I have completed the rebuild of the engine. The coking was very significant, but no lasting damage seems to have occurred.  Two new oil control rings were fitted on pistons 2 and 3, a new head gasket of the latest composite type was used, and new head bolts and breather unit were fitted.
I wanted to remove the head complete with the turbo and manifolds. To do so, the turbo needed to be disconnected from the exhaust (simple enough) and the oil pipes. The supply pipe to the top of the turbo is easy – it’s just an easily accessible 13mm banjo bolt. The bottom retun pipe is another matter – there’s just no reasonable access to get a spanner on that big nut. The solution was to get the big circlip pliers out and remove the turbo’s compressor casing – with that out of the way (hinged up ontop of the turbo body with the waste gate still connected), disconnecting the oil retun from the turbo was very easy.
The pistons and bores were given a good clean out, removing all the coke deposits. The pistons were then sloshed about in a bucket of petrol to wash away all the small granules and bits of debris. The bores and crank journals were cleaned with oiled and then dry cloths.
The pistons were refitted with a generous oiling of their sides and rings, the head refitted and all the various pipes and electrics reconnected. The ladder frame, oil pump and sump were simple to refit, especially with the use of a cordless drill with 10mm socket fitting. They have been sealed with the correct high temperature sealant from Turner Engineering.
So far, the only alteration to the fuel system has been to reinstate the tank return lines, reconnecting the injection pump’s spill line to the return selector valves and tanks, and to replace the T joint where the return line had looped back into the lift pump supply with a straight connector. The fuel filter was replaced with a new one, and the system purged properly with fresh diesel before reconnecting the injectors to their pipes. I added a bottle of STP diesel fuel system cleaner to the existing half-tank of diesel, as it claims not only to be good at cleaning the fuel system, but also the pistons and bores. It’s stronger than the usual additives, with instructions to use not more than once every 4000 miles, and will hopefully remove all the last traces of carbon deposits.
I found problems on starting up for a test run – I couldn’t select high range on the transfer box. After a lot of cursing, getting annoyed and worried about the lack of time to sort this out before Sunday’s brief holiday and working tomorrow, and having drained the transfer box oil in preparation for removing the 4wd housing, I found the fault. It was a simple mistake when I refitted the transfer lever and bracket after drilling out the bell housing to remove the engine’s adder bolts. I had refitted the lever’s bottom pivot bracket on the back of the bell housing’s mounting flange instead of on the front of it. With the fault rectified, the transmission is working correctly again.
I also had problems with starting the engine while working on the transfer box – initially, the engine was starting fine, but all of a sudden, the starter solenoid stopped working. It turned out to be a weak terminal on the solenoid – the new female connector on the end of the ignition switch wire (replaced when I swapped out the faulty starter motor a couple of weeks ago) was loose on the male blade of the solenoid, and needed squeezing tighter with pliers before refitting.
I was then able to test run the vehicle. The first 1/2 mile saw some big black smuts coming from the exhaust when accelerating. These were probably just a combination of particles of coke being cleared out of the injectors and the oil on the pistons from their fitting. The exhaust rapidly cleared, and a test run of six or seven miles saw only grey smoke when accelerating at full throttle in second and third gear, gradually decreasing throughout the run, to give very little smoke by the end. There was another hiccup during the test run: after entering the dual carriage way, I started getting intermittent power losses, until the engine failed completely. I was very lucky to be approaching a lay-by at that moment, and was able to coast in at about 30mph to safety. I had suspicions of the fuel solenoid terminal being the problem, having worked on the fuel lines adjacent to it, and this proved to be the case – the ignition wire was hanging clean off the solenoid. A quick reconnection resulted in a continuation of the test with no further events.
A frustrating day, with some stupid errors and problems, but at least they were easily fixed and the engine is back together. There seem to be no leaks so far, and the oil level is where it was at the beginning of the test. I’ll just keep my fingers crossed that tomorrow’s fifty mile round-trip to work doesn’t show up any more issues. The outstanding tasks for the big trip now are to fit two DIN power sockets in the back of the vehicle, and to fit some floors to the Jerrycan lockers.
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