help!!!! coolant rises then gets too hot?? water pump??

[chipvan]

Off the road till cap and stat,and bleed up Monday
Thanks guys for your input !!!!

[chipvan]

Knew something was wrong this morning as my vegi oil temp senser didnt click on,it normally does at about 56,its plumbed into rear heater flow and return.its connected to heatexchanger to heat vegi.
If loss of presure could that effect coolant flow?

Its weird as everything was great after bleed last night,spose could be hit and miss,ie works sometines

[haydn callow]

Sounds as though you bled it o.k. to me.......you got the bottom hose hot.
Did you use the funnel/see/saw method.??

You either did it all wrong....doubt it !!
or
You have some other problem lurking...

[haydn callow]

whereabouts in Dorset are you ???

[chipvan]

in poole,yep did seesaw method..

The bit that i cant understand is it wasfine last night after we bled it,i went miles on a test drive...

Think will just put in a new stat,can bleed again and then see.

[widdowson2008]

in poole,yep did seesaw method..

The bit that i cant understand is it wasfine last night after we bled it,i went miles on a test drive...

Think will just put in a new stat,can bleed again and then see.

Don't think I got this over, but I'll try again.
You can fit a new radiator, new heaters, new pipework, new stat, bleed it all again, and you may STILL have the same boiling over. Reason? Expansion tank cap. If that's duff, it will boil over for ever.
Can't see why you don't just change the cap. No bleeding needed, cheapest AND easiest part to replace,...... AND it may just solve the problem, cos everything you have said so far points to the cap.

[chipvan]

yup got it..thanks..will change cap on monday ..waiting for delivery from mazda..

wont drive it or do anything else befor that point!..thanks mate

[haydn callow]

Steve ...you say that but.....2 weeks ago I left my Ex cap off by mistake......the first I knew about it was 3 days and many miles later when the Low Coolant Alarm went off......it was defo not/hadn't boiling......it had just been gently "steaming" away at about 85C.
Conclusion....leaving cap off/duff cap dosn't have to mean a boil over.
Coolant at atmospheric pressure still has to reach about 100C to boil

[rita]

Steve ...you say that but.....2 weeks ago I left my Ex cap off by mistake......the first I knew about it was 3 days and many miles later when the Low Coolant Alarm went off......it was defo not/hadn't boiling......it had just been gently "steaming" away at about 85C.
Conclusion....leaving cap off/duff cap dosn't have to mean a boil over.
Coolant at atmospheric pressure still has to reach about 100C to boil

Hi,
Very interesting,what engine is in your vehicle.?

Cheers.

[widdowson2008]

Hi Haydn
Last year, when I hadn't fixed the cap correctly after checking the level, mine certainly threw coolant out of the tank. Frightened the crap out of me I can tell ya. Mines a diesel. Not be doing THAT again.
Don't know if it's different on a petrol engine (yours is petrol isn't it?) which may answer Ritas question.

What you are suggesting is that it's OK'ish to run with the cap off. But I'm sure you mean it that way.

[haydn callow]

A diesel should be no differant....they do not normally run much over 90C which is way below boiling........
The only way coolant can be chucked out is if the pressure reaches 1.1 bar
The cap fails fails at below 1.1 bar but above the boiling point of the coolant....

It really shouldn't erupt past a leaky cap....just gently steam past it...

I'm probably wrong but that all makes sense to me

Defo not saying you should run with cap off....but if you do the coolant will gently steam off untill either the LCA goes off.(happened to loads of peeps) or it steams long enough for the tank to empty and air gets in and you overheat...

[haydn callow]

Thinking about your cap incident...you say it was on there but not properly....It was probably holding pressure and then gave way....that would be like taking the cap off when up to temp.....the coolant would quickly erupt due to the sudden loss of pressure.

[widdowson2008]

.they do not normally run much over 90C which is way below boiling........
The only way coolant can be chucked out is if the pressure reaches 1.1 bar
The cap fails fails at below 1.1 bar but above the boiling point of the coolant....

It really shouldn't erupt past a leaky cap....just gently steam past it...

I'm probably wrong but that all makes sense to me

Defo not saying you should run with cap off....but if you do the coolant will gently steam off untill either the LCA goes off.(happened to loads of peeps) or it steams long enough for the tank to empty and air gets in and you overheat...

90C is below boiling at 1.1bar, but at atmospheric? (which is loose cap/cap off). Not sure.
All I know is that mine DID boil over - violently. The TM-2 screamed, I pulled over, tank like bloody Vesuvius. Waited half an hour, topped up, replaced cap PROPERLY, and never had a peep since. One thing I would say here is....thanks to the TM-2 from Haydn, I was given warning before catastrophe struck.

Sorry Haydn - just read your last post.

[chipvan]

OH noo dont tell me this.I thought i was on the right tracks here !!!

2nte i bled yet again just to be sure, and fitted a new cap(ok its a blue print one )but have a mazda one on order for monday.

well i drove maybe 15+ miles,60-70 mph on open roads, round town heater off heaters on..

and level didnt go up none of the alarms went of either... .

just wonder with the old cap it stuck overnight in the cold,or maybe didnt work when cold.last night had the same thing,all ok at this point.....

I spose wait and see till the morning if all the problems start again!!but at the moment i feel i could drive 100 miles no trouble..couldnt get it to go wrong 1nte and i tried..booted it where safe to do so !! just pray its sorted....

[widdowson2008]

OH noo dont tell me this.I thought i was on the right tracks here !!!

2nte i bled yet again just to be sure, and fitted a new cap(ok its a blue print one )but have a mazda one on order for monday.

well i drove maybe 15+ miles,60-70 mph on open roads, round town heater off heaters on..

and level didnt go up none of the alarms went of either... .

just wonder with the old cap it stuck overnight in the cold,or maybe didnt work when cold.last night had the same thing,all ok at this point.....

I spose wait and see till the morning if all the problems start again!!but at the moment i feel i could drive 100 miles no trouble..couldnt get it to go wrong 1nte and i tried..booted it where safe to do so !! just pray its sorted....

Or perhaps the cap was faulty or not not screwed down. Time will tell.