sailoppopotamus
Well-Known Member
I know I'm reviving an old thread.
Today I removed the fuel pipe to the #2 cylinder (the forward one) of my 2GM20F. After removing the injectors and getting them professionally cleaned, my engine developed a leak between the #2 injector and the fuel pipe leading into it. I have tried tightening the joint as much as possible, but the leak has persisted. So my amateur diagnosis is that the compression(?) fitting on the pipe has been distorted and damaged, and the whole pipe needs replacing, since the 'olive' type thing is captive on the pipe and cannot be replaced without replacing the whole pipe.
So far so good. In pretending to be a diesel mechanic I'll accept some collateral damage that will be paid for from money saved by not employing an actual diesel mechanic.
And here is where my tale relates to OP's thread. While undoing the nut connecting the fuel pipe to the delivery valve holder, the delivery valve holder moved (loosened). At this point I did what I should've done from the very beginning: I removed the clamp holding the raw-water hose leading from the raw-water pump to the heat exchanger, and disconnected the-raw water hose from the heat exchanger and the supporting bracket. This gave me enough space to insert a spanner to hold the delivery valve holder in place while I undid the fuel pipe nut. But the damage had already been done, and the delivery valve holder had moved. My advice -- if you are attempting to replace the fuel lines on a GM engine, start by getting the raw water hose out of the way so that you can get a spanner on the delivery valve holder to hold it in place while you're undoing the other nut.
Looking through the Yanmar manual, I find no reference to thread lock as described by the OP. Yanmar do indeed warn against overtightening the fuel valve holder. They say tighten to around 40Nm, and explicitly warn that overtightening may lead to damage and loss of performance, but otherwise the performance of the pump does not seem to depend on precise adjustment of the valve holder. I retightened the valve holder as per the spec, and I'm waiting for a replacement pipe. I really, *really*, hope, that I'll be able to simply install the new pipe and have everything work fine.
Yet I'm a bit troubled by OP's story. The torque of 40-45Nm specified by Yanmar is quite substantial, so being able to casually overtighten that by 10-15 degrees beyond that seems a bit odd.
Today I removed the fuel pipe to the #2 cylinder (the forward one) of my 2GM20F. After removing the injectors and getting them professionally cleaned, my engine developed a leak between the #2 injector and the fuel pipe leading into it. I have tried tightening the joint as much as possible, but the leak has persisted. So my amateur diagnosis is that the compression(?) fitting on the pipe has been distorted and damaged, and the whole pipe needs replacing, since the 'olive' type thing is captive on the pipe and cannot be replaced without replacing the whole pipe.
So far so good. In pretending to be a diesel mechanic I'll accept some collateral damage that will be paid for from money saved by not employing an actual diesel mechanic.
And here is where my tale relates to OP's thread. While undoing the nut connecting the fuel pipe to the delivery valve holder, the delivery valve holder moved (loosened). At this point I did what I should've done from the very beginning: I removed the clamp holding the raw-water hose leading from the raw-water pump to the heat exchanger, and disconnected the-raw water hose from the heat exchanger and the supporting bracket. This gave me enough space to insert a spanner to hold the delivery valve holder in place while I undid the fuel pipe nut. But the damage had already been done, and the delivery valve holder had moved. My advice -- if you are attempting to replace the fuel lines on a GM engine, start by getting the raw water hose out of the way so that you can get a spanner on the delivery valve holder to hold it in place while you're undoing the other nut.
Looking through the Yanmar manual, I find no reference to thread lock as described by the OP. Yanmar do indeed warn against overtightening the fuel valve holder. They say tighten to around 40Nm, and explicitly warn that overtightening may lead to damage and loss of performance, but otherwise the performance of the pump does not seem to depend on precise adjustment of the valve holder. I retightened the valve holder as per the spec, and I'm waiting for a replacement pipe. I really, *really*, hope, that I'll be able to simply install the new pipe and have everything work fine.
Yet I'm a bit troubled by OP's story. The torque of 40-45Nm specified by Yanmar is quite substantial, so being able to casually overtighten that by 10-15 degrees beyond that seems a bit odd.
