Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: billdn on December 26, 2017, 11:54:05 AM
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Not withstanding my cylinder head troubles, my main ride also 400/4, has developed an oil leak below the barrels on the near side front-it seemed to appear after I used an oil flush when doing an oil change. It's not gushing out but weeps slowly and I now have a well oiled left boot. It then runs over the crankcase as the heat and wind disperses it. The big question is it an engine out job ? There is no loss in compression and starts and runs fine, unfortunately the scrutineer at Brands Hatch didn't like it so I couldn't take part in a VJMC parade☹ which is what motivates me to get it done. As far as I'm aware the engines never been out,40 year old nuts and bolts fills me with dread.
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Y remove the head and barrels on a 400 in the frame but first you need to clean it all off and find exactly where the leak is from
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It could be running down the cyl. head studs via the head nuts/washers, and showing up at the bottom of the cylinders, but as already said can be done in situ.
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Any pointers Ka Ja that might give a clue as to what to look for on cylinder head bolts -I'm guessing perished rubber washers, seals etc.
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Original washers were copper coated steel except for the ones fitted under the long head nuts which accept the cover bolts, these had a built in rubber? seal, all the washers were single use only, I use sealant on the washers as new ones are scarce
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Yes, the washers under the long head nuts have Dowty type washers fitted, ie built in rubber washer in the centre of the washer.
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I know the ones you mean. Mr. Silver has them. Would be nice if that's all but the way my lucks running at the moment I suspect not but changing them wouldn't be a bad idea while I'm doing it.
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The copper ones on my engine are pure copper so I annealed them by heating to red hot then plunging in water. It seemed to work ok as I don't have any leaks (yet)
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The copper ones on my engine are pure copper so I annealed them by heating to red hot then plunging in water. It seemed to work ok as I don't have any leaks (yet)
That's interesting as mine are copper covered steel. I wonder, as yours is an F1 and mine is a F2, if they changed them between models?
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These washers are bloody expensive. For the 10 copper and the 2 Dowty it works out at £46 a set.
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I suspect that solid copper washers under the head nuts have been fitted after previous engine work, as the part number for F1 and F2 appears to be the same, maybe something to do with not mixing too many different metals all with different expansion rates
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I did buy a couple of new ones from DS because 2 were badly scored and I'm pretty sure they were copper. Anyway Julie if they're copper and in good condition then anneal them if they're steel just use them again. Replace the Dowty seals of course.