Overheating problem

[Driver+Passengers]

[orielvilla]

Have just ordered an OE quality pump from Autojapspares.
Should all be fixed next Monday.

Happy days!

[chipvan]

[Northern Bongolow]

im glad its working out for you mate .

[orielvilla]

Update.

New water pump fitted and heater blowing hot like it used to.

Once again thanks for your diagnosis.

[chipvan]

due to my painfull experience,iam going to do a full coolant flush,change the stat and pump every 2 years now...

glad your sorted

[orielvilla]

Trouble again!

So, garage fitted new pump and thermostat and I've only done around 50 miles.

About 2 miles into my journey today temperature gague rose and heaters are cold again. Again, no drop in water in the reservoir.

After my last experience I have joined the AA with a repairs policy so called them and they helped my back to my garage who were not happy to see me so soon! Their mechanic was sure he'd got it sorted and is going to pressure test it overnight.

I'll keep you informed...............

[Northern Bongolow]

i would say there is no need to pressure test it over night mate, theres nothing that good. plus natural cooling of the coolant will show as a slight pressure loss. so he may be chasing a leak that is not there.
when you fix one problem the increase of pressure can put a strain on other parts that were not pushed before, if another leak is not found then it is likely that the head has gone.
ive seen several that are really hard to diagnose as cracked head or gasket, they can lead you a dance for weeks then suddenly dumping the coolant etc. this may be because the crack or gasket fault is so small it takes a week or two to build up a sizeable air lock that dumps the coolant.

good luck mate.

[orielvilla]

Northern Bongolow,

I need to go back a bit with this story.
A couple of months ago the head went. I suddenly noticed plumes of white smoke after driving 7 miles. I noticed the smoke first and looked at the temp gague which was at 11 O'Clock but then just shot up.
Turns out the head had cracked and so I had a brand new head fitted along with gasgets etc plus main water hoses, the 3 way little pipe that enters the head and thermostat. The persistent overheating problems since then I'm assuming are because the original cause has not been found.

I can't contemplate another head failure! The two overheats I have had since I think I have spotted early due to the heating going cold and drawing my attention to a problem before the temp guage has reacted. I've taken great care not to drive it an inch when I know its overheated.

I'm thinking there are two major components of the cooling system left which is the rad and that long metal pipe that runs to the rear. As I have a repairs policy which covers me for up to £500 (I have to pay first £35), I'm going to see if I can get these two components sorted under one claim?

I'm hoping its a pin hole leak somewhere. BUT WHERE?

[New Forest Terrier]

I had a very difficult to find leak on the rear heater matrix last summer. Bongo was loosing coolant very, very slowly. No overheating and not even dropping much below the low level on the tank,but there was something wrong. I checked the coolant level every day and spotted some on the ground behind the drivers door. Both hoses were absolutely fine and it passed a hot and cold pressure test, showing no leak. Bypassing the rear heater matrix solved the problem though.

[Simon Jones]

A clogged up radiator is going to result in poor cooling performance which could lead to overheating. The long pipe would not impact on the cooling, but a slight leak would allow the coolant level to drop as well as potentially draw air in which expands and forces more coolant out. If the level in the expansion tank is not changing from day to day (up or down), then it's probably safe to asume the system is leak-free and the problem lies elsewhere.

[orielvilla]

Update.

Garage topped up and took for a spin. Blowers all nice and hot and when they got back they noticed a cool spot on the radiator.

So, going for a replacement radiator and if I can't get the metal pipe done under the repair policy then I'm going to pay for that part myself for peace of mind.

I have two questions.
1. I've seen you can't get either O/S or N/S for the pipe. Are there two pipes or is it a case of either / or? I've only noticed one on the drivers side.

2. The garage wondered wheter a pressure cap somewhere was weak and releasing water since the new head was done and the system under proper pressure. Are there any other pressure caps other that the one on the reservoir?

Thanks for your wisdom all. Much appreciated.

[Northern Bongolow]

there are 2 pipes that conect the rad to the engine one to the top hose(drivers side ) and another to the stat housing (passy side ). the one on the driverside has a little bleed nipple fitted to the lower side (to the ground) make sure this is not leaking.
these pipes are about 2 inch dia.
then on the driver side is a pipe which runs from the front heater to the rear heater, this is the one that has a T off at the rear end to the block.
on the passy side there is a pipe that runs from the front heater/expansion tank to the rear heater, this has a T off to the stat housing. both these run along the chassis rails and are difficult to replace when they rot out. all are available from most good mazda dealers in a few days.
http://igmaynard.co.uk/bongo/forum/view ... ater+pipes

[orielvilla]

Garage have now decided the rad is not a problem and think the thermostat is defective as they can't get the bottom hose hot.
This is despite the thermostat being renewed twice in the last 3 months! They are now going to buy a Mazda one and fit and see.

Anyone know what temperature the thermostat opens at?

On it goes............

[Driver+Passengers]

Should start opening at 82 degC. Full open at 92-odd, iirc.