Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Drew400 on March 22, 2020, 08:50:19 AM
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Hello all,
When I rebuilt my 400/4 some years ago, I didn't quite seal it properly so I have oil weeps from most of the major split points (i.e. cylinder head, block base, etc.). They're not bad enough to worry much about, I just wipe it over every time I use it... it's hardly old British bike territory!
However (you know what's coming), this enforced isolation business is a good opportunity to spend time in the garage fixing it.
My question is this:
I would like to buy all the bits I need to do the job IN ONE HIT (especially as some of it will come from David Silver and so I'd just like to pay one lot of postage please)! Is there anything else I need on my shopping list in addition to these items:
- Gasket set
- Oil seals set
- Head bolts (with oil seal washers)
- Hylomar or some such
Thank you, D.
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Ditch the Hylomar from the list Drew. Its only the crank cases that need sticking together with the lightest, lightest smear of Honda Bond as they are machined surfaces and have no gasket. Other than than that the gaskets do the job everywhere else.
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Thank you Nurse Julie. Maybe using that stuff last time is my problem... not that I can remember what I did/didn't use!
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Out of interest Drew, why are you going to use new head bolts?
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Can't remember that either, but I know they leak all from the top if the wrong ones are used, so I guessed they can't be re-used.
No doubt when I actually start the work, some of this will come flooding back!
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Can't remember that either, but I know they leak all from the top if the wrong ones are used, so I guessed they can't be re-used.
No doubt when I actually start the work, some of this will come flooding back!
They can be re used with no problems at all Drew. No point in spending money on something that is not needed. When you are stripping the engine you just need to have a close look at what you did before that has caused the engine to leak.
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To keep an awkward gasket in place I find a light smear of high temp grease helps.
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To keep an awkward gasket in place I find a light smear of high temp grease helps.
Me too Bob 👍👍👍
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Did you re torque all the head bolts after a few miles riding? ( then check tappets ) been a long time since I did anything on an sohc engine so I am really rusty, might be worth trying. I have cured the odd leak with things like that - just not sure it's the totally correct fix.
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Head is studs not bolts, some of the nuts have special "copperised" washers to seal oil and they ometimes need replacement but are dear.
Hondaman on the US site has worked out that modern gaskets are thicker so you need thicker cross section O rings to seal properly. Could be worth going there and asking him for sizes.
Retorque was never done in dealerships and if everything clean and flat shouldnt need it
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Thank you all for your wise council.
Bryanj - the copperised ones are the ones I was thinking of. I'll check out Hondaman too.
I think we can all agree, there's probably no rush to do this as I think we've all now got lots of spare time on our hands!
Stay well everyone.
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You don't need new copper washers on the head studs. Heat them up to cherry red and quench them. This annealing process softens them so they seal better.
Hope it all goes well with the strip and you don't find anything narsty.
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Thanks Mike, will do. I'm hopeful it will still be like a clean sewing machine in there!
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Unfortunately they are not solid copper but i think coppered steel
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Ah, thank you experts all. Cheer, D.
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I have a few Brit bikes, so I have a wealth of experience on oil leaks! Firstly all mating surfaces should be flat, clean and dint free. Secondly, yes, use a new gasket, and third, a smear of Wellseal does not do any harm. Tighten all bolts to the sequence shown, or failing that, diagonally. Do not overtighten.
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DO NOT use any gasket compound on any Honda
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DO NOT use any gasket compound on any Honda
+1 with Bryan. One day I will collect up all the red, blue, black and white gunge found in our customers engines that have blocked oilways and restrictor jets causing very, very expensive damage when they tried to rebuild the engine before bringing us to repair. I will make something out of it 😁😁(yes, white, where someone used bathroom sealant on their gasket faces 😭😭😭). It not needed, or necessary on these engines. Just Honda Bond or similar on the crank case mating surfaces as they are machined and have no gasket. Even then, it has to be applied so thinly you can hardly see it.
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Thank you all again.
This forum has always been a refreshing change from the bleating and moaning on other forums that I have since left!
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Julie has said it right i just got fed up of writing the long version!!!!!
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Wellseal is a jointing compound - a million miles away from silicone based stuff.
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Might be but bits still flake off and/or go hard
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The inevitable additional question...
Looking at the parts book (see attached photo of oil pump assembly), there are 0-rings numbered 286 & 287 but only one item is shown.
Does that mean both are required or that they're optional or they're model-dependent?
Mine's an early bike (i.e. not an F1 or F2).
Thank you all (again),
D.
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Solution provided via this forum, once again. :)
Thank you!
D.
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Solution provided via this forum, once again. :)
Thank you!
D.
Does this refer to the recent o-ring question? If so, care to share with the rest of us?
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Yes indeed. I received a suggestion by PM hence not sharing, sorry.
I was shown a picture of an 'oil pump gaskets set' that had only two of the questioned O-rings therein. The two options shown in the parts catalogue are shown on David Silver's website to be of different sizes, 13.8mm or 15mm. I simply then measured the ones off my bike (15mm).
I'm still unsure as to why there are two sizes, but at least I got the answer I needed to progress.
Cheers,
D.
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Yes indeed. I received a suggestion by PM hence not sharing, sorry.
I was shown a picture of an 'oil pump gaskets set' that had only two of the questioned O-rings therein. The two options shown in the parts catalogue are shown on David Silver's website to be of different sizes, 13.8mm or 15mm. I simply then measured the ones off my bike (15mm).
I'm still unsure as to why there are two sizes, but at least I got the answer I needed to progress.
Cheers,
D.
Thanks! I was curious about the two item numbers myself...
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Hondaman on the US site has worked out that modern gaskets are thicker so you need thicker cross section O rings to seal properly.
Bryanj - the copperised ones are the ones I was thinking of. I'll check out Hondaman too.
Did you ask Mark? Did you get a reply you can share with us?
There is a thread on the same site that might be worth looking at - it's "Branden's leak free top end thread"
http://forums.sohc4.net/index.php/topic,107040.0.html (http://forums.sohc4.net/index.php/topic,107040.0.html)
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Dear expert peeps,
Here's another inevitable follow-up question...
The oil weep clearing job has taken a little longer than expected (what's new?) thanks to one of my exhaust pipes literally falling apart from the collector box. Clearly, it's rotted through from the inside but only became noticeable when disturbed. Hey ho, some miracle welding from a genius welder mate of mine and it'll be ready to go back together next week.
During the intervening period, with no head on the engine, oil is now weeping from the cylinder base gasket area.
Does this mean I now have to remove the block and replace that gasket, or will it seal up again when the head if finally reattached and torqued down?
Ta, D.
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It would be better to replace the base gasket and O rings now as they will only leak later
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Thanks BryanJ. I guessed as much, but always nice to hear from a real expert! Cheers, D.
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Is that ex as in used to be and spurt as in drip under pressure?
Following a few threads on the board it would probably be best to check the rings anyway
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Ha ha, quite so! ;D
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Now fitting a new genuine Honda cylinder base gasket.
Is there any reason why it's green on one side and blue on the other (i.e. does it matter which way up it goes, as it fits properly both ways up)?
Ta, D.