Tractor fixin' (Updated)

 "When someone is properly grounded in life, they need not look outside themselves for approval." - Epictetus

Yesterday brought some badly-needed rain to the region.  It was enough rain to keep the major fires from growing larger, and to buy fire fighters time to extend their containment lines a little.  The rain was surely steam by the time it fell on the wildfire areas, but at least it wet down surrounding vegetation.  Also the humidity helped suppress the fires a bit.  It didn't cut down on the smoke much, if any.

Yesterday was also tractor repair day.  Replacing the engine's rear shaft seal failed to stop the oil leak, so it was time to try again.  I mentioned in that earlier post that perhaps a little square cover was the source of the oil leak, and had ordered a replacement gasket for it.  That was not the case.

The process went like this:  Drain the engine of coolant, remove everything attached to the cylinder head, remove the cylinder head, fix the leak, clean everything up, then re-assemble.  That process took about 6 hours.

Below is a view looking over the engine from the driver's seat before the start of the project.  It became troublesome almost immediately.  Just to remove the exhaust pipe (right side) required removing the front loader attachment from the tractor, as the exhaust could not be slid off the mounting studs with the loader arm in the way.   Also note the gnarly-looking radiator hose.

 Below:  Clearance issue with the exhaust.  It has to slide 5-6 inches to the right to clear the studs.

Below:  Part way there.  The intake is set aside (upper left), the exhaust pipe is removed, the radiator hose is off, and the valve cover is off.  The fuel lines have a couple of glove fingers over them to prevent contamination, and the fuel injectors are partially disassembled.  The rocker arms are off and the pushrods have been removed.

There was an issue removing one of the fuel injectors.  They were probably assembled as a unit and then installed in the correct orientation for the fuel line to connect.  However, the upper part of one injector could not be unscrewed, because it hit the casting on the cylinder head.  I had to use an angle grinder to remove a bit of the metal from the cylinder head - to provide enough clearance to unscrew the top of the injector.  After the top of the injector was removed, it was possible to connect the injector removal tool (special slide hammer) to the bottom part of the injector and remove it.  This all had to be done while the cylinder head was still attached to the engine.  The slide hammer would not have been able to pull the injectors out with the cylinder head on the bench.

Once the injectors were removed, the six nuts holding the cylinder head could be removed, and it came off easily.  Oh yeah, the radiator fan had to come loose, as it mounts to the front of the cylinder head (right side)

I don't know why, but I didn't take any pictures of the valve rockers, fuel injectors, or pushrods while they were loose.  Below is a photo of the engine with the cylinder head removed, before prep for reassembly.

Below:  Under-side of the cylinder head, as found.  Diesel engines are pretty nasty, hahaha.

Below is the square cover plate that I suspected being a possible source of the oil leak.  It is held in place by two Phillips screws and two bolts.

Below:  The cover plate allows access into the coolant system, possibly to inspect the casting after manufacture.  But no oil would leak from this... 

Below:  The under side of the cylinder head, partially cleaned up.  Look at the top right hole.  Pretty oily still, yeah?  That's the source of the leak.  There was RTV sealant on the cylinder head gasket here, and possibly the previous owner had re-used the gasket - a big no-no.  You also don't use RTV on a cylinder head gasket.  

That hole is the oil supply passage that routes oil from the oil pump in the bottom of the engine, up to the valve train - the rockers, valves and pushrods.  Oil was weeping out the rear of the engine due to poor installation of the cylinder head gasket.

Everything then got cleaned.  All the mating surfaces had the old gaskets removed, the injectors got the wire wheel and soaked in Simple Green parts cleaner.  Lots of lapping with fine grit sandpaper.  Nasty work.

Below:  Engine block cleaned up, with the new cylinder head gasket in place.  Didn't realize this was such a blurry photo...

Below:  Cylinder head bolted back down, injectors in place again at left.  Valve hardware not yet installed.  Note for anyone stopping by to fix their own 155D:  Final torque spec for the head bolts is 115 ft-lb.  Tighten them up to 55 ft-lb, then torque them all up to 115 ft-lb in 10 lb increments.

Rear cylinder valve rockers installed.  Adjust the valve lash to .006 inch.  It's probably redundant to say this, but make sure the cam cam isn't lifting the rockers when you do this :).  Roll the engine as necessary to get the lifters off the cam.  I know... duh.

And after this, I quit taking pictures.  The valve rockers got adjusted, the fuel got reconnected, the coolant hose got replaced, and it all came together pretty nicely.  It no longer leaks, which is the best part of the day.

UPDATE 25 August 2023

More pictures and more repairs...

Here's a nice picture I got before installing the head on the new head gasket.  You can see the pushrod lifters down in the oval opening, and the hole that had been leaking at the lower left just outside the stud.

Below at the bottom is the air inlet.  The old gasket was cracked and leaking in unfiltered air, so I made a new one.  You can see the new blue gasket material just above the silvery inlet.  Also there was a wasted rubber sleeve gasket that fit over the silvery inlet.  It seals the air filter housing to the inlet.  I cut up the center of a plumbing fitting to go seal the inlet pipe to the air filter housing.

Below, you can kind of see where the air filter housing slips on to the inlet pipe.  Also one of the injectors was missing a copper gasket, so I picked up an oversize one at the hardware store.

After removing the fan/alternator assembly for this project, I noticed that the alternator wires were cut off.  This really has never been a big deal on this tractor.  After the engine is started, it doesn't use any electricity unless the headlights are on, and those don't draw much power.  I always leave it on a trickle charger, so the battery keeps a full charge.  

Nevertheless, it has a charging system and it should be connected and working.  That yellow wire and red wire coming from the alternator were dangling free, with nothing obvious nearby to connect to.

Fortunately the owner's manual has a wiring diagram, and it wasn't too difficult to splice in some extra wire and get the alternator connected.  The loose alternator wires are marked with an arrow.  It wasn't hard to find where the loose end was cut off on the wiring harness and re-connect.  Charges just fine now without needing the trickle charger, although it will get trickle charged during the winter.

Lastly I tackled an issue that has been a problem since day 1.  There was an exhaust pipe clamp on this, that kinked the metal and allowed a minor amount of sooty exhaust to escape right into my face.  Decided to remove the clamp and weld the pipe to the muffler.

Turns out I am not a very good welder...  I burned a lot of holes in it, and now it leaks worse than before.  I think I'll have to braze it, or switch to Argon gas instead of flux wire.  It really was splattering - impossible to get a clean weld.

And there is the current state of affairs:  New cylinder head gasket, new intake gasket, new radiator hose, clean injectors, functional alternator, and it still smokes like a steam train and leaks at the muffler, LOL.