TEMP Alarm Sensor Position

[lindeelu]

When an over temperature event occurs, which is not caused by a bearing or piston problem, the oil is last in
the queue after the cylinder head, coolant, pistons and block.

Everything else has to get hot first before the oil heats up.

So why would you want to use it as a front line reference point?

As I said before, someone is trying to re-invent the wheel.
Try a square wheel if you want to, but where I live, all the wheels are round.

Yes I will be the first to agree that on aircraft, oil temperature is a significant indicator,
mainly on air cooled aircraft engines with no radiator or coolant.

First the pistons, bores, head, coolant and block get hot.
Then the oil catches up.

The oil has a large reservior under the engine, and very little of it is actually inside the engine,
Unlike the coolant which has roughly 50% of it's volume inside the block.
The coolant circulates the engine many times faster than oil does.
(one of the reasons why oil gets so hot)

A modern engine runs its oil up to 25 degrees hotter that it's coolant, so is a 5 to 10 degree rise in block temperature
going to make a significant, readable difference to oil temperature?

The oil temp won't rise significantly in the short term unless there is a piston / bearing problem.

[mikeonb4c]

Thanks lindeelu

I see where you are coming from, though I don't think this is about round wheels or square wheels. It is about two valid but different lines of thought; it is really about whether we are trying to monitor a 'peak event' or the overall health of an engine.

For monitoring 'peak events' we have:

Low coolant alarm - should cover any potential peak event likely to result from loss of coolant
Mason Alarm - should cover sudden rise in temp. provided sensor immersed in coolant (but LCA should insure against that)
TM2 alarm - should provide equivalent alarm to Mason, though at higher cost.

None of these though will allow an owner to know if the overall 'health' of their Bongo is below what it should be. The Mason alarm has no temp. calibration, and the TM2 (as it stands) has yet to decide on a reliable sensor position that might allow owners to have safely comparable figures.

Overall health:

I'm suggesting that oil temp. may be better in reflecting the overall health of an engine including the state of its cooling system ('my engine is running hot') as it is not as susceptible to surface effects (which will effect water cooled engines as well as air cooled ones). But since that seems to be what is afflicting a lot of ageing Bongos (failed sensors, partially blocked rads, tired thermostats etc.), it might allow owners to tackle a problem before it produces a 'peak event' when on the road, or contributes to shortening of component life. A TM2 block sensor might achieve this too, IF a suitable location can be found and owners standardised on it.
Mike

[lindeelu]

With all due respect Mike:
If seriously suggested an oil temperature gauge as a front line warning system in Australia.......
I would be laughed out of town.

[haydn callow]

. A TM2 block sensor might achieve this too, IF a suitable location can be found and owners standardised on it.

This is exactly what I am endevering to achieve......

How many peeps on here would be prepared to "poke" a temp sensor under their top hose cylinder head outlet with all the risks involved....??
Getting it to reseal
Losing coolant
Bleeding the system
Damaging the hose.

To do the job properly you would have to remove the hose and use a "shaped" insert that would accomodate the wire....We have such a insert which is used to place our under hose sensor for low coolant.....the hose has to be removed and everything dried to fit it.

We work on the KISS principal wherever possible

[lindeelu]

Try this:

Drain all the coolant out of your Bongo.

Go for a drive.

The engine will cook within 2 miles
The pistons will seize, the head will crack, the block will get hot and tinkle.
The oil will start to get hot as heat soak from the pistons and small ends sets in.
The conrods will blue & twist, the big ends will score.

This is the real scenario.

Been there done that on a couple of cars.

By this time the rise in oil temperature is real, dramatic & sudden, but too late.

In both cases the problem was due to a split hose.

A LCA would have been brilliant.
A block sensor would have gone off shortly after.
A coolant temperature gauge of any persuation would have been useless.

The bits at the top of the engine were destroyed.
(Pistons, cylinder head)

The bits at the bottom of the engine (where the oil is) were still intact.

I know where I invest my engine monitoring dollars these days.

[mikeonb4c]

It’s probably best if I start a new thread simply asking members for advice on the simplest place (if there is one) to pick up the oil temp of a Bongo. I’m aware of devices you can buy that fit at the oil filter mounting and allow an oil sensor to be screwed in but maybe there is somewhere simpler and/or some way that is cheaper.

To answer the latest postings though:

Not a lot I can say in reply to lindeluu’s post. I acknowledge that LCA and TM2 are great devices for preventing a ‘peak event’ becoming a catastrophe. But I’m suggesting that possibly, once an LCA is in place to guard against the scenario he outlines, the TM2 could be more usefully employed in monitoring general engine health.

Haydn, your point is fine, but it was not me (TGP I think it was) who was discussing inserting probes into the coolant system. Also…

How many peeps on here would be prepared to "poke" a temp sensor under their top hose cylinder head outlet with all the risks involved....??

is a moot point because much the same could be said of drilling holes in the header tank for the LCA (about which nervous users have before now asked for reassurance).

PS - for anyone not aware KISS = Keep it Simple Stupid. It was drummed into me years ago when I learned to fly, Haydn too no doubt!

[patnben]

I have to agree totally with your comments lindeelu, I don't understand why anybody
would consider oil temperature as a viable option for engine protection on a road vehicle.

[mikeonb4c]

I have to agree totally with your comments lindeelu, I don't understand why anybody
would consider oil temperature as a viable option for engine protection on a road vehicle.

Oh dear! Care to explain why?

[The Great Pretender]

Well you try to offer some input into the thread and this...................

Haydn thermistors are tiny, you only need to loosen the top hose and open it up with a screwdriver to slide one in by its thin cables that the hose will seal.

into...................
How many peeps on here would be prepared to "poke" a temp sensor under their top hose cylinder head outlet with all the risks involved

So here is how to "poke" a temp sensor into the top hose.

Damaging the hose.
Disconnect the top hose, no damage should occur.
Losing coolant.
As you are working on the high point of the engine only a small amount of coolant will be lost.
Getting it to reseal.
As I said, the hose will reseal around the thin cables.
Bleeding the system.
I understand that most peeps here are not mecanically minded and scared of the cooling system, well there is no need to "bleed the system" after doing this.
As the hose has only been prised off then refitted the small amount of air will be in the head and easily removed from the bleed pipe under the passenger seat.

Haydn, I thought the information may have been helpfull. If anyone is intrested here is a temp sensor.

[mikeonb4c]

Well you try to offer some input into the thread and this...................

Haydn thermistors are tiny, you only need to loosen the top hose and open it up with a screwdriver to slide one in by its thin cables that the hose will seal.

into...................
How many peeps on here would be prepared to "poke" a temp sensor under their top hose cylinder head outlet with all the risks involved

So here is how to "poke" a temp sensor into the top hose.

Damaging the hose.
Disconnect the top hose, no damage should occur.
Losing coolant.
As you are working on the high point of the engine only a small amount of coolant will be lost.
Getting it to reseal.
As I said, the hose will reseal around the thin cables.
Bleeding the system.
I understand that most peeps here are not mecanically minded and scared of the cooling system, well there is no need to "bleed the system" after doing this.
As the hose has only been prised off then refitted the small amount of air will be in the head and easily removed from the bleed pipe under the passenger seat.

Haydn, I thought the information may have been helpfull. If anyone is intrested here is a temp sensor.

This does sound like a good alternative sensor for a water temp gauge. Will it be robust enough not to break off from engine vibration over time? How do you calibrate a temp gauge linked to the sender? Also, just to remind me, why is the standard Mazda temp gauge sender not sufficient?

[The Great Pretender]

This does sound like a good alternative sensor for a water temp gauge. Will it be robust enough not to break off from engine vibration over time? How do you calibrate a temp gauge linked to the sender? Also, just to remind me, why is the standard Mazda temp gauge sender not sufficient?[/quote]

Yep it is.
It has been "poked" into my top hose for a year now without breaking off.
The sender comes with the gauge, or you use a meter to read the resistance.
The standard sensor is.

[lizard]

To sum up then, I think that the average Bongo owner would like an agreed position for a fitted sensor. It may not give an accurate reading on temperature, engine/oil/coolant but it may give the driver a better warning when there is something different from the norm' and a comparison made with others in the event of a boil over.

To date we have been advising a position for the Temp Alarm Sensors on the exaust side in one of the threaded holes in the cylinder head.

None of these though will allow an owner to know if the overall 'health' of their Bongo is below what it should be. The Mason alarm has no temp. calibration, and the TM2 (as it stands) has yet to decide on a reliable sensor position that might allow owners to have safely comparable figures.
Overall health:

I'm suggesting that oil temp. may be better in reflecting the overall health of an engine including the state of its cooling system ('my engine is running hot') as it is not as susceptible to surface effects (which will effect water cooled engines as well as air cooled ones). But since that seems to be what is afflicting a lot of ageing Bongos (failed sensors, partially blocked rads, tired thermostats etc.), it might allow owners to tackle a problem before it produces a 'peak event' when on the road, or contributes to shortening of component life. A TM2 block sensor might achieve this too, IF a suitable location can be found and owners standardised on it.Mike

The fastest reacting medium to engine temp is the cooling system, forget bolting it, strap it to the outlet to the top hose. It will always read lower than the actual temp and slower to react but the best way to monitor overheating.

[cheffy34]

This does sound like a good alternative sensor for a water temp gauge. Will it be robust enough not to break off from engine vibration over time? How do you calibrate a temp gauge linked to the sender? Also, just to remind me, why is the standard Mazda temp gauge sender not sufficient?

Yep it is.
It has been "poked" into my top hose for a year now without breaking off.
The sender comes with the gauge, or you use a meter to read the resistance.
The standard sensor is.
[/quote]


Yip ya got me hooked sounds easy enough for me to do what was the dollar value do they do them for cat pipes aswell looks like we are gonna be on for a late night chat in the near future Mr P


Dar

[The Great Pretender]

This does sound like a good alternative sensor for a water temp gauge. Will it be robust enough not to break off from engine vibration over time? How do you calibrate a temp gauge linked to the sender? Also, just to remind me, why is the standard Mazda temp gauge sender not sufficient?

Yep it is.
It has been "poked" into my top hose for a year now without breaking off.
The sender comes with the gauge, or you use a meter to read the resistance.
The standard sensor is.

Yip ya got me hooked sounds easy enough for me to do what was the dollar value do they do them for cat pipes aswell looks like we are gonna be on for a late night chat in the near future Mr P





Dar[/quote]

[haydn callow]

All sounds good to me...I would be interested in any feedback regarding the fitting process. I think some sort of audible/visual "abnormal temp" alarm would have to be built in for the average user.