Holy hoses, dodgy stats.

[Mountain]

What a weekend.

Drained coolant...fine.
Flushed with water...fine.
Backflushed rad...fine.
Removed stat and replaced seal & housing....fine.
Holts 2 stage flush..fine...but all that waiting for the engine to cool down Crudorama!
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Spotted 2 leaks....OK, they were both at the end of the hose and I had enough length to cut an inch off as a temporary measure. New ones on order.
Replace stat with new one....fine
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Top up 50/50 water antifreeze.....fine.

Start the bleeding malarkey.....fine....to start with.
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No more bubbles, heater hot, all going ...fine.
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But, bottom hose still cold. 45mins the same.....1hr the same...????
The stat simply will not open. (BTW it is in properly, housing nice and clean top and bottom)
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So. let it cool. Check coolant levels. Pressure test-fine, no leaks.
Try the bleeding process again. This time no bubbles of course! Hot heater, cold bottom hose.
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So, I took the stat out completely. Re-bled and all is well.
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I tested both stats earlier with boiling water. Both opened, but the new one opened fully faster.
So now,I put both stats in a saucepan of water and heat. I use an accurate thermometer. Both open at 85C though the new one opens fully faster again.
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Am I to assume the new stat is no good? 85C at the bottom of the engine =100C at the top(fitted a digital gauge to top hose).
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I have now ordered a genuine Mazda stat....I hope this will solve things ???
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The Bongo is running much better with no stat....just takes a little longer to get up to temp. I have to replace the crap hoses at the weekend, so I'll try the genuine stat and see if it actually opens before the engine boils!!!

[missfixit70]

Did you check the inside of the stat housing to see if the top disc of the stat can seal against the recirc/bypass flow when it's fully open?
Sounds like the stats are ok, that's about when they're supposed to open, it's down to the flow around the heater circuits, that isn't the temp going into the engine. This may help explain - http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=36433
Is the bottom hose even getting warm?
Did you get a load of crud out when you flushed?

[Northern Bongolow]

hi did you flush out the heater circuits as this loop acts on the stat to help it open it,just a thought if you havnt got 82 degrees at the stat housing it cannot open you may have 100 deg at the top hose though.

[Northern Bongolow]

god i wish i could type quicker

[Mountain]

hi did you flush out the heater circuits as this loop acts on the stat to help it open it,just a thought if you havnt got 82 degrees at the stat housing it cannot open you may have 100 deg at the top hose though.

Wish I could too...type quicker!

Yep, rear heater is bypassed...2 pipes connected. Front was flowing freely. However, it does not get 'really' hot.....just kind of hot, but more than warm...if that makes sense?
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So, if the heater matrix is "partially blocked" would I get these issues?

[Northern Bongolow]

possible. as you now know weird things happen.

[missfixit70]

Yup, any problems with flow around the heater circuit will cause problems, but it you've bypassed the rear heater, there should be flow through there, worth bypassing the front one & see what happens.

[Mountain]

Is the bottom hose even getting warm?
Did you get a load of crud out when you flushed?

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Not even warm most of the time. Only once got warm when the coolant was getting close to boiling!
Yes, loads of crud...loads...
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I did think the top housing may be blocked but all holes were clear!
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I'm still tempted to try a new heater matrix.....hmmm.
Maybe a new top housing to be on the safe side?
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Anyway as things stand it's.
Thermostat in=too hot.
No thermostat= maximum top hose temp of 89C...no chance of boiling my head off
So for the moment, that is the safest option.

[Mountain]

Yup, any problems with flow around the heater circuit will cause problems, but it you've bypassed the rear heater, there should be flow through there, worth bypassing the front one & see what happens.

Back heater-bypassed-you can feel the flow around as things heat up.
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OK will do. I'm convinced I got all the air out so I do think it may be a restricted flow through the heater matrix....it just does not get really hot.
My mother has a Bongo and the front heater could fry eggs

[missfixit70]

I'd suspect your rad too then if you had a load of crud out, it's got very small channels that will block very easily & no amount of flushing will shift that once it's there.

[Mountain]

possible. as you now know weird things happen.

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LOL, is there anything weirder than the Bongo cooling system?
Honestly though, I need to get it sorted. I'm pretty much to the point of replacing every hose and the heater matrix. Sooner the better.

[Mountain]

I'd suspect your rad too then if you had a load of crud out, it's got very small channels that will block very easily & no amount of flushing will shift that once it's there.

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Don't say that I've never spent this much on a vehicle within 2 years nevermind 2 weeks

But, there is definitely some flow through the rad, so surely a cold bottom hose brings us back to the stat not opening?
Even if the rad was full o crap with a restricted flow, once the stat opened the bottom hose would at least get warm?
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It's only if the rad is blocked near the bottom outlet to the bottom hose that it would prevent flow completely. I know it's at worst partially restricted as water flows through to the bottom hose connection..I removed it and flushed from the top.

[Mountain]

Well, despite all efforts......
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Driving along this morning and my Bongo died. Revs dropped heard a hiss....I knew what that was
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So, I suspect the head gasket was gone after the initial boil up, and this morning it has just completely gone. Proper squirting coolant out gone.
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Of my 2 weeks of Bongo ownership the first 4 days were OK.
Then the loss of coolant-due to previous owner putting caps on the wrong way around.
Then the boil up, after which strange things started happening.
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I've been deluding myself haven't I?
Looks like the head gasket had gone and was the cause of all the other problems.
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Bongo now in Bongo friendly garage while I'm praying the head is not warped or cracked.
I now can't afford to get rid of it. I can just scrape the cash together for the head gasket being done but I doubt if I can stretch to a head replacement
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Am I just unlucky, or have I bought a jinxed Bongo?
Well, actually if some idiot hadn't put the caps on the wrong way around I wouldn't have lost coolant in the first place

[mikeonb4c]

Well, despite all efforts......
-
Driving along this morning and my Bongo died. Revs dropped heard a hiss....I knew what that was
-
So, I suspect the head gasket was gone after the initial boil up, and this morning it has just completely gone. Proper squirting coolant out gone.
-
Of my 2 weeks of Bongo ownership the first 4 days were OK.
Then the loss of coolant-due to previous owner putting caps on the wrong way around.
Then the boil up, after which strange things started happening.
-
I've been deluding myself haven't I?
Looks like the head gasket had gone and was the cause of all the other problems.
-
Bongo now in Bongo friendly garage while I'm praying the head is not warped or cracked.
I now can't afford to get rid of it. I can just scrape the cash together for the head gasket being done but I doubt if I can stretch to a head replacement
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Am I just unlucky, or have I bought a jinxed Bongo?
Well, actually if some idiot hadn't put the caps on the wrong way around I wouldn't have lost coolant in the first place

Don't know what to say dude - a very sad story indeed

The only thought possibly worth hanging on to is that unlike most old scrappers a healthy Bongo should retain a useful resale value, so the cost of the work will not be completely wasted. A couple of people on here are busy rebuilding their (Bongo) heads. Maxheadroom has just done his, and ADAMD is on the case at present. Simon Jones has also done his own some time back with good results. The job appears quite doyable for a DIY mechanic. So provided you don't need the car back on the road tomorrow, and with weather getting warmer, maybe think of it as a rewarding DIY project. Hopefully all the other bleeding problems (no swearing intended) were linked to excess system pressure due to a compromised head gasket. But as part of the project, thorough evaluation of all components (rad. heater matrix, thermostat, water pump, fans and temp sensor etc.) would be a good idea.

Good luck - we're here to help and ease the loneliness, and a healthy Bongo is a great motor to own

PS - recommend buying the complete head etc. kit from Bongo Fury shop as it has everything in it and SHOULD make sure you avoid the risk of buying a cheap pattern one - price is not bad and this is not a place for making false economies on cost.

[Mountain]

Yeah, just bad luck I suppose...and I do need to be back on the road ASAP.
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I can't afford not to get it fixed. Fixed it keeps it's value, broken I'm more out of pocket. Plus the Wife & Son love it and are looking forward to a summer of adventures
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I've changed heads on cars before, but to be honest I don't have the time or equipment at home.
It is in a Bongo recommended garage and the guy was on the ball about the 'bleeding coolant' system. He's replaced lot's of bongo gaskets and heads.
He's assessing the damage this afternoon. I'm hoping for a gasket replacement, but after the last fortnight....well
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On the plus side a gasket replacement or at a push, a new head isn't the end of the world. Replaced and sorted by an experienced Bongo mechanic, I should have a nice vehicle.
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and a healthy Bongo is a great motor to own

Yep, my mother has one...not a bit of trouble in nearly 3 years......