Thermostart problems

[etpm]

Greetings All,
I have a Yanmar YM2310 tractor. The thermostart quit so I bought the one recommended here from Amazon. This same thermostart is used on many other tractors, Ford being among them. Here is the link to the one I bought: https://www.amazon.com/dp/B00WIX756E?psc=1&ref=ppx_yo2ov_dt_b_product_details
I installed the thing and pulled the air intake hose from the manifold so I could watch it work. Turning the key to the thermostart position I saw the thing heat up, smoke, and then saw flames. The flames showing that diesel was flowing into the device and catching fire, just as it is supposed to do.
So then a few days later it was pretty cold and when I started the tractor it started much faster than it did before I replaced the failed thermostart. But then a few days after that the tractor was taking too long to start. It was very cold out but it still should have started faster.
Now, today, it was cold out and so I cycled the thermostart 2 times and still the tractor seemed to be taking a long time to start. So I climbed off the tractor, raised the hood, and took the intake hose off of the intake manifold and watched the thermostart in action. It heats up just fine, gets good and red, but no smoke or flame. Looking at the hose that goes from the diesel reservoir to the thermostart I see no movement of fuel. I am using Tygon fuel line which is translucent so a person can see bubbles and since there is an air bubble I should be able to see fuel flow if there is any.
Since there is no flame or even smoke, no visible fuel flow, and a good red glow from the thermostart I surmise that no fuel is getting to the hot parts of the thermostart. The fuel reservoir is full. Could it be that a brand new thermostart failed that fast?
I am pretty sure the new thermostart works differently than the original one. The original was much longer and had two wires going to it. I think the original one had a solenoid that opened a valve letting diesel flow. The new one uses only one wire. I don't know how it works but there doesn't seem to be enough room for a solenoid. So I'm thinking it uses something that opens a valve when it gets hot, like a bi-metal washer.
Anyway, since the thermostart is new it seems odd that it would fail so fast. Does anybody know how these things work? Rather than wait I would like to get the darn thing to work. I don't mind taking it off, even though it is a pain, because I have to take it off anyway to put a new one in.
Thanks,
Eric

 

[dodge man]

I had to look at the part on Amazon and figure out what it is. They call it a thermostat but it’s really an intake heater. It sounds like a little fuel flows into it and catches fire to heat the intake? If you see it glowing it’s getting hot but maybe the fuel flow to it is the problem.

 

[Tinhack]

My ford has that type, but the fuel feed is off the injector return to tank line. That means the only fuel supplied to the Thermostart is what's in the injector overflow line or when the engine is cranking. There's a valve inside which opens to allow fuel to drip through the heat coil. It takes about 3-5 seconds of heating to open the valve. I'd check your fuel supply line and reservoir to make sure fuel drips from them.

Here's a video of how they work. You could test yours the same way.

 

[dodge man]

I get it now, thermostart, I was reading thermostat.

 

[etpm]

My ford has that type, but the fuel feed is off the injector return to tank line. That means the only fuel supplied to the Thermostart is what's in the injector overflow line or when the engine is cranking. There's a valve inside which opens to allow fuel to drip through the heat coil. It takes about 3-5 seconds of heating to open the valve. I'd check your fuel supply line and reservoir to make sure fuel drips from them.

Here's a video of how they work. You could test yours the same way.

I know how they work and said so in my post. I have the reservoir that is fed from the injectors. It is full. Fuel is not flowing through the thermostart. Fuel does flow out of the hose to the thermostart If I remove it from the thermostart. I was wondering if anyone had had this problem before with a thermostart, new or otherwise and fixed it. The valve must not be opening. Maybe I just need to take the thing off and try to get the valve to open by pushing something thin through the fuel opening. I hate it when I buy something new and it only works a time or two. Because of where the fuel injector plumbing is routed and where the air intake hose is located itis a pain to remove the thermostart. GRRR.
Eric

 

[LouNY]

Possibly the little port caught a bit of dirt or garbage while it was being worked on, that is a very small orifice that is supposed to open when hot.

 

[Tinhack]

I know how they work and said so in my post.

I didn't mean anything to the contrary. I meant you should test it like in the video.

 

[etpm]

I didn't mean anything to the contrary. I meant you should test it like in the video.

I did. I removed the intake hose and watched the thermostart while I turned the key. It just gets hot. I mentioned that in my first post too.
Eric

 

[thepumpguysc]

I like Lou’s #6 post..
Give it a shot..

 

[etpm]

Possibly the little port caught a bit of dirt or garbage while it was being worked on, that is a very small orifice that is supposed to open when hot.

I too think that might be the problem. So I am going to get it hot and try to blow air through it backwards.
Thanks,
Eric

 

[LouNY]

It's going to be a bit difficult as it has to get glowing hot before the heat will open the fuel orifice.

 

[etpm]

It's going to be a bit difficult as it has to get glowing hot before the heat will open the fuel orifice.

So I took the thermostart out today and looked at it. Blew it out. Got it red hot and blew it out. Got it red hot again and no fuel would flow through. Set it up in a vise, got it red hot again and tried pushing on the valve from the fuel inlet side and there was no motion of the valve. I even went so far as to measure the position of the valve when the thing was cold and then again after I let it heat soak for 30 seconds, which is longer than the tractor timer lets it work. It did not change position even a few thousandths of an inch. I made these measurements in my machine shop, using the proper inspection equipment. For some reason the thing doesn't work. The valve is stuck. It did work when first installed but quit after only a few uses. So I am returning it and getting another. I'm sure it was just a defective one. But darnit, I hate having to go through all the hassle of removing and installing another. Because of the injector plumbing being in the way I had to grind excessively on a wrench in order to fit in the tight space. I also have to remove the air intake hose and the side panel below the cowling. Now I sound like a baby complaining. At least I can return it without paying any shipping costs. Living on an island means I can't just go shopping at the local tractor store and must rely on mail order for lots of stuff. But I couldn't have afforded this beautiful chuck of land on the mainland and the community here would also be very hard to find on the mainland.
Eric