Underheating?!

[curlew]

After lots of time and money be got our bongo back yestersday with a new cylinder head, thermostat, water pump and a coolant level indicator.

Naturally, I am watching the temperature gauge like a hawk - and it seems to be taking ages to warm up. For example, before all the work, the needle would get to the 11.00 position after about 5 or 6 miles. Now it hardly shifted this morning on the school runs and I have just driven 6 miles home and the needle has barely risen at all. Is this normal - or am I recording the first known case of a Bongo underheating????!!!!

[apole]

Hi there,

Could be a duff gauge, or sensor. Was it properly bled, the sensor only works if it's in water.

Does your heater work and if so how hot can it blow?

Andy

[curlew]

The work was done by a highly regarded bongo person recommended by lots of people on here. I've checked the coolant level - it's fine and the heater works fine.

[mikexgough]

Mine takes 5 to 6 miles to really warm up now it's autumn.....take it yours is a diesel..... have you seen this thread... http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=35902 discussing How the Cooling system works.....

It could be now you have a "new" cooling system then it is behaving as it should be from a new vehicle....I'm sure others will give you their thoughts.....

[haydn callow]

Somthing isn't right....I belive my system is in good condition and my gauge (before I made it work properly) used to get up to 11 0'clock in a couple of miles....

Have they left the Stat out for some reason ????? (would cause your problem)

I see your post about your garage so perhaps I'm wrong...(has been known)

[curlew]

I'm waiting for the garage man to ring me back, but in the meantime should I drive it or not? (disclaimer - I won't hold anyone responsible for the consequences of their opinion!)

[mikeonb4c]

Somthing isn't right....I belive my system is in good condition and my gauge (before I made it work properly) used to get up to 11 0'clock in a couple of miles....

Have they left the Stat out for some reason ????? (would cause your problem)

I see your post about your garage so perhaps I'm wrong...(has been known)

If Haydn hadn't written it first, that's exactly what I'd have written

[haydn callow]

Get checked before driving........Your temp gauge is useless at the best of times....

[mikeonb4c]

Your temp gauge is useless at the best of times....

Wouldn't have said that. Its very useful for telling me when my thermostat has opened.....but that's about it

Actually, on that serious note, you should be seeing a definite 'kick-off' point as the thermostat opens (after about 5 mins running approx on a healthy one) and the temp gauge needle moves off its COLD stop to its 11 oclock position. If you aren't it strongly suggests either that there is no thermostat fitted or else that there is but it is jammed open

[curlew]

Oh bum. What's the worst that could happen if I drive 10 miles?

[haydn callow]

Your temp gauge is useless at the best of times....

Wouldn't have said that. Its very useful for telling me when my thermostat has opened.....but that's about it

Actually, on that serious note, you should be seeing a definite 'kick-off' point as the thermostat opens (after about 5 mins running approx on a healthy one) and the temp gauge needle moves off its COLD stop to its 11 oclock position. If you aren't it strongly suggests either that there is no thermostat fitted or else that there is but it is jammed open

Mike the gauge dosn't start to move co's the stat opend....the gauge starts to move when the engine temp reaches about 50C and is at 11 o'clock by the time it gets to 60C .. it then stays at this position till it reaches around 110C then it "wips" across to hot and Bingo.

I doub't a stat could Jam open....if they go wrong they would jam shut
The stat starts to open when the temp of the stat reaches 82c and should be fully open at about 90C

[haydn callow]

Oh bum. What's the worst that could happen if I drive 10 miles?

worst that could happen is you get kidnapped by a couple of physco killers that like to hurt before killing you/

Seriously...if ther is a fault in the cooling system you could damage your engine...Phone your garage and ask what they want you to do....after all they will have to sort it in the end.

[mikeonb4c]

Your temp gauge is useless at the best of times....

Wouldn't have said that. Its very useful for telling me when my thermostat has opened.....but that's about it

Actually, on that serious note, you should be seeing a definite 'kick-off' point as the thermostat opens (after about 5 mins running approx on a healthy one) and the temp gauge needle moves off its COLD stop to its 11 oclock position. If you aren't it strongly suggests either that there is no thermostat fitted or else that there is but it is jammed open

Mike the gauge dosn't start to move co's the stat opend....the gauge starts to move when the engine temp reaches about 50C and is at 11 o'clock by the time it gets to 60C .. it then stays at this position till it reaches around 110C then it "wips" across to hot and Bingo.

I doub't a stat could Jam open....if they go wrong they would jam shut
The stat starts to open when the temp of the stat reaches 82c and should be fully open at about 90C

Just lost a well composed reply as failed to notice Haydn 2nd post.

Haydn, I have to disagree. Two examples:

1) My wifes Nissan Sunny had a temp gauge that varied position between summer and winter, an whether stationary or on the move. I suspected thermostat failed in open position and sugested she ask garage to change it. They told her it was OK. On the 3rd year I'd had enough (cold heaters in winter etc.) and insisted they change it anyway. Instant cure. Gauge now left COLD stop promptly after 5 mins running, moved to 11.00 oclock and stayed there, in summer winter, moving or stationary car, just like my Bongos in fact. (turned out real reason for not wanting to change it was probably very tight housing blots that garage was frigthened of breaking)

2) When I changed my Bongos temp gauge, time to move from COLD stop reduced from 10 mins to 5 mins

From this I conclude:

* Temp gauge appears to be a useful indicator of thermostat performance
* Thermostats appear to be able to fail in the open position (why not?)
* It is probably incorrect to call the Bongo temp gauge u/s (as many do - the 'chocolate fireguard' expression gets used a lot) even though it may be overdamped. The real point is that you will not be watching it when it shoots over to hot (esp. while you are driving), so a better warning device is needed
* Don't believe all your mechanic tells you. Their agenda may be different from yours.

[apole]

I always thought the thermostats were designed to fail in the open position. I've had that in a older merc and smarts seem prone to thermostat failures, tell tale sign being they take forever to warm up. Maybe wrong and I'm sure it's possible for a stat to fail jammed shut.

Anyway if it were my car I'd be reluctant to drive it unless it was a real emergency. You don't really know what is wrong until it's found and fixed, likelyhood is it's taking longer to heat up mind but if you can avoid driving it I would, just to play on the safe side.

It could be many things, some more likely than others.

I'd personally be outside checking it's bled properly and feeling/checking all the pipes to be sure no leaks and they all appear to be in good condition. It takes a long time but eventually the car will heat up enough on tickover to make the bottom hose hot. This won't really rule out a missing or duff thermostat but it's good to rule out what you can.

Keep us posted and good luck.

Andy

[missfixit70]

Thermostat fails closed on the bongo, have a look at this thread - http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=35902.