Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: dieffe on May 10, 2015, 06:35:15 PM
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Hi, I know it's not a new problem for you lot but it is driving me nuts. The oil is leaking from the tacho drive on the cam cover, which is not uncommon I gather.
How can this be fixed, I have been told to replace the oil seal but I am having the devil's own job getting the old one out, any hints?
Someone also told me that as they are quite a loose fit and a new seal might not do the job.
Is there a sure fire fix for this?
Ta.
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A small pick will get it out.
A new seal solved my leak
Mick
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Even cheap ones like these are one of the handiest tools ever invented.
http://www.ebay.co.uk/itm/4-Hook-Pick-Set-Probe-Tool-Clips-Switches-Ring-Oil-TOOL-SET-/191490332004?pt=LH_DefaultDomain_3&hash=item2c95b69564
Mick
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This is how I got mine out after some advice from them that know better, I was a bit nervous about it but it worked a treat. http://forums.sohc4.net/index.php/topic,26190.msg268316.html#msg268316
(http://i192.photobucket.com/albums/z244/DennisMcc/teething%20troubles/MCandTachoseals002M.jpg)
Cheers
Dennis
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Thanks Dennis, the wood screw idea worked brilliantly, put a new seal in and bingo, no leak.
Trouble now is I took it for the MOT, about a 10 mile round trip and there is oil coming out from somewhere near the bottom of the barrels, lots of oil. I thought maybe base gasket but the bottom four or five barrel fins are covered in oil at the front only and I can't think how the oil could travel up from the base gasket.
I read somewhere that the four round oil seals under the cam carriers should have sealant on them but I just put them in dry. If they let oil through where would it come out?
I am going to have to take the engine back out to sort this but it would be nice to have a head start so I can figure out what has gone pear-shaped.
"Do it right first time" comes the cry. :-[
Oh, it passed the MOT though. :)
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I had a mysterious oil leak on my 400four, couldn't work out where it was coming from. I used compressed air to pressurise the crankcase via the breather tube at the top of the engine. Under pressure, the oil squirted out of the gearchange oil seal, which was new from DSS. Replacing it solved the problem.
I think this would only work for low pressure leaks but it's worth trying.
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Is the oil by any chance coming out around the spark plug cavity's. If it is, could be the rubber penny washers leaking. They are under the cam carriers so engine out for that. Hope its not.
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I am suspecting the penny washer seals so the motor is coming out again to check it out. Can these be obtained separately as they weren't in the last gasket set I had.
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91318-300-013 quantity 6
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Thank you, I will see if DS has them, unless you know of somewhere else.
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Always worth checking tappet access cover O rings, as often fully compressed/hardened and hot oil can sneak down in all directions >:(
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Thanks Dennis, the wood screw idea worked brilliantly, put a new seal in and bingo, no leak.
Trouble now is I took it for the MOT, about a 10 mile round trip and there is oil coming out from somewhere near the bottom of the barrels, lots of oil. I thought maybe base gasket but the bottom four or five barrel fins are covered in oil at the front only and I can't think how the oil could travel up from the base gasket.
I read somewhere that the four round oil seals under the cam carriers should have sealant on them but I just put them in dry. If they let oil through where would it come out?
I am going to have to take the engine back out to sort this but it would be nice to have a head start so I can figure out what has gone pear-shaped.
"Do it right first time" comes the cry. :-[
Oh, it passed the MOT though. :)
Glad to help
Cheers
Dennis
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Whizzed the cam carriers off today and sure enough one of the penny washer type seals was leaking, there is oil all over #3 spark plug area and is was running down and out from between the lower fins of the barrels.
Major lesson learned, always renew seals on a 44 year old bike!!!!!
I seem to remember that these came with the gaskets sets when I had my K6 in the 70s but obviously there is more money to be made by selling them separately now, or am I being cynical. ::)
I have ordered some new ones from DS, should I coat them with some ThreeBond (other sealants are available) when I fit them?
As usual, any info gratefully accepted.
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Yes, but not so much it squeezes into the oil ways!
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Its better to put the Threebond into the seat that the washer sits in, then bed the seal into it. That way it seals well and can only squeeze harmlessly out into the spark plug cavity. What a faff to change a few tiny rubber washers though. Big Honda mistake not designing the cam cover to come off in the frame. Would have taken you 1-2 hours to do. Not good.
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Your not wrong there Roy. I once heard of a mod where the frame tubes were cut above the engine and made into bolt on rails.
Don't ask me how, when or where, it is something I seem to remember way back when.
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Honda did not believe that the bikes would still be going after 40+ years and also from what was said earlier if they had been changed there would have been no problem. Gordon in the US was doing the "Kits" to modify the frame but for the manufacturer to do it on the line would had added quite a unit cost and Honda were trying to keep the costs down hence crosspoint screws, unchromed top of fork tubes etc, might only be a few pounds here and there but when you look at the quantity made it don't half add up. When we were working on them regularly we developed a "knack" for fitting engines whilst retaining gonads in correct position but I agree that for the occasional mechanic/owner it's more difficult
I can also remember when they were in gasket sets and also a bag full of those little dampers that go between the fins, but same as everything else customers want the cheapest possible so bits are left out
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When I was doing my 750F2 (first Honda I had done), I could not believe you had to remove the engine to get the cam cover off. So I had a look around at ready engineered frame kits and I thought they were all crap. They almost all remove the triangulation around the three tubes, this adds greatly to the torsional stiffness around the steering head and really should not be removed. So I decided I could do better than that myself, and as I have a TIG welder etc this is what I did. http://www.sohc.co.uk/index.php/topic,8188.0.html (http://www.sohc.co.uk/index.php/topic,8188.0.html).