Radiator overheating.

[Faribaandme]

Bongo 2.5 diesel 31-7-1996.

Radiator overheating.
New Radiator and thermostat.
Replaced engine fan heat sensor as fan would come on early before thermostat opened.
Overheating.
Did system bleed according to Youtube; bottom hose warm and heater working van running good.
Next day checked water level in overflow tank same as day before.
Took for test ride.
I have dual engine sensors and water low level alarm in overflow system. After several minutes noticed water temperature getting hotter with no heat coming out of heater so pulled over.
Next day replaced thermostat with one with holes to let the water run through the system. Started to bleed water gets to point of boiling; bottom hose was lukewarm top hose was hot. Engine temperature sensor at normal running temperature.
Ran engine longer than a normal bongo bleed to try to get hot air out of heater "to no avail" so gave up. Took for test ride overheated within minutes. Could my heater be the problem could the heater be clogged?
Could I have a clog somewhere else perhaps in rear heater?
If clogged front heater any pictures and instructions how to clean flush it out or cut it out as in a test.
I would not care if rear heater was disconnected so any photos and information on doing that?

I discounted the water pump as I think the heater should work even if water pump did not however not qualified to know I also wonder should the bottom hose be hotish not lukewarm?

Any Bongo repair places in the north east London area as I live in e4 7et.

Thank you in advance for any help and advice.
Robert.

[cmm303]

What made you think the old radiator was causing the overheating?

In last phase of bleeding the bottom rad hose should be hot, too hot to comfortably hold. So the first bleed appears to be incomplete.

With the "holy" thermostat it could take a long time to get up to temp. However you say on the second bleed it was near boiling point but temperature gauge (which one) at normal running. What made you think it was near boiling point?

Check that your new thermostat opens properly around 82 deg in hot water with a thermometer.

During bleeding, were you able to get all the air out before starting the engine, then before the thermostat opened, then finally before you finished?

The level in the expansion tank should drop 0.5cm to 1cm as it cools from running temp. (Fluid expands when hot). If you didn't get this, it suggests it wasn't fully up to temp at the end of bleeding.

[cmm303]

P.S.
I wouldn't assume any coolant flow even in heater matrix without pump.

Pumps more often fail by leaking rather than not pumping. Belts all good?

Front heater hoses: their "other ends" are easier to get at from underneath. Access from top to heater hose connections requires removal of cabin heater fan stuff. Flushing out is easily done with a garden hose! There are reports of the heaters clogging up but this should not cause overheating.

[Northern Bongolow]

if you think carefully of what has gone on it can help narrow down the area that could be at fault, all the above info is correct but start from what you know happened and work backwards.

air rises to the top of the system, or more accurate it flows to the highest spot that it can reach and collect . you state that the first signs were temp increase and heater cool or cold, this would point to a leak at the rear T piece under the drivers door B post or the pipe that goes from there towards the front of the van from it, this is the supply to the front heater or a leak in the pipe over the starter motor, this goes to the T piece. a leak here will let in air which will rise and collect in the front heater matrix, thus no flow in the heater and an airlock.
a leak elsewhere would result in a different outcome.
no flow leads quickly to an engine overheat.

[Bongolia]

All of the above for sure.
Has it had a pump change?
Not sure if Bongos have metal impellers or plastic but both can fail giving the symptoms you describe.
If your confident you have bled the system of air and you are still getting overheating I would next be looking at circulation to eliminate pumping issues. Try it with the stat out and check for good volume of circulation.
A quick and dirty way.
Do this cold with stat out. Refill it, loosen top hose at rad, get someone to hold it at fast idle and pull off the top hose water should come out like a fire hose.
If no, then change pump if yes, place clothing in tumble dryer.

[Faribaandme]

Thank you for responding.

What made you think the old radiator was causing the overheating?

I had the system pressure tested due to a leak. They replaced the radiator had one of those machines that sucked the air out of the system and told me the water may drop a bit which it did however no problem after that.

In last phase of bleeding the bottom rad hose should be hot, too hot to comfortably hold. So the first bleed appears to be incomplete.

First bleed was successful bottom hose was hot heater worked cap on no overheating however next day took for a test drive heater did not work and overheated in a short time.

With the "holy" thermostat it could take a long time to get up to temp. However you say on the second bleed it was near boiling point but temperature gauge (which one) at normal running. What made you think it was near boiling point?

After a long time the water rose to boiling point steam bubbling and jumping with water at boiling point in both overflow tank and funnel. Even after a long time much more than usual the bottom hose was lukewarm top hose hot. The water temperature gauge was normal running next to the fuel gage and the two engine temperature gages. Turned off engine for a few minutes then everything went back to normal however if temperature rose again starts boiling thus decided could not go any further. When and if put cap on expansion tank temperature gage next to fuel gage will rise immediately.


Check that your new thermostat opens properly around 82 deg in hot water with a thermometer.

New and old thermostat were checked worked fine. Thought as cooling fans were going on early I replaced the engine heat sensor. Now the fans are not going on early.


During bleeding, were you able to get all the air out before starting the engine, then before the thermostat opened, then finally before you finished?

I have bleed the bongo many, many times and "believe" I did however on the last one with the water boiling and lower radiator/bottom hose lukewarm we stopped.
You are correct however in theory as no thermostat .... system should be running as if we waited for thermostat to open. The air would be pushed around the system to the bleed hose from the start. Yet bottom hose was lukewarm how can that be that means blockage perhaps air. We took a lot longer on this bleed to try to get the bottom hose hot and for the heater to work we know something was wrong.


The level in the expansion tank should drop 0.5cm to 1cm as it cools from running temp. (Fluid expands when hot). If you didn't get this, it suggests it wasn't fully up to temp at the end of bleeding.

I didn't check to see if .5cm or 1cm just look about the same.

I wouldn't assume any coolant flow even in heater matrix without pump.

Pumps more often fail by leaking rather than not pumping. Belts all good?

All the belts seem to be fine however will check; should I look in a particular area?
Would the pump not working correctly cause this? Can't understand why the heater is not working.

Front heater hoses: their "other ends" are easier to get at from underneath. Access from top to heater hose connections requires removal of cabin heater fan stuff. Flushing out is easily done with a garden hose! There are reports of the heaters clogging up but this should not cause overheating.

Do you have or can you direct me to any information on how get to other ends of hose from underneath. I can then perhaps flush water through?
If heater's are not stopping flow? Some blockage must be causing the water to boil. What is causing the radiator top hose to be very hot and the bottom hose to be lukewarm?
Thanks again,
Robert.

[Faribaandme]

Thank you Supreme Being
you state that the first signs were temp increase and heater cool or cold,
Yes

rear T piece under the drivers door B post or the pipe that goes from there towards the front of the van from it
this is the supply to the front heater or a leak in the pipe over the starter motor, this goes to the T piece.

I will look for a leak. I am at a disadvantage as I don't have a driveway and work on the street. I will do a search to see if I can come up with a picture of the t piece and pipe over the starter motor.
Robert

[Faribaandme]

Thank you for responding Bongolia

No pump change.

Do this cold with stat out. Refill it, loosen top hose at rad, get someone to hold it at fast idle and pull off the top hose water should come out like a fire hose.

If no, then change pump if yes, place clothing in tumble dryer.

Very funny .......... I am crazy or desperate enough to do that.

[cmm303]

....
Not sure if Bongos have metal impellers or plastic but both can fail giving the symptoms you describe.
...

metal

[cmm303]

...

Do you have or can you direct me to any information on how get to other ends of hose from underneath. I can then perhaps flush water through?
If heater's are not stopping flow? Some blockage must be causing the water to boil. What is causing the radiator top hose to be very hot and the bottom hose to be lukewarm?
Thanks again,
Robert.

Heater pipes exit from bulkhead off centre, passenger side. From underneath looking upwards you can see the pair, one above the other quite high up. You can then trace them along. Recall one is more awkward than the other. Cover under the engine doesn't get in the way.

I can only think of two reasons for bottom hose not getting hot. Coolant not flowing through rad or enough wind blowing through rad to cool it, and we're not talking hot air relating to In or Out!!

[Bongolia]

Ok, so you have an old pump and the impeller is metal.
It is very possible that the impeller is badly eroded or missing.
Seriously, It is important to eliminate pumping issues next before moving on to other possibilities and the way I have described is a simple and sure fire way of finding out if the pump is delivering a good volume or not.
You could look through the radiator cap but you need to get the stat out and it wouldn't give you as good an answer as pulling off the hose.

[Faribaandme]

Thank you Chris with BertieB for the info .......... will use it.

Thank you Bongolia should be able to check and get WET this morning.

[Bongolia]

Well you have a nice day for it. you should be able to air dry your clobber, hopefully.

[Faribaandme]

Checked the belts all seemed to be okay.

While holding top hose to radiator wife started bongo put peddle to the metal while I pulled off the top hose ............... wait for it ........................
I am dry as a bone didn't get wet just a trickle.
That would explain a lot.
While I was at it did the block check combustion leak tester.
Blue stayed blue no blown head gasket or cracked head etc.

Life is good!!!!!!!!!

Thanks to you all .............

[Bongolia]

Dont know if that`s good news or bad, spose it depends on how you look at it.
You should have the engine at working temperature or at least the coolant should be very hot before you do the fluid block test so you would need to repeat that after the pump swap and bleed out.
Good luck.