Calling those with modified temp gauges

[adscatt]

I have finally got round to carrying out the mod on the temp guage recently. Driven round town a few times and the needle stays at approx 75% (using the scale of 0% being the start of the white arc line and 100% being the end of the arc before reaching the H block) Drove on the motorway today approx 70mph for 18 miles and in stop start traffic for about 20mins and about 27'C ambient all with AC on, the guage frequently reached 100% then dropped back to 80%, never reached the H block. Does this sound about right for a modded guage?

I have no reason to believe I have a problem after about 2000 miles since owning from april just curious.

Thanks

[Steptoe]

Using the same criteria, mine normally sits around 10%, dropping back to below the 'C' block if coasting down a long hill with little throttle, and climbing to 20-30% on motorway hills. Climbing up long steep hills I can get as far as 75-85%, and when towing a loaded trailer up the same long steep hill, I was a bit concerned to be approaching 100%, but it didn't boil over and soon cooled down after reaching the top (I bled the system again following this, but it all seemed OK - have since replaced the water pump as it had been leaking at the time).

Yours sounds a bit high to me - did you use a 100 ohm resistor and bypass the diode?

[Northern Bongolow]

as the gauge works by splitting the voltage (half down one of 2 legs then measuring/reading the difference) it sounds like you may have a broken wire, this can happen when refitting the gauge into the pod if you over tighten the screws one of the posts spins breaking one of the very fine wires.

[adscatt]

Yours sounds a bit high to me - did you use a 100 ohm resistor and bypass the diode?

Yes, bypassed the diode and fitted 100 ohm resistor, going off the fact sheet for the mod the gauge doesn't move til 75'c which sounds about right for mine now and then at 80% sweep its at 100'c sounds about right, looking at the factsheet again it could indicate my radiator is becoming blocked hence the higher temp cruising up a steady incline.

More monitoring and testing needed I think.

Pretty sure I didn't overtighten the screws as would this not result in the gauge rising swiftly to H or staying on C?

[cmm303]

Higher than mine. Once warmed up my min reading is 60%, hottest reached is 90% and always drops quickly back to %75 once over brow of the hill. Sitting in traffic never gone higher than say 80%. (I recall two resistor values were suggested and I used the value that read lower requiring non-standard resistance so paralleled two resistors)

[Simon Jones]

I've got a Mason alarm which also removes the damping on the gauge although I don't know what value resistance is used. Mine seems to match the findings of cmm303: 60% normal and goes up to around 85/90 at which point the fans come on and bring it down to 75. If driving at night when the air temp is much lower, it can drop to about 50% but never any less.

[adscatt]

Thanks for your feedback people, I'll monitor over the next few journeys, yesterday was very hot here, also not used any coolant in the 4 months I've owned our Perry.

[the1andonly]

see additional info
http://igmaynard.co.uk/bongo/forum/view ... 42#p608475

Iv'e modified mine with a 100ohm res from maplin as mike w with add mod. It runs on the warm side (2/3 scale) as normal.
when towing uphill (serious hill 1st gear North wales 4 hr trip) it frightened the sh1t out of me hitting the H but at top on going downhill soon temp went down with no load. This is too frightening for me, 110/120 ohm maybe more appropriate.
but at least you can see a change.
since added 10 ohm in series still moves on load but a significant gap to the H, not quite so worrying. Also added a cheap temp gauge with sensor on head water stub at front.

[silvern]

I have finally got round to carrying out the mod on the temp guage recently. Driven round town a few times and the needle stays at approx 75% (using the scale of 0% being the start of the white arc line and 100% being the end of the arc before reaching the H block) Drove on the motorway today approx 70mph for 18 miles and in stop start traffic for about 20mins and about 27'C ambient all with AC on, the guage frequently reached 100% then dropped back to 80%, never reached the H block. Does this sound about right for a modded guage?

Thanks

Mine used to behave exactly like this. It was only after I had a new rad and water pump that I noticed it ran cooler. It now sits at 25% most of the time, sometimes going up to 75% but never higher than that. Can only assume that the old rad was pretty sludged up and flow was not too good. Was probably like that for a few years until the rad sprung a leak and I had the work done.

[cmm303]

Higher than mine. Once warmed up my min reading is 60%, hottest reached is 90% and always drops quickly back to %75 once over brow of the hill. Sitting in traffic never gone higher than say 80%. (I recall two resistor values were suggested and I used the value that read lower requiring non-standard resistance so paralleled two resistors)

Confirming I used 110 ohm (made from 2 x 220ohm in parallel)

And based on the fact sheet and Silvern's comment, its prob running a bit hot. Maybe a rad flush? I would need to learn the bongo bleeding ritual!!

[adscatt]

Once again, thanks for your time replying, drove Perry again today, gauge sat at 60%, rose to about 90% then dropped back to 60%, no motorway involved today and very similar ambient temps as the other day, still thinking I have a contaminated radiator, think I'd best start looking into a replacement rad!

[Simon Jones]

Gauge going up and down is a sign that the thermostat and fans are working. Mine goes up to about 90% then 'stat opens, fans come on and it drops back down to about 70% in a matter of seconds.

[adscatt]

Thanks Simon, its looking like my cooling system is working, perhaps just a little tired, will look at my options of 110 ohm resistor or a cooling system overhaul. I've got a few jobs planned for it over winter, perhaps the cooling system has now been added to that list

[adscatt]

Sorry to resurrect an old thread but there's nothing worse than searching for answers on a forum only to find your exact issue but without a resolution.

So removed the radiator, emptied, lay flat and poured in boiled water until full, as suspected it had cold spots (blockages). New rad required.

Removed thermostat, in a bowl of boiling water it opened but only by about 2mm, new one in a bowl of boiled water and it opened several mm's.

Fitted both new components and now we have a lot lower reading on the gauge, more conventional and expected readings.

Really glad I modded the gauge as without that our Bongo would be cooking itself every journey, thanks again everyone for your input.

Bring on the adventures!

[Simon Jones]

Good news. Neat trick about filling the rad with boiling water to test it. I've got an infra red digital thermometer which which would be perfect for the job.

It's always worth testing a new thermostat against the old one in a pan of boiling water. I found new one opened faster, further and closed slower than the original one. That way, you have peace of mind that such a vital component is doing it's job.



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