Lymouth for some real ale and didlly die music at the weekend, just need to work on the beard!

Any advice or hints appreciated - even if it's take it to a garage!

Thanks

[Peg leg Pete]

Is your Bongo 2 or 4 wheel drive? If 2 wheel drive you can access it from above using a socket with extension fitted

[Simon Jones]

If 4wd - you can change the stat without disconnecting front prop shaft as the manual states. I think you need a 12mm socket on a wobbly drive thing (universal joint), several extension bars to make about 30cms long. Remove the 10mm bolt that fixes the oil dip stick tube to the stat housing. Don't try to remove the tube, just move it to one side.

Drain the coolant out first, undo the 2 bolts holding the stat housing & pull out the stat. Take the oppportunity to flush the system properly, then re-fit new stat, noting that it has a notch on it so it can only go in one position. Tighen it up, re-fit the oil dip stick tube bolt. Refill & bleed using the process that has been well documented on here. Getting all the air out is crucial.

BTW - an interesting test is to try your old & new stat in a pan of boiling water. You'd be suprised how 'lazy' the old one can be.

Good luck.

[Windysurfer]

Many thanks Gents,
Managed to pull it apart and change over the thermostat last night. Thanks for the tip about the UJ - it was a bit tricky to get to. Other than emptying about a litre of coolant onto my head it was fairly painless. Took it for a spin and all seem to be good as gold. Temperature gauge back up where it should be and no evidence of leaks.
First involved job attempted so far on the van so this will give me confidence to start taking apart more of it should the need arise (and I'm sure it will!).
Thanks again for the tips,

Jamie

[haydn callow]

Was the old stat jammed open????

[mikeonb4c]

Great new Windsurfer - big confidence boost too. As Haydn has asked, was it a stuck open thermostat? Will be useful for other members to know as I think someone else is having similar symptoms.