Hitchcocks Forum

I recently got a chewed up oil pump, as in the threads that connect to the worm drive of the crank shaft were toast. As of course were the threads on the worm drive. I pulled the top end off, head and cylinder, to check that the big and small end bearings were still to the good, which they were, so I reassembled.


Now maybe I should have split the engine but I was lazy and thought that was the source of my problems. For a while I'd be listening to the bike thinking something wasn't right but struggling to find what ever it was. To cut a long story short after putting it all back together with new oil pump and worm drive it did 60km and died. It wouldn't start and I assumed that it was the classic, fuel, compression and spark at the right time problem, which is a way it was. So there was I faffing around in the top end cleaning carb, grinding valves to make sure they were seating properly and checking the spark. I've electronic ignition so sort of assumed that it was still to the good. I could not find the problem, well the spark plug was not getting damp from a fuel/air mixture but the carb was clean.


Having not found the issue, and struggling for something constructive to do, I decided that I'd strip the bike again. I pulled the timing cover to find the source of my problem. The new oil pump was chewed up again as was the worm drive. Kicking the engine over easy with the kick starter revealed that the crank shaft bearing on the timing side is shot to shit. Not only was it shot to shit but it had enough play to come away from the timing gears it drives to totally change the timing of the bike. It's probably sucking when it should be blowing and vice versa. No wonder the spark plug ain't getting damp with fuel! And very luck that it didn't damage valves, not sure it can reach them but who knows. In hindsight the compression ain't perfect but at the same time it's not the worst.


Now it's a chicken and egg, in that did the crank shaft play chew the oil pump or did the oil pump cause the bearing to eat itself. I think that it was the bearing that went first. Like I say there's been a nose for a while that I've stripped the bike trying to find the source of but never found. I never even though of checking the crank shaft bearings. In hindsight I'm not even sure how I would have. It's only because it got so bad that it became self evident.


So now I've got the engine out, if not split just yet and I just thought what am I replacing. I think I'll replace the crank shaft bearings at both ends but the big end bearing on the connecting rod? Hmmmmm that's a big job and I'll have to get it to somebody to do that, and it's an expensive bearing so with paying somebody to fit it, along with all the rest that has to be replaced, it's going to cost. On the other hand with all the crud that's been floating around the engine from a shattered bearing and chewed up oil pumps I'm guaranteed that there's crud in the engine where it should not be. I think I've answered my own question. Well lets say I'm leaning towards replacement. I've not ordered up parts from or hosts as yet. I'll split the engine case and see what wonders await.


Having said all that I'll just go and do that. Have to borrow a tool to get these two halves apart. Well done if you got this far I started this post wondering about the big end bearing but I think I'll probably have to play safe and replace it. Given I've sort of answered my own initial question here's another. How would you have early detected a crank shaft bearing problem? I now know that when there's a suspicious noise to check it, if not how to do so.


John

Hi John
Be sure to split the rocker blocks in the cylinder head and clean out the oilways. Debris from a failure collects in the oilways in the blocks and blocks them. The oil pump continues to pump against the blockage. If you are lucky the oil pump gasket blows but more often the worm strips again under the strain.
Regards
Edward

I had exactly the same problem on my Lightning when it had only done 1500 miles from new. The cage that holds the rollers in place on the timing side main bearing had disintegrated. I ended up with a 'borked' oil pump. 'Clapped out' rockers. A 'fudged' exhaust valve and a 'skew-wiff' exhaust push rod. Thankfully, the big and small ends were fine. The collapsed bearing had made a mess of the crankcase half, but some grinding with a Dremel cleaned it up nicely. The outer race had to be cut out with the Dremel, but it wasn't a hard job. The replacement parts came from our Hosts. The Lightning has been purring like a kitten for the past two years!

I feel your pain! As you said, seperate the crankcase and assess from there. Remember that there is also the diesel option!

John,
I have found it so many times, stripped pump spindle says big end is failing, whitemetal gets stuck in the rocker blocks and as there is no relief valve on the skavenge pump it continues to try pumping till the pressure is too great and as something has to give it strips the spindle. Motor was going to fail anyway, all you have done is wasted a new pump spindle. Look inside the rocker blocks and you will find the grooves blocked

Thanks people!


A lot of useful stuff there. Thanks for the advice on the rockers. I've been in there already and yes they're on the list Still thanks for it. It's something that people should be aware of, for sure. I'm actually shocked that people have had the same problem, especially on a Lightening with 1500 miles on it. I never ever ever thought I'd be replacing these bearings. On the subject of the noise I was looking for, but failed to find. I once found an interesting smart phone app which analysed data from a microphone. It did fourier transforms and the like on the data to produce meaningful human readable information. Those things are used on mechanical watches to listen and work out if they're running well. Anyhow I was just thinking imagine there was a central server where you could post a recording of your engine. The server would do all the math, compare it to a database of sounds for that make model and engine and spit back out a result. What was that bit in "The Hunt For Red October" where if the computer didn't know any better it spat out "whales humping". Ok there would not be a great deal of demand for it. It's just me that's busting main bearings.


Barry_q: You jammy.... Chap! I know I might be cautious but as Norm says "stripped pump spindle says big end is failing" those are words you could live your life by. You did well to keep going with the same big end but I know if I don't change it then in 500km I'll be back splitting the engine again.


Midge: Diesel indeed! Since I blew the bike, which is my regular ride, I've become a cyclist. That has warned me that my knees aren't ready for kicking a diesel It's something I actually ponder every now and and the fuel economy is tempting but the acceleration and weight of the lump is the other side of the coin.


Thanks again people

One of the things you ought to do is drain the oil from the sump. If there's flecks of silvery metal in the oil, then you can kiss goodbye to your big end. I was lucky. When I drained the oil from the sump, it was free from metal flecks (but completely black). I can only conclude that oil continued to seep (via gravity from the timing chest) through the end of the crank (oil plug bolt was broken) and protected the big end. I don't subscribe to the notion of 'stripped spindle means big end is failing'. I'm more of a 'stripped spindle means the big end is going to fail if a related problem isn't sorted out' kind of person.

Hi matey !! Have only just seen this thread------------ OK, I'll tell it how it is, no punches held------ it's a FULL ENGINE STRIP----COMPLETELY!!! Followed by a thorough wash and COMPRESSED AIR blow dry of ALL COMPONENTS..then an assessment of all those components involved..You've already lost an oil pump and drive shaft..Do you want to repeat that ?? of course not... It might only be a crappy Enfield but your engineering approach must be of a Rolls Royce nature....Then the re-build MUST include the latest spec bearings (from our hosts--naturally).....One bit of good news is that the engine can be removed from the frame with the gearbox left in situ.....Also, it's a lot lighter when you remove the head and barell first....Looking on the bright side, you could say that the first time around was only a practice session-LoL !!............... The main database in the computer in Red October was developed from an Oceanographic Survey one used for recording underwater activities such as the "Humping" whales.etc.. So when, in military use it encountered an "unknown" sound, it reverted back to something familiar ... Have you checked your Baffles lately ???---- I do mine on the half hour and always turn to port !!------------- I know, I know, ..I'm a sad case....Doh !!!...ps here's a "Basic" Typhoon Sub...It's one of these that's supposed to have that "Tractor" impulse system fitted to---- http://en.wikipedia.org/wiki/Typhoon-class_submarine ------------------- They're old hat now and are being phased out....

Barry, once upon a time everybody was running around blaming crappy pump spindles as the cause of engine failure. I never supported that because I have seen so many of these engines fail. I'm about to to build my last one which I recently bought with a failed bush and I will be doing no more of them because I can no longer be bothered working with so many parts that just don't fit and I have to spend so much time machining them to make them fit or just throw the bits in the bin

John,

As you're replacing the big-end bearing, I hope you will be having the Hitchcocks roller-bearing installed? That way ongoing oil-pump and oil-feed problems will be minimised. It is, of course, NOT a DIY job to build a Bullet crank properly. In the UK, I can recommend Alpha Bearings in Birmingham for this job (they build the 612cc cranks!)

Martin