I have been rebuilding the yanmar 3TNE88 engine in my Takeuchi TB135 excavator and having some trouble getting it to start and run right. I ended up getting a 3TNV88 block and using most of my 3TNE88 parts. This engine has an idler gear as part of the timing gear set with the three marks A B and C to line up with the crank, cam and pump drive gears. When i assembled everything and tried to run it it would barely fire and wouldn't stay running. One of the difference between the TNE and TNV is that the idler gear on the TNV has three mounting holes whereas the TNE only has two, so i had to use a TNV bushing and gear. I looked back at a picture i had and compared the TNV to my old one from the TNE and noticed that the distance between the A and B and A and C were each one tooth off between the two gears. I took the timing cover off and moved the gears each one tooth in the right direction so that they matched my old gear. The engine is hard to start now but once its up and running at full speed it sounds and runs good. It idles rough though and doesn't restart really easy either. Im wondering why the timing could be off between these two engines that are supposed to be mostly the same. I can understand the pump gear being slightly different since the TNV uses a different pump, but im wondering why the cam gear would be a tooth off between the two. And is there some reason why i wouldn't want to put the timing gears in the same position as my old engine was? I also have new injectors but the old injector pump. Other things worth noting, the new engine would bog down under load (which was also a problem with the old engine) until i adjusted the fuel screw out on the governor about a turn and a half and it no longer bogs down under load, and give a slight bit of black smoke when loaded. Could this be a sign that i have injector pump issues?
I think i determined why the timing marks are different, looking up parts for the TNE and TNV the parts manual shows a different crank gear for the TNV that is about half as tall as the one on the TNE, since its a spiral gear being half the height moves the location of the A mark on the crank gear one tooth, which moves the mark on the idler gear to match. Moving the A one tooth is the same as moving the B and C each one tooth which is what i did. So i think my gear timing is correct, that leads me to maybe my pump is the problem with hard starting. The fact that i had to turn the fuel screw out so much to get it to run under load makes me think maybe its worn internally and adjusting the screw made up for that but is still not giving enough fuel at idle? (it had the tamper proof cover on it still so i dont think it had been adjusted before)
You need to set timing according to the TNV Design and possible get or use the proper gear for a TNV series on the Crank. Determine position of timing mark against First the Crankshaft Key slot of each engine then the THE as to #1 TDC and then the THV against #1 TDC. Had start is likely too Much timing, and then you Do have to set Pump timing against a New install, it is not a unbolt/boltup.
I think i determined my gear timing is right as in the post above, but since there are different options for gears on these things and i dont know exactly what my idler gear came off of i guess im not 100% sure. But id think that id want it to match as per my old engine, and the shorter gear im seeing as an option on the TNV leads me to that same timing marks as i have on my old gear. im using the crank gear, pump, cam and head off my old engine. So i think i have that right. I guess is there a way to verify my valve timing is right if i cant trust the timing marks? Each tooth is about 6 degrees so if i was off a tooth id be off 6 degrees, not knowing when the valves are supposed to open and close i cant really tell for sure. As for the pump, im having trouble telling if i have that the injector timing set correctly, ive tried advancing it and retarding it some, but ive been trying it more on the advanced side than retarded. The method of turning the engine over by hand and and watching for flow out of the injector pump nozzle seems tough to get an accurate read on. So maybe ill try retarding it more and see if that helps. How would i be able to tell if its a bad pump causing the hard starting?
Go back to manuals and look up injection timing, Guessing will gain you nothing
You didn't pull the gear off the injection pump shaft itself did you ?