Engine Temperature Gauge Help Please.

[TrentePieds]

Originally Posted by Wotname

But please, if anyone knows a simpler or better solution, please share you knowledge.

Thermostats are right down there with borscht, cost-wise. And dead easy to change. So put a thermostat change on you maintenance schedule, say every third oil change, and Bob'll be your engine's uncle. You, however, may not feel secure without a gauge to reassure you. That's a whole different discussion :-)

TrentePieds

[GILow]

Does this gauge have the same problem...? Pulled these out of our boat because our thermostat STARTS to open at 85 degrees C, engine temp is usually stable at around 92 degrees C. Very, very un-nerving to run with the needle constantly over to the right. Does not matter how hard you tell your self the temperature is fine, it just feels wrong.

[charliehows]

heres what i did last week. My eng. 2qm20 raw water cooled. Bought a triden tts010 temperature sender from supacheap autos for $17. Because it has a 3/8 npt thread i went to a plumbing supplies place and bought 1 male/male 3/8 bsp coupling and 1 female/female 3/8 bsp coupling $5. screwed the temp sender into the female coupling and put a bead of solder around the base to help it seal. Screwed the male/male into the female and screwed the whole thing into the engine. Heres the best bit. When i tested the temp sender out of the engine 60deg water caused a reading of about 75deg on the temp gauge...BUT...when i put it in the eng. and ran it for a test run the gauge rose to operating temp mark and sat there like a rock.
not sure if the temp sender on a 2gm is 3/8 bsp but if it is and you've got a spare $22, you should be back in business. good luck.

[charliehows]

read your post a bit closer - the gauge on my boat which has been sitting dead for 6 years or longer 'cos it didnt work when i got the boat, reads from 0ish to 200 with a reading at 40, an operating mark 1/3 of the way to the next reading of 80, then on to 200 i think, so the op. temp is pretty low on the scale but it is unmistakeable so on your boat an auto gauge ought to work.

[Wotname]

Originally Posted by Stu Jackson

Buy four thermostats.

Change them every other year.

Seriously.

I hear you but……

Sorta goes against the grain

And having a temp gauge is nice thing, just gotta find one (or make one) that actually works for a low temp engine.

[Wotname]

Originally Posted by Cap Erict3

Best advice given. Thermostats are bimetallic and are a very dependable component of an engine.

Adding a high temp alarm would be worthwhile.


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Looking for another pretty place to work on the boat.

Bimetallic ones on a fresh water cooled engine may be dependable but the Yanmar wax pellet type on their raw water cooled engines - not os much .

High temp switch alarm is fitted as standard; checked it tonight and it operates at about 62C or 145F.

This confines that I really need a gauge with a meaningful range between say 40 & 70 C

[Wotname]

Originally Posted by deblen

Wotname is looking for an analogue mechanical engine water temp gauge that displays a temp band from 40C to 80C.
That is 120F to 175F for us North American metric illiterates
I don't think he will find one,but here is a link:

I'm reaching out to the educated North American :big grin:

And you are right, I don't think I will find anything off-the-shelf in the range I want.

……...

There are also "self powered" cyl head temp gauges for small engines-bikes,atv's,snowmobiles,etc that have a sensor that goes under a headbolt,or whatever, & no ext. pwr reqd.

Yep, the Engine Watchdog units mentioned earlier may be the way I'll go in the end. There is a suitable tapped blind hole in the water jacket already

A water temp sensor (Mech. or Electric)must go into the water in the water passage or hose. It will not be meaningful if you just tee it,like you can with a oil pressure gauge. This means finding an extra tapped hole into water jacket,or replace existing electric sensor with a mech. one. Mech. sensors typically have a longer sense element than electric senders.This means you need enough depth in the water jacket to accommodate it,without it hitting the "back of the hole" & touching the interior surface.or..worse.

Again, you have hit the nail on the head but I do have a potential solution (providing I can get the resistance curve suitable). The existing temperature switch is a M14 or M16 (x1.5) tapered thread. There is plenty of room behind it in the water jacket and I have found a VDO sensor that is a combination of temperature sensor and temperature switch that will drop right in. But I'm not sure yet that the temp figures for both the gauge and the alarm will work out.


Most sensors are standard NPT national pipe TAPER & I believe BNPT/BSPT? British TAPER thread is compatible.Stay away from NP Straight or British equiv.-they are meant for seacocks & other special situations & do not seal by simple tightening.

Hope this helps
Cheers/Len

Thanks Len

[Wotname]

Originally Posted by GILow

Does this gauge have the same problem...? Pulled these out of our boat because our thermostat STARTS to open at 85 degrees C, engine temp is usually stable at around 92 degrees C. Very, very un-nerving to run with the needle constantly over to the right. Does not matter how hard you tell your self the temperature is fine, it just feels wrong.

Interesting gauge, I'd love to know the NTC curve of the sender.
As I have just posted, the high temp alarm switch operates at 62C (145F) and so this gauge with the right sensor may just do the trick; perhaps with tinkering with some external resistors

[GILow]

Originally Posted by Wotname

Interesting gauge, I'd love to know the NTC curve of the sender.
As I have just posted, the high temp alarm switch operates at 62C (145F) and so this gauge with the right sensor may just do the trick; perhaps with tinkering with some external resistors

PM me your details and I will post it to you. If it works, I will send the other one. I was only keeping them on the boat for emergencies, better they do someone some good. If they work, you could send me your old higher temperature gauge as a trade then I'll have useful backup.

Uses the same sender as my current new higher temperature range VDO gauge, which is also the same sender as used on the original Nissan truck engine setup, so nothing special. I assume there are some standards for these things because I have had mostly good luck with doing these conversions. I dropped a 6 cylinder Nissan RB30 petrol donk into our Toyota Coaster bus and the original temperature gauge on the bus instrument panel worked fine, with the Nissan sender, literally plug and play. The only time it did not work for me was on a very old French engine to which I was fitting a VDO gauge, but that car would have predated any defined standards (1969)... and hey, it was French.

Matt

[GrahamHO]

On my seawater cooled 2GM20 I use a digital temperature gauge. That is I stick five digits of my right hand on the valve cover. If I can leave my hand there the temperature is OK. If I need to remove my hand quickly it's too hot. Keep clear of the belts!!

I have a little trapdoor in the top of the engine box for general routine checks such as temperature or leaks during long engine runs. I carry a spare thermostat and replace it every couple of years.

Remove and check the thermostat every few months. It's quite easy to do. If you can spring it with your fingers it's usually OK. A more thorough test is to put it in a pot of water and heat it on the stove to see if it opens OK. If you're still really paranoid you could put a glass thermometer in the pot and see if it opens at around 55* / 60*c.

Calcification from seawater builds up on the moving part and eventually jams the thermostat. The reason for seawater cooled engines running at such a low temperature is to decrease calcification deposits. Don't remove the thermostat or the engine will run far too cool.

I also looked for a suitable gauge and gave up on the idea as not worth pursuing, but if you find one I suggest you still do the checks I've suggested.

[GILow]

Originally Posted by GrahamHO

On my seawater cooled 2GM20 I use a digital temperature gauge. That is I stick five digits of my right hand on the valve cover. If I can leave my hand there the temperature is OK. If I need to remove my hand quickly it's too hot. Keep clear of the belts!!

And have one of these handy...

[GrahamHO]

Originally Posted by Wotname

I hear you but……

Sorta goes against the grain

And having a temp gauge is nice thing, just gotta find one (or make one) that actually works for a low temp engine.

Yanmar 2GM20 seawater thermostats are a consumable just like the engine oil.
Change the thermostat every couple of years and check a few times between and you won't need a temperature gauge.

Maybe you could have 2 gauges in case one is faulty. But then you wouldn't know which one is faulty so you should really have 3 temperature gauges and if 2 read the same those will most likely be correct.

The temperature reading gun someone suggested sounds a good idea. You could direct it at different parts of the engine occasionally.

[cheoah]

Some automotive temp gauges don't actually show moderate temp changes, they stay pegged in the center until,you're 40 degrees up. I have after market digital gauges on all of my diesel farm trucks and even have them on my two diesel cars. They're there for very specific reasons, but man I'd love to be able to monitor my marine diesel like that. I'd want intake water flow, exhaust water temp, oil/coolant temp, vacuum in the fuel, transmission temp, shaft temp, and more. I only say that because it's kind of like that with my vehicles, just a ton of data.

There's just nowhere to plug into a 3GM35f and utilize the host of sensors found on my cars and trucks.

Seeing an actual real number and being able to set alarms is the minimum. I'll check out some gauges listed here.


Sent from my iPad using Tapatalk

[GrahamHO]

Cheoah, I'm with you. Can't have too much information. As you say hard to fix a satisfactory sensor on a small marine Yanmar. Your farm trucks sound set up like aircraft and I bet you keep a close eye on things.

[Wotname]

Originally Posted by GrahamHO

.....
Don't remove the thermostat or the engine will run far too cool.
..........

Allow me to correct this statement

A 2GM20 will almost certainly run hot if the thermostat is removed and in tropical waters can seriously overheat with the thermostat removed.

The reason is that most of the cooling water bypasses the block and head when the thermostat is removed. The moving disc of the theromstat actually closes off the water bypass circuit when the thermostat is fully open. Without that disc, most of the water goes straight into the exhaust, not into the block / head.