Sealant here or not? CD175

Windmill John

Windmill John

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Location
East Sussex, England
Hi All,

Generally speaking, I’m not a sealant guy, but…

I’ve got a decent leak which appears to be coming from this joint. I also gone in because a PO has broken off a stud which I’m going to fix.

But, back to the question. With a new gasket, I’m tempted to apply a bit of sealant both sides. Yeh, ney, go for for it, don’t, and other options.


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I've rarely seen an outer cover leak when the surfaces are properly clean and all cover screws present. I have, in the past at times, used a thin smear of silicone sealer on cover gaskets when it was anticipated that the cover might have to come off again in the near future so the gasket wouldn't be destroyed. I'd say it wouldn't be necessary in your situation as long as things are prepped well and that broken off cover screw is removed and replaced.
 
I personally wouldn't. A new gasket on clean dry surfaces ( We are talking Honda here, not ancient British iron ) shouldn't leak. Once it's been through a few heat cycles the gasket sticks to those surfaces, needing attention with a razor blade to get them clean next time around. In fact, I've been known to grease on side of the gasket just to stop that happening, still didn't leak.

Digressing slightly, in the monthly comic 'Motorcycle Mechanics', there's a regular columnist who also reviews and sells tools, as well as mending Kawasakis. He is always banging on about some stuff called 'Welseal', with which he anoints all his gaskets. Perhaps old Kwackers leak more ?

Interestingly, for a self appointed expert and tool seller, he only discovered JIS screws in the last few years, used to be a believer in Phillips.
 
Yes, I’m tempted to grease, that’s what I often do.

I think the oil is from this joint. There were drips from the two red areas and the bolt marked yellow which holds the two halves of the crankcase together was wet. But it certainly looks and feels tight. Because that is forward of the red bolt, I can’t see how oil Is on it; unless it’s from the joint round the broken bolt.

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The broken stud may be a sign that the screws were over torqued, resulting in "pulling out" aluminium from teh crank. This way, the area around the screw hole is rising above the crankcase surface, leading to leakage, mostly inbetween two screw holes. I see these issue's a lot when using allen screws, the remedy is to use a wetting stone to equalize the surface again. This way, there is no need for any sealer. however, using grease on one side (outside of the gasket, and sealer between gasket and crankcase could avoid issue's later.
 
Thanks for that. I’ll check the flatness once I get the stud out.

It still has cheesehead screws, but I don’t know the history before a few months ago. The PO has restored the bike externally, but I don’t know what has happened to the engine historically.
 
The day is young :)
I’d only just taken the cover off and wiped away the oil.
Oh and some loose very thin orange sealant from various areas.
 
Check you have the o-rings on the outer cover screws, that can cause a leak that looks like it comes from different place.
Check cover for cracks, bike has probably been 'dropped' a few times in it's life.
Screw probably broke off trying to remove it, your in Britain, they salt the roads and people used to ride year round in all conditions when the 175 was a 'ride to work' bike (I did when I had 1968 CD175, it was actually fun in snow as long as no cars about)
DO NOT USE Silicon sealer
I've seen it cause way too many seized cams after oil-way, pump pick up or gallery gets blocked by it
 
crazypj said:
DO NOT USE Silicon sealer
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Too late! :) But don’t worry, I’m pretty anal and only applied a token amount, more to fill in any imperfections in the gasket; definitely not enough to come away and block passages.

But…. Went to pick something up, five mile ride and when I came out of the shop, there was a drip. Couldn’t work out the exact location, so rode a spirited ride home, got the bike on its main stand and quickly put a bit of A4 white paper underneath and left it there……. Not a drip!
I’ll get the bike out again hopefully tomorrow and try another ride with a side stand rest at the end. If there is a drip, I’ll have to get a detective to hunt for the source; or just lay on the floor underneath for hours. :rolleyes:
 
Windmill John said:
Too late! :) But don’t worry, I’m pretty anal and only applied a token amount, more to fill in any imperfections in the gasket; definitely not enough to come away and block passages.

But…. Went to pick something up, five mile ride and when I came out of the shop, there was a drip. Couldn’t work out the exact location, so rode a spirited ride home, got the bike on its main stand and quickly put a bit of A4 white paper underneath and left it there……. Not a drip!
I’ll get the bike out again hopefully tomorrow and try another ride with a side stand rest at the end. If there is a drip, I’ll have to get a detective to hunt for the source; or just lay on the floor underneath for hours. :rolleyes:
Click to expand...
Talcum/baby powder helps find the source, just throw it on the suspect areas and it turns into a gooey mess where the leak is.
 
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