Injector pump clatter

California · May 27, 2006

A friend asked about this noise and I had never thought about it:

Cranking the cold engine with compression released, there is a muffled sound at TDC that sounds like the normal ''Yanmar Hammer' but much quieter.

Does the injector pump fire even when the throttle lever is at zero?

California · May 27, 2006

A friend asked about this noise and I had never thought about it:

Cranking the cold engine with compression released, there is a muffled sound at TDC that sounds like the normal ''Yanmar Hammer' but much quieter.

Does the injector pump fire even when the throttle lever is at zero?

mark777 · May 27, 2006

Sure does.

I works off of a short cam shaft attached to the outer cam gear, and separate from the engine cam shaft. So each plunger, one per cylinder, compresses during cam lobe rotation and "cracks" open at TDC of that lobe.

There is a set of helical gears that rotate and act as fluid metering valves...the gears are attached to a sector rod that couples to the outside throttle linkage. With or without fuel....OR throttle fully opened or at stop, the pump plungers will continue to crack open if the engine rotates.

Mark

mark777 · May 27, 2006

Sure does.

I works off of a short cam shaft attached to the outer cam gear, and separate from the engine cam shaft. So each plunger, one per cylinder, compresses during cam lobe rotation and "cracks" open at TDC of that lobe.

There is a set of helical gears that rotate and act as fluid metering valves...the gears are attached to a sector rod that couples to the outside throttle linkage. With or without fuel....OR throttle fully opened or at stop, the pump plungers will continue to crack open if the engine rotates.

Mark

normde2001 · May 27, 2006

Now who else would know that but you, Mark?...What's the latest on your injector adventures?

normde2001 · May 27, 2006

Now who else would know that but you, Mark?...What's the latest on your injector adventures?

mark777 · May 27, 2006

Hey Norm, thanks for asking.

It's complicated, but here's the short version.

About 4 months ago, I sold Pops 1601D as he has always wanted a Yanmar with shuttle shift. I gave him the 1610D and worked diligently to repair all the little problems, which I was able to provide most parts for. After the head gasket, valve job and hydraulic pump repairs....He insisted that everything else he would pay for. Now he's a proud, stubborn man, and at 70 there are some things you just can't do for people. I respect that he wants to do this (and I know he has a limited income) but the tractor will feel more like his when he gets enough money for a rebuild or good used pump.

I did have another 3T75U engine with the exact same pump, so that I could swap and verify 100% that the injection pump is indeed the fault....but someone bought the tractor before I could try. I have since disassembled the pump and it is bad. The tractor is currently sitting in the corner of my shop and covered waiting for a replacement pump.

Mark

mark777 · May 27, 2006

Hey Norm, thanks for asking.

It's complicated, but here's the short version.

About 4 months ago, I sold Pops 1601D as he has always wanted a Yanmar with shuttle shift. I gave him the 1610D and worked diligently to repair all the little problems, which I was able to provide most parts for. After the head gasket, valve job and hydraulic pump repairs....He insisted that everything else he would pay for. Now he's a proud, stubborn man, and at 70 there are some things you just can't do for people. I respect that he wants to do this (and I know he has a limited income) but the tractor will feel more like his when he gets enough money for a rebuild or good used pump.

I did have another 3T75U engine with the exact same pump, so that I could swap and verify 100% that the injection pump is indeed the fault....but someone bought the tractor before I could try. I have since disassembled the pump and it is bad. The tractor is currently sitting in the corner of my shop and covered waiting for a replacement pump.

Mark