Overheating? Shall I panic now?

The Great Pretender · Post by **The Great Pretender** » Tue Mar 18, 2008 1:20 am

dandywarhol wrote:
The Great Pretender wrote:Dandy, exellent description of an expansion tank, allowing exess out as pressure is high. Then sucking it back when less than atmospheric pressure. But that isnot what a Bongo has.
Mine has It's what the cap does.

Then you have a non standard cap

dandywarhol · Post by **dandywarhol** » Tue Mar 18, 2008 1:30 am

Maybe - All 5 Bongos I've worked on have the same Japanese marked pressure/vacuum cap. All 5 except 1 also have the same cap on the radiator - now that I don't understand

The Great Pretender · Post by **The Great Pretender** » Tue Mar 18, 2008 1:37 am

dandywarhol wrote:Maybe - All 5 Bongos I've worked on have the same Japanese marked pressure/vacuum cap. All 5 except 1 also have the same cap on the radiator - now that I don't understand

The vacuum (small spring centre part) of the cap is used to allow water pushed out of the system INTO THE HEADER TANK to be pulled back into the system under negative pressure. The Bongo tank is not designed to do that ok?

dandywarhol · Post by **dandywarhol** » Tue Mar 18, 2008 1:42 am

Yep, Thats what it does but as the tank isn't connected by the radiator overflow pipe (cos it doesn't have one except on the wrongly fitted aftermarket rads) then any excess pressure goes straight out to atmosphere via the expansion tank overspill pipe.

When the system cools again the negative pressure will draw air into the expansion tank to eliminate hose collapse

OK?

Happy days are here again ............

The Great Pretender · Post by **The Great Pretender** » Tue Mar 18, 2008 1:56 am

dandywarhol wrote:Yep, Thats what it does but as the tank isn't connected by the radiator overflow pipe (cos it doesn't have one except on the wrongly fitted aftermarket rads) then any excess pressure goes straight out to atmosphere via the expansion tank overspill pipe.

When the system cools again the negative pressure will draw air into the expansion tank to eliminate hose collapse

OK?

ok your getting there, forget about it being an expansion tank because it isnt.
Tell me what pressure you think the system runs at under normal use?

haydn callow · Post by **haydn callow** » Tue Mar 18, 2008 10:43 am

Dandy.....I don't disagree with anything you have said so far in this topic....going back a few posts ..I did not say there is no air in the system...I know there is air above the tank coolant that gets expelled/drawn in....What I said was that "once bled there should be no air in he circulating coolant" unless a problem arises. I think we both have the same understanding as to what is happening.
The bit I'm not sure about is...I think the stat is open under normal conditions but agree that this is at odds with the cool bottom hose.
The pressure caps are also a mystery. It would make sense to fit a non pressure cap to the Rad (I have) or a higher pressure cap to the rad than the header tank. I have seen one bongo with a 1.1 on the rad and a 0.9 on the tank..That makes sense to me. The rad cap does nothing on a bngo except block up and seal the hole.

mikeonb4c · Post by **mikeonb4c** » Tue Mar 18, 2008 2:38 pm

Gorgeous weather outside my office window today. Going to get cold and nasty for Easter though. Pity

lizard · Post by **lizard** » Tue Mar 18, 2008 10:07 pm

Yes camping at Easter will certainly be off.

lizard · Post by **lizard** » Tue Mar 18, 2008 10:15 pm

The Great Pretender · Post by **The Great Pretender** » Wed Mar 19, 2008 1:24 am

Im with you on the rad cap Haydn, waste of time, the top tank whatever you want to call it will feed the system with help.
I am going to start a new thread as I feel im hijacking this one. Im looking at getting input to find out where the heating problems are. 82c at the return to the engine is wrong. That temp should be exiting the head.

smac02 · Post by **smac02** » Tue Mar 25, 2008 11:26 pm

Hi again all. I've been reading every thread about everything Bongo and feel that I'm geeting to know this unique, quirky but somehow loveable vehicle.

After changing the thermostat I had to risk a drive to London, Reading and then back up to Yorkshire. No problems whatever but still had the fans rad running a lot.

Went ahead and changed the radiator even though I thought it was ok. Things are much better now. The temp gauge needle is less wild in its swings and has not yet gone towards the H zone. Rad fans have not cut in at all yet. I do think though that I spent a lot more time bleeding the system this time around as I understand it better now. I used the see saw method and a funnel. Very slow to get the air out but at least one can see when the air is coming through the system. Not going to change the water pump yet but will wait and see.
Have now fitted, coolant loss alarm, temp gauge alarm and am waiting for the TM2 alarm. Starting to get ringing in the ears!!!
Might just save me money later I reckon. Even had time to get on with some of the other jobs including a cheap rear view camera to my DVD player, great gadget.
The Billy Bongo is slowly getting licked into shape and seems smoother running for every litle job I do.

Let's hope that's the last of my cooling probs

One last thing re bleeding the coolant. Would it work if coolant was slowly pushed/pumped into the bleed hose via a suitably large pump/syringe so that it pushed the air up into the expansion tank? Surely there's got to be a mechanical way of bleeding the system that gives surefire results without all the heat and revving of the engine? I've done similar with heating and water systems to ovecome airlocks.

Any thoughts

Steve Mc

dandywarhol · Post by **dandywarhol** » Tue Mar 25, 2008 11:32 pm

Sounds like good news Steve. If you block off the lower pipe on the old radiator and fill it with hot water you could feel for cold spots indicating a blockage. Does the new one feel lighter? - I'd be interested to hear the result.

smac02 · Post by **smac02** » Thu Mar 27, 2008 9:49 pm

Not had chance to test the rad with hot water but the weight difference between the old and new is not noticable

Steve Mc

BongoNess · Post by **BongoNess** » Fri Apr 04, 2008 9:36 pm

Useful info on radiator caps in the previous posts - thanks. I've been noticing a slow but steady loss of coolant for a while now and I think I've tracked down the cause to the radiator cap (tell tale water marks under the bonnet around the cap). On close inspection the rubber seal is slightly perished which could be causing pressure (and coolant) release through the radiator cap rather than the header tank. After reading this thread I've decided to put a new 1.1 bar cap on the radiator and a 0.9 bar cap on the header tank. We'll see how it goes...

Cheers,

Overheating? Shall I panic now?

Cooling ok

Radiator

Re: Overheating? Shall I panic now?