Engine Monitoring Gauges

[helebah]

Guy,
You have stated that coolant temp 75-80 deg C and oil temp 85-90 deg C is strongly advised. I am about to add some gauges to my 125 and have a few questions.

- Exactly where do you measure water(coolant) temperature, oil temperature? Would oil temperature measurement position change if you have a oil cooler?

- Which gauges are better electric or mechanical ?

thank you

[Guy Croft]

You should measure:

1. Coolant/engine - you're looking for the metal temperature not the fluid temp. Position the sender on the cylinder head as far from water pump as possible.
2. Oil - you really need to know both the temp coming out of the engine and the return temp (feed back into the engine downstream of oil cooler), by doing that you can verify the cooler is working. No-one ever does that! So I say put the oil temp sender in the return line so I know what temp it's going in at. Mounted in a nice little inline adaptor or remote filter head (see below) eg: from renowned firm Think Automotive:

http://www.thinkauto.com

Electrical/mechanical? Well, that is of secondary importance to the quality and accuracy so I am going to dodge that question as such and say that I SWEAR by Raceparts UK instruments:

http://www.raceparts.co.uk/racetech/instruments.htm

and yes I have a pref for non-electric. That said, I have known many instances of oil lines to gauges causing fires when the little hose chafes thru and sprays hot oil over the engine (not the instrument's fault of course but something to think about).

The only exception to Raceparts is Elliott tell-tale tachometers which are simply dreamy.

http://www.elliotdesign.co.uk/products/ ... ports.html

Those firms export daily all over the globe by the way.

GC

[Rich Ellingham]

And in use on a Tipo 2ltr 16v
Brass sensor into the thermostat housing for water temperature


Another brass capilary sensor into Mocal (think automotive remote filter head)


The small hose between the large oil lines is the presure line for the oil pressure gauge.


The gauges are all racetech from raceparts. I opted for the raceparts tacho its a stepper motor design, with tell tale and includes shift light which is set by adjusting a pot on the rear of the tacho, it is very nice.


Rich

[johnv]

so you have one oil temp, coming out of the filter head? could an oil pressure guage be taken from here?

[Guy Croft]

Yes, it can Jon.

Think Automotive can supply the RFH (remote filter head) type 3/4 UNF (unified) centre thread & 1/2BSP ports tapped for most senders. 3/8 BSP (British Standard pipe) being the most common for senders, incl Racetech.

However the RFH 1 type that Rich has featured can only take one sender, if you want two tappings for oil press and temp in the unit, rather than using the TGA type in-line adapter - then you want filter head RFH 2.

RFH2 is left-to right flow only, whilst RFH 1 is aval L-R or R-L. Not that direction matters that much in most of our applications.

GC

[Os7213]

Hi

I don't have any tech infos to add about differents sensors positions but I want to show you the module I use instead of conventional gauges for water/motor oil/transmission oil/diff oil temps (or any other temps) because the unit is 4 channels:

This is a Yashio Factory water/oil temp display.


(Sorry about the size of the pic)

The other interresting part aside you can set 4 sensors is that you can set alarms so the unit will make noise if pre-set high temps is read on any channels and you also have total control on the channel displayed with a simple switch or automatic display mode . This module save me alot of money because precise conventional gauges(elec/mec) are pretty expensives.

If you look at the right of the picture you can also add programmed/manual water spray control to the unit(I dont use It right now since the operating temperature for my application are respected)

Here the adapter I have made(Not this one but the same model) to fit water and transmission temp sensor . These are really simple to do if you can get machine shop services and will take around 20-40min to do each adapters.



For the differential and motor oil I use fittings.

The last point I want to add is about oil temp... Many racers or car enthusiasts want to have oil temps readings from motor,transmission or diff but most of time they dont even know the operating temps. of their particular oil used.
So I think its really important to get all the infos on YOUR particular oil like viscosity index,flash point,operating range before trying to get some readings.

And Mr.Croft you're right Elliot Desing Tachs look really nice...
For now I use STACK St-430 ,0-4-10500 RPM Im really satisfied with the tach but if one day I want to change it ill will look carefully at Elliot Desing models!

Thanks for this interresting discutions
Hugo

[L200]

Ok - I did a quick search on the question I want to ask and found a few posts that hovered around it. This one seemed a bit closer than any other, so I decided to add it to this discussion rather than start a new thread (please advise if I should have started a new thread).

I want to explore the best place to place a water temp sending unit? I recently cracked a head because my water pump let go and the water disappeared before the temperature gauge tipped me off. The sending unit was in the side of the thermostat housing (stock engine, stock position). It seems that this is a common problem, as when the water goes, the temp sensor becomes ineffective. I have read elsewhere, that often the temp gauge will go high and then back off as the water is lost. As we know, air is not a very good conductor of heat, thus the sending unit becomes inefficient.

I once had an old van that had a water sensor in the top of the rad, which set off a buzzer if the top tank became empty. My plan is to install one of these into my rad, as a safety measure but I wonder if there is a more efficient and practical place to stick the temp gauge sending unit.

thank you,

Darren.

[Guy Croft]

A simple answer may guide you.

The temperature gauge is there to measure the temperature of the metal, not the coolant, and the sender should always be sited on highest, hottest part of the engine, normally the head - furthest from the pump and coolant outlet pipe on the head if the coolant outlet is at the front end - or half-way between the two if the outlet from the head is at the back.

GC

[L200]

A simple answer may guide you.

The temperature gauge is there to measure the temperature of the metal, not the coolant, and the sender should always be sited on highest, hottest part of the engine, normally the head - furthest from the pump and coolant outlet pipe on the head if the coolant outlet is at the front end - or half-way between the two if the outlet from the head is at the back.

GC

Thanks Guy – this now has me wondering why these temp gauges tend to stop working in the absence of coolant? Or is it that the coolant in the hottest part of the head is actually the conduit between the head and the sensor - thus measuring the temp of the head itself? If so, how does one avoid this problem? Can you recommend a specific type of sensor or sending unit?

Also makes me wonder why people cut their radiator hoses in half to place a section of pipe with a sensor in there?

thank you,

Darren.

[Guy Croft]

Sorry, I've only once run an engine bone-dry and the gauge certainly told me the engine was red hot, I have no exp of their not working when the engine has no coolant left in it.

GC

[L200]

No probs - wonder if it was the type of sending unit? Spoke to a person the other day who had the same thing happen - temp went up but then went back down and then motor didn't want to run! Turned out his water pump packed up.

Either way, I have taken a water level sensor from an old vehicle that I will fit to the top tank of my rad. This will tell me if the coolant level drops.

Darren.