Yanmar 186D - hard to start

[DawsonAcres]

You said that you just bought the tractor and you don't have a manual. So maybe you don't know the starting procedure. I bought my 42 year old YM2310 about a year and a half ago and it was my first diesel anything. It did come with a real thin operator's manual though. And the manual says to pull the throttle lever all the way to full throttle. Then once it starts the throttle should be set to 1800 RPM while it warms up. I may be wrong about that 1800 RPM setting. It might be 1500 RPM. I'm tired, its been a long day. Are you setting the throttle lever to full throttle? I was surprised the tractor was supposed to be started at full throttle. All the gasoline engined stuff I have is not supposed to be started at wide open throttle. I guess with a diesel the full throttle is kinda like choking a gasoline engine. The engine needs excess fuel, but for different reasons, when started cold.
Eric

My starting procedure is to turn the key to the left for about 30-45 seconds to heat up the thermostart (can feel it’s hot to the touch) then crank it over for ~15 seconds with the throttle open. Doesn’t even sputter, just black smoke. I repeat that usually 1 to 2 more times and it jumps to life. Once started it doesn’t have black smoke. I have tried to start it with less throttle as well as without the thermostart and neither seem to make much of a difference.

 

[ponytug]

My starting procedure is to turn the key to the left for about 30-45 seconds to heat up the thermostart (can feel it’s hot to the touch) then crank it over for ~15 seconds with the throttle open. Doesn’t even sputter, just black smoke. I repeat that usually 1 to 2 more times and it jumps to life. Once started it doesn’t have black smoke. I have tried to start it with less throttle as well as without the thermostart and neither seem to make much of a difference.

Turning a thermostart on for 30-45 seconds seems long to me. Hoye tractor suggests 10-15 seconds.

Inside a Yanmar thermostart (glow plug) unit.

Yanmar tractor thermostart (glow plug) operation explained.

www.hoyetractor.com

Have you looked to verify how fast your thermostart starts flaming? You want the thermostart to burn enough diesel to warm the manifold enough to feed warm air to the combustion chambers. Lots of black smoke makes me wonder about unburnt diesel in the intake manifold.

All the best,

Peter

 

[winston1]

How much blow by out the crankcase vent?

 

[etpm]

My starting procedure is to turn the key to the left for about 30-45 seconds to heat up the thermostart (can feel it’s hot to the touch) then crank it over for ~15 seconds with the throttle open. Doesn’t even sputter, just black smoke. I repeat that usually 1 to 2 more times and it jumps to life. Once started it doesn’t have black smoke. I have tried to start it with less throttle as well as without the thermostart and neither seem to make much of a difference.

I have been having troubles with my thermostart so I understand how they work in my tractor and maybe your tractor works the same since they are both Yanmars. When I turn the key to the left the thermostart heats up and a red light turns on. This light turns off after maybe 15 seconds. While the light is on fuel from the little reservoir drips onto the heating coils, though the coils will stay energized as long as the key is turned to the left. But this is when using the stock thermostart. My stock thermostart burned out and so I bought a replacement. They work differently. When they heat up a valve opens from the heat and lets fuel drip onto the hot coil. So as long as they are hot fuel should be dripping on the coils. I ended up getting 3 thermostarts and none of them worked properly. They all get plenty hot but they don't let any fuel drip onto the coils so there is no flame in the intake manifold. I diagnosed this by removing the air intake hose from the intake manifold. On my tractor when this is done the thermostart is quite visible because it protrudes some into the air path into the intake manifold. So, even though my thermostart gets plenty hot it doesn't start a fire like it is supposed to. This means that the intake air won't get heated very much. So when it is cold outside my tractor takes a long time to start. When the air temperature is in the high 30s I have to crank the engine long enough that I worry about cooking the starter motor. And when the engine finally starts it puts out black smoke for a short period of time, just like yours. After the engine warms up it doesn't smoke. And when the weather is warm, say 60 degrees and above, the tractor starts right up. Maybe fuel is not getting to your thermostart. Pull the intake hose and take a look.
Eric

 

[DawsonAcres]

Turning a thermostart on for 30-45 seconds seems long to me. Hoye tractor suggests 10-15 seconds.

Inside a Yanmar thermostart (glow plug) unit.

Yanmar tractor thermostart (glow plug) operation explained.

www.hoyetractor.com

Have you looked to verify how fast your thermostart starts flaming? You want the thermostart to burn enough diesel to warm the manifold enough to feed warm air to the combustion chambers. Lots of black smoke makes me wonder about unburnt diesel in the intake manifold.

All the best,

Peter

I have been having troubles with my thermostart so I understand how they work in my tractor and maybe your tractor works the same since they are both Yanmars. When I turn the key to the left the thermostart heats up and a red light turns on. This light turns off after maybe 15 seconds. While the light is on fuel from the little reservoir drips onto the heating coils, though the coils will stay energized as long as the key is turned to the left. But this is when using the stock thermostart. My stock thermostart burned out and so I bought a replacement. They work differently. When they heat up a valve opens from the heat and lets fuel drip onto the hot coil. So as long as they are hot fuel should be dripping on the coils. I ended up getting 3 thermostarts and none of them worked properly. They all get plenty hot but they don't let any fuel drip onto the coils so there is no flame in the intake manifold. I diagnosed this by removing the air intake hose from the intake manifold. On my tractor when this is done the thermostart is quite visible because it protrudes some into the air path into the intake manifold. So, even though my thermostart gets plenty hot it doesn't start a fire like it is supposed to. This means that the intake air won't get heated very much. So when it is cold outside my tractor takes a long time to start. When the air temperature is in the high 30s I have to crank the engine long enough that I worry about cooking the starter motor. And when the engine finally starts it puts out black smoke for a short period of time, just like yours. After the engine warms up it doesn't smoke. And when the weather is warm, say 60 degrees and above, the tractor starts right up. Maybe fuel is not getting to your thermostart. Pull the intake hose and take a look.
Eric

Yeah this is a good idea. I was assuming that because it feels hot, I had a flame. I will pull it apart to take a look. Also, I agree that 45 seconds is too long to hold it on. I think it’s plausible that I’m holding it too long plus it’s not lighting and instead dripping fuel past the manifold.
One interesting observation though, even when it’s 60-70 degrees out it still has a hell of a time starting.

Any recommendations for checking blow by? I pulled the oil cap, laid it over the hole a throttled up to see if the cap blew off. It didn’t but not sure how valid a test that is.

 

[Williy]

What about the air filters?

For a manual/service manual:

Yanmar 186D free manual or service manual - Google Search

willy

 

[winston1]

This is to much blow by. I think your vent comes off the rocker arm cover.

 

[careyo63]

When It's cold I noticed that My 550CCA. battery was barely enough power when Using my TS.. Rarely ever do I or have I needed to use the TS.. As long as I hold my Key in the TS Pos. I get power to It. Dash light stays on. Replaced that Battery with a 800CCA. Big difference. I use to have to put the charger on it in the Winter or cold months. I would put a Chrg. on it And Hit the TS. Then go back and put the Charger back on it for a few Min. That way it starts right up!! No need now with the bigger battery. I was doing something right Spalding put the Org. battery in it. New Battery Rec.1/04/21 Old Battery 13yrs. before I had to replace it. Low amps...
I get blowby after sitting over the Winter. You can see the Vapor coming out of the Hose when first starting it up. Noticed this Decades ago. Not that much though. After I finally finished a carport addition and it stay pretty much dry. The vapor goes away after running it. Never see it again or any Radiator fuid loss. Until th next season.

 

[ponytug]

When It's cold I noticed that My 550CCA. battery was barely enough power when Using my TS.. Rarely ever do I or have I needed to use the TS.. As long as I hold my Key in the TS Pos. I get power to It. Dash light stays on. Replaced that Battery with a 800CCA. Big difference. I use to have to put the charger on it in the Winter or cold months. I would put a Chrg. on it And Hit the TS. Then go back and put the Charger back on it for a few Min. That way it starts right up!! No need now with the bigger battery. I was doing something right Spalding put the Org. battery in it. New Battery Rec.1/04/21 Old Battery 13yrs. before I had to replace it. Low amps...
I get blowby after sitting over the Winter. You can see the Vapor coming out of the Hose when first starting it up. Noticed this Decades ago. Not that much though. After I finally finished a carport addition and it stay pretty much dry. The vapor goes away after running it. Never see it again or any Radiator fuid loss. Until th next season.

FWIW....I suspect that the "sitting over the Winter" blowby might be just steam coming out of the oil when the oil is warm/hot, from water condensation into the oil. I have a non-Yanmar diesel that shows the same behavior, and doesn't steam or have gases if it has been running recently.

All the best,

Peter

 

[California]

Also in NorCal, an hour north of SF, and a YM186D. This tractor starts easily in our climate and likely would without using the thermostart at all. After 15 seconds of thermostart it fires instantly or within a couple revolutions of the crankshaft. But it does smoke when it hasn't run for a while. My theory is like an old car, there is oil running down the valve stems when it sits.

I suspect you are running the thermostart far too long and it may be warm but not igniting the dripped fuel. So all that black smoke is the dribbled fuel from the thermostart.

Yanmar's manuals - and my experience - (that's my YM240 thermostart photo in the Hoye description) - say the thermostart flame ignites with an audible pop, or poof, after 15 seconds. You might need to remove the air filter element to hear it on this model. I would investigate that, next.

With no glow plugs, testing compression is a major project on these. Getting the injectors out then back in and sealed completely is nearly a pro mechanic project. And needs a $100 tool to get the injectors out in condition they can be re-used, at least on my similar YM240. Then the cost of the compression tester. If you can feel compression resistance while it cranks I wouldn't worry about compression yet.

You are spinning it with compression released, then dropping the release lever after it's spinning, no?

Thermostarts are cheap, under $20 on Ebay. There's only one version regardless of description. But some include a screw for the wire while all accept a slide-on connector. Its trivial to install. I would replace that as the next effort.

And finally, Don't use Starting Fluid like they use on large diesels!!!