Another Overheating Bongo

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rchambers84
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Another Overheating Bongo

Post by rchambers84 » Sat Feb 22, 2020 3:15 pm

I hate to post another thread on Overheating but I've tried the forum and YouTube videos recommendations without success. (Diesel Bongo)

From the start, a few weeks ago I lost a lot of coolant due to a split in the bleed hose giving u. I managed to limp home as I was fairly close. I have since bled the cooling system twice using the fuel and seesaw method. The bottom hose gets hot to the touch and the heaters blow hot. But when I take it for a drive, it overheated again. There must be air somewhere but I just can't get it to shift!
As a not, when I bleed the system I pull the fan fuse so it gets to temperature, should I leave it connected?

Is there another method to try or is there something I'm missing?

Any help would be apriciated because I'm dying to drive it again. I haven't had any issues up to now in the 6 months I've had it
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Re: Another Overheating Bongo

Post by g8dhe » Sat Feb 22, 2020 4:23 pm

I hate to say this the other possibility is that the head cracked and you now have the system pressurising with exhaust gases causing the coolant to exit from the de-gassing tank due to the pressure ....
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rchambers84
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Re: Another Overheating Bongo

Post by rchambers84 » Sat Feb 22, 2020 4:34 pm

Thanks for the reply. That was a thought but didn't want to think it. Is there any easy way to check without a strip down?

Is it worth giving it one last bleed or am I just wasting coolant?
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Northern Bongolow
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Re: Another Overheating Bongo

Post by Northern Bongolow » Sat Feb 22, 2020 7:45 pm

Check the water pump isnt leaking, search on here for how to. There are 2 holes in the casting, one at the Passy side you can see, but it usually leaks from the one you cannot see, it's at the 6 o'clock position so needs a mirror and torch to see the coolant snail trail ( clean).
It usually leaks when the engine is run but the leak is hard to spot.
Worth a check. Pressure test the syst too.
rchambers84
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Re: Another Overheating Bongo

Post by rchambers84 » Sat Feb 22, 2020 8:05 pm

Thanks I'll have a look

Do you mean pressure the head by a leakdown and check for bubbles from the radiator or pressure test the coolant system. If so, how?
rchambers84
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Re: Another Overheating Bongo

Post by rchambers84 » Sat Feb 22, 2020 11:10 pm

Thanks I'll get one ordered and do some tests

I'm hoping it's just me being a nugget and not bleeding it correctly
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Re: Another Overheating Bongo

Post by surfkernow » Sun Feb 23, 2020 12:58 am

I used this to pressure test the cooling system...one of the adaptors fits the expansion tank. You can pump pressure into the system below 1.1 bar and see if it holds pressure on the gauge. If it does not then you have a leak somewhere one the many cooling pipes...go round and check for any drips of wet patches.

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rchambers84
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Re: Another Overheating Bongo

Post by rchambers84 » Sat Feb 29, 2020 4:44 pm

So, a slight update.

I found that the coolant expansion tank had a slight crack in underneath so fitted a new one today. Bled and bled and bled. Bottom hose hot, all other hoses hot, heaters hot.
I hooked up the snip test and the chemical stayed blue, but then suddenly coolant came up and out of the shift test?! Surely this isn't normal?
Would that mean there is still air in it or something else?

Another thing to note is that once it all go to temperature and everything seemed bled, holding the funnel high and applying revs brought the coolant level up in the funnel? I thought it was supposed to go down?
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Northern Bongolow
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Re: Another Overheating Bongo

Post by Northern Bongolow » Sat Feb 29, 2020 9:43 pm

Whilst bleeding it, when reved the funnel empties, when the stat opens when reved the funnel then fills, so when the stat opens you have to raise the funnel or it will overflow and burn your bits and bobs.
rchambers84
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Re: Another Overheating Bongo

Post by rchambers84 » Sat Feb 29, 2020 10:06 pm

Thanks I'll get back on it tomorrow.

Would the bubbling out of the expansion tank mean there is still air trapped?
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Re: Another Overheating Bongo

Post by rchambers84 » Sun Mar 01, 2020 12:35 pm

Back on it this morning, bled it again after replacing the expansion tank and it overheated again within a mile. Thankfully didn't boil over though.
Think it's time to take it to the garage tomorrow
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JulesMartin
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Re: Another Overheating Bongo

Post by JulesMartin » Sun Mar 01, 2020 1:35 pm

You made mention of the fans coming on, so you removed the fuse? The fans come on really at the end game of the bleeding process so if yours are coming on before the engine is fully hot there may be a problem there. Bleeding fully, allowing two cycles of the fans on and off takes me about an hour by which time I'm juggling a funnel up high full of boiling water and leaning across to push down the accelerator with a long stick :D. it is a long process. the sudden release of air maybe an air lock or it may just be the thermostat opening which is usually quite sudden and spectacular!
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Re: Another Overheating Bongo

Post by haydn callow » Sun Mar 01, 2020 3:11 pm

Time to get the cylinder head looked at, get the garage to sniff test the ex tank.
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