Air Lock? considering removing the stat....

[haydn callow]

The flow is from the Bottom Hose UP through the Stat....I asked before...How are you trying to get the bottom hose hot ??
It takes 30 mins plus of rev 2500/idle..rev2500/idle..
There is no quick way.
Other reasons the bottom hose stays cool....blocked Rad....major air lock

[Aunt Trumpet]

The flow is from the Bottom Hose UP through the Stat....I asked before...How are you trying to get the bottom hose hot ??
It takes 30 mins plus of rev 2500/idle..rev2500/idle..
There is no quick way.
Other reasons the bottom hose stays cool....blocked Rad....major air lock
The flow is from the Bottom Hose UP through the Stat....I asked before...How are you trying to get the bottom hose hot ??
It takes 30 mins plus of rev 2500/idle..rev2500/idle..
There is no quick way.
Other reasons the bottom hose stays cool....blocked Rad....major air lock

I have been trying to open the stat as you've decribed but i get the feeling it would sit there all day with out opening!!! I don't understand though why it still wouldn't open on a short drive? Surely when the water has reached the desired temperature then it should open?

Going to flush the rad thoroughly on Thursday then apply you r bleeding method.....cheers for reply....

[haydn callow]

Why don't you get in touch with Allans Vehicle Services garage (ad on this site) He is very good and knows Bongos inside out.

[Aunt Trumpet]

Thanks, I might just do that. I'll conquer the cooling system if its the last thing I do!...

[Aethelric]

I have been trying to open the stat as you've decribed but i get the feeling it would sit there all day with out opening!!! I don't understand though why it still wouldn't open on a short drive? Surely when the water has reached the desired temperature then it should open?

Going to flush the rad thoroughly on Thursday then apply you r bleeding method.....cheers for reply....

There is quite a lot of coolant in the system and it takes quite a while to warm up. If you have the heaters on they will provide cooling too.
When the stat begins to open it will allow a little cold coolant into the engine from the radiator. This will result in hot coolant flowing into the radiator. The radiator is very efficient. By the time the coolant passes through it and into the bottom hose it has been well cooled, so the bottom hose remains cold, or luke warm at the best.
The bottom hose will be hottest (or warmest) when the engine has been ran fast when stationary (no airflow over the radiator), and the heaters all off (no extra cooling) and the air conditioning is off (no radiator fans on when cold). As the engine heats up though, the engine management system will switch on the radiator fans so the radiator can do its job.
It may be a good idea to bleed the system when cold, before you do your flushing etc. This will enable you to see if you have air trapped in the head.

[Aunt Trumpet]

It may be a good idea to bleed the system when cold, before you do your flushing etc. This will enable you to see if you have air trapped in the head.

Ok thanks, when you say bleed the system when cold, do you mean engine running but before the stat has opened?.....this is what I was doing the other day as the stat seemed to stay shut....if I do have air trapped in the head how can I get rid of it if the normal bleeding method isn't working?....

[haydn callow]

I think the issue is becoming confused....Bleed the system when cold ??? surely we are doing that every time we are waiting for the stat to open....

[fatcatlawyer]

The test I do after I have bled the cooling system, (and I have done it twice so far) is to see saw the coolant with the engine running, check for leaks and then take the bongo to Castleton (twenty miles) and drive it up the pass that is a 3 in one at places. Watching the temp. guage like a hawk. At the top check coolant level and if all is ok treat the job as being done.

I think having the bongo at that sort of angle is enough to dislodge any residual air bubbles.

I suppose another way would be to jack up the front end to a high elevatation to achieve the same result.

ian G

[Aunt Trumpet]

Ok. I have just flushed through the rad....seems there is no blockage.
Taken the stat out (again!) and tested it and it opens fine when heated up in a saucepan.
Flushed through from the top hose through to the bleed pipe..seems to be no problem there.

I've just refilled the system by opening the bleed pipe, keeping it high, and filling up the header tank with a hose until water comes out of the bleed pipe. Close the bleed pipe and header tank.

Started up and after an initial warm up started to rev it at 2500 revs.....after about 10 mins the fans cut in and the temp gauge is going up. 5 mins later I look at the guage and its at about 2 O'clock!! both top AND bottom hose are still cold though....just switched off for a re-think.....any more ideas?

[Simon Jones]

The top hose should get hot fairly quickly when running the engine at those revs for 10 mins. When you squeeze the top pipe, do you feel the pressure inside & does the level in the header tank rise slightly?

[haydn callow]

Is water pump impeller going round ??

[Aunt Trumpet]

Is water pump impeller going round ??

This was one of my thoughts as we were not getting a decent flow out of the bleed pipe so the water was just sitting there getting hot and turning to steam....however,

After a lot of faffing about we put the exhaust gas tester on the header tank to see if any emissions were getting into the coolant, if there is, the liquid turns green/yellow..but it stayed blue. We used the funnel method for bleeding and the bottom hose got hot indicating the stat was finally open and we carried on burping and farting the bubbles out of the funnel until we were sure there was no air left. It all pointed towards an air lock so we decided to go out for a spin. We didn't even get off the drive before I noticed the gauge going up again... ......so we turned it all off.
What appears to be happening is that as soon as we replace the bleed hose bung the whole system becomes pressurised and overheats....its ok with the bung out. This means that either air or emissions are still getting in.....so we decided to do the emission test again while the header tank was bubbling a little....this time the liquid turned green and went to yellow.....indicating at best a head gasket failure...

So can I ask, how big a job is this to do? Is it a straight forward job or are there any hidden problems?
My mate is tempted to do it and I'll supply the parts but he needs to know if there is anything he needs to know first?.....Is it just the cooling system that is a pain in the arse?......

[haydn callow]

Personally..I would see if Allans can fit the job in.

[Aunt Trumpet]

Personally..I would see if Allans can fit the job in.

Yes, I'm inclined to agree but I'm in Portsmouth and they're in Plymouth...hang on, both Navy towns, I wonder if I can sneak it on to HMS Invincible and they could drop it off for me.... ....seriously, if there was an "Allans" near here I'd do it.

Any idea of cost?

[haydn callow]

What about discount trucks NEWBURY....Call out the recovery boys.