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Is Chasing Oil Leaks a Futile Endeavor?

17K views 53 replies 17 participants last post by  o1marc 
#1 · (Edited)
I just replaced a 1967 Daytona with a 1968 Bonneville. The Daytona leaked from above the pistons. I'd just wipe it clean after riding as my efforts on the bike were focused on correcting other concerns (carbs, correct part additions, etc.). My Bonneville developed a leak from the pushrod tubes shortly after buying it. I paid a great shop to replace them and all upper gaskets on the bike. I actually had a leak free vintage Triumph as a result....for a week. Now oil is leaking from the gear box (unsure exactly where at this point). I could have this fixed, but what next? I'm relatively good with mechanics when thing work out well. When they don't, I smash sh!t with hammers, so I'm really not comfortable doing this one myself. Guess my question is, should I even be concerned with these leaks or just accept them as inherent to these bikes and get a rag?
 
#3 ·
The PO was a "mechanic" who rebuilt the engine himself. His shop looked legitimate when I went to pick up the bike. However, when I had the gaskets replaced recently, I was informed that the parts used previously were incorrect. Although I was informed that the pistons/guides and valves looked fresh upon disassembly, I'm not too confident about the quality of the rebuild. Time will tell, but I've already replaced the carbs, battery and addressed the initial leak at a cost of about 1K (total) so far, only a few months in.
 
#4 ·
Oil leaks are really annoying. I have rebuilt several Triumph engines and it seems that eventually those damn push rod tubes will leak again. As for the covers some of the previous owners have used screw drivers or something like that to separate them at sometime in the past and left large dings that are hard to seal. If the dings are not too large you may be able to remove them with sand paper on a flat surface. It is also important to retorque the head after a newly rebuilt engine has run for a while. You may have to retorque several times until it finally settles down.
 
#6 ·
For a few reasons Triumphs may tend to leak oil. Maybe the biggest reason is not flat sealing surfaces. The next reason is some dumb design concepts. One being there is no seal for the shift quadrant shaft fitted & trans fluid leaks by the shaft & along the cotter pin that holds it in.
Triumphs have pistons that rise/fall together which makes more crankcase pressure which tends to push oil out anything that may be leaking, but if no joints leak, it's not a problem.

The main problem is the sealing surfaces were not precision machined from the factory. Pretty much every gasket surface on the motor needs to be flattened. That is very time consuming & not always easy. If you pay a mechanic to do that there would be many hours of labor charge, which I expect you'd think was too costly.

Also many push rod tube leaks are really the tappet blocks which require removing cylinders to replace. Again all the surfaces must be de burred & finished perfectly. Much time.

The mechanic must have the skill & heart to do all this without cutting a single corner.

Good news that improvements in gaskets & seals have been made with use of viton & other modern gaskets. Modern sealants are amazing at stopping leaks, but again must be skillfully applied on a flat surface. Coventry Spares makes some modern gaskets that work good.

The play/tolerances of the bushings & shafts must be good.

Then if..... you can find a mechanic to do all this, &... you can afford to pay him..., the bike will be leak free. It will stay leak free for a surprising long time too.

Getting back to your bike, you need to clean the areas well. Road test & keep looking with flash light & mirror until you find & diagnose the leaks. Expect to spend many hours. Sometimes you will have leaks from areas so close together you can't tell what is leaking for sure. You might have to make a best guess & fix one, then go after the other. Don't guess on leaks, you need to diagnose them.

If you can really work on motors you'd be best to do it yourself. You first step is an accurate diagnosis of where the actual leak is.

In the mean time if leaks are minor you can zip tie folded rags under eng. I'm not kidding. One thing my local coffee hang out hates is bikes dripping oil on the sidewalk. They allow bikes to park there, but you must wipe any leaks.
Don
 
#8 ·
nugpop, I've had a couple of Bonnevilles that leak gear oil around the shift quadrant shaft. Someone here may know a permanent solution to this leak, I have not figured that out yet. However, you can keep it from reaching the floor with about a 3" square of oil absorbent. I fold it up, or roll it up, then wedge it in the area in front of the gearbox inside cover just behind the outside cover, sort of above the oil feed tubes. Fastenal sells 2' squares of oil absorbent, I buy them buy the dozen, because I use them when I work on these machines, to keep my work area clean. The little 3" square will absorb quite a bit of oil, when you see the drip on the floor again, replace the little pad.
 
#38 ·
Fook it...I surrender. Every time I stop it from leaking successfully in one spot, another one develops. I've been to several vintage bike shows over the past month and have yet to see a leak free Triumph. I easily inspected at least 20 running riders and every one drips from somewhere. $750 in gasket replacements later, I've come to the conclusion that I'm chasing unicorns. Can you take a pic of the absorbent solution that you discussed? That seems to be as good as it's going to get. Thanks!
 
#9 ·
My 71 has oil seals on the kickstart shaft and the gear shaft.Didnt realise some years were made without oil seals.I replaced mine last engine out so i get no leaks at all.Clean road under my bike when it parks up.
Does anyone else have seals fitted at the factory? Interesting to know when they started fitting them.
 
#10 ·
I'm not talking about kick start or gear shift lever shaft, but the quadrant with cotter pin.

What has worked well for me is surgically cleaning area 1st. Then "painting" a layer of silicon sealant over end of shaft & all around cotter pin. The cotter pin must be completely covered well all around it. Keeping in mind the shaft moves slightly the silicon layer has to be a good 1/16-1/8" thick so it can work & not tear through or pull loose. Since it's thick it must cure for at least 48 hrs. The surface must be totally clean & oil free.

This can be done on bike by reaching up with silicon on a small brush like an acid brush. I bend a few brushes as needed to reach to the top. Not easy on bike with trans outer cover installed but very doable. Very hard to see up there, but you just gob silicon around until you're sure all is covered well. It's a big mess & most ugly. However it cannot be seen so that's not an issue.

If you clean it really good which is very hard to do & goop on enough silicon it will not leak for some years in my experience.

Of course silicon sealant can be time consuming to remove at next tear down, but it's worth it.

During an overhaul it's easy to silicon the area nice & neatly.

I use Mercedes Benz black silicon to 100% success.

You can also "cheat" & silicon joints from the outside such as my trans cover leak. I hate to admit to doing this but works good.

My cover leaked from day one, but I don't want to do proper repair just yet. I'll wait until I need to get into trans for some other reason.

Again perfect cleaning is key.

I spent some weeks getting an exact diagnosis of leak area.

I really don't approve of or like this type of repair, but thoughtfully done it can work well. (However silicon on the quadrant shaft is a good fix for a factory flaw).

Pulled eng plate & put tiny bead along rear edge of outer trans cover. Here's a photo. This has held good for a few years so far.

The root problem I'm sure is non flat cover.
Don
 

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#11 ·
I wonder what was going on to get these faulty surfaces ? Maybe the machines were wearing out or fed up staff.My engine has very good surfaces from new and i have never had to do any more than fit gaskets with sealant.Not tried fitting a timing chest or inner gearbox cover without a gasket though.These engines came with no gasket fitted in that area.
 
#15 ·
Old Triumphs are sort of like old Jaguars: If it's not leaking some fluid or other, it's probably out of that one. A leak-proof '60's and '70's Triumph is probably an unknown device. I always figured that on my '71 Daytona, if the spot on the floor was no larger than a silver dollar, we were good to go.
 
#17 ·
I never had any leak from horizontal seams of my BSA A65 engine, current sealants make this problem nonexistent.
Only leaks I head are leaks from the gearbox sprocket area where a couple places could leak, mainly oil from a gearbox on mainshaft, oil from primary when a seal gets bad, and some engine oil from the air valve opening - not more than a drop or two.
Another area is a head, but BSA head is much better than Triumph with oil tightness, so only oil leaks there is oil getting through unprotected threads of valve cover.
Triumph engine has a problem there with rocker boxes, which aren't solidly attached to the cylinder head, in my Trident I simply added some dowels to keep them in place.
 
#19 ·
One thing about our cases is with the way the crank is shaped & the roller/ball bearings is the way it splits saves weight & space & is fairly stiff. Many motors use vertical split cases & don't leak a drop. Porsche, BMW, Harley Davidson come to mind. Plus all the oil pans Mercedes cars use with joints below the oil level. Dry as a bone. BMW & Harley pistons rise/fall together also so crank case pressure is high & pulsing just like ours. Remember Harley pistons almost rise/fall together, so much so they used a single carb.

Harley's had split pushrod tubes for many years. A flare in middle & at each end. Simple rubberized cork seals. Tensioned by a coil spring. They would hold perfectly for a good 10 years & were disturbed at every valve adjustment on Sporsters, still didn't leak.

On thing Triumph has is the press in tappet blocks. Would need to change that arrangement if they cast in prt. Cast in would be good though. Sure makes it simple. Always use all viton O-rings in the motor that really helps. Except the lower silicon square prt seal. Good smooth surfaces for O-rings to set against is a must. If you build motor like factory it will leak like factory built.

One Triumph went to the "Loctite" type sealant in the case joint in later 1969 the case leaks were greatly reduced. The sealant worked pretty good.

The real problem with Triumph was poor machining due to both worn out machinery & poor production methods. Top that with "piece work" assembly workers, meaning they were paid per unit so they went as fast as possible.

BSA the owner of Triumph was really only interested in short term profits, never really willing to invest in the future. Of course that put all the Brit bikes out of business. The worker does what is expected & demanded of them in every time & every country. Triumph workers in fact were following management's wishes when they slammed out bikes. Also the designers were beat down by BSA when they wanted to improve & bring out new products. Again a management problem. The old saying couldn't be truer. A fish stinks from it's head down.

So that is why we have to go back & "blue print" the bikes. Then they work quite well & are a joy to ride.

I was sad to see modern Triumph move production to Thailand, but they seem to be holding up well. Guess the Made In England sticker isn't needed for these bikes. Still if the design is good & good workmanship is demanded from the workers the bike will be good. Time will tell.
Don
 
#20 ·
I have to disagree with you TR7, at least to some extent. I was the second person to split the cases on my TR6 and best I can tell the first on my T120. The machined surface of the case joints on both bikes was very well finished and the only blueprinting required was a gentle scrape with a razor blade. However every other mating surface on both bikes had been marred with screwdrivers and other similar Monkey operated levering tools.

Neither of my bikes are late enough to have an O ring groove on the tappet blocks, a light skim of 3 bond is all that's required to keep them oil tight. In a similar vane, assembling the push rod tubes with the crush figures recommended by the likes of Mr Pete and John Healey has seen mine stay dry.

As for Merc, I'm sure you see far more than I but I recently had a late model (2014) AMG V8 pissing oil from the Crank Carrier to Engine Block joint. Poor customers face dropped when I told him.

Regards
Rod
 
#21 ·
I took the Bonneville in to John's Cycles in Woodside. The leak is definitely transmission related. He's going to replace all gaskets and alternator wires as well for $250. Considering the fact that if I did it and it still leaked, I'd be inclined to break out the hammer, this is my best option. The engine was rebuilt 5 years ago, but ridden very little (300 miles) after the rebuild. Mechanic believes the the gaskets were degraded over time from lack of use/exposure to fluids.
 
#22 · (Edited)
nugpop,


Quote:
"I'd be inclined to break out the hammer"

I understand, you have to enjoy the work. There are many jobs on these bikes I've earned the opportunity to do over. However, when you do your own work, you will take ownership in the work that is done. Not all shops will have that ownership in your bike. That is probably why it leaks now.
 
#24 ·
I enjoy working on bikes, for sure. I've been at it since I was a kid, making my dilapidated bikes run by all means necessary. However, my time is spread much more thinly these days, and when I invest time/effort into something that doesn't pan out, I lose my sh!t. I'm going to have to err on the side of caution and sit this one out. I have full confidence in this particular shop. They've been around since the mid 60's and are still in operation with the original mechanic/owner. One of the few folks in any industry today who still guarantees his work.
 
#23 ·
I read in the preface of an old Triumph manual that owning a Triumph Motorcycle turns ordinary men into mechanics overnight!

:surprise:





Two t shirts on my "to order" list.

>:)

It really is better to do the things you can on your own bike. You really NEED to know "how to" to better your chances of not being stranded somewhere and facing a long push home.

You need to know how to do the routine maintenance and troubleshooting.

Now you won't find ME on the inside of the cases but I there are plenty of things to keep you busy on the outside of the engine.

Happy Wrenching! (Is Happy Spanning the correct usage?)
 
#31 ·
Is this lower bush in the transmission a potential leak spot? I ask because mine was completely filled with a silicone sealant upon disassembly. I am not concerned about it leaking there now that it is powder coated.
i've never had one leak, but i still goop the outside too. it's the recommended procedure keep the gearbox oil from seeping out.

is that a sealed bearing for the mainshaft? i've never seen that done.
 
#26 ·
nugpop,

"I lose my sh!t". LOL

I know exactly what you mean, that is what makes tools become airborne. Just a couple of weeks ago I broke a primary cover attempting to replace an unnecessary, broken, timing mark pointer. Look out for that flying ball peen hammer.

I also know from experience, that taking ownership, is the key to doing, (and getting) good work. I hope everything works out.
 
#27 ·
Yep, familiar. Inanimate objects in my vicinity tremble when I break out the tools. I threw a wrench through the window of a '57 Chevy after stripping a bolt, busting my knuckle and getting rust flakes in my eye (all concurrently). That was a HUGE expense. That glass is about as big as some cars are today! Just one of many victories over uncooperative possessions :)
 
#28 ·
This is a difficult thread.A transmission leak is a lot different from a primary leak.I am guessing this shop will be dismantling the gearbox inner and outer covers to change those gaskets and changing the primary gasket which is not an area that transmission oil leaks from....I am also guessing the shop could tell gear oil from engine oil or maybe just going in both sides to be sure.
Alternator wires are not something that can be replaced as they are sealed into the alternator.There is no point cutting and joining a new bit in within the case.
Anyway,lets hope he is right in saying it is gaskets as i would be looking at the gearbox inner rubber oil seal myself or that lower bearing pictured earlier which should have a bit of epoxy over its end or some other good sealant.
If it is engine oil leaking under the primary area,i would be looking at the seal behind the clutch.
You might be into more work than just gaskets so budget a lot more than $250 if paying garage rates.As already said,an owner will usually be more thorough with investigations.I may be wrong but a mechanic really needs to know these twins well before taking on jobs,they are full of surprises hiding away.
 
#29 · (Edited)
Apologies for the difficulty...My descriptions are vague, as is my knowledge of the internal specifics of these engines. This will change, as I plan on keeping this bike until I kick the bucket The mechanic mentioned a gasket/rubber that the alternator wires pass through and replacing that (I could have misunderstood if this isn't accurate). From what I recall, he's replacing every gasket that could be/become a culprit while he's got it apart (Both sides). I'll update and detail everything that was done to address this when I get it back and have an itemized list. Thanks again to all for the feedback. Much appreciated here.
 
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