new radiator and thermostat = running hotter

[phil 1]

Hi
As the bongo passed its 4th mot in a row with out anything needing I thought I would treat her to a new radiator and thermostat as the coolant needed changing. So last weekend I changed them bleed the system and checked for leaks all was looking good took it for a spin around the block taking in as many hills as I could find. To my disbelief I find it is running HOTTER than before so next day re bleed the system but it’s still running hot I have bleed the system 4 times now and I am confidant there’s no air in there. I use the bongo daily as its my only vehicle for work and over the last week I have covered 200+ miles the temp gauge sits approximately at the 12.30 mark (masons fitted) under normal driving but when going up hill it steadily climes up to 2 o’clock mark it has not got so hot as to set the alarm off yet but it would not get this hot before changing the rad under the same conditions. I am planning a trip at Easter and I am not confident that its not going to over heat so any help and advice you can offer will be greatly appreciated I have considered deactivating the masons alarm to see if the gauge reads more than the normal 11 o’clock mark or even putting the old rad and stat back in as it ran cooler then than it does now. Please help!!

[missfixit70]

To be honest that doesn't sound too bad, but wierd that it's running hotter.
What rad did you fit? has it got a vent pipe at the rad cap? if so it needs blanking off, any pressure relief is taken care of at the expansion tank, 1.1bar cap should be on there, doesn't matter at the rad once the vents blocked as it can't then vent.
What stat did you fit? did you test it before fitting in a pan of water brought to the boil? (alongside the old one so you can see when they open & how far relative to one another)
Did you flush the system? did you replace the coolant with the same as was in before?

[phil 1]

Hi
Thanks for the reply
I got the rad of ebay but it’s the same as this one http://www.japautosolutions.com/acatalog/info_828.html looks much the same as the original no vent pipe but did come with a 0.9 cap on but I have replaced with a new 1.1 bar one as well as the header tank. The stat is a blueprint I did test it against the old one it opened faster and stayed open longer than the old one so I was expecting it to run cooler and I flushed the system and refilled with new antifreeze I think it’s the same type i.e. its blue but a different brand. I still have the old antifreeze container so I will check

[mikeonb4c]

An outside chance this but are you confident that you have not disturbed anything to do with the radiator fans and the circuit/sensors etc. that activate them? If the engine is getting hot beyound a certain point I'd expect them to be cutting in and you'd see the temp coming down again. Similarly (but seems even less likely) if anything such as slack belts was causing the water pump not to be turning well. Finally (and I don't know the answer to this one as I have a std. damped gauge anyway), could there be any significant difference in outside air temp between the 'before' period (we've had a v. cold winter) and the 'after' period and could this affect things? You'll soon be able to check this last one as winter weather returns this week we're told

[missfixit70]

I wonder if it's down to it being a pattern part replacement rad? maybe not as much cooling going on?
If you do decide to change it back or mess about with the cooling system have a look up into the stat & check the top recirc/bypass inlet sealing ring as per, I doubt it'll be that though as it was ok before.

We started for a change with a Bongo with a "Good Coolant System" instead of trying to fix an overheating Bongo, we tried to remove heat from an untouched for 3 years plus Bongo with no oil or water leaks, original head and water pump etc,

Bongo A


1st Attempt

Mason alarm fitted

Good readings generally.

Actions:
New Blue Print Stat
New Intermotor Temperature Sensor Switch
New Blue Coolant
Speed Flush
New Gear Box Oil used millarmatic DM

Results Observed:

Slight but definate raised temperature according to gauge (suspect sender inaccurate) by could be copy stat. Ran for two weeks, but not happy as would have expected lower general readings.
Spoke to you reference Stat Operation with regard to disc at the top of the stat shutting off hot head water return.

2nd Attempt

Drop Coolant, not reused
Fitted New Mazda Temp Sender
Fitted New Mazda Fan Switch
Fitted New Mazda Stat
New Red Coolant fitted (Carplan)

CHECK STAT TOP HOUSING CLEAN – It was gasket face clean

Results Observed:

Tremendous difference, the control temperature is achieved and maintained easily (Stat control) at a lower temperature band well away from the fan level temp, and away from the danger level.
The auto box warms better and quicker therefore performs better with less heat generated which would need to be cooled by the rad.
Engine and Gearbox now working at correct temperature levels giving smoother results.
Conclusion:

The stat is key. To us the £7.00 copy or £15.00 Mazda, it has to be genuine.
Thermostat housing needs to be very clean to seal correctly

Mason or one of Haydns gauge modifying instructions would show up this in relation to narrow working or operating temperature band and if these temps stray either up or down then the stat/housing should be checked .

Bongo B

History:

New Ranger Cylinder Head fitted 2 Years ago
New Mazda Radiator, 2 Years
New Water Pump, Unknown Brand, 2 Years Ago
New Copy Stat, 2 Years ago
New Coolant, 2 Years ago

Garage Bill = £1800

Full Silicon Hose set fitted, 18 months ago
12 months satisfactory running.

Then bought a light weight Caravan, raised temps noted via Mason Alarm to excessive levels. In the last three months over the winter period symptoms getting steadily worse to the point where anything over ½ hour high speed motorway driving temperature would steadily increase and would not decrease until fan level is reached. It would maintain levels, not cool levels. Fans where then wired manually and water wetter was used to pull down excessive temperatures.

Transfer of Knowlege from Bongo A to Bongo B

New Mazda Stat fitted
Bongos A's Original Old Mazda Temperature Sender Fitted, cleaned up.
Bongo A's Original Old Mazda Fan Switch fitted
Stat housing Top Disc Port from Head found to be dirty and deposit build up particularly at the flow from heaters across the stat edge: See Pics









Removed and Cleaned as per pics.






New Mazda Housing/Engine Gasket fitted
Red Coolant (Carplan)

Result:

Result!!!!!!!
as per Bongo A

Final Point:
One final point of note is that in "my opinion" a used lazy stat, when pan tested to boiling point only gives a low or inaccurate reading the 1st time tested. On second test it will normally be "Re-awakened" to work apparently normally and test well against a new stat. "Very confusing"!!!!!!!

Do they become Bongo Bound??????

My mason modified gauge sits about here at normal -



Here after towing a medium sized trailer up a longish hill (telegraph hill) -



Goes up this high before the fans kick in (only when I'm bleeding it & trying to get it to that point or under very heavy load, ie pounding up Italian Mountains in 35degree plus temps loaded with camping gear & back box)

[mikeonb4c]

I wonder if it's down to it being a pattern part replacement rad? maybe not as much cooling going on?

Yes, I didn't like to raise that possibility. Not very good if so though is it esp. as the current received wisdom is that fitting a new rad. can never be a bad thing. But I guess its important to keep a sense of perspective even so. As you said earlier, the figures don't sound bad, just disappointing.

[phil 1]

The fans cut in during the bleeding process briefly and the temp gauge dropped back to normal very quickly. Its not get so hot that the fans would cut in when driving but getting very close. for the fans to cut in the needle on the gauge gets just to the line before the H area this is where I have the alarm set as at this point. The alarm has not sounded yet during driving but it is getting close before the rad change it has only sounded on very hot day driving slowly up hill or long delays on motorways.

[mikeonb4c]

Incidentally Kirsty, I'd not seen those Bongo test results before (probably missed them deep in some coolant related thread ). Very impressive. Who was involved in the work/experimentation (you?).

[missfixit70]

Are both heaters chucking out heat ok?

[mikeonb4c]

The fans cut in during the bleeding process briefly and the temp gauge dropped back to normal very quickly. Its not get so hot that the fans would cut in when driving but getting very close. for the fans to cut in the needle on the gauge gets just to the line before the H area this is where I have the alarm set as at this point. The alarm has not sounded yet during driving but it is getting close before the rad change it has only sounded on very hot day driving slowly up hill or long delays on motorways.

So fans and sensor may reasonably be assumed to be OK. What about outside air temp and/or repeatable driving conditions. Do you have enough 'before' and 'after' gauge readings to rule those out? Also, are car heaters set to identical conditions as before? Etc. etc. - gotta ask just to eliminate them from enquiries

[mikexgough]

When my Rad split I fitted the same rad...... But mine runs cooler and i have to work hard to get the rad fans on....and they run for maybe 20-30 secs and then off....

[phil 1]

Yes both heaters blow hot.
The outside temp wouldn’t affect the temp gauge as much be for the change as it dose now.
In the pics above of the temp gauge my fan doesn’t cut in until the needle gets to the line just before the square of the H if that makes sense it has done that since fitting the masons which is a lot higher than yours kirsty do you think this may de some thing to do with it ?.
As mikexgough has fitted the same rad without any problems it looks like the stat might be the problem can anyone tell me what other vehicles have the thermostat fitted to them so I can ask for that at the local Mazda Dealer?.

[missfixit70]

If you suspect the stat I'd go for a Mazda original, there seems to be quite a difference in construction & operation etc, Ian sells them in the club shop.

[phil 1]

Will defiantly get a Mazda original the one I have was supposed to be an original but came in a blue print box so clearly its not. Ian has sold out of originals and I need one asp as planning to go on our travels on Thursday so I need to try and get one locally tomorrow . Am I right in thinking that it’s the same stat that’s fitted in B2500 and the ford Ranger? If I can’t get a new one I think I might refit the old one and see what happens

[rita]

Hi phil 1,

Check your radiator for cold spots once the engine is at operating temp.

Did you flush out your new radiator before you fitted it.