Bongo Fury

I had a Low Coolant Alarm squawk a couple of weekends ago as I started up to leave the Southern Softies meet after visiting for the day, put about quarter of a litre of coolant back in & set off, keeping a beady eye on temps & ears & nostirils open for anything amiss (although I did have a bit of a race with a boy racer corsa ) It was running a bit hotter than normal, but not over heating even at ever so slightly illegal speeds, (just wanted to see what was going on & if it would cool down better if I went faster - honest ) The Mason was beeping at me (mine is set to go off just before the fans kick in @94 at the top hose, just over halfway between 12 o clock & the end of the scale - Mason modified ) & didn't really stop, until I got down to below 50 on the flat, any load on the engine was setting it off again.
I had already found a couple of weeps from the hose connections the week before & thought I'd sorted it, but obviously not got it home, checked it the next day, no level drop from the night before, no sign of any leaks, so set off back to the softies as I hadn't managed to catch up with every one I wanted to, made it there & back ok, it did feel a bit sluggish & not quite "right", still running a bit hot, didn't seem as bad as the night before.
A very kind Northern Bleeder sent me down his pressure test gizmo http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=38823 as I hadn't got around to making one, put it on the header & instantly found two trickles & 3 weeps from hose connections I've lost count of the number of weeps I've had with the silicon hose connections that seem to have started since the really cold snap, getting fed up with it now (I now know that they should be fitted with constant pressure clamps, not standard - even good quality - jubilee clips.)
I was hoping that would have sorted the issues once I gave it a good bleed, (lots of air out) but it was still running a bit hot & still not quite right, I was also just picking up an almost subsonic squeal after 2000rpm
I fitted a digital temp gauge to the top hose to see if it was temp sender issues & it was running in the low 90's which I wasn't very happy with, so I ordered a Mazda stat. While I was waiting for it to get here I was trying to get some temp readings using an IR thermometer jobby, when I realised there were exhaust fumes in the engine bay, had a look around & there was nothing showing on the exhaust manifold, then noticed soot on the turbo & investigation revealed this -





The bolthead had gone completely (found it on the undertray later) & the bottom of the bracket was hanging free allowing this to happen



Stuck a new bolt in, pulled it back into positon & clamped it up again, all cleaned up, along with all the air inlet pipework & anything else that was grungy, all seems to be ok



Mazda stat arrived this morning, so took out he blueprint one (about a year old) pan tested them both, I've got to say the blueprint one seemed to be repeatedly opening a tad earlier than the Mazda one, BUT, it wasn't opening as far as the Mazda stat at boiling point (supposed to be 9.5mm+ at 95 degrees - YOU try getting it to sit at 95 degrees ) but there really didnt seem to be too much in it to be honest. I was hoping for a "Eureka" moment at that point & was a bit disappointed.
Fitted the Mazda stat after checking the recirc seat in the top of the stat housing was clean & not worn, took out the temp sender & fan switch & wire brushed the internal bits 'til they were back to bare metal (they weren't too bad though initially) filled it, bled it up really easy, did a quick pressure check & bu66er me, one of the bottom hose connections was weeping again, tried to tighten it up, & the jubilee clamp gave up (I wasn't overtightening - honest), luckily found a spare one, checked it again, found a couple of tiny weeps on the heater hoses, nipped them up, & then it was finally holding pressure, quick bleed to check no air had been introduced, then took it for a test drive.
I wasn't convinced it'd be any better as the stats didn't seem that different in operation, but it was noticably different, it wouldn't go above @ 87degrees on the top hose, it was controlling nicely between 83 & 87 even up Abbotsbury hill which is a nice big 1 in 5, where it had been mason alarming at me a few days before, it was now hovering around the 12 0 clock mark on the temp gauge. It also had lot more "go" thanks to the turbo being sorted .
So if you're running hotter than normal, check for leaks, pressure test the coolant system & I know it's been said before - fit a genuine Mazda stat.
If you're hearing a really high pitched almost subsonic whistle ( I wondered why I had a pack of dogs chasing the bongo) & it isn't the exhaust manifold gasket, have a quick check on that turbo clamp, haven't heard of it going before, but it's not an easy or obvious one to spot.

Very interesting Kirsty, the failed Turbo clamp is likely to happen again to others as the bolts age and fatigue due to heat cycling, so well worth highlighting.

(Maybe yours was one of the first due to the 'lively' way you enjoy your Bongo? )

As for the leaky hose connections, it does look as if the silicone hoses may be hard to seal, it might be an idea to try 2 clamps side by side on the connections, I used to make up pressure assemblies for Fire Brigades and this technique was needed for some applications.

I suspect the basic issue is the wall thickness of the silicone is higher than the OEM, this then reduces the clamping pressure at the joint, if anyone has access to both, I would be interested to get a comparison between both types.

As a Marketing thing, getting a thicker hose looks 'stronger' and 'better', but the hose has to work as part of a system, which it looks as if the silicone ones are struggling with.

Thanks again for your comprehensive reports, they help more the knowledge base onwards and upwards!

Being honest, I can get a bit bored with reading this forum. And then a really juicy report like this comes in, and suddenly I'm lapping it up. What an excellent write up Kirsty (complete with pics)

I've never looked really closely to the turbo before i gotta admit kirsty... I take it the damper saved the day by helping to keep the turbo in place? I'm just glad the bolt/bracket didn't fragment and find it's way into the vanes!

Interesting point you made regarding the silicone hoses, If i remember correctly, didn't i source you the hoseclips luv? They are the same type/source (batch number?) as the clips fitted to my bongo... I had one of the clips that needed nipping up after 500 miles or so of fitting (maybe a turn and a half?) But they have all held up well with no leaks since then (couple or so years ago?). I wonder why you've had leaking issues with the same hoses, same clips, same vehicle and age, but i've (thankfully) not?

I'll be keeping an eye on em now for sure though!

Regarding the ram air effect... I find that 95MPH seems to keep the bongo cooler, i definitely run a higher temp even at a steady,even 56MPH! Slightly lower at 65.

Hi
Munroman...
What I have seen with the silicon hoses, is that in sub-zero conditions, the type of silicon used in these hoses seem to lose resilience below a certain temperature, as the weeping I have had below minus 10 last winter, was more than previous winters with rubber hoses in the same conditions. The spigot on which the hose sits seems to shrink, and the hoses "stay put" , to a certain degree, even with the Mazda spring clips, as rubber itself age-hardens to the point when it no longer operates in an elastic manner after the length of time most Bongo hoses have survived. Every winter in England, I lost a tiny amount or coolant, and here, because of the lower temperatures, it has been a bit more....even taking into account that the mass of fluid in such a large cooling system contracts a fair bit. This is noticeable from day to day sometimes....Fill the Expansion tank to the mark...next day, same engine block temperature on the TM2, and it's up to the same mark...following a good storm, and the ambient temperature drops 10-12 degrees, and the coolant is a couple of millimetres below...next day, return to normal temperature...bach to the same mark, but in winter, it is anything up to 65 degrees lower than summer heat...so a BIG decrease, and taking this into consideration, the fluid lost in weeping is not as much as imagined!....BUT, yes, there is a small seepage.
Back to silicon...I actually find that at 20 celcius and above, the silicon hoses seem more pliable than rubber in some respects, as I've just replaced the heater hoses, and, no criticism here, they seem slightly "free" pushing some of them onto the metal pipes, but they tighten down well, even with the crabby quality clips available in Eastern Europe, where everything seems to be made of melted-down Ladas ...I am sending to England for proper clips!!!! ....
So, I think the problem is more temperature-related than material...and The UK has had some chilly old temperatures last winter.....I think it's more like "ChecK Thy Clips", as you say...and buy Good-Uns, having lashed out on good new hoses!!!!...I must admit to not having good clips, but here there is a choice...bad or worserer
Cheers
Helen

Hi
Kirsty...
Aha...turbo leaky ....I'm out to check mine tomorrow....I have been getting the odd niff, but put that down to the local's propensity for burning plastic beer bottles on their bonfires....EEeee it don't arf pong after a bank holiday here....so...I'm jotting myself a note to check that tomorrow ...It's raining at the mo. after a good storm the other day......I was fighting with the dog for a place under the dining room table
Cheers
Helen

Excellent, interesting write up to the point. no bull, and pics too - but having thought about it, wouldn't have expected anything less from Kirsty

What a fantastic write up as usual Kirsty complete with great pictures, WELL DONE
BY THE WAY, HOW MANY HOURS ARE IN YOUR DAYS !! Dont know how you do it.
Must be them kirsty energy crabbie drinks.

great stuff.strange init,the stat stuff.
but now which gave the decrease in temp in your oppinion,stat?temp sender clean up.or fan switch clean up or just a air tight system well bled?

Mazda stat - simplez. The fan switch doesn't really come into it unless temps get extreme, temp sender is irrelevant to a point as I fitted an extra digital temp gauge at virtually the same point which showed the temp drop due to the stat.
It's not about the stat opening temperature so much as the temperature it reaches the point where the top disc shuts off the recirc forcing most of the coolant around the rad for max cooling.
playing with engine revs (thus controlling waterpumpflow) vs speed driving to Bristol & back last night, I could dump 4-5 degrees when it got to the top end. Max I could get it to on the top hose stub temp was 88 (where it had been going up to 93ish) which was after really pushing it up a hill then letting revs drop right back down in auto so the coolant flow was slower, then drop into S & maybe hold aswell to bring the rvs up to 2500 & 3000rpm & the temperature only took a minute or so to fly down to 83 -84. Not sure if this will happen with everyone's as I don't know what state my waterpump is in & my rad is still original (but seems to be cooling okay & has been flushed & doesn't seem to have any cold spots).
Smiles per mile driving to Bristol & back - priceless (especially with 2 leccy bikes picked up too), I reckon that turbo clamp had gone a while ago (especially by the rust on the head that I found.
To answer BDC's concerns on shrapnel being sucked in at that point - it ain't gona happen as that's the exhaust side ie under pressure as can be sen by the soot that was blowing out all over the turbo.
The jubilee clips, are good quality, BUT IMO they are not designed to the job they are doing on the silicon hoses (ie expansion & contractiong etc), borne out by several peoples issues, especially since this winter (whether the extreme cold was the issue or the age of the hoses, but some of those had only been on 6 months, so I suspect the former TBH).
I'm not pointiong any fingers or laying blame, just highlighting it as an issue to anyone that has them fitted to check, preferably with the coolant system pressure check, especially if you're having to top up at all, because that means your system possibly isn't holding pressure as it should (despite the risks of dumping coolant, airlocks etc) & therefore may not be running right temperature wise.

missfixit70 wrote:Mazda stat - simplez. The fan switch doesn't really come into it unless temps get extreme, temp sender is irrelevant to a point as I fitted an extra digital temp gauge at virtually the same point which showed the temp drop due to the stat.
It's not about the stat opening temperature so much as the temperature it reaches the point where the top disc shuts off the recirc forcing most of the coolant around the rad for max cooling.
playing with engine revs (thus controlling waterpumpflow) vs speed driving to Bristol & back last night, I could dump 4-5 degrees when it got to the top end. Max I could get it to on the top hose stub temp was 88 (where it had been going up to 93ish) which was after really pushing it up a hill then letting revs drop right back down in auto so the coolant flow was slower, then drop into S & maybe hold aswell to bring the rvs up to 2500 & 3000rpm & the temperature only took a minute or so to fly down to 83 -84. Not sure if this will happen with everyone's as I don't know what state my waterpump is in & my rad is still original (but seems to be cooling okay & has been flushed & doesn't seem to have any cold spots).
Smiles per mile driving to Bristol & back - priceless (especially with 2 leccy bikes picked up too), I reckon that turbo clamp had gone a while ago (especially by the rust on the head that I found.
To answer BDC's concerns on shrapnel being sucked in at that point - it ain't gona happen as that's the exhaust side ie under pressure as can be sen by the soot that was blowing out all over the turbo.
The jubilee clips, are good quality, BUT IMO they are not designed to the job they are doing on the silicon hoses (ie expansion & contractiong etc), borne out by several peoples issues, especially since this winter (whether the extreme cold was the issue or the age of the hoses, but some of those had only been on 6 months, so I suspect the former TBH).
I'm not pointiong any fingers or laying blame, just highlighting it as an issue to anyone that has them fitted to check, preferably with the coolant system pressure check, especially if you're having to top up at all, because that means your system possibly isn't holding pressure as it should (despite the risks of dumping coolant, airlocks etc) & therefore may not be running right temperature wise.

Wow - you got both the bikes then. We expect a full road report in due course (I got out on mine on Saturday for the first time in months - very handy things).

Is there anything wrong with using the old clips on silicon hoses? I due to replace the main four hoses this week....along with a new rad (again ) and a genuine stat.

by the old clips,do you mean the original mazda clips that are fitted as standard?
some research needs to be done on this imo,as to my knowledge no one has yet done this!
the silicone hose walls appear thicker so the clips may need to be slightly bigger od to allow for the temp/expansion.or the sidewalls may crush down enough for the clips to work through their normal expansion range.
anyone out there done this yet?

If the silicone hoses are thicker, this will reduce the clamping pressure on the joint with the spigot, making leaks more likely.

The extra thickness of material will dissipate the pressure within the hose.

As Silicone rubber is the expensive part of the cloth the hoses are made from, it is not unheard of for a thicker cloth and a thinner Silicone coating to be used, but again the thicker cloth reduces the effect of the hoseclips, and there is less rubber to 'flow' to make a seal with the spigot.

If some peeps are having problems whilst others seem ok, it may be that there are different constructions of Silicone hoses on the go.

thanks for that info on the tecky aspects of the hose/clip.So its either standard hose construction and standard clip,or silicone hose and constant pressure clamps is it.