Yanmar's Thermostart

[rScotty]

With winter coming, it's a good time to clean out the the thermostart reservoir and check the connections.

Thermostart itself is kind of unique to Yanmars. It's a combination of a plastic reservoir, relay valve, and heating element all located on top of the intake manifold and activated by turning the ignition key CCW then holding it in that position for a moment.

When actuated, thermostart dispenses and then ignites a small drop of diesel fluid from the special reservoir. You can hear a faint "pop" as it ignites. That's the notice that it is time to crank the engine. If you time it right, the warmer air and maybe even some of the burning fluid is swept into the manifold along with the fresh air charge.

Simple, pretty nifty and just about bulletproof.

Enjoy, rScotty

 

[jerrybob]

Thanks for the reminder. I've had my 186D for several years......it still amazes me how she starts year round.....even if I haven't turned her over for weeks. Those old Yanmars are great little tractors.....they just keep starting, working and going.

 

[6thgpSF]

don't forget the decompression release,,,russ

 

[4get gto]

I think they say to hold for so many seconds, something like 10. That doesn't always means that it ignited. I've listened for mine and it takes about 15-17 seconds.

 

[clemsonfor]

I think I saw don't hold for more than 30 seconds.

 

[California]

Clever? Fer sure! Unique? I'm not so sure. It's a Perkins patent and my neighbor says his MF 135 (Perkins engine) uses it. He says the Perkins diesels are legendary for starting in any weather due to Thermostart. Tractor Supply stocks them as a MF service part.

I read long ago that Yanmar and Perkins exchanged some patent licensing, maybe this was one of the items covered.

Photo: Old and new. The New one was found at the local ThermoKing (semitrailer refrig unit) facility, stocked for the Yanmar diesels they used back in the day. I think ThermoKing in the 70's had the same basic 2TR20 as YM2000.

 

[Kustrud]

I have the little reservoir and everything but my key doesn't turn to the left.....?

 

[rScotty]

don't forget the decompression release,,,russ

Right! And thanks for the reminder. It's a balancing act between starter, thermostart, and decompression. It might be that to avoid the need for three hands is what convinced Yanmar to build the thermostart actuation right into the ignition switch. It still helps to have a sense of syncopation, though.
rScotty

 

[rScotty]

I have the little reservoir and everything but my key doesn't turn to the left.....?

Don't know, but looking to see where the thermostart wire goes will give the clue.

 

[careyo63]

Really not much to it. The blue wire to the Ign. switch. It's been yrs. but I believe it's R-2 on the switch... Rarely do I ever have the need to use mine and I don't have the plastic cup. So the very few times I did use it this is all I did to get fuel to it. After I started the tractor I just squirt it back in the tank. If the switch is not working just run a wire to the battery + for a few Sec..