Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board 69 Bonneville oil breather pouring oil

I was doing some pre-season maintenance on a family friends 69 Bonneville, valves, chain tension, carbs. when i was kicking it i could here gurgling noise coming from the breather tube that goes up over the fender, thought that was a bit odd... but didn't think it was a show stopping event.

so i get it running and oil starts pouring out of it, probably about a US pint total when it was done.

i did not drain the sump so i thought that is where it came from.
i told the owner about this and he said that it gurgles a bit of oil when he shuts it off, always has for the past 20 years.


i am not intimately familiar with this year bike. my 63 has an oil seal on the primary side to keep engine oil separate. my 74 does not and the oil is shared, so how about a 69? i was thinking if it is supposed to have the seal that it could have failed? if not...

what to do?

thanks, Mike

Does the breather start at the engine or at the primary?

at the primary

Then that is not a 69, it's a 70. No seal on the crank and shared oil. Drain all the fluids and the sump, refill to the proper levels, and keep an eye on it. Run the piss out of it and check out the levels. When you fill the primary stick a coat hanger down through the top inspection cover and put a scratch at the oil level. Use the coat hanger to check the level after a run. Oil dumping out of and gurgling noises at the pipe usually means rings.
Wet sumping on Triumph's while rare is not unheard of. Check the return side of the oil pump for debris.

thank you, i did not check the numbers on it to confirm it was a 69, i should have known with the vent...

i'll give this a shot when i get another free day to tinker.

ehh, rings, thats not good news. is that something that could just be fitting new rings only would suffice? he's an older guy and only rides it a few times a year. i doubt he wants to do a full rebuild, he may not even want to mess with rings and just ride it like he has been.

Thanks for your help!

This is more likely a wet sumping issue caused by dirt in the oil pump, as Desco says. Did you clean the sump filter recently?
Dave

i didn't, i cant say if it ever has been this is the first time I've even seen this bike. but i'll give a good oil change or 2 to see if anything changes, thanks

Okay so I got back over today and there is not a vent from the primary. The hose that runs along the fender goes to a junction by the battery and oil tank.

I emptied the sump, changed the oil. It does not pour oil while running anymore, I assume that was from sitting.

When I shut it off it still dribbles oil every time.

This is my first time with a stock bike pre-oif so i am learning they are not all the same...

My '69 TR6R will pop/poop out some foamy oil from the end of the crankcase breather after shut-off. And sometimes people overfill the oil tank a little, and the motor will just breathe out oil til it gets it down to a level it can live with. I put in a little less than is called for when changing the motor oil, otherwise, it just breathes out the breather.

Sounds like it could be a '69 with that breather setup. What's the serial #? Just curious ... should read

T120R [letter][letter] then 5 digits ...

-- what are those two letters after T120R?

While you're at it, it would a good idea to change the primary (clutch) oil, check the primary chain tension, and change the gearbox lube, too. If you haven't already.

If it continues to blow a significant amount of oil out the breather while running, drain the sump again. If there isn't a lot of oil in the sump, then the problem is most likely combustion pressure getting past the rings.

If it is a blow-by problem, you won't know if you can get away with just a new set of rings until you inspect and measure the pistons and the bores.

I have just got my 66 TR6 running after rebuild and oil is pouring out of my breather too. It has a healthy oil return so it doesn't make sense - I got about a pint in 5 minutes! Engine has been fully rebuilt, PO had rebored and replaced pistons, I replaced rings which were 14 thou end gaps, and the breather disc is definately in there. Any tips?

First guess, sounds over-filled ... [dunno]

Hi Mike,

That'd be because you'd emptied the sump! Being 'dry' sump engines, there should be very little oil in the crankcase at any given time. How much oil exactly did you drain from the sump? If it was more than 60 - 100 cc's, you may want to check the oil pump....if the return valve on the pump is not working properly, it will just be a matter of time before the sump fills up again and you start spitting more oil from the breather tube...

Steve

Don't forget the fork oil, Kurt!

Steve

Steve -- OMG, yer right, I forgot!

Most probably a case of "fuel wet sump". The bike sat over the winter with a full tank of fuel. The petcocks leaked, the float valves couldn't hold it, so the fuel ran past the piston rings and into the engine sump. It will then give the exact same symptoms of "oil wet sump", but because no dirt entered the oil pump with the bike in storage, it must be the fuel.

The fuel has now seriously diluted all the oil in the engine and primary. Do not run the engine again until all the lubricants are changed.

And next winter drain all the fuel out. :bigt

My 66 TR6 still has this issue. I drained a lot of oil out of the sump and restarted it. After a while the oil return started and oil came out of the breather again (I should add it only goes down to the bottom of the frame but is properly connected to the engine breather and oil tank top fitting). The oil is slightly blackened, which an above post gives as blowby. When i stopped it, a gurgle came out of the breather tube. When I put the motor together it was at the upper end of clearance tolerance. I am thinking now I need to rebore again? I am thinking about trying just connecting the breather from the engine directly to the oil tank top fitting without venting it, ie using it as another oil return???

Don't connect the breather to the oil tank because it is for getting rid of water and various combustion chemicals that have leaked to the crankcase.

When the top end is worn you don't get a lot of extra oil in the sump. I think that if it was that bad the spark plugs would be wet and the engine wouldn't run. Normally if the rings are bad you get yellow emulsified oil in the breather which is from blow by gases mixing with the oil. In the front of the manual there is a list of wet sumping fixes which you should go through one by one.

Dave

I just checked the manual, section A21 as recommended. I don't have any exhaust smoke and the plugs are fine. I am now suspecting the oil release valve in bypass condition as the most likely and will check at the weekend.

Tc, whether the oil travels through the bearings or release valve, is of no consequence, in fact at normal speeds it does both. The amount of oil reaching the sump is a function of oil pump speed and efficency only, as is the amount of oil returning to the tank. I suggest you clean out your return pump valve, sometimes you can't even find the little piece of grit that causes the grief, it can be really small. This is relatively common after overhauls, there is always some dirt that got in there somehow, but the #1 cause seems to be blobs of liberally applied sealers...

Stein Roger

Another thing TC. You mention that you have just replaced the rings. You will get extra oil out of the breather on a timed breather motor until the rings are seated. Run in the rings and then your problem just may have gone away.

I got a near new oil pump from a friend and fitted it. After running for a few minutes oil started coming out of the breather again. I stopped the motor and drained almost a pint from the sump. There is a steady oil return in the tank, which really should be intermittent. As the scavenge side pump is a bigger bore, I am now at a loss as to why the oil is getting to the sump in such quantity, I have never had this happen with a 650 motor before. I don't now suspect the rings unless as stated above they need to bed in. But this doesn't explain the wet sumping - or does it?? I am now stuck as to what to do so any help appreciated.....

If you're getting a steady return of oil into the tank,the pump is trying to empty the sump,therefore,you must find how the bike is inducing more oil into the sump,than the return pump can handle??? If you run the bike for several minutes it should eventually clear the sump.How long have you run the bike while watching the return to the tank and, does the tank suppply go down??? Dick

Maybe the feed is going direct to the sump with no resistance to reduce the flow, incorrectly set OPRV or the timing side crank feed seal has come loose or is inverted from too much pressure.

My thinking tends to agree with Stein Roger. The total oil being fed the sump is always less than the oil being returned. Therefore I think it is well to discount the entire 'delivery side', since there is not a way to make the 'feed side' deliver more volume.

That may only leaves 2 scenarios....
1) The oil can't get back from the sump. Pump may still be fouled on the return side. Return oil ways may be constricted. Kinked return hose. Etc.

2) The oil tank is being by-passed. That is to say, the rocker feed is being flooded, which returns oil back to the engine and not to the oil tank.


One has to remember here that the bike in question is a 1966 which calls up a special case. So it really doesn't matter how much experience you have with 1967 and on, or 1965 and before. In 1966, Triumph introduced several new oil path ideas: the pressure lubed ex tappets, a special metering quil for the ex tappets, special ex tappets, and a special oil tank. These "features" only lasted for 1 model year, and most of them have been removed 50 years on. Therefore experience in dealing with them is limited to say the least.

It wasn't but about 3 or 4 months into production that Triumph had most of the 1966 oil tanks replaced under warranty. There's a Service Bulletin out there if you care to check me out on this one. The problem was that the "top rocker feed" tank had internal issues. If your rocker feed comes off the top of the tank, then you might want to try a 1967 to 1970 oil tank with the bottom rocker feed. Note that the oil tank issue covers both items 1 & 2 above. So your "engine oil" issue may not even be in the engine.

Proper oil pressure and oil suction readings would also help.


Hope this helps. :bigt