Intermitant Over heating problem!

[mcgivern2326]

Hi All,

Im after some advice from any wise bongoliers outhere who may be able to help. Freddie Freeda has developed an intermitant over heating problem and im running out of options as to what it can be,

We use our Van everyday as our main car and as a general rule it never falters, so much so that all ready this year its taken us to Portugal and back and clocked up plenty of miles back at home. However everytime we put the Engine under pretty intense pressure (going up very steep hills aka sutton bank this weeknd) its starts to Progres through the tempreture gauge pretty raipidly. Once the load is off the engine it drops back down to its normal running temp.

This only ever happens when we tackle something like sutton back, which for those who arnt familur is a bloody big steep hill / Cliff .

Im convinced it isnt a coolant leak, having had a few of those in our time i check the levels constantly and it never moves, its also had a new thermostat and water pump in the last few years aswell.

I think ive resounded myself to the fact that im going to have to replace the radiator. Not the most pleasant of repair bills but cheaper then a new head! have contemplated a rad flush but we had one done when we first got the van and im not convinced it made much difference. Plus if it doesnt work and I do end up with a new radiator ive then got to pay the Garage twice to replace it.

Can anyone offer any final suggestions before I commit to the Radiator?
Also could it be linked to the Auto gear box in anyway?????

[ronhud]

Have you still got the original Freda temp gauge? This will refuse to move normally but on engine loading can then alarmingly shoot over. The Mason alarm modifies the behaviour of the gauge so you can see the temp increasing gradually and also has an audible alarm that you can set manually. I know Sutton Bank and would expect the engine to warm up considerably. At a certain point the rad fan should start and cool it down. You can check this by driving it until it gets hot then get out of the van and you should hear the fan clearly. I tested mine on Hardknott Pass and the fan did cut in and did cool the engine down but it can be alarming to see the gauge get over to the first extreme mark on the gauge.

[mcgivern2326]

Hi Ronhud

Thanks for the response, I am still on the origional temp gauge, and havent invested in any other monitoring / Warning system yet but having read some of the posts on here I think im about to.

the Rad fan seems to be working fine and does come on when the Engine starts to work harder. We also put the heater on to remove the heat from the engine and once we had reached the top (about 200 Yrds) the engine temp returned to normal. It did the same thing en route to Portugal, going through the spanish montains. Oustide of these circumstances it runs fine and doesnt move at all past the 11 oclock position.

Hence the reason why ive come to the conclusion that the radiator isnt working properley so when the coolant needs to be moved around the engine under load, its struggling to do it! - I only hope im right!

[westonwarrior]

You can flow check the Radiator but to be honest a new one is probably a good investment as the do clog up

[mikeonb4c]

You can flow check the Radiator but to be honest a new one is probably a good investment as the do clog up

I agree. Its one of those expenditures that - even if it didn't fix the problem - I would regard as having been worthwhile as it can only improve things (and not that expensive compared to the 'biggies'). But with luck it will improve things.

Also, although fans are cutting in, I guess there is a possibility that the sensors are tired and not triggering the fans at the right temperature. Might be worth checking that one out. I like the idea of fitting over-ride switches, but there is controversy over whether this could cause the ECU to blow (I suspect not personally but am not about to risk other peeps Bongos by recommending it!). But such switches, if used with the Mason alarm as suggested by Ronhud above, would allow you to switch on extra cooling as soon as the gauge started to move upwards.

Good luck - keep us posted.

[Lewy]

I have just this very morning invested in new rad - and had very similar issues to you. New rad and couple of new hoses too - and not a massively noticable or dramatic difference driving really, although I've only done one trip so far. Engine temp and water temp still goes up on hills but does seem to come down a bit quicker and is slower to rise with steep inclines.

Although I do feel more confident that the cooling system is much more efficient - when Allan used a infrared temp gauge on the old rad there was a significant difference in temperatures from top to bottom. New rad is hot all over - so I assume must be working in a much more efficient manner.

[mikeonb4c]

I have just this very morning invested in new rad - and had very similar issues to you. New rad and couple of new hoses too - and not a massively noticable or dramatic difference driving really, although I've only done one trip so far. Engine temp and water temp still goes up on hills but does seem to come down a bit quicker and is slower to rise with steep inclines.

Although I do feel more confident that the cooling system is much more efficient - when Allan used a infrared temp gauge on the old rad there was a significant difference in temperatures from top to bottom. New rad is hot all over - so I assume must be working in a much more efficient manner.

Sounds promising to me from what you've said. The process of removing the heat invested in the engine block must be a complex one but the coolant temp coming down quicker seems to me to be very significant as ability to conduct heat away from the thermal mass of the block must be a function of temp gradient from block to coolant, rate at which coolant passes through cooling matrix, efficiency of matrix as a cooling device, thermal capacity of coolant, , ambient air temp and time (+ other factors? ). The first of these is showing signs of improvement, the second and third must lie behind the first suggesting they too are improved.

It would be interesting to know about efficiency of the sensors that trigger the cooling fans as mentioned higher up.

But, fingers crossed, the Bongo is better