Hitchcocks Forum

Today the Meteor, somehow and at this stage I have no idea how, but it has broken the crankcase washer on the timing side in half, Half is still in there and the break is so clean you can spin the remaining piece in the case so the break has been very clean.The piece then got caught up in the cam chain and broke that so the valves may be damaged as well. Any thoughts as to how/why this would have happened? And just after I ordered an alternator for it.

Norm, I'm not sure what you mean by crankcase washer but I assume it's the thin piece of alloy (that is part of the crankcase) in the timing chest that covers the timing side main bearing? This is often broken, usually by a previous owner incorrectly fitting the inner timing side race to the crankshaft without enough end clearance (or too much!) and the resulting pressure when the cases are assembled means the crank or bearing trying to push it's way out. The missing piece can't get upstairs to the valves but might cause wear in the bushes and timing chain. Personally I'd clean up and ignore it, it doesn't really do anything. Later Twins didn't have it anyway. If you mean the steel washer that sits between the bearing and the case, that would be quite a surprise, never seen that!
REgards, Mark

Mark,
It is the steel washer that has broken it half, half got tangled up in the chain, the other half stayed in the cases and I was able to rotate it around with a screwdriver and then it just came out through the upper section which appears to be missing, without any problems so I have both bits of the steel washer out, one nice and flat, the other a mangled bit of steel. My concern about the valves is that some may have been open when the chain broke but the pistons go up and down many times before before they come to a stop. Annoying part was it was going like a train and was sitting on over 60mph when it happened Mark, another question, this is obviously the only seal on the timing side, so what stops the timing case oil from ending up in the sump and it wet sumping. I have never really thought about this before but with the washer missing I am looking straight at the bearing and the thought occured to me, what stops the oil from draining straight through the bearing?

"so what stops the timing case oil from ending up in the sump and it wet sumping."

Absolutely nothing it has to go via the sump to the scavenge pump.

Dennis,
I'm still confused, oil pumped through the big ends falls to the bottom of the crank and is scavenged by the scavenge pump and on the twins as far as I know the oil is then pumped to the rockers, exhaust rockers oil drains back to the timing cover and the inlet drains back to the oil tank correct? If what you are saying is correct and I have no doubt it is, what stops the oil in the tank from working it's way back through the pump/timing cover and then into the sump

Hi Mark,
If you can send me an email and I can send you some pics and see what your thoughts and sugestions are [email protected]

Hi Norm

The oil system on the twins is a bit different to the singles, both the pumps are in effect two pumps in one, on the feed pump as the plunger goes in it feeds oil through the filter into the big ends, at the same time it sucks oil into the outer chamber where the spring ETC are, this oil is forced back out as the plunger rises and fed to the rockers, from here it drains down into the timing case, of course as it rises the plunger chamber is refilled for the next stroke, the scavenge pump works in just the same way with one side scavenging the sump and the other removing any excess from the timing case, not the easiest thing to explain but I trust you understand, as you should see it does not matter if some of the oil from the timing case ends up in the sump. the oil fed to the rockers is unfiltered so in effect the filter system is a bit hit and miss. HTH.

Thanks Dennis,
Makes it a bit clearer now and helps explain why when I remove the timing covers off these twins there is never much oil in them. I have thought about it every time I have removed them.
Thanks for the Info Mark, and it is interesting to note that the damage was the result of a previous owner attempting to remove the timing sprocket without the drive sprocket on. This is obvious because the breaks have been filed smooth and the missing ally bits were not in the timing cover. Any idea how I could get a copy of Jack Grays article?

Mark,
I've been thinking, so how's this for an idea as you have seen the photos. I get a new washer and cut it in half, slip them into the case and then JB Weld all around the outside of the washer. This will prevent the washer from turning and stop it from coming out again and I can push it in between the case and the washer so it will be very strong. The Jack Gray article makes me think along this line. Seems a pity to have to pull the motor down when apart from this it is running well

Hi guys---------- have been following this thread for the tech. info. content, not having a twin myself but always keen to pick-up other ideas, methods etc. A mechanical "Nosey Parker" you might say--------- Joyce says I'm just that anyway, never mind the mechanical bit!!!!!! That type of use for those pistons is quite common in Steam engineering ---- usually known as "Double-acting" ie the steam is admitted to alternate sides to extract the maxm. power from the design. NORM---- If you just cut the one washer then it won't "re-assemble" exactly to the same size because you'll be missing the small amount removed by the cut itself------again I don't know the design intimately and only have our hosts "On-line" parts drawings to follow------so I assume there is a bit of thickness to it? I'm thinking to buy 2 washers (Sorry, did I say "B-U-Y" ?? I meant OBTAIN---yes, that feels better)---cut them over size and then file-back the two larger ones to give an assembled ORIGINAL diameter size, if you see what I mean ?? Could you not Soft Solder them in situ ?? JB Weld is only an epoxy resin and not at all flexible when cured. Just some thoughts from "Rambling Sid Rumpole"-------------- Have a nice one !!!