running temperature

[salexander]

My new gauge seems to be working nicely, a great relief to know exactly what's going on!
Only problem is that the engine seems to be running quite cool. Takes quite a while to get up to temperature - in traffic it's around 80-81 and going up one or two degrees if sitting at lights. On the motorway at 65-70mph the temp drops back to 78-79 and not surprisingly the bottom hose is cold. The cooling system is all new - radiator, pipes, stat, pump. Still running with the undertrays off, so wondering if this and the low ambient temps are the problem?

[g8dhe]

And your vehicle is ....... ?

[Driver+Passengers]

My new gauge seems to be working nicely, a great relief to know exactly what's going on!
Only problem is that the engine seems to be running quite cool. Takes quite a while to get up to temperature - in traffic it's around 80-81 and going up one or two degrees if sitting at lights. On the motorway at 65-70mph the temp drops back to 78-79 and not surprisingly the bottom hose is cold. The cooling system is all new - radiator, pipes, stat, pump. Still running with the undertrays off, so wondering if this and the low ambient temps are the problem?

With a cheapy 99p eBay digital LCD temperate sensor (NTC probe) mounted with a jubilee clip to the coolant stub on the driver's side of the head, these are precisely the values I was reading on my van (2.5TD 4WD AT). Gasket subsequently failed allowing combustion gas into the coolant and I was reading up to 5 or 10 degC higher across the range of driving conditions. Fixed gasket, but temp sensor no longer fitted.

[Velocette]

And your vehicle is ....... ?

Mine is a 95 2.5 TD single battery type.

[Velocette]

Mine has the TM2 sensor back of cyl head. 87 to 89 in town and A Roads 87 to 94 on motorways depending on gradient and weight of right boot. Higher on huge moutains in Yirrup up to 101 IIRR.

With regards to town and motorway, your sensor reads the opposite to mine. Mine is in the coolant leaving the head.
Stop start driving heats the Bongo up faster than motorway driving it also locks the gearbox up sooner. It only takes me a minute or so to get to the M6 from home so comparison is valid at startup.
In reality we are only reading numbers, so if they stay the same we know all is well, but as I have said before, reading the coolant temp leaving the head allows you to be proactive rather than reactive.

McGill Motorsport are exellent to deal with and supply CNC alloy connectors to take sensors at a price I couldn’t buy the billet to machine.


http://www.ebay.co.uk/itm/Water-Temp-Ga ... 589066d970

When I say town, I don't mean heavy traffic. I don't use the Bongo in the rush hour except on very rare occasions as I use the Motorbike for those trips. Then it would probably get up around the hundreds. The last time I did it two years ago the head went and I didn't have a TM2 in those days.
I think I uderstand what your saying but for the coolant leaving the head too be too hot the head would have to be too hot too so surely the early warning is only going to be by a couple of seconds. I confess I don't know how fast the coolant circulates at average speeds.

Is your sensor active before the stat opens? I haven't considered this in depth before so may not have read your earlier posts on the subject at least not recently and I would have to study the coolant flow diagrams to even know what I was talking about really but am always open to anything that might improve my bongo's reliability.

[rita]

Hi All . this unit has a 1/8" bsp (british standard pipe) thread. there are two options.
1 /like i did . above the oil filler there are two 8 mm tapped holes . approx 25 mm deep the same as the sensor probe, if you drill this hole out to the depth of the probe 7.3 mm dim ,and then drill out to 10.3 mm to depth of 12.5 mm and tap 1/8 " bsp. screw in sensor with dialectric ht grease to help make contact.
2/ make alloy boss with 1/8" bsp female thread with 8.5 mm hole at 90 deg for bolting to cylinder head..

will take picture tomorrow for clarity. if anyone want's the second option i can make for you for the cost of postage as i have all the equipment to make. regards to all.

Hi,
is it not possible to use the original temp gauge sensor position for the new sensor,or even piggy back the wiring.

[Simon Jones]

I don't think any two vehicles will read exactly the same value even when using same make of gauge. Each gauge will have it's own calibration error, then each owner will fit the sensor in a different location using different fixings which may have differing thermal transfer properties. Different types of coolant & the relative strengths of the mix will make a difference to the readings. The amount of debris in the system, especially at the bottom of the radiator will affect performance. Lots of other factors too will have an impact: auto/manual 'box, aircon on or off, 2WD or 4WD, driving style, ambient temperature, tin top / AFT, converted / MPV, petrol / LPG / diesel.... the list goes on.

The main thing is to get a feel what is 'normal' for your particular usage & then look for anything which changes.

[salexander]

My new gauge seems to be working nicely, a great relief to know exactly what's going on!
Only problem is that the engine seems to be running quite cool. Takes quite a while to get up to temperature - in traffic it's around 80-81 and going up one or two degrees if sitting at lights. On the motorway at 65-70mph the temp drops back to 78-79 and not surprisingly the bottom hose is cold. The cooling system is all new - radiator, pipes, stat, pump. Still running with the undertrays off, so wondering if this and the low ambient temps are the problem?

Sorry, 2.5TD 4WD AT.
It's very noticeable that the engine gets up to 50-60 degrees fairly quickly, but seems to be much slower to achieve full running temperature. Similarly, when you end a journey the engine holds temperature for hours. Probably just an indication of how big a lump of iron the engine actually is

[Simon Jones]

That sounds completely normal .

[salexander]

Same problem on the drive home tonight, 78-82Deg and cold bottom hose. I suspect the problem may still be air in the heater matrix, I'll do another bleed at the weekend.
It really is an annoying cooling system I suspect it could be sorted with a totally different setup - electric water pump, no stat and a closed-loop controller. Same setup that I have on my racecar, and one that I understand and can control! It also means you can bleed it without actually running the engine for an hour!

[Simon Jones]

Most people worry about their engine running too hot rather than too cold . An airlock in the system will tend to lead to overheating as the coolant will not circulate properly. If you've got an efficient cooling system then it will taking the heat out the engine so you will expect the temp of the block to be at the low end of the range.

At this time of year, you will struggle to get the thermostat to open and get the fans on unless you keep the revs up for a while when stationary. All the time the van is in motion, cool air is passing through the radiator as well as under the van which takes the heat at from the engine. If you had been driving along for say 30 minutes and then got stuck in a traffic jam for say 10 minutes, then you may be able to get the 'stat open.

I've got a sensor on the pipe out of the thermostat housing which goes to the bottom of the radiator. After a 100 mile motorway journey it gets to about 20 degrees C which will be considerably lower at the radiator end. Although mine is a V6, the setup is the same as the diesel.

[The Great Pretender]

Same problem on the drive home tonight, 78-82Deg and cold bottom hose. I suspect the problem may still be air in the heater matrix, I'll do another bleed at the weekend.
It really is an annoying cooling system I suspect it could be sorted with a totally different setup - electric water pump, no stat and a closed-loop controller. Same setup that I have on my racecar, and one that I understand and can control! It also means you can bleed it without actually running the engine for an hour!

Not sure where you have your sensor fitted from your previous posts.
If your sensor was reading coolant leaving the head the temps sound ok, bottom hose would be cold at those temps.
Have you read up fully on how the cooling system works?

[The Great Pretender]

Sensor reads from cold Velocette.

[salexander]

The coolant sensor is in a tee in the top hose. I've read a pile of the discussions on the cooling system and think I've got a reasonable understanding of the setup now, all thanks to the 'wisdom of the forum'

[Velocette]

Sensor reads from cold Velocette.

What happens if you lose water, how would the sensor react or would it be too late to matter if the LCA hadn't alerted you?