Add temp gauge to Yanmar 2QM15

[Binkyburdett]

Hi

I've just bought a Crown 34 powered by a Yanmar 2QM15 that has at some stage had a sen-dure fresh water cooling conversion added.
When this was added it appears that the original over-temperature warning switch was removed and where the Yanmar service manual indicates the switch (and a zinc) should be has been replaced by a blanking plate.
This means I effectively have no overheat warning on this engine.
I would be grateful for advice and specific details as to how to fit a temp gauge (preferably third party due ridiculous Yanmar prices) and reinstate the temp switch connected to the warning light. I am not sure if there are spare ports on the engine block, if there are spare ports their locations and what thread size yanmar would use.
In a similar vein the original oil low pressure warning switch has been replaced by a pressure sender and gauge, again I would like to reinstate a warning light to run in parallel with the gauge but think that this would necessitate a "T" fitting, again are these fittings available and what thread sizes do I need, what make of oil pressure switch etc etc

Thanks for any input

James

[GregSteimel]

I addressed the same problem with a yanmar and to make it affordable, used automotive senders. After all, temperature is temperature whether it's a boat motor or a Ford.



I bought a temp sensor at a car parts store and took it to a Home Depot to find the plumbing parts I needed to insert the sensor into one of the water lines on my engine. The only trick,was to ground it somehow. I decided to solder a wire to the fitting which I connected to a bolt on the engine.

For oil pressure I needed a adapter because I wanted to keep the original switch sensor as a backup to drive a buzzer.



These adaptors are available online (Google "Pegasus") because many Japanese cars lack gauges. These adapters have both NPT and BSPT threads. You can also get the fitting I mentioned above online, although the Pegasus fitting was too big for my water line.

[Binkyburdett]

Thanks Greg for your reply, found the website. Presume I'm looking for a male on one part of the T and two female ends to take sender and switch. Being a bit thick, any idea what the receiving thread in the Yanmar block is and precisely what you used as it looks exactly what I'm looking for. Additional thoughts/methods welcome

[shakey doug]

G'day,
For ease of installation google engine Watchdog Tm1 or Engine guardian temperature monitiors. Have used Tm1 a great product, Engine guardian looks similar.

[GregSteimel]

From an article I'm writing:

Yanmars are built in Japan, and Japan uses the British Standard Pipe Thread (BSPT) standard. Danger lies in the fact that the threaded shaft on most of these sensors are 1/8” and the NPT and BSPT versions are very nearly the same. The thread density and coarseness are the same; but the American version cuts the threads at 60⁰ while the British version uses 55⁰. One will screw into the other, but it will leak. Luckily, adding domestic sensors to Japanese cars is common enough that at least one retailer, Pegasus Auto Racing Supplies, stocks NPT sensors as well as the NPT/ BSPT adaptors. And they cost a lot less than the marine versions. For my 2GM Yanmar, the oil pressure sensor cost just $40, the temperature sensor, a measly $17.

Note: There is a third pipe standard, British Standard Parallel Pipe (BSPP). Both NPT and BSPT are tapered, meaning the threaded hole is cone shaped. BSPP threads have instead parallel sides. And like a spark plug, adapters for engines using this standard must use a crush washer in order to seal.

[Binkyburdett]

Greg, thanks again for your advice, nice straight answers.

Last dumb question, what diameter are the rubber cooling hoses on yanmar and does putting the brass sensor in-line with the rubber pipe impede the flow at all?

Thanks, James

[GregSteimel]

Not dumb at all.I suspect not all Yanmars are alike, but mine are three quarter-inch, just like a heater hose in a car.

And the brass fitting I made did indeed reduce the inside diameter a bit, but the water seems to come out the transom at about the same rate.

[boatpoker]

Why not forget all that stuff and install a raw water flow detector alarm.
If your temp starts to rise you may not be watching the temperature gauge and miss it. By the time your temperature sensor sends an alarm signal the engine is already overheated.

A raw water flow detector will sound an alarm the very instant raw water flow is restricted or stops.

You can buy one of these for about $60 and buy an alarm for about $5 at an electronics outlet. Installation should be less than an hour.

[Arthur Garfield]

Good stuff.
I might ad temp system that is mechanical through to the gauge.
This gives extremely accurate reading in my experience and also,Steve Dashew
goes this way exclusively for same reason.
You can add the alarm also.Lol



All the Best

[GregSteimel]

The flow detector does make more sense. I'll have to give this some thought.