Overheating problem

[orielvilla]

Hi all.

Advice needed please.
Drove approx 40 miles tonight when I noticed the temperate inside the cab drop. The heating had stopped blowing hot. I stopped and checked coolant level which was OK. The bottom hose was stone cold and the top hose under pressure. I kept going but very soon the temp gague started to shoot up.

Having just had a new head I'm very vigilent but am now losing confidence in my beloved Bongo!
I've had to abandone it in the middle of nowhere!

What could the trouble be? I wonder if the garage did not do a thorough bleed job? Could there be an air lock?

Any advice would be gratefully received.

[wonkanoby]

its could be many things

blockage in heater

dodgey themostat

did you flush it out

[mikeonb4c]

Is your coolant at all rusty looking? It could be that poor coolant system performance caused the head to go in the first place. If so, you'll need to address this if a repeat is to be avoided I fear.

[321Away]

heaters blowing cold usually indicates an air lock

Julian

[orielvilla]

Thanks for the replies.

With the new head job I had a new thermostat and the coolant is all new.

I'm going to ask for a flush and another bleed.
I hope this is going to be something simple. Since the head was done my heater has blown warm only whereas before it was a great heater.

I'll let you know what happens.

[Driver+Passengers]

You may be well advised NOT TO DRIVE until you bleed, if you suspect that there is an airlock in there. Even an incomplete DIY bleed may be better than nothing if you're intending to drive it to a garage.

One cause of persistent troubles can be a pinhole leak in a hose, a poor hose joint or a leaky water pump gasket. Get a static pressure test done on the whole system to ensure it holds pressure. If it doesn't, then coolant may be leaking from the system and consequently when cooling down, air can be drawn into the system and accumulate over time, eventually resulting in an airlock.

Do you have a Low Coolant Alarm? If not, get one.

Good luck,
Matt.

[orielvilla]

Thanks Matt.

I'll ask the garage to do a pressure test. They are going to recover the vehicle on a trailer for me so no danger of repeating a cracked head.

When I had the head done I had the water hoses renewed. However, I am aware of that long metal pipe that runs back to front that seems like another weak link.

I do have a low coolant alarm but am yet to get round to fitting it. I will asap!

Chris

[teenmal]

Thanks Matt.

I'll ask the garage to do a pressure test. They are going to recover the vehicle on a trailer for me so no danger of repeating a cracked head.

When I had the head done I had the water hoses renewed. However, I am aware of that long metal pipe that runs back to front that seems like another weak link.
I do have a low coolant alarm but am yet to get round to fitting it. I will asap!

Chris

Hi,is it leaking (weak link)

[mikeonb4c]

Thanks for the replies.

With the new head job I had a new thermostat and the coolant is all new.

I'm going to ask for a flush and another bleed.
I hope this is going to be something simple. Since the head was done my heater has blown warm only whereas before it was a great heater.

I'll let you know what happens.

You really could do with establishing that the flow rate through radiator matrices is healthy. There's just been another thread about this one. Flushing can only achieve so much. Can you recall if the old coolant (before it was changed) was rusty?

...but with any luck this will be a bleeding issue

[Bob]

Bloomin' bad luck, Mate.

Hopefuly warranty will cover further repairs if you've just paid the garage to fix it, but are you using a 'Bongo Savvy' garage?

Unfortunately not all garages know as much as they think they do, and some won't be told about bleeding the system.

[orielvilla]

Update.

Cold and hot pressure test was OK so no leaks.
Garage suspect a dodgy thermostat and it should be fitted tomorrow. I had a new stat fitted when the head was done before christmas but I bought a cheap one so lesson learned!

If its not the stat, the next action is to have a flow test on the radiator. In the meantime, I have got myself AA cover!

[Simon Jones]

The genuine Mazda thermostats are generally considered to be the best ones to fit. I think they cost less than £20 and can be ordered from the club shop or most Mazda dealers. I would always recommend testing old and new in a pan of boiling water as its always possible for a new one to be duff.

[francophile1947]

I can't see why a duff thermostat would stop the heater working - doesn't it only block the flow into the main radiator, not the heater rads?

[Northern Bongolow]

Hi all.

Advice needed please.
Drove approx 40 miles tonight when I noticed the temperate inside the cab drop. The heating had stopped blowing hot. I stopped and checked coolant level which was OK.
What could the trouble be? I wonder if the garage did not do a thorough bleed job? Could there be an air lock?

in my opinion this sort of symptom is usually caused by a leak that is low down in the system, the reasons for saying this are that a high level leak usually clears itself via the expansion tank, this causes the coolant level to drop. as you are not seeing a coolant level drop this means air is entering low down, then maybe pushed into the front heater, this stops flow and usually causes overheating.
ALL the hard to find leaks ive come across are later found to be the water pump, this can leak at 2 points one of which is really hard to spot as its hidden by the belts and the crank pulley. the way to test is get it hot if safe to do so then work your finger round to the 6 oclock position on the water pump casing, it may be damp.
try this link
http://igmaynard.co.uk/bongo/forum/view ... mp#p482224

[orielvilla]

Good call Northern Bongolow!

Got the garage to check the pump and sure enough there is a small leak and staining indicating it's been leaking for some time.

Going to renew the pump. Any suggestions on where to buy one? The garage are going to price one from their suppliers but are happy for me to source a cheaper one if I can.

Really appreciate the help from people on this forum.

Chris