Bongo Radiator replaced - now overheats periodically

[Mike_Ackee]

I recently needed to get the bongo's radiator replaced, which was done by our local garage - who have been servicing my bongo uneventfully for a few years now. To aid them in this I gave them the instructions for bleeding the system, which they claim to have followed but still ended up having problems getting the air out.
All was well until about a week later when the temp gauge shot up to HOT and when parked up I could hear water boiling in the header tank. The bongo went back to the garage who drained, refilled and bled the system again. Guess what? About 2 weeks later the same thing happened again.
When the system gets too hot it's followed by a couple of loud pops or bangs and then the temperature dops very quickly back to normal. Also, I can tell when I'm gonna have a problem because the cabin heater remains stone cold even though the temp gauge is warming up.
Any ideas what's going on (and what I can do to fix it) ?... pretty soon I'm gonna have to re-mortgage the house to pay for the garage bill!
Thanking you all in advance.
Mike.

[spout]

When the system gets too hot it's followed by a couple of loud pops or bangs and then the temperature dops very quickly back to normal. Also, I can tell when I'm gonna have a problem because the cabin heater remains stone cold even though the temp gauge is warming up.

Mike, at this stage (ie before any boiling over etc) has the coolant level dropped?

[missfixit70]

EDIT - Just read it again, if it is cooling eventually & the heaters are cold before it goes, it sounds like the stat or fans

It does sound like you've got leak or an airlock, possibly, they haven't tightened the hoses onto the rad properly, or you've got a pinhole in one of the hoses, are you checking the level before every journey or have you got a coolant level alarm?
Did the garage give it a thorough flush through?
Why did you have to get the rad replaced? had it leaked & overheated before?
Have a thorough check around all the hoses, front of the engine in case it's the water pump & see if there's any sign of leaks of residue indicating a leak that may only be present when it's up to pressure/temp?
If it's something the garage haven't done correctly, it's down to them, but it's worth checking what you can.
what was the temp gauge doing?, could it be the rad fans not kicking in or the thermostat not opening?

[bigdaddycain]

It sounds like they aren't running it up to full temp whilst bleeding, no point in bleeding if the stat hasn't opened.

Are the garage checking they are getting a steady constant heat from BOTH heaters before wrapping it up?

Bongo bleeding isn't to be rushed.

[mikeonb4c]

It sounds like they aren't running it up to full temp whilst bleeding, no point in bleeding if the stat hasn't opened.

Are the garage checking they are getting a steady constant heat from BOTH heaters before wrapping it up?

Bongo bleeding isn't to be rushed.

I wondered this too. Have they bled it by the book as anything less will not suffice. Once confident that has been done, and if the problem persists, the debate can move on. The big concern is that if it hasn't been bled properly and something serious happens as a result, will the garage acknowledge their failure to follow proper bleeding procedure? Will they 'eck as like

Other than that, Kirsty's list covers the possibilities. Hmmmm - what about thermostat. Could that be stuffed and contributing to anything (if stuck shut or blocked it would prevent proper bleeding for starters)?

Good luck - keep us posted.

Mike

[bigdaddycain]

- what about thermostat. Could that be stuffed and contributing to anything (if stuck shut or blocked it would prevent proper bleeding for starters)?



Mike

If the stat is jammed the bongo would not bleed properly, the tendency is for trapped air to "butt up" against the unopened stat, then be released into the flow of coolant as the stat opens.... Then hopefully vents to atmosphere.

[Mike_Ackee]

Thanks for all your suggestions so far. I haven't had a chance to look at anything much yet, but here's answers to your questions...

The radiator was originally replaced after it had split open and dumped its contents onto the road. The cabin filled with steam and my wife stopped the car very quickly!

The garage have had 3 attempts at bleeding the system now. I gave them the procedure from the forums the first time, but I can't guarantee they used it on subsequent attempts (it's a big garage with a fair few mechanics). I've decided that the workshop manual will be a good investment, and so when it turns up I might have a go myself.

Further to my first post, I drove to work in the bongo yesterday - it behaved itself, did not overheat. On arrival I checked the coolant level and the reservoir was completely empty. I had no choice but to just fill it before driving home again. I checked the reservoir this-morning and it was empty again, filled it up, drove to work and the level had dropped from the high mark to well below the low mark in just 11 miles and 20 minutes. I guess there's a leak somewhere - will investigate when time and daylight allow.

[missfixit70]

Please bear in mind the temperature guage is pretty much useless, it's damped so heavily, it takes a lot to get it to move off the 11 0clock position. Fitting a Mason alarm taps into the circuit & removes the damping so the needle actually moves & provides a settable alarm. Fitting a Coolant level alarm would be a help as well.
Personally I would not drive it with the level dropping so much, you will end up with a head gasket situation if it's not already, & possibly worse, Bongos do not like running without coolant .

[scanner]

I've decided that the workshop manual will be a good investment, and so when it turns up I might have a go myself.

The general view appears to be that the manual is next to worthless compared to the "free" (subject to membership) fact sheets available in the member's area.

Who are you using? Manchetts?

If they aren't following the procedure to the letter they are likely to cause you a lot of trouble.

Make known to whosoever is doing it that if they don't do it FULLY in accordance with the instructions you provided - you will hold them responsible for any subsequent failure.

[ScubaBongo]

Please bear in mind the temperature guage is pretty much useless, it's damped so heavily, it takes a lot to get it to move off the 11 0clock position. .

Now, I never knew that, I thought I'd be ok as long as I monitored my gauge while driving and my header tank between drives (only use the Bongo occassionally)

Damn, now I have a reason to spend out on an alarm.

Thanks for the advice though.

[scanner]

Please bear in mind the temperature guage is pretty much useless, it's damped so heavily, it takes a lot to get it to move off the 11 0clock position. .

Now, I never knew that, I thought I'd be ok as long as I monitored my gauge while driving and my header tank between drives (only use the Bongo occassionally)

Damn, now I have a reason to spend out on an alarm.

Thanks for the advice though.

Yep sticks at 11 o'clock until it suddenly shoots over to 2 o'clock to tell you the head gasket went 10 minutes ago.

It's nearly as well designed as the exhaust back box.

[Simon Jones]

I've decided that the workshop manual will be a good investment, and so when it turns up I might have a go myself.

The general view appears to be that the manual is next to worthless compared to the "free" (subject to membership) fact sheets available in the member's area.

Very true - I couldn't make much sense of it. The manual does have some good bits, but there is a lot of info missing, such as how to change the radiatior.