Overheating Issue

[GICarey]

Hi Mike,

We've got a new waterpump on there, garage did it (again without my asking / being asked), so pretty sure we do. Head gasket is what i'm wondering, entirely possible that tests didn't pick it up I suppose.

Can a head-gasket problem be intermittent? i.e not rear its head for 200km+ then suddenly be back again? Similar question, could I have a pinhole leak somewhere which is sucking air into the system when cold and making a bleed necessary over & over?

[scanner]

I'd get it recovered to somewhere that knows what's what and can diagnose the problem instead of just making wild guesses and swapping stuff out "just to see if it cures it".

[mikeonb4c]

I'd get it recovered to somewhere that knows what's what and can diagnose the problem instead of just making wild guesses and swapping stuff out "just to see if it cures it".

Quite right. The problem is of course that the garage are the ones who appear to be doing this, not us, and not Gav.

[GICarey]

Howdy,

Well, currently still stuck 100 miles from home, but at least in the comfort of parents home with ready supplies of tea and sympathy, and also a step-father who knows his way around an engine and isn't afraid to follow fact-sheets....

We've just drained, refilled and rebled the cooling system again, following Mikeon4bcs notes and the coolant fact sheet throughout, bottom hose getting nice and hot (as hot as the top hose into the rad), observations whilst doing so (appreciate "that's normal" or "that's odd" comments as appropriate):

* Whilst idling to warm up, water (cold then warm then really quite warm...) will intermittently run out through the header tank, and spurt out of the breather hose (which I had hanging from some wire on the "pull yourself in" handle above engine/header tank height).
* every now and again the header tank level would drop quite dramatically from the situation above, requiring really quite a lot of hose pressure to keep the header tank full.
* am assuming that key point here is to keep above the two hoses into the header tank, to avoid introducing new air into system
* During the "rev to 2500rpm for 6 mins" period, after a minute or two, we had a pretty much full on stream of hot (slightly rusty looking - suggesting perhaps not a full drop, flush and refill buy the garage?) water gushing its way out of the bleed hose, difficult to tell given the velocity, but appeared to have quite a lot of small bubbles in it initially, and fewer towards the end of the 6 minute period. Whilst this stream was being generated, once again, had to work pretty hard with the hose to keep the header tank topped up.
* Cooling fan didn't cut in except for about 20 seconds during the final "3 min idle", where it did so for about 20 seconds. Instructions to the letter say to shut down and start again when cool if this occurs - something to worry about at this late stage in the process? or just one of those things when the cars been running at a highish number of revs for so long?

Finished the process (5 mins or so at 2500rpm with bleed bung and header tank cap on), 3 min idle, 5 x 5 second 2500rpm blips) with header tank level sitting around the flange.


Throughout all of this, the temp guage sat at 11 o clock, as normal, and I clambered under the car to check the rear heater matrix was nice and hot, as were the pipes in and out of it.


So, now, waiting for it to cool, check levels, then get in it and go for a bit of a run to see how it fares. If ok, will reload the misses, and the dog, and attempt the 100 mile slog home. If anything goes awry on the way, Green Flag will get us there eventually I'm sure.


Cheers,

Gav.

[GICarey]

I'd get it recovered to somewhere that knows what's what and can diagnose the problem instead of just making wild guesses and swapping stuff out "just to see if it cures it".

Totally agree, said local garage shant be seeing the bongo any more (nor any future car I may own), any futher issues and i'll be off to AGS in Biggleswade, even if i have to pay to get it taken there, as they're on the "club approved" list.

[mikeonb4c]

Fingers crossed for you Gav.

Rusty water is indeed interesting, as is the rad. fan coming on. As scanner says, it needs the judgement of a specialist. Not heard talk of AGS - double check they are indeed regularly working on Bongos as that's really what you want. A pity Discount Trucks, Newbury aren't nearer for you.

Very sorry you are having so much trouble. Total bummer.

Mike

[scanner]

Throughout all of this, the temp guage sat at 11 o clock, as normal, and I clambered under the car to check the rear heater matrix was nice and hot, as were the pipes in and out of it.

If it hasn't been modified by fitting a "Mason Alarm" that is all it will do across a large temperature range - it will only rise higher than that after quite a large temperature rise.

The standard gauge is not linear in it's read out and cannot be relied on to indicate an accurate temperature reading.

[haydn callow]

you had a good flow of coolant coming out of the bleed hose and had to "work hard" with the hose to keep up..I would be worried about all that cool water going in and "shutting" the thermostat.
Personally I put the bleed hose "up" into a large funnel (a plastic bottle with the bottom cut off will do) and then by raising / lowering the funnel you can keep the header tank level steady.
Just ensure that at no point does the funnel become empty nor the level in the tank drops below LOW.

[haydn callow]

Th"rusty" water was probably even more "crud" being disturbed by this most recent overheat. No amount of flushing will do the job as well as a good "boil up"

[scanner]

Also don't run it for any length of time on plain water - they must have the correct concentration of coolant containing corrosion inhibitor in the cooling system NOT just plain water.

[GICarey]

you had a good flow of coolant coming out of the bleed hose and had to "work hard" with the hose to keep up..I would be worried about all that cool water going in and "shutting" the thermostat.

Yeah, this was our concern at the time also, but short of boiling up a few kettles, weren't sure what else we could do.

Personally I put the bleed hose "up" into a large funnel (a plastic bottle with the bottom cut off will do) and then by raising / lowering the funnel you can keep the header tank level steady. Just ensure that at no point does the funnel become empty nor the level in the tank drops below LOW.

Ah, good idea.

Also don't run it for any length of time on plain water - they must have the correct concentration of coolant containing corrosion inhibitor in the cooling system NOT just plain water.

As scanner says, can't run the system with just clear water for long, so I expect to have to go through this whole thing again in the not-too-distant future (probably the weekend after the bank-hol) having dropped the water, and refilled with a good 50/50 mix, we'll try the funnel method when we do that (as I was concerned as to quite how much coolant I'd need to buy to finnish with a good 50/50 mix when jetting it down the driveway at fairly high speed during the bleeding procedure.

Any further tips on performing this process beyond those in the various fact-sheets (coolant, water-pump, radiator all read), and mikes type-up from the workshop manual, greatly appreciated.


Regards,

Gavin.

[GICarey]

Th"rusty" water was probably even more "crud" being disturbed by this most recent overheat. No amount of flushing will do the job as well as a good "boil up"

Provided it's only the crud which is disturbed, and not the head/gasket...

[scanner]

As scanner says, can't run the system with just clear water for long, so I expect to have to go through this whole thing again in the not-too-distant future (probably the weekend after the bank-hol)

Seriously - I wouldn't even run it that long, the inhibitor is what stops the alloy corroding/eroding and I've been told it doesn't take long at all for enough to flake off to start to block the rad.
I've had Hillman Imps in the past and a pal had a TR7 that both suffered from serious overheating problems after running for only shortish periods on neat water. They were all alloy engines, not just an alloy head like the Bongo, but you don't want to tempt fate.

I think a lot of Bongo problems could probably be traced back to either running on neat water or mixing incompatible coolants.

[GICarey]

Seriously - I wouldn't even run it that long, the inhibitor is what stops the alloy corroding/eroding and I've been told it doesn't take long at all for enough to flake off to start to block the rad.

Sadly I might not have too much choice, work eats up all the daylight hours for me at the moment. If it were a 5 min job i'd get it done one evening this week, but it's gonna need a proper bleed again, which was clearly a 2/3 person job, and took a couple of hours to complete yesterday, might be able to do it on the bank-hol weekend if I'm lucky.

Unlikely that el-Bongo will get much use over the next week or two though - not sure if that's a good, or bad, thing with it just containing plain ol H2O?

[mikeonb4c]

Seriously - I wouldn't even run it that long, the inhibitor is what stops the alloy corroding/eroding and I've been told it doesn't take long at all for enough to flake off to start to block the rad.

Sadly I might not have too much choice, work eats up all the daylight hours for me at the moment. If it were a 5 min job i'd get it done one evening this week, but it's gonna need a proper bleed again, which was clearly a 2/3 person job, and took a couple of hours to complete yesterday, might be able to do it on the bank-hol weekend if I'm lucky.

Unlikely that el-Bongo will get much use over the next week or two though - not sure if that's a good, or bad, thing with it just containing plain ol H2O?

Did you get back home OK? (assume so). I wonder if just siphoning off as much header tank water as possible and replacing with 'anti-freeze' might not be simple and provide a measure of protection until the job can be done properly?