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I have a 1976 cb750k SOHC. I bought it and wasn't sure how long it had been since it had an oil change. I got some synthetic 20w-50 oil and a FRAM ch6009 and put those in. I did not put in the new oil filter seal, because it looked different (smaller/round). It started to leak oil from the pan bolt and the oil filter housing... So, I figured it was because I used synthetic oil and/or didn't change the oil filter seal.
I did another oil change and used standard 10w-40 and again went with the FRAM ch6009 filter, but this time did change the oil filter seal. Now it's REALLY leaking oil from the same places when the oil heats up.
So, is this an oil viscosity issue? or something else?
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Administrator
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Welcome to the forum. The leaking has nothing to do with oil viscosity. It is a seal problem. Did, you put some oil on the new seals before installing them? Did, you cross thread the drain plug, or over tighten it?
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Administrator
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Some Japanese engines (my son's Miata for one) use a crush washer inbetween the oil drain bolt and the oil pan. It's possible yours may be overly crushed or cracked, and needs to be replaced. That _may_ address the issue of why it's leaking there. If that's not the issue, then I'd recommend draining it again, and looking for cracks in the threads or around the drain hole. Let's hope that's not the issue here: that might be expensive to fix.
As far as the leak around the filter, I can't help you there, but there are enough of the SOHC riders on this forum who should be able to answer that one.
Good luck, and I hope this helps.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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Also check the Oil Filter Boss, which is the receptor for the filter housing bolt. It screws into the block. Use a Lock Jaw Pliers to snug it to the block (the book specifies a torque value, but I don't have a way to use my torque wrench on it, so I just snug it, then give it a little extra umph, to seat it properly). These can sometimes turn out a bit, which will prevent the filter housing from sealing properly against the block.
New O-rings usually come with the filter. I always change both of the O-rings, with the filter: the smaller O-ring on the bolt, itself, and the larger O-ring on the housing. As Tools says, wet the O-rings with fresh, clean oil, before applying them. This will prevent dry patches leaking oil around them.
Check to make sure you are torquing the filter bolt correctly, I always go for the middle of the specified range (if the book says, 25-29 lb.-ft., I set my clicker torque wrench to 27 lb.-ft.). With regards to the drain plug leaking, are you properly torquing it? The book specifies a value for this, too. If there are cracks in the oil pan, these can be welded, if necessary. A replacement oil pan can likely be found on e-Bay, as well. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Hmm, I definitely didn't cross thread anything putting stuff back together. I did put oil on the seals prior to installing them. It is possible that I didn't tighten the filter housing very good. I don't have a torque wrench.. but I will try and crank on both of those bolts and see if that helps...
on a side note, anyone know a good way to clean a bunch of oil from the underside of a motorcycle?
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Administrator
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Car wash.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Administrator
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So for the pan bolt, you will need a new crush washer. And check the threads for cracks. I cracked my pan threads and it would drip. I JB welded it but still had to get a washer that had a rubber insert to fully seal it. The I got a replacement pan. If you do not want to get another pan, drain the oil and pull off your pan, keeping track of which bolts go where as some are different lengths. Get a tap with the correct pitch of the threads. The fix the inside of the threads with the jbweld. let it dry and tap it. While doing that, fix the outside too with a good jbweld layer.
The filter housing, is it leaking between the housing and engine, or the housing and the bolt?
The ride IS the adventure. The destination is just to get gas!
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It was leaking between the housing and engine. Apparently I just didn't crank on that bolt hard enough... I don't have a torque wrench so was unsure how tight it needed to be. Apparently pretty tight. I cranked on it a bit more yesterday and it seemed to do the trick.
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Administrator
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The bolt requires about 17 foot/pounds or so.
You will want to get yourself a good beam style torque wrench or a more expensive clicker style.
Cheap clickers are frequently inaccurate.
The ride IS the adventure. The destination is just to get gas!
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Even a cheap clicker is more accurate than no torque wrench at all.  Harbor Freight, Mills Fleet Farm, etc., should all have a cheap clicker. Been using mine for several years, no leaks, no issues, yet... Better to be 'close', than 'nowhere near close'. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Administrator
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Sweet.
Now go out and RIDE THAT THANG!  That is, if you've cleared up the problem with the drain bolt issue.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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I did. Just cranked on that one too. Seemed to do it.
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Locked
