Forum for air cooled diesel engines and clones

[ponytug]

To close the loop on this issue:

I traced this back to an air leak at the intake of the fuel pump, where the solenoid threads into the fuel pump body. Apparently, some sort of rigid thread sealant was used at the factory that must have fractured, causing an air leak. The air seems to have caused poor injection performance, leading to over fueling and high exhaust temperatures and the pinned governor lever.

I removed the fuel pump assembly and disassembled the solenoid from the fuel pump. You need a very thin 12mm or 1/2" open end wrench to loosen the locknut that keeps the solenoid in position on the fuel pump. I found that clamping a vise on the flat plate of the fuel pump, where there is a cutout to view the governor lever the best place to get a safe grip on the fuel pump. I discovered that there is space for a 7/16" nitrile o-ring between the solenoid and fuel pump, cleaned the threads, (lots of nondescript black gunk in mine) installed a nitrile o-ring, and used a flexible thread sealant approved for diesel contact. Reassembly is just the reverse. I find it easiest to manually prime the pump with diesel by pressing the spring plunger with pump off of the engine, but YMMV...

One caution: the solenoid is only weakly glued to its body, so do not apply much torque to the M3 (5mm) nut that holds the solenoid power wire to the solenoid.

Runs great now, cool exhaust, and with about an 8mm gap between the governor lever and the over-fuel limit pin even under full load.

I hope that this helps.

All the best,

Peter

I have a 186FA on a 5000W/6500W surge generator that I am having speed control issues with. I put in a new injector, having previously replaced the fuel pump. (Old fuel pump leaked around the fuel intake.) I put on a new air filter as well, and I changed the oil while I was at it (filter was spotless).

This morning, I ran a load test of 4500W for 45 minutes or so. Air temp 60F. Light smoke from the exhaust the whole time, getting slowly less as time went on. The exhaust smelled fully combusted, unlike the old injector when the exhaust smelled like diesel. The engine held speed under load, the governor functioned normally. On target voltage and frequency. I will say that engine exhaust got HOT. The muffler turned from black to a grey and the little label on the frame over the muffler warning of the hot exhaust slowly got baked black. Then again, I have never really pushed the generator before. The generator has forty eight hours of use, mostly light duty backing up the house during power outages, where the microwave and the 3/4HP booster pump are the biggest load it sees. So, yes, probably lightly loaded for much of the forty odd hours.

The problem: after I took the load off and was letting the engine run to cool down, I heard the speed drop, and noticed that the governor was pinned against the high fuel limiter. I added back load and the engine came back up to speed, and the governor came off of the limit pin. I then cut the load again, and the speed dropped. Just for grins, I tried adjusting the speed downward a few hundred rpms, which brought the governor off the limit pin for a minute or so, and then it was pinned again.

I am stumped. Any ideas?

All the best,

Peter

 

[ponytug]

I have run the 186FA generator for another fifteen hours, and it is running well. Unloaded to full load is about 1% (36rpm) difference. I am actually quite impressed how well this generator holds frequency and voltage. It is an AVR model.

The engine is running much cooler now.

All the best,

Peter

 

[bmaverick]

I have run the 186FA generator for another fifteen hours, and it is running well. Unloaded to full load is about 1% (36rpm) difference. I am actually quite impressed how well this generator holds frequency and voltage. It is an AVR model.

The engine is running much cooler now.

All the best,

Peter

Peter,

That's really nice to hear. Until I stumbled on this thread, I thought it was for Yanmar tractors. BUT, it's mostly the engines in applications. So, I've poked around looking for what's out there for a Yanmar genset. Do you have any pointers on this?

 

[ponytug]

Peter,

That's really nice to hear. Until I stumbled on this thread, I thought it was for Yanmar tractors. BUT, it's mostly the engines in applications. So, I've poked around looking for what's out there for a Yanmar genset. Do you have any pointers on this?

I would try googling it, and you should find a couple of sellers, and some on eBay as well. Keep an eye out for clones posing as Yanmar. One of the giveaways that I have noticed is the air filter, which is square on the Yanmars and has diagonally opposite spiral intakes on the clones.
Here are a couple of part numbers : YDG6600TN (6,600 surge / 5,500 running watts) and YDG5500W (5,500 surge / 5,000 running watts)

I would love to be able to point you to a particular vendor, but I bought a used clone, so I have no experience with real Yanmars or Yanmar vendors, beyond saying I expect that original Yanmars are much higher quality. I tend to agree with 90cummins' view that I wouldn't use the clones in mission critical applications, or at least not with a backup.

That said, I am really impressed with the Yanmar design.

All the best,

Peter

 

[goeduck]

Can you run these Yanmar air cooled engines out of diesel and not have to bleed the injector line after refueling? In the back of my mind I thought I ran mine dry once and did not have an issue restarting.

 

[ponytug]

Can you run these Yanmar air cooled engines out of diesel and not have to bleed the injector line after refueling? In the back of my mind I thought I ran mine dry once and did not have an issue restarting.

Generally, it isn't a great thing to do in any diesel, as the injector and fuel pumps are very tight tolerance devices, and diesel fuel lubricity isn't what it was.

Based on the issues that I have had with air in the low pressure fuel line blocking the pump from priming, I would say don't bet on it, but I have never run one out of fuel. (As an aside, it isn't great for most generators to run to a stop while under load as that tends to demagnetize the windings, and it is the residual magnetism in the windings that is used to get the field established when starting a generator. However, that is a separate issue from your question.)

All the best,

Peter

 

[goeduck]

Generally, it isn't a great thing to do in any diesel, as the injector and fuel pumps are very tight tolerance devices, and diesel fuel lubricity isn't what it was.

Based on the issues that I have had with air in the low pressure fuel line blocking the pump from priming, I would say don't bet on it, but I have never run one out of fuel. (As an aside, it isn't great for most generators to run to a stop while under load as that tends to demagnetize the windings, and it is the residual magnetism in the windings that is used to get the field established when starting a generator. However, that is a separate issue from your question.)

All the best,

Peter

I certainly would not run one out of fuel as a matter of course, but being a generator I could see it happening. I have a 7500W gas Honda I use for the house but it is a bit of a gas hog. My 3000W diesel Yanmar is usually at my remote property to run tools, etc. but I have run the house at night on it so I do not have to refill so often. We lose power for a few days when we do lose it.

I did not know that about generators running to a stop when under load. Thank you, very good to know.

 

[ponytug]

I certainly would not run one out of fuel as a matter of course, but being a generator I could see it happening. I have a 7500W gas Honda I use for the house but it is a bit of a gas hog. My 3000W diesel Yanmar is usually at my remote property to run tools, etc. but I have run the house at night on it so I do not have to refill so often. We lose power for a few days when we do lose it.

I did not know that about generators running to a stop when under load. Thank you, very good to know.

I didn't know that either for the longest time; You are welcome! I admit that I have done it more than once before I knew that you shouldn't do it. All these little things that aren't in the manual...

All the best,

Peter

There are ways to reflash the windings with a 9v battery on the internet, but that assumes that you have internet when you need to do it...

 

[keith71]

Great thread.

 

[keith71]

China now producing bigger bore and stroke air cooled diesels to about 500cc's