The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: nhmaf on January 20, 2013, 07:10:11 PM
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Well, at some point, there has to be a first time for everything...
My 3 motorcycles were tucked away in the back for the garage for their long winter's nap. Fuel tanks were filled up and had a good dose of Marine formula STABIL and/or SeaFoam in them to prevent varnish/gunk and water damage. Around New Year eve, I noticed a strong gasoline odor coming from the R100/7. A day or two later, I noticed some wetness on the cement under the engine. A day or two after that I discovered the left side of the engine wet with gasoline, and the left side fuel line was soaking wet with fuel. I checked the fuel bowls, pulled the fuel line fromt he petcocks and noted that the fuel wasn't going through the line(s), nor was it overfilling the carb bowls. I checked the dipstick - oil level normal and not mixed with gasoline-good. I noticed the starter cover, engine badge were also wet with fuel. Oh....... fudge.
The fuel leak seemed to stop after a bit. I opened the filler cap and noted that the fuel level in the tank was somewhere around 2/3 full - over a gallon had leaked out but the level was now somewhat below the internal "hump" where the tank goes over the frame backbone. I pulled the tank, drained the gas, and, as I feared, the tank seems to have been leaking at the udnerside of the center seam where the 2 halves are joined, in the area directly beneath the filler cap. The tank itself (inside) still has most of the original red liner and doesn't appear to be rusty. But I figure that at least some bit of rusting must have compromised the weld joint (or is it hard-soldered?), or perhaps some strange form of metal fatigue. I cannot find any evidence of rubbing, denting, etc, and the undertank M/C has not been leaking/corroding.
I have to do some cleanup of the tank, but I am wondering if I thoroughly clean the inside and re-line the tank with tank sealer kit if that will adequately do the job, or should I see someone about welding the tank, or try to silver solder it with propane torch, etc (and yes, that will precipitate a repaint).
At first I thought that one or both petcocks were leaking, then I thought maybe the very bottom edge of the tank had rusted out, but neither was the case. I haven't seen an airhead (which doesn't go on motocross/offroad trails) have a tank seam leak in this place before.
Suggestions?
Mike
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That IS an unusual place to leak - normally it's down by the petcocks.
This isn't due to rust but parting of the seam?
New paint wouldn't be needed in that spot. Just touch it up -- it is the underside, after all! I'd think brazing would be the best fix for it.
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I'm letting the tank air-dry for a bit and will try to clean it up some more inside and out to see - but it was leaking enough to drain out about 1.5 gallons over the course of a few weeks. After taking the tank off, I saw that the frame tube area just behind the M/C was wet with fuel, and even the left side coil was wet with fuel. It had been dripping slowly on the top of the starter cover and running down the side of the engine, and also it seemed to run down the side of the tank, along the lower edge to the left petcock, and then down the outside of the fuel line (which was soaked). I've seen tanks leak at the seam in this area when they were dual purpose, steel tanked bikes that saw alot of off road jumping, etc and the seam parted. I don't know what the PO did with it, but I've had the bike a couple years now and it has only seen paved roads and maybe 100 miles of graded gravel roads. Weird.
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Here's me thinking a virtually intact red liner means the tank is good and solid.
That is an unusual place to leak and to rust so it will be interesting to see what the cause was. Not a simple problem then. Depending on how much of a gap there is I might be tempted to try high temperature high strength soft solder to minimise the paint damage. You need an active flux to solder steel but it can be done.
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Will not the solder/braze/weld repair ultimately lead to R&R of the heat damaged liner?
In this case, it seems one thing leads to another. :'(
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POR 15 will seal seam leaks .
One drawback, is that the original OEM liner has to come out before you apply it .
So, which ever way you go, it's going to be a bit of work .
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I have a leak at the seam of the tank on my old Triumph right about where it meets the seat. I prepped it and used POR on it and the seal lasted for a few years but the leak did come back. One thing that I have heard from from an aircraft mechanic is Green Loctite 609 can be used to seal tiny holes in gas tanks. You create a vacuum on the tank and let it draw in from the outside and then set up. That is the next thing I will try on my tank as I don't look forward to stripping the liner out and starting over. Good luck.
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I just got a BIG soldering iron and simply soldered the split with a generous bit of solder using flux .That was years ogo with no probs .
I did ask a welder but he would not touch it since any residual fumes
would just explode with the heat .
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+1 on the POR15.
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I'll post an update after it warms up a bit - it is just barely above 0F (-18C) in my garage right now and it is too cold to work in their bare-handed!
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-18 ! wow makes it seem like summer here! its only 6" of snow and 0c!
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i once had an old cd175 (still got one best jap small twin ever) filled it with petrol , the seat had rubbed through the tank , (thin steel) rubbed it down used araldite , repair was still fine when i sold it , funny how some bodges turn out as permanent solutions! a fluke?
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Yep snow here in Bolton Greater Manchester (england if your wondering ) 6 inches of it ! but it only snows at +2 degrees centigrade so its WARM here by comparison .....we should grumble .
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for a temporary repair to a small split a 50-50 mix of Loctite and non-setting jointing compound works well.
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If you can find this I know it works great. Since it is on the unseen underside and is used to seal fuel tanks it is a natural.
http://www.newpig.com/pig/US/patch-repair-maintenance-7240/pig-epoxy-putty-patch-repair-7459/pig-plug-n-seal-patching-paste-7494/0/20
I have seen it used to seal a leak on a diesel locomotive with fuel in the tank above the level of the leak, press in place, hold with a piece of duct tape until it sets then remove the tape. Done and it is permanent.
I have used it to replace broken off threaded inserts. Mold a blob in place and once it is hardened, drill it and tap it and it is as strong as the original.
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available in the uk? looks good stuff
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Yes. It is available worldwide. Just click the little flag icon to change the country. They specialize in industrial spill containment and cleanup and the epoxy sealers are just one of the tricks of the trade.
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Hmm, I might take a look at that pig plug stuff - could be handy for other things even if I decide a different course of action with this fuel tank.
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Well, this whole project with the mystery bike has turned a rather embarrassing and frustrating direction...
1. To remedy the incredible strong gas smell in my garage and to stop gas from ending up all over the bike. I had pulled the fuel tank, completely drained it, and left it to sit until it was warmer to work in the garage.
2. I decided this weekend to get to work on pinpointing the leak location. I cleaned off the bottom of the tank and removed large patches of semi-soft paint, and exposed some rusty looking areas beneath. I examined it closely under a very strong light, and couldn't see any holes or pin-prick openings.
3. I decided to fill the tank up to the neck with water and let it sit overnight, figuring that the water would find whatever way the gasoline had used to escape the tank. I examined the tank carefully again today with bright lights and camera. The bottom is perfectly DRY! It isn't leaking anywhere! Hmmm.
The red liner inside look very good - better in fact than my R65LS liner. This is very weird.
4. To add insult to injury, I discovered that the (undertank) master cylinder seal had apparently failed during the winter and drained all the brake fluid out. Now, I had changed the brake fluid this fall just before I put the bike up as the fluid looked old, and I couldn't tell when the PO had last changed it. I wanted to avoid having to rebuild those dastardly undertank gizmos, so I drained the fluid. The cap said DOT3 fluid, and the bike had a sticker on the frame that said DOT4 fluid. Trying to avoid any reaction, I bought a new bottle of synthetic DOT3&4 compatible fluid, drained the system, filled it and bled the air out (which was tedious) and it was working nicely before thanksgiving. Grrrr.
5. On top of it all, just before I put the bike up for the winter, it has begun to weep or leak oil from what appears to be about every seal on the engine. Originally, it seemed to just be the oil pan gasket, which I replaced - had to soak the sump in acetone for a week to get the old hardened gasket off, too. Oil still kept appearing down there, so I thought - well, it is probably the rear main seal or the oil pump cover, I'll get to it when it gets worse. Then the bike started to weep/mist slightly from the cylinder bases, and leak from the pushrod seals (3 of the 4), oil filter cover, as well as the other places. I know the PO had screwed up installing the oil filter (didn't use metal shim, and he had cut the o-ring and caused a leak at the oil filter cover, but thankfully the oil pressure light didn't seem to come on -- who knows, perhaps that wasn't working either until I replaced the guts of the instrument panel.. I only run dino-oil in my airheads, so it shouldn't be from switching to synthetic oil. The engine seems to run quite strong, so I am thinking (and hoping) that the cause of the oil leak isn't excessive crankcase pressurization from blowby past the rings - I guess I'll have to check the compression next. I was thinking if the crankcase breather valve wasn't working or was stuck closed that perhaps it could cause these leaks all over. I took the top cover off tonight and it looks like maybe someone had switched the valve from the spring-type one to the reed type one, but I've gotta re-check.. Maybe the PO installed it upside down? Is that even possible?
I think it is going to be a while yet before I have the thing solid enough to then get around to attaching the sidecar. At least my Kawasaki and the R65LS woke up from their winter's nap without any issues!
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Sounds like you have a lot of work ahead. I wonder if the extreme swings of temperature have anything to do with the various leaks.
You could do with something that will fix itself so I'll relate that I've noticed excessive crankcase compression after winter storage which did seem to cure itself after some running. Assumed it must have been sticky rings.