Bongo Fury

finally got round to changing my stat as it seemed to have stuck open ( max temp reaching only 55' on TM2) was going to use loal Bongo garage but the bad weather in December put paid to that.

anyway gave it a flush as i didnt know what antifreeze was in it changed stat (must remember water still in bottom hose next time. )

refilled with Comma red and bled as per videos as far as i can tell all air out (bottom hose was hot kept see sawing for a few more minutes until no more bubbles, blocked bleed pipe cap back on expansion tank, left it idling while i refitted underpan, turned off and left it to settle for half an hour then took it for a long run. are these temps about average.

temp whilst bleeding got to about 87' on the TM2 fitted at rear of engine
when for the drive mixture of between 30 to 50 mph temp rose to 92' to 94'
then took it along the bypass 60-70 mph temp maxxed at 95'
from what i can remember it only used to get to about 87' before but it did get to 99' on a really long run to staffs on holiday.

Temp gauge on dash sits a slightly to the left of 12 o'clock i think it sat a little further left before.
are my readings about average realise different areas may produce difernt readings

will check levels in the morning, should i remove the bleed bung the check for any trapped air which may have settled during the night.

many thanks to all those who may answer

Was the atat easy to change cos that is on my list of jobs to do.
Stuc

a bit fiddly. you're best using ramps as you need to take the undertray off to get at the stat housing bolts X2. 1/4 inch socket set is best with extension bar, one other bolt fixing dip stick tube to housing need to be undone so use can twist lower housing around other pipes, there will be water left in the rad pipe, so dont lay underneath it.

other than that not too bad you will need help to bled the system. unless you can extend the bleed pipe so you can hook the funnel somewhere round the front so you can keep an eye on it whilst you fill and massage the pipes. give yourself all day started mine about 12pm finally finished 16.30, had to use torch in teeth to refit undertray

sounds like you've had a busy day .
did you get the bottom hose hot--not just warmish. if you did the stat will have opened,and it will have bled ok.
dont forget that the tm2 on the head is the head temp, so the readings may be slightly higher as the motor has ben running for a long while. see what the temps are like tomorrow when you drive it normally.
there isnt a set temp for a bongo,so these temps are probably fine.
has it had a new rad,or new pump,or are they age unknown.all these things affect the readings.if changing the stat i usually replace the temp sender and the fan switch with gen parts just to rule out dodgy readings from these components.

yes bottom pipe did get hot, wife was doiing the funnel end off things, kept see sawing until all bubbling stopped, had a few fine bubbles which i put down to cavitation by waterpump, definitely no proper bubbles so to speak.

maybe stat was on its way out when i got it, one thing i did notice was on the new stat it had a wobble pin, the old stat had a hole drilled in it ( not a factory punched one but drilled some damage to the inner rubber, so an amature job me thinks)

aaaaahhhhhhhhhhh! that explains a little something!!maybe.
did you clean the top port in the top of the thermostat housing.???

Darkstar wrote:
maybe stat was on its way out when i got it, one thing i did notice was on the new stat it had a wobble pin, the old stat had a hole drilled in it ( not a factory punched one but drilled some damage to the inner rubber, so an amature job me thinks)

Your original stat probably wasn't opening properly, or maybe not at all... Drilling the stat is a bodge that renders the stat useless at it's job, except it plugging the hole! When a stat is drilled,the temp gauge tends to show a lower reading, and you probably found the heaters not particularly good. You now seeing higher readings is perfectly normal now that a proper stat has been fitted, because now it should be doing it's job! Hopefully, whoever drilled your old stat did it simply because the stat wasn't opening. It beggars believe though... Why go to all the trouble of removing the stat, drilling it out, then re-fitting it? They may as well have simply fitted a new one! That's where i become suspicious.... Often a stat is drilled because the bongo won't bleed up, this is indicative of a failing cylinder head gasket. Even if the person who originally drilled the stat out didn't have the first clue about how to bleed the bongo,it's not really on to re-fit a modded stat. Maybe originally there was a huge airlock, (drilled stats helps promote the system to bleed)OR... (and i hope not) the CH gasket was/is failing and was taking in more air than the bongo can self bleed. Let's assume it was originally an airlock. Just make sure you manually check the level of coolant before you start the bongo up, don't be alarmed to see the level has dropped,that is perfectly normal. Coolant expands at different rates depending on it's ratio/brand of coolant etc etc. In a fully bled bongo the amount of coolant shown in the tank shouldn't alter that much whether it's hot or cold (1/4 inch maybe?) If you discover the level is nearer the "MIN" mark, that means that more air has escaped post bleed, (a good thing) As a precaution, it'd be wise to carry some pre-mixed coolant around with you in the bongo, and i'd personally check the level daily (for the next week or so at least).

Northern Bongolow wrote:aaaaahhhhhhhhhhh! that explains a little something!!maybe.
did you clean the top port in the top of the thermostat housing.???

No, did'nt even think about it, what are the concequences of not cleaning it??

There are 2 schools of thought on the subject of cleaning the stat housing.....The stat is not a machined fit into the housing and the bit that does the closing (the bit that moves up on the top of the stat is a bit of pressed steel) will never be a perfect seal under pressure. Therefore,,it is doubtful if cleaning this housing surface is of any benifit..(unless the housing is full of crud etc)
(and anyway the stat dosn't totally open very often)

Also when you fill with new coolant and as far as I understand it, Comma Long Life Red in particular...when first put in the system it deposits a protective "layer" around the cooling system to help protect it from cavitation bubbles etc from damaging the metal surface (around the water pump and stat) cleaning this area would remove this layer....

You say you have put new Comma Coolant in......If you have a Low Coolant Alarm fitted it may start playing up after a week or so.....this will be because the protective layer mentioned above will have coated the sensor screw in the header tank.....just remove the screw..clean..replace....the coolant only lays this layer down the once...


Those are my thoughts on this subject !!

thanks for the info on cleaning stat Haydn, i wont worry too much, water level did drop overnight, did'nt show on my indicator ( i use a clear straw so i can keep an eye on colour,)

the antifreeze is Comma X30, not sure if this is the same as Comma Red, though it might be as it was red

anyway bus gets warm in no time now, ready for the next ice age.

thats one line of thought haydn,and it is of couse correct, but if the cooling system has been neglected for some time,and the coolant hasnt been changed for a while,the floating solids present in the old coolant get squashed and pressed by the stat as it trys to open fully,this gradually builds up an uneven layer on the port as the flow is from one side. this seriously restricts the stats ability to close the port properly.
to clean the port is probably over kill,but the port must be flat and parallel to the stat top to do its job well.

i did give the engine an engine flush and no discolouration came out with the flush when i emptied the system, the old thermostat looked clean with no crud on it, so hopefully i got away with it this time, will remember to check at next change, all the pipes i could reach were flexible and not hard when i squeezed the during the flush. so no scale build up.