Reassembling the Tdi

Reassembly is well underway.

The block came back from reboring very clean, having been put through the parts washer to remove all traces of swarf. This meant I was able to give the exterior a spray of silver Hammerite (I have found Hammerite to be very good for painting engines, with good adherence and resistance to heat and oil – the 12J’s paint has lasted immaculately for nearly a decade).

Once the paint was dry, reassembly commenced with the fitting of the piston oil jets. This was a bit of a trauma – several of the bolts sheared. Though quite large, they’re very delicate as they’re hollowed out to act as banjo bolts, with valve assemblies inside them. None of the local LR suppliers, including the franchises, stock these bolts, so I had to roll the dead 19J on its side, remove its sump and canabalise it for the oil jet bolts.

Once they were in, I fitted the main bearing upper shells to the block. You can use engine oil during the build up, but it’s better to use engine assembly grease as it doesn’t thin out while the engine is standing. A generous smear was applied to both sides of each shell and the thrust bearings before fitting, and the clean crank shaft was then lowered in to the bearings. Then, the bearing caps were fitted with their shells (again, with a generous application of assembly grease) and fitted to the block. The rear cap is a bit difficult with its T-seals, but it went in after a little bit of fiddling about, using feeler gauges as guides for the seals to fit them between the block sides. The cap bolts were then all torqued down to the correct figure.

With the crank shaft properly installed, the pistons were next. The crank shaft was rotated to have cylinders 1 and 4 at bottom dead centre and the bores were given a coat of engine oil. The old gudgeon pins and pistons were removed, the little end bearings inspected (these seldom wear significantly) and the new items fitted, with special care to ensure that the conrods faced the same way in the block as before. More of the assembly grease was used on the gudgeon pins for reassembly.

The new AE pistons were boxed with their rings already fitted, so all that was required was to align the ring grooves properly. Viewed from above, with the front of the engine away from you, the groove in the top ring of each piston should be in the 10:30 position, the second ring in the 4:30 position, and the oil control ring at 7:30. With the rings aligned, the number 1 and 4 pistons were sat into their bores. The ring compression band was then used to squeeze the rings to allow the pistons to be tapped lightly down into their bores with the wooden mallet handle. Once clear of the ring compressor they were pushed down by hand until the big end reached the crank shaft.

With the first two pistons pressed in, the block was swung inverted (the stand I’m borrowing is making life so much easier!) and the pistons wer pushed back out 1/2″ to create enough room to fit the big end shells. More assembly grease was used on the shells, the conrods were pulled tight against the crank shaft again, and then the associated caps were fitted to their conrods, again with greased shells. It’s critically important to make sure you don’t mix the caps and rods up, as they are individually matched. They are both numbered, though, so it’s easy to keep the matches correct as long as you pay attention as you fit the caps.

Once the number 1 and 4 conrod caps were torqued down, the crank shaft was rotated 180 degrees to make pistons 2 and 3 bottom dead centre, and the process was repeated for them. Even though plenty of assembly grease had been applied to all the contact surfaces, I then poured a small amount of engine oil onto all the bearing areas and rotated the crank shaft a few times to make sure all the areas were well protected from condensation and to ensure they are all well lubricated for the first start.

With the crank shaft and pistons complete, I then fitted the two rectangular side panels (breather and lift pump), complete with new gaskets. The oil pump skew gear bush was refitted with its grub screw (more grease), followed by the filter housing and gasket, the skew gear assembly (with two new O-rings and another dollop of assembly grease) and the brake vacuum pump. You need to leave the two bolts passing through the injection pump rear bracket and crank case breather panel slightly loose at this stage.

New gaskets were fitted to the front of the block, using LM grease to hold them in place, and new seals replaced the old crank shaft and cam shaft seals in the timing case. The new seals were installed with a smear of silicone, which acts as a lubricant for fitting, but then helps seal and secure the seating face to the timing case once set. With another smear of assembly grease to the seals’ lips, the timing cover was then refitted to the front of the block. The timing sprockets were fitted to their shafts (a light smear of grease was used to prevent reoccurence of the crank shaft sprocket and pulley seizing onto the shaft) and the idler and tensioner sprokets were fitted (though the latter’s bolt is only finger tight).

The injection pump was fitted to the timing case, with the new gasket smeared again with LM grease. Once the nuts on the timing case studs were tightened up, the two bolts through the pumps rear bracket were fitted and tightened, allowing the tightening of the two bolts through the bracket and block breather plate (that had been left loose to allow this bracket to align with the injection pump). The sprocket and retaining ring were then fitted to the pump spindle.

Finally, using a digital vernier gauge, each piston was measured for its crown’s protrusion above the block face at top dead centre. All of them were between 0.73 and 0.78mm, so I now know I need a 3-hole head gasket (there are several different thickness gaskets available, matched to different piston protrusion measurements. I’ll be buying two gaskets so that I have a spare for next summer’s trip.