Bongo temp gauge suddenly at maximum then suddenly fine again.

[ComtesseDeSpair]

Hello! I'm a newbie member with a bit of an issue that I was wondering if anyone had experienced.

Back in the spring I bought a 1996 Bongo. Drove about 500 miles in it without any issue, then on one long trip it started drastically overheating, temp gauge at maximum, steam coming from the underside. Called breakdown and they found a leak in the coolant hose. Replaced the hose, topped up coolant and all fine. I drove about another 500 miles over three long trips with no problem at all.

However, the past two times I've taken it out, the temperature gauge has suddenly rocketed from the normal position right up to maximum a few minutes into the journey. The first time it happened I pulled over immediately and switched off the engine for a few minutes, then started it up again and all was fine again - gauge back in normal position, I drove about 40 miles with everything still fine. Took it out again this morning and gauge did the same thing, suddenly right up into max after a few miles. Pulled over, switched off, restarted, gauge maxed right up again. Knew that I had more luck of finding a garage if I drove a couple of miles to busier part of town so kept driving that way. However, after about a mile driving, the temp gauge went back into normal position as suddenly as it had maxed, and carried on fine for the rest of the drive.

What could this be? It seems strange that I've been able to do so many miles with no issue and that it suddenly goes back to (apparently) normal. There's no burning smell and the engine bay doesn't feel particularly hot, so I'm not sure whether anything's overheating or not or if I have a fault somewhere.

Any help really welcome. Bongo's previous owners were also members of this forum (I inherited the sticker!) which is how I found you and am looking forward to getting into things.

[teenmal]

Presuming the vehicle is not Overheating It could be a bad connection on the transmitter or the dash PCB , or even a knackered transmitter.

What vehicle do you have.??

[ComtesseDeSpair]

Thanks for your reply. It's a 2.5 diesel, 1996 reg. I am really hoping it isn't too serious an issue, I am smitten with my new toy so far.

[jimmo62]

could be an airlock in the coolant system, who bled it after the hose was replaced, was it a garage familiar with the Bongo bleeding process?

[Ian]

If it's not an airlock then it's probably the upper temp sender unit that needs replacing. You can get them from the club shop, see https://bongoland.co.uk/product/top-tem ... nder-unit/.

What I'd do is get a Bongo expert to have a look. Tell us where you are based and we can recommend someone.

[haydn callow]

Sounds as if you just topped up the coolant after the first overheat and new hose fitted. If you didn’t have the system bled correctly at that point I suspect you have goosed the cylinder head...
First get it bled properly, try it and see what happens, if it overheats again get it to a Bongo specialist garage for diagnoses.