100c seen twice on the temp gauge

[Merlot man]

Hello all
We are just back from a three week trip to France where we seen awful rain but also plenty of sun !
We where for some of the time in the Auvergne region , quite mountainous so lots of climbing and high reves and twice the temp alarm went off indicating 100c , I pulled over let the bus tick over to cool down a bit .
My question is how hot is it it safe for the coolant to get and still avoid damage ? Also Is there a way of allowing the scavenger fan to come in earlier and stay on later even with the key removed as I feel this would really help.
After the mountains the temp never passed 90 and all seems ok
On a side note I can't recommend the Haydn temp alarms enough , the dash gauge would not move until after 50c then raise to 11 o'clock by 75c as it got to 100c the dash gauge didn't move at all , no indication as to potential trouble
Thank in advance for all advice and insight
Brian

[mitchelln]

Which Haydn temp alarm have you got?

The TM2 and TM4 have a relay output that could be used to override the scavenger fan. Probably much more accurate than the factory sensor.

Considering doing this with my TM4. I had an annoying time at the weekend doing short stops. The alarm kept going off for 10 seconds or so when starting off again as the block obviously heats up a little bit when you switch off. If you're not stopped long enough for the temp to drop off you exceed the 100 degree threshold for a few seconds.

Triggering the scavenger fan (which has never come on by itself) should stop this scenario.

Sorry, not sure what the maximum safe temp when running is though.

[Northern Bongolow]

when climbing i would always recommend putting on the air con, this brings on the front rad fans at slow speed. there is little airflow through the rad when working hard at low road speed so this pushes air through to aid cooling. sounds like it may benefit from a new front rad, maybe an uprated one if you plan to work it hard regularly.

[Merlot man]

Thanks for the replies gents .
I have a Hyden tm2 I think , digital thermostat and a low coolant alarm , is that the one ?
If that would work it would be great ! Any idea as to how it's done
The scavenger fan seems to be very effective when it comes on it just seems to come on a bit late , I'd like it to switch on between 90 -95 c ( i e when the thermostat is fully open )
That's a good tip re the AC as I did notice the temps dropping with the AC on .
As for the rad it's about a year old fitted by the previous owner , the rest of the cooling system was replaced last May so all should be good there .
do you know of any company doing an up rated rad for the bongo as this bus with hopefully be going to these areas in the future . also is there an up rated coolant fan I can fit to these ?
After the mountains and now at home temps don't pass 92c .
Sorry for all the questions and thanks for the replies
Brian

[mitchelln]

If it's LED it's a TM2, LCD it's a TM4. Here's my TM4:


I think you can add a relay to the TM2 the same as a TM4 and set a temp for it to activate:
http://www.coolantalarm.co.uk/shop/inde ... oductId=27

Just need to work out the scavenger fan wiring. I'm sure someone here will know!

[haydn callow]

100c is fine when the beast is working hard.....I would reset the alarm to trigger at 105c....110c will not do any harm...anything more is risky.
This is providing you have the sensor in the recommended position

[Merlot man]

100c is fine when the beast is working hard.....I would reset the alarm to trigger at 105c....110c will not do any harm...anything more is risky.
This is providing you have the sensor in the recommended position

Thanks for that reply Haydn that is reassuring re the temperature limits , either way is it possible , like Mitchelln said , to wire up the scavenger fan to switch on using the tm2 ?
Brian

[haydn callow]

Yes, it's possible but don't ask me exactly how.....MIke has fitted a over ride switch which is a simple worthwhile mod.

[mitchelln]

I've just ordered the fan override kit for my TM4.

Once I've worked it all out I'll create a fact sheet.

Hopefully it shouldn't be too hard as Bongo electrics rely on grounding things to activate them.

It's at that point I'll probably find my fan is dud It's definitely not coming on at present even when the housing is 90+. Of course, it looks like the sensor is in a different place on the 2L petrol...

All in all, the TM4 should provide a nice reliable adjustable method of triggering the fan.

[teenmal]

I must be missing something here,why modify the scavenger / engine bay fan to cool the engine when the vehicle has a more efficient coolant cooling fan ,its the coolant that needs to be controlled more than the engine bay area.

[g8dhe]

I have to agree! Its always bemused me that people believe that the scavenger fan will cool the engine significantly, it doesn't it removes the hot air from the engine housing, normally when your static and the normal airflow is pushing air thru all is fine, when your static the heat from the engine fills the housing and heats the seats and handbrake up, but its a very small amount of heat compared to what is removed via the radiator!

[teenmal]

Peeps tend to forget that these old vehicles are WATER COOLED and not AIR COOLED , the same goes when monitoring the engine running temp ,car Manufacturers / Designers monitor the Coolant (WATER)Temperature NOT the engine block Temperature.

By all means make sure that the Scavenger/engine bay fan is working as it should doing the job that it was intended to do IE "Scavenge"

[mitchelln]

I'm very much coming at this from the angle of cooling the engine bay area, not the engine directly.

The TM4 sensor is attached to the block and is indicating >100 degrees after switch off sometimes. I just want to drop that to avoid things above heating up. It can't be good for things like wiring either. As it stands, my scavenger fan never comes on and TM4 alarm goes off.

[haydn callow]

Peeps tend to forget that these old vehicles are WATER COOLED and not AIR COOLED , the same goes when monitoring the engine running temp ,car Manufacturers / Designers monitor the Coolant (WATER)Temperature NOT the engine block Temperature.

By all means make sure that the Scavenger/engine bay fan is working as it should doing the job that it was intended to do IE "Scavenge"

Much better if you can get a sensor into the coolant....but most peeps would not be prepared to attempt this.......so the diy alternative is to put a sensor on the cylinder head and note what temp is normal for that situation....then if anything untowards happens you can be warned in time to prevent overheating......as long as the sensor is in a half sensible position this works....it really doesn't matter what temp reads normal, what you need warning about is the abnormal

[mitchelln]

Very much so Haydn. The TM4 is excellent and accurately shows me what the "normal" parameters are. Currently with it all working right, it displays between 88 and 91 degrees (same as Radio 2 FM ). The radiator fans kick in on the dot at 93 degrees. So anything outside this will indicate something is not right.

The adjustable TM4 relay output is just a bonus - I can accurately trigger the scavenger fan to lower the engine bay temp if it gets high. For me, this happens primarily when starting up after a short hop.