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..

 

[Neat 1500]

I used mine years ago a few times then the reservoir ran out of diesel and that was it, never used it again.

 

[Kustrud]

Do you manually add fuel to the reservoir?

 

[rScotty]

Do you manually add fuel to the reservoir?

I've seen some models where the res is auto-filled from the return line, but that is really guilding the lilly as well as asking for a leak. Older Yanmars had a manual-fill plastic container with a matching pop-top lid. Capacity of an oz or four. Overall construction similar to the brake or power steering fluid res in older cars. Maintenance consists of checking every few years to see that there is still some fuel in it.
It's typical Yanmar construction: A simple but clever system built to the highest standard.
rScotty

 

[clemsonfor]

yes Kustrud you have to manually put it in there, pour from like a solo cup or something. A fuel can you will spill all over most likely. It only holds like an ounce or two at most

 

[Kustrud]

yes Kustrud you have to manually put it in there, pour from like a solo cup or something. A fuel can you will spill all over most likely. It only holds like an ounce or two at most

Understood, I prob won't ever need it in GA but was curious. I always wondered what that little reservoir was for haha!

 

[clemsonfor]

I have started mine down around 30F without it. Only one failed attempt.

 

[clemsonfor]

Double post

 

[6thgpSF]

my 1610d has the auto fill to the reservoir . I live in Ks. and it gets pretty cold here in the winter.Ive never had a problem getting it started using the thermostart and decompression release. I def. hear the small pop when I use it...russ

 

[4get gto]

I often wondered how you would know if the thermostart was working. Holding the switch for 10-20 seconds is what they tell you to do but the average guy wouldn't have clue if it's working or not. Should be some kind of indicator that tells you it's on and did it's thing. I'm sure newer tractors have something like this but we're left to listening for a very faint pop or just assume that it worked.

I've seen a few good u-tube videos that show you how they work and what they look like when they ignite with the air filter intake tube off. Pretty cool to actually see them work.

I took my intake tube off ,watched and timed it to get a better idea how long it takes in the event I don't hear it.

 

[winston1]

Some of the models do have a red light that comes on and goes off after a period of time. My old 2002D had that but it quit after a period of time. Thermostart sill worked. Red light to the left of switch. Also notice the little light for the work area.