ANOTHER OVERHEATING BONGO, HOPEFULLY SORTED

haydn callow · Post by **haydn callow** » Thu Apr 05, 2007 6:45 pm

O>K> How about this.. Your temp gauge sits on zero before you start up co's the engine is cold therefore so is the sensor. You start up and it slowley rises to the 11 o clock co's that is what the engine is doing. At about this point the system pressurises and unless you start flogging the engine or it is a hot day or whatever the temp stablises at this point. Remember the bypass pipes go from the cyl head to the expansion tank then out of the tank to the TOP of the rad then back to the cly head via the top hose. A certain amount of cooling takes place at the top of the rad.

francophile1947 · Post by **francophile1947** » Thu Apr 05, 2007 6:50 pm

This is a guess, but seems to explain your query Mike.
The temperature gauge probably only reads over a limited range, so it probably doesn't register anything until the water reaches (say) 65-70 degrees. If this is so, it will show nothing until this point is hit and then climb quickly to it's normal temperature. Anybody know??

haydn callow · Post by **haydn callow** » Thu Apr 05, 2007 6:50 pm

mikeonb4c, Hi there, if like you think, the needle on your guage "kicks off" co's your stats opening your bottom hose would get hot. It dosn't so it carn't be open. franco..I think you could well be right about the way the gauge works.

alphabetter · Post by **alphabetter** » Thu Apr 05, 2007 6:51 pm

mikeonb4c wrote:And then there is this. If the thermostat only opens occasionally, when the engine is really heat stressed, what is it that causes my temp gauge to stay on the cold stop for 5 mins then visibly kick off and move up to 11.00 o'clock. I had always assumed it was a classic thermostat opening symptom but I now need another explanation

I think this is quite easy to explain - the left stop on the temp gauge clearly isn't 0C and probably isn't 25C it is more likely to be around 60C - so all the time your Bongo is warming up to close to its operating temperature the temp gauge will read 0.

Harry · Post by **Harry** » Thu Apr 05, 2007 6:55 pm

That bit makes sense!

Peg leg Pete · Post by **Peg leg Pete** » Thu Apr 05, 2007 7:09 pm

If I remember correctly before Mike changed his thermostat, his temp guage took 10 mins to rise to correct temp. When he replaced stat with new one, the temp guage rose to correct temp in 5 mins So if thermostat is not involved as much as you say, why the speedier rise in temp guage registering?

francophile1947 · Post by **francophile1947** » Thu Apr 05, 2007 7:11 pm

Old stat jammed open, therefore allowing flow through radiator??

mikeonb4c · Post by **mikeonb4c** » Thu Apr 05, 2007 7:12 pm

Thank you Peter. I still couldnt 'buy' the new theory, but was struggling to think of evidence to support my case. You just did. Balls in your court guys

Jamesnjane · Post by **Jamesnjane** » Thu Apr 05, 2007 7:13 pm

some good points made there. can anyone explain the little hole already in the thermostat does it remain closed on that ball thingy under pressure or does it let water through, im starting to think maybe in japan there used less at a lesser speed so under less stress but come over here and get used alot more so maybe there not coping too well ( i know alot of bongo owners motors are running spot on mine did for a year) its just a thought, alot of cars in the past have been known for overheating problems so i cant help but think a couple of holes in the thermostat are just helping the old girl along!! id love to solve the problem though

what does everyone else think??

Peg leg Pete · Post by **Peg leg Pete** » Thu Apr 05, 2007 7:18 pm

Also if the radiator only plays a small part in the cooling system as suggested, why is it so large and have two fans to assist cooling??

francophile1947 · Post by **francophile1947** » Thu Apr 05, 2007 7:21 pm

Jamesnjane wrote:some good points made there. can anyone explain the little hole already in the thermostat does it remain closed on that ball thingy under pressure or does it let water through, im starting to think maybe in japan there used less at a lesser speed so under less stress but come over here and get used alot more so maybe there not coping too well ( i know alot of bongo owners motors are running spot on mine did for a year) its just a thought, alot of cars in the past have been known for overheating problems so i cant help but think a couple of holes in the thermostat are just helping the old girl along!! id love to solve the problem though

what does everyone else think??

Could be a valid point - maybe, as Bongo not exported, system was designed for only 60mph.

francophile1947 · Post by **francophile1947** » Thu Apr 05, 2007 7:23 pm

peter humphrey wrote:Also if the radiator only plays a small part in the cooling system as suggested, why is it so large and have two fans to assist cooling??

In case it gets hot????

Peg leg Pete · Post by **Peg leg Pete** » Thu Apr 05, 2007 7:25 pm

still does not ring true - run less and at lower speeds, They would not have fitted such a large double fanned radiator.

Peg leg Pete · Post by **Peg leg Pete** » Thu Apr 05, 2007 7:26 pm

After all mazda skimped fitting spacesaver wheel

francophile1947 · Post by **francophile1947** » Thu Apr 05, 2007 7:28 pm

If the traffic in Japan is as bad as we are lead to believe, the Bongo could spend a long time stuck in traffic jams - a large radiator and fans are then essential because there is no airflow without the fans.