|Posted by RedTR250 on May 26, 2011 at 11:04 PM|
It was supposed to be a two-day project – one day to take things apart and measure them, and a second day to install new parts and close everything back up again. Thrust washer failure is a common condition for the 6-cylinder Triumph TR engines. The two half-round flat bearings that control the crankshaft's axial motion are known to wear down and fall into the oil pan. When the thrust washers throw themselves into the murky goo, your crankshaft obligingly pulverizes itself and the engine block into expensive scrap metal.
I've checked The Sporty Red Car's thrust washers at least twice over the past decade, but not in the last four or five years. Lazy dog, me. The tolerance was marginal the last time I measured it, but not quite yet in the "oh, crap" zone. I've been spending time on the 6-Pack forum lately (the Triumph TR6/TR250-specific club and information base), and thrust washer horror stories are a common theme. I love driving my TR and I also enjoy working on it, but I've neglected my roadster for far too long, thanks to preoccupation with fixing up my old house, buying my new house, selling my old house, and fixing up my new house. It was time to take action and give my Triumph TR250 some lovin' care.
Once you raise the car on stands and commit to removing the 200 or so oil pan bolts (it just feels like that many), you might as well poke around a bit and see what else is going on down there. I pulled one big-end bearing cap just to have a look. I didn't check for roundness, but the surfaces looked very good and my Plastigauge indicated normal tolerances. I torqued two new big-end bolts to spec (the old ones are considered "stretched" and not re-useable) and moved on to the main bearings.
The original Vandervell-brand bearings had worn to the point of showing a lot of the copper layer. Fortunately for me, the crankshaft journals still looked great. I Plastigauged each used bearing and ended up ordering new, standard clearance County bi-metal replacements. I didn't see the point in buying premium tri-metal washers – there is a high likelihood that the moving parts are out of spec enough to grind my new bearings into paste, sooner rather than later. I intend to pull the engine and rebuild it, maybe as soon as this winter, but I couldn't bring myself to put the old worn bearings back in.
Now, the main reason I started this project: the thrust washers. It is not easy to get a thrust washer reading from outside the engine, although it can be done. It's tough, though; there's a lot of stuff in the way and good luck getting your dial gauge lined up. I already knew I was going to pull the pan, so I took my measurements directly from the crankshaft webs. The "normal" range of end float is between 0.006" and 0.008" and my averaged reading was 0.011". Worn out, but not a crisis. Considering the engine's mileage must be in excess of 80,000 miles, not bad at all. I guess I'm a big fan of Triumph's Vandervell bearings and thrust washers.
I love to boast about classic British car parts availability, but trying the line up my list that included main bearings, thrust washers, two big-end bearing cap bolts, eight main bearing cap bolts (can't re-use them, either), oil pan gasket, and associated seals and whatnot proved to be impossible to source from a single vendor. To complicate things even more, I had decided to replace the gearbox oil since I was going to be under the car anyway. My Moss distributor did not have Red Line 75W90NS synthetic in stock; I waited for Moss to ship it to him, and after a week's delay he and Moss sent me Red Line's synthetic differential oil by mistake. Although it was more or less sorted out in the form of a refund, I ended up getting the stuff from Summit – by no means a Triumph specialist! It was in stock, they are in Ohio the same as I am, and the product arrived quickly and for a reasonable price.
Thanks to back orders, long shipping times, and dealing with unexpected home maintenance issues, my two-day project ended up taking six weeks. There's been so much rain lately, I don't think I missed much driving time.
I've changed thrust washers and bearings before, but it was a spare TR6 motor that was flipped upside down on an engine stand. Funny how much harder it is when you are laying on your back, with chassis schmutz in your eyes and assembly lube dripping honey-like down your arms. A few more days and I'd have the neck muscles of a Formula 1 driver. After the past year's challenges, home improvements, and construction projects, that greasy space beneath the Sporty Red Car was my refuge, my chapel, my Nirvana.