Wet Sumping

Ah, that old age problem for the Coventry/Meriden Riders. I'm sure you Hinckley/Thailand lot (I may become one, one day, just for the easy ride and electric start - but only a carbed version) have your own problems.

You wake up one morning, decide to go for a poodle around, and a gallon of oil is on the floor, coming out of the zorsts or out of the breather. Bugger.



You wrestle out the sump plug and, hey ho, the whole oil tank is in the sump. Here's a whole 4 pint plastic bottle full supplied directly from the sump - less the oil on the floor.

So, I thought I'd do a check list for starters, for those Chaps and Chapesses with the same issues. And for the in house experienced among us to add to and therefore get a pretty extensive list for a DIY approach to fixing and/or finding the problem/s.

 

This is the cause for the mess above (just in case you were wondering) - it's the dismantled oil pump - can you spot the problem?

 

Correct! Rounds of applause, and also that relief inside that you've found the problem, here's some more:

Wet Sumping - possible causes - check list

The oil pump has two different sized pistons driven by the inlet cam shaft. The feed piston is smaller than the return piston so there is always more oil pumping back to the oil tank than being delivered. This is why, when you look into the oil tank, the oil is pulsing, it's continually emptying the sump down to the bottom of the scavenge pipe and running out of oil to pump. When the sump fills up a bit more then the return pumps a bit more. The sump will, therefore, only be filled to the bottom of the scavenge pipe - which is about 100cc. (I think this is about 4 ounces).

Have you recently carried out some work on the bike - the problem is probably related to what you've done, think it through while running down the following list:

Majority of causes fall on the oil pump:

Have you replaced the pump recently with a cheap one - the original Triumph pumps were good enough to race with and were designed by people much cleverer than us so they are good enough for us, stick with the good make ones or go for a Morgo pump (you don't need the rotary one by the way).

Is there lodged material under a check ball - take the pump apart, inspect and clean it. Check all parts, reassemble as required and test with your finger covering the holes one at a time making sure you get a squirt of oil when you push/pull the pistons (mind where you are looking when doing this as the oil will squirt into your eye before you can blink - yes exactly )

Is the oil pump seated properly against the crankcase - on older models, the butterfly valve and spring oil breather on the end of the inlet cam must be in correctly. If not the cam pin driving the pump's pistons will be too far out and not allow a seal against the crankcase.

Is the oil seal against the crankcase in good condition and not allowing oil leaks.

Blockages:

Obviously blockages will not aid circulation so be careful with those gasket sealers when reassembling the engine or casings. There's a lot of materials out there now particularly silicon based stuff. These will squeeze into the engine just as much as the amount you wipe away on the outside. If this dislodges and gets in amongst the oil ways it's gonna do more harm than good.

Start at either end of the oil system and work your way through to make sure all oilways are clear and clean:



This is a 500cc machine but the oil system is just about the same on all Triumph twins, work your way through the whole system

 

Normally the issue will be on the return side so start there:

Is the scavenge pipe being restricted by the sump plug? Have you removed the seal from the sump plug thereby letting the plug screw just that bit further onto the scavenge pipe. Stick some blue tack into the sump plug and check for indentations - careful as you don't want to block the whole thing up with blue tack.
Is the sump plug mesh blocked up with 'orrible stuff (like silicon or blue tack ).
Is the sump plug mesh too fine - I believe 1960 and 1968 machines had that issue.
Is the scavenge pipe too long - if you've just replaced it, maybe it's not seated correctly or has it become loose (this would also cause a leak).

Check the oil way from the scavenge pipe to the pump (do this with the pump off). Attach a rubber pipe to the scavenge pipe and blow the oil line through.
You can also hold your finger over the appropriate hole on the pump side and suck on the pipe, put your tongue over the end of the pipe and hold the vacuum. If there's a leak it will not hold the vacuum.

Use the same blow through from the pump to the return block under the engine (obviously you've removed the oil lines).

Blow through the oil lines. You can check the oil delivery to the rockers while you're at it

Clean the oil tank out and ensure the vent pipe isn't blocked.

Check the delivery system in the same way while you are doing it.

Check the Oil Pressure Relief Valve - is it all blocked up, is the piston moving freely against the spring, if in doubt, get a new one. These aren't cheap, again buy a decent one.

Are your oil lines connected correctly. Check your parts catalogue and maintenance manuals to ensure you have them the right way round.

 

Leaks:

Some older (and newer shoddy 70s workmanship) have porous crankcases. However, these should have gone into the scrap yard years ago by now but you never know, it may be older damage (slack/broken chains etc years ago wearing into cases) that has raised it's ugly head to bite.

Plug of oil way (part number E4539) not sealing:



Build up of pressure:

New big bore kits, new barrels, re bores, pistons, rings will take some miles to bed in. Chrome rings take longer than iron rings to seal. This allows pressure from the compression and ignition to make it's way into the sump and expels that pressure out of the oil breather.

This normally makes it's way to the 'froth' tower on the oil tank or all over the back wheel. Or onto the floor if you've binned the long breather pipe. You can channel this into a makeshift bottle to collect the coffee looking frothy oil or (as HD users do) send it straight back into the oil tank. This should stop after the rings are bedded in.

I'm sure they'll be some things I've missed, and some disagreements, please add them.

Hopefully this and comments below can be used to allow those new to this erm... annoying little issue with the older Triumph twins to again ride their steed with that warm glow of satisfaction that they are not riding a.......

Good luck Gang

 

EASY

It’s in bits

 

I go along with everything Iceman, Speeder and Tricky say.
Also an oil light/gauge is the best investment for an old Triumph - I ALWAYS include one or the other on all my re-builds or customs builds. (I learned this the hard way when I detonated an A75 - the real rocket three - engine in one of my first chops).
See the little red light built into the frame? The only idiot light you need on a Trumpet.

 

That's a very fine bike you have there Tricky. Two gauges, a light AND a buzzer! Blimey. Belt and 3 sets of braces.

I can't say I blame you though, those triples are a bugger to set up and expensive when they let go. The engine seized on mine just as I was passing a bus, the centre big end came out the crank case and the rev counter drive shot off somewhere never to be seen again. But it rolled nicely to a stop once the bus full of shouting kids undertook me.

 

Still, good idea to have loads of warnings against a pressure drop on whatever you've got.

These are 5 quid - that's a nicker each. Proper bright too. I stick them into the top of the headlight (there's a convenient pre drilled hole in the top of a small Bates style)