Urgent HELP...Maybe radiator?

[vanvliet]

Mazda Bongo parts quoted £212.00 for a Genuine Mazda rad incl vat / delivery

[haydn callow]

I'm not sure I would use a bit of the rubber pipe that overflows the expansion tank to block off the extra outlet below the radiator cap. I don't think this is pressure hose and may well fail with dire results.
SHAD...have just been and checked and I very strongly advise you change that bit of pipe you used. It will fail.

[helen&tony]

Hi
That's interesting, Vanvliet.....It's a bit more than I'm paying, but probably worth the extra!....Haydn....the overflow pipe doesnt need to be pressure pipe...you're right....If I need to do likewise, i'm sure i've got small dia. pressure hose in a box somewhere!
Cheers
Helen

[brorabongo]

I plugged the pipe, (the whole length) with "radiator stop leak" putty, Its very like "chemical metal". So far so good.......well the coolant alarm has'nt gone off yet.

[The Great Pretender]

Hi
Two days ago, we stopped in the local town...steam from under the bonnet...lifted the air scoop for the front heater, and it was coming from the hose which goes to the clear plastic degassing tank. Drove home (18Km), wathching the TM2 alarm, and temperature gauges, and the temp was good, until needing to slow, when a rise was indicated on the TM2. The coolant in the tank was mostly below the minimum mark, and the coolant loss alarm had been going off. Replaced the hose, which was due for replacement with silicon ones, and it just slid off the radiator. Problem solved , we thought, but there was seepage around the radiator header/ matrix junction. Went to town today (18Km), and more steam. This time at the seepage point mentioned.
The coolant in the rad looks normal colour, no frothing in the plastic degassing tank, and the temperatures when running are only marginally higher, except when slowing in town. The TM2 sensor is bolted under the 1st rocker cover bolt on passenger side and reading 51- 54 Deg. C whilst running.
Would the problem be just the rad. header to matrix seal?, in which case I can get the rad repaired/ flushed / re-sealed locally, or could there be something else....The car has never got over- hot, except in the snow, as Bongos don't handle deep snow without a struggle, and that was ages ago.
Help and advice appreciated
Thanks in advance
Cheers
Helen

Sorry to read about your problems, now some of what i'm going to ask is chicken and egg.
Did it overheat when engine was off? Im assuming it did as I dont think the coolant loss alarm was going off before you stopped. When you drove home was the coolant level below the top hose in the degassing tank? This can stop coolant flowing under certain conditions as the stat will only open when the return temperature from the rad is over 82c or stuck in traffic the pump is working to slow to remove the heat so it feeds back to the stat reversing the flow.

[helen&tony]

Hi GreatPretender
The coolant dropped on the way home very slowly, and was above the return hose when I stopped....it slowly dropped when parked as , I presume, pressure forced it out of the top radiator/ matrix joint. I replaced the radiator to degass tank hose, did the same journey again, thinking the water round the seal/ joint had come from the hose, which is when I noticed the radiator joint was at fault. The water loss in the clear plastic degass tank on the second journey was about 1 inch on a round trip of 36 Km (as seen in the degass tank). Temperatures dropped on the TM2 gauge when driving, only increasing in town, and the visible water seepage was at the matrix/ top rad. tank joint after stopping to look.
Hope that helps
Cheers
Helen

[haydn callow]

TGP....In your quote above it says the coolant alarm had been going off.

[haydn callow]

TGP....In your quote above it says the coolant alarm loss had been going off.

[Shad]

I'm not sure I would use a bit of the rubber pipe that overflows the expansion tank to block off the extra outlet below the radiator cap. I don't think this is pressure hose and may well fail with dire results.
SHAD...have just been and checked and I very strongly advise you change that bit of pipe you used. It will fail.

Cheers Haydn - good point. I will use a more suitable alternative this weekend.

[The Great Pretender]

Helen the TM2 reading looks low, the head studs on mine are around 100c, so your position isn't picking up heat fast enough (it is dissipating). If you must read metal temp fit it as close as you can to an exhaust valve, that is the hottest part of the head and the temp will rise there first. I think my view on temp measurment is well known, I would fit the sensor on the water outlet on the head. If an engine is going to overheat it is normally because of inadequate cooling, so for the metal temp to rise the coolant has already seen a problem.

You didn't repy to my first question, was the Bongo running when the problem started, or was it a pressure problem when off as this could point to a secondary problem.

Hope this is useful.

[The Great Pretender]

TGP....In your quote above it says the coolant alarm had been going off.

Yes on the way home, the question was asked to try and understand the problem not to slate the coolant loss alarm.

[helen&tony]

Hi The GreatPretender
My apologies...yes the engine was idling as I was stopped for a few mins....the water level was still above the coolant alarm, but I just noticed steam, which was coming from the hose as described in my first post....I presumed it was just that the hose was loose, as discovered when removing it. I thought the water round the top of the radiator was due to this . After replacing the hose, I noticed the seepage at the top of the radiator was more, as the hose wasn't venting.The water level continued it's drop after the engine was turned off,as the natural pressure slowly dissipated during cooling. After cooling, the loss stops. The water loss alarm worked perfectly.
Funnily enough , I had been thinking of moving the temp. sensor for the TM2, as where it sits, I believe the alternator is blowing cool air over it....however, it does indicate any temperature rise, and thet's the important thing.
Your continued thoughts are certainly appreciated,
I've certainly had an opportunity to look again at the Bongo cooling design, which appears to be not as daft as I first imagined.
Cheers
Helen

[Aethelric]

Mazda Bongo parts quoted £212.00 for a Genuine Mazda rad incl vat / delivery

I have ordered one from ebay, item no 380023180595 from Auto Jap Spares.
£158 inc postage and VAT.

[helen&tony]

Hi
Mmmm Aethelric..seems like a spate of Bongoraditis at the moment...we've all caught a coolant virus. I now realise why the Bongo sludges up at the bottom of the radiator, as it only works on stop -start journeys at the bottom, and on long journeys, it manages to stay cool without using the bottom half of the cooling system, as the thermostat will stay closed....unless I am reading it all wrong.....oh for the far off days of yesteryear when cars was cars
Cheers
Helen

[Aethelric]

Hi
Mmmm Aethelric..seems like a spate of Bongoraditis at the moment...we've all caught a coolant virus. I now realise why the Bongo sludges up at the bottom of the radiator, as it only works on stop -start journeys at the bottom, and on long journeys, it manages to stay cool without using the bottom half of the cooling system, as the thermostat will stay closed....unless I am reading it all wrong.....oh for the far off days of yesteryear when cars was cars
Cheers
Helen

Yeah Helen, there is a lot of metal to heat up, and the heaters make a good job of cooling so it takes a good few miles before the stat opens at all. My bongo runs fine around town and general motoring, but monitoring the head and the mason modified temperature gauge I can see that its getting too hot under heavy load. I don't think I'd have noticed this without the mason alarm, but monitoring the head temperature confirmed it. I am 90% sure its the radiator clogged up. Maybe flushing and back flushing would fix it, but if it didn't I'd then have to get the new rad anyway, and I don't want to have to bleed the system twice

My pet theory (no proof) is that a lot of the problems arise when European coolant is added to a system with Japanese coolant still in it.

I'm going to do some tests on the new one and the old one and will put the results on line.

Dave