Over heating - thermostat not opening - any ideas?

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ADAMD
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Over heating - thermostat not opening - any ideas?

Post by ADAMD » Sat Feb 10, 2018 7:38 pm

Hello all, My 97 2.5TD overheated last night, gauge up high, all my alarms going.
This morning I could see coolant on the road, but no obvious source.
I proceeded to refill and bleed, hoping to see an obvious leak - nothing obvious.
As temperature rose, bottom hose didn't get hot, but all alarms went off, gauge high water burbling up through funnel.
Decided it must be thermostat not opening, change it (twice!!) same issue.
Thermostat appears not to be opening when it should - overheating before bottom hose gets any heat in it.
whole day spent laying on wet drive in rain and cold!!

Any ideas gratefully appreciated.

Thanks, as always,

Adam
Bob
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Re: Over heating - thermostat not opening - any ideas?

Post by Bob » Sat Feb 10, 2018 7:44 pm

Bad luck. :(

It's easy to test a thermostat by putting it in a pan of water, pop in a thermometer, and turn on the gas.

Other thoughts, It may well be worth pressure testing to check for leaks, and how far did you drive it once 'all the alarms went off'?

I'm guessing these are low coolant and high temp?
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Sat Feb 10, 2018 8:50 pm

Hi Bob, I tested old and new thermostats, both looked fine, but changed anyway, and then changed for another just to be sure!!
I just can't work out why stat doesn't appear to open when it should, and engine quickly overheats.
I didn't drive far with alarms, yes low coolant and high temp.
No obvious stem in exhaust.
Thanks, Adam
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Re: Over heating - thermostat not opening - any ideas?

Post by mikeonb4c » Sat Feb 10, 2018 9:18 pm

ADAMD wrote: Sat Feb 10, 2018 8:50 pm Hi Bob, I tested old and new thermostats, both looked fine, but changed anyway, and then changed for another just to be sure!!
I just can't work out why stat doesn't appear to open when it should, and engine quickly overheats.
I didn't drive far with alarms, yes low coolant and high temp.
No obvious stem in exhaust.
Thanks, Adam
Maybe coolant isn't circulating properly? Blocked radiator matrix maybe? If you squeeze the top hose, does it feel crunchy (suggesting scale build up that could have clogged radiators also)
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Re: Over heating - thermostat not opening - any ideas?

Post by Northern Bongolow » Sun Feb 11, 2018 3:10 am

if you had coolant on the floor then its likely you have a leak somewhere, if you try to bleed it before repairing the leak you run the risk if damaging the engine/head. do a pressure test on the entire system by pumping up the system with a bike pump or similar, this will usually show the leak.

as its lost coolant already, fill up with coolant/water then get an old car tyre valve thin it down with a stanley knife to the correct diameter then shove it up the bleed pipe and inflate the system to no more than 1 bar then look for leaks
it sounds like you have air in the system, this air stops flow of coolant round the system, no flow makes the coolant/air in the head super hot.

take a bit of time watching the 3 vids on youtube on how to bleed a bongo, they may help.
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Re: Over heating - thermostat not opening - any ideas?

Post by WestyK » Sun Feb 11, 2018 11:04 am

Hi Adam, All

Could this be a water pump problem.
Not sure if this is a common thing on a Bongo to be honest but I once had a car where the impeller came lose and so wasn't circulating water when revved.

When your bleeding dose the level in the bleed pipe change when your rev?

Others will know better than me is this ever happens.

Cheers
Ian
ADAMD
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Thu Feb 15, 2018 10:19 pm

Found I had a weeping metal pipe, NS rear heater pipe.
Will replace and report back.
Fingers crossed.
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Fri Feb 23, 2018 7:14 pm

Long ns top metal pipe replaced, what a nightmare that is - I salute anyone else who has managed this.

As expected, still cannot bleed it - all looks fine , air bumbles come up through funnel, levels change during revving etc etc,
but as temperature rises to where the thermostat should open, it doesn't and coolant appears to start boiling up into funnel
as gauge goes right up and high temp alarm goes off.

Not sure where to go.
Water pump - not moving water - broken shaft? -Seems unlikely
Blockage in pipes or radiator, could be - no way of knowing.
Cracked head/head gasket - coolant seems normal during bleeding, exhaust seems normal colour.

Any support gratefully welcomed.

Thanks,

Adam
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Re: Over heating - thermostat not opening - any ideas?

Post by Northern Bongolow » Sat Feb 24, 2018 3:21 am

has the top hose (the 1st one out from the head on the passy side got coolant in), squeeze it or release the clip and back fill it. same with the front heater hoses, these 2 areas are the ones that stop good flow it they are airlocked.
ADAMD
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Thu Mar 01, 2018 9:34 pm

Aiming to have another look at this at the weekend, if temperature gets above zero!

I have the coolant/exhaust testing kit - will give it a go, any tips plonkatronix?

Thanks Northern B, I will check these pipes - which are the front heater hoses?
Cheers,

Adam
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Re: Over heating - thermostat not opening - any ideas?

Post by Northern Bongolow » Thu Mar 01, 2018 11:30 pm

as you have removed the heater return pipe to replace it the front heater maybe airlocked.
look between the leisure bat if fitted and heater fan, you may just see 2 x 25mm pipes going into the bulkhead first squeeze them a bit until you feel heat in them when the engine is running, if they a warming up you have flow, or you could just turn on the front heater while on hot setting, if they are cold you may need to crack the top pipe clip to let the air out.

squeeze all pipes including the rear heater pipes near the back drivers side wheel try to fill the bongo with as much coolant as poss before running the engine, fill then squeeze, repeat until happy. then start to bleed with it running.
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Tue Mar 06, 2018 4:00 pm

Update: After the snow had thawed on Saturday, I was able to squeeze pipes, backfill and give it another go.

Bled with funnel until it was hot, then plugged bleed hose and used the CO2 detector on the expansion tank.

Gas bubbled through every so often as heat rose, no change in colour, all looked good until coolant started rising up and out of the expansion overflow – and then through the plastic device and

Through the fluid – end of test!!



So I do not yet know if there is a cracked head.

I also removed water pump – all well.



At the weekend I will get a hose and hose through the radiator and all accessible pipes, back fill everything, and try to bleed again and get that stat to open!!

Failing that I will drill holes in a spare stat and see it that does anything!!

I do have a spare head, but really don’t want to have to fit it!!



Thanks,



Adam
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Re: Over heating - thermostat not opening - any ideas?

Post by Flanners » Wed Mar 07, 2018 9:08 am

I think you may be calling that 'spare head' into service :(
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ADAMD
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Re: Over heating - thermostat not opening - any ideas?

Post by ADAMD » Mon Mar 12, 2018 11:40 pm

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