|
Post by colin4255 on Mar 9, 2012 18:56:59 GMT
I knew it would only be a matter of time.... I have just completely rebuilt my engine. I put a new DR 180 kit on it last year, so all we did there was to check the bore and fit new rings. Elsewhere its been a complete set of bearings, complete set of seals, new clutch, new christmas tree, new cruciform, rear hub bearing etc and all new gaskets. I did have some issues last year when I bought this scoot as the previous owner had not put any washers back on the two bolts that bolt the carb down and it was only looking at Beedspeed that I realised that without the right washers, the carb was not bolted down tight, as they were bottoming out, so we sorted that, and also, he had filled in the hole left by removing the autolube with silicone RTV, so we did a proper job of filling that with liquid metal as air was leaking past what he had put in.
It has a new sito plus exhaust (been on the scoot since last sept) and when I got it running the other day it runs really well, EXCEPT for a massive gearbox oil leak! Ran it for only about 5 miles to check it out, bed it in etc. The leak is nice clean green gearbox oil which seems to be coming from the base of the carb tray where the gasket between the engine casings and tray is. There is no oil leaking around the breather (which I suppose could be blocked? I just tried to remove that and the damm thing is turning and won't undo so tomorrow I am going to drop the back of the engine and get that out.
My guess would be that its building up pressure somehow, though the exhaust is clear and it runs like a top! Only conclusion is the breather needs replacing, or that the base gasket to the carb tray is damaged somehow, but thats quite high up on the engine so why would neat gear oil leak from there profusley? BTW there are no other areas where leaks are evident.
I am going to get to the bottom of this, but just wondered if any of you have had similar issues at any time and/or have any ideas as to what to look for that I may have missed so far.
I have not yet dropped the gearbox oil so I have no idea if there's any fuel in it, but given how well it runs and the new seals etc, I would be surprised - it was very, very carefully assembled.
Any help/ideas appreciated
|
|
bsr65
High Number
Posts: 114
|
Post by bsr65 on Mar 9, 2012 19:25:45 GMT
colin what colour is the two stroke oil your using, it sounds from the area its coming from that its 2 st, like you say damaged gasket or blocked channel under carb bottom. did you replace rubber o ring on clutch cover, clutch arm? if your gear oil is not leaking from main case gasket id look at that if its not the breather.
|
|
|
Post by colin4255 on Mar 9, 2012 21:20:28 GMT
2 stroke oil I use is bright red in colour. Leak is pure green gearbox oil, with no fuel in it at all. i can see where you are coming from with clutch cover. I have actually looked tonight at the back end of the engine. No leaks at all from around the clutch cover, I replaced all the seals in it when I rebuilt the engine. Its bone dry as is back wheel. No leaks at all from around the breather. Its just loads from what looks like base of carb tray. What puzzles me most is this. All of last year I had various amounts of fuel leaking from the carb tray. It was when I dicsovered on stripping it down over winter that no washers were used on the cfarb bolts and they were bottoming out effectively, that I realised carb and tray were not that tightly sealed, yet never got any oil leaking out, it was mainly fuel mix. The thing is non autolube. This stuff i can see leaking is pure gearbox oil. The oil is all coming ou tbetween the right of the rear shock as you look from back of engine and the flywheel and near the top where the carb is bolted to the tray.
I am very mechanically minded ( I managed to strip and replace all bearings, seals and everything else with no issues having bought the right tools), but for the life of me, I can only think the oil is being 'forced' out by pressure - like due to a blocked breather. Its just that I have no idea if such a leak could actually be caused by a bad gasket at base of carb tray. It just seemks so unlikely to me unless something else was causing or helping the oil to get out if you follow my drift? There was an awful lot of gear oil dripping donw the back of the engine casing after just 5 miles of riding. In that time the engine ran like a top, never missed a beat - no issue at all with how it ran and peformed. Odd really....
|
|
|
Post by sbwnik on Mar 10, 2012 10:33:54 GMT
If you've been running the engine I'll be surprised if it's coming out green, it tends to go brown and then black in pretty short order. What oil are you using?
I'd be inclined towards the leaking seal if it's blowing out the top of the engine. To test it, fire the engine up and unfasten the drain plug for the oil. If the revs pick up as the oil drops, then the seal is blowing.
|
|
|
Post by colin4255 on Mar 10, 2012 23:58:38 GMT
Its putoline gearbox oil. Only ran it 4 or 5 miles. Not much chance for it to get dirty really. Will try what you suggest tomorrow and report back. Of course its always possible new seals got nipped or marked. Hope not but will advise. Looks like the breather may have gotten damaged while we had engine out. Got a new one. Will try your idea and if no luck, change the oil and fir new breather and try again. Thx for the suggestions guys...
|
|
|
Post by colin4255 on Mar 11, 2012 15:52:49 GMT
Tried running it on tickover as i dropped the oil. No sign of revs increasing at all. Replaced breather. All I can think is we've nipped the casing gasket, so its off with that next I guess.
|
|
|
Post by colin4255 on Mar 11, 2012 18:14:51 GMT
Stripped the casing off with engine still in the scoot. Didn't find anything obviously wrong with the casing gasket and all seems well in the engine. Only thing I did notice was roller bearing in RHS casing where main shaft sits was just slightly proud of the casing hole, so tapped it in a little further so it was dead flush. Maybe this has caused casings not to sit flush or flat on the gasket? It definitely looks like it as been leaking from the casings adjacent to carb tray. Had no time to finish rebuilding it all or put any oil in and try it. Will let you know what happens when we get it running!
|
|
|
Post by kru251 on Mar 11, 2012 19:57:15 GMT
Well that sounds encouraging that you found something 'not-quite-right'. It's the strip it to find no fault whatsoever issues I hate!!!!!!!!
|
|
|
Post by colin4255 on Mar 19, 2012 12:46:39 GMT
Main seal had actually failed. Rubber coming apart from the metal part near seal centre. Not seen this before, but there is the answer. In bits again now soon be mended.
|
|
|
Post by sbwnik on Mar 20, 2012 14:00:42 GMT
I've seen that, in fact I've had it myself... What colour is the seal - black? There were a lot of bad ones around a couple of years ago or so.
I think my current one - after destroying three of those in a year - is a green one that I got from Welsh Scooter Parts
|
|
|
Post by colin4255 on Mar 20, 2012 21:30:16 GMT
Yeah, it was black on the crank side. Most likely I didn't knock it on far enough. First time I changed one - was being careful - silly old me! It did last about 5 miles. Oh well, have just rebuilt the engine for the second time in as many weeks. Will let you know how I get on. Soon, like the SAS do with rifles, I will be able to build it back up blindfolded!!
|
|
|
Post by sbwnik on Mar 21, 2012 10:32:21 GMT
The black ones are crap. Get on to WSP and get one from them, last I knew they were one of the few places selling the decent ones. Oh, and it may be blue, not green, without looking at my spare I'm not sure.
Just ask them for a main seal anyway.
|
|
|
Post by frankie1954 on Aug 19, 2014 8:41:41 GMT
Hi Colin, I have the exact same problem as yourself on my T5 motor, clean green pure gearbox oil leaking from just below the carb box directly below the air screw. Have checked the breather and carb gaskets but no joy. Can you tell me exactly how you fixed yours. Cheers, Vaughan.
|
|