Help! Tachometer gasket install hone horribly horribly wrong!

[AgentMichaelScarn]

Hey guys! I've been browsing this forum for awhile but this is my first official post here. I wish it were under better circumstances. I've been riding my 1980 CB750K for a few hundred miles when an oil leak developed from where the tachometer cable goes into the engine.

I watched a few how to videos and read some guides, it seemed super easy and simple, what's the worst that could happen?

Now the tachometer housing on the DOHC is super inconvenient its pointed right at the frame with very little room to work. Every guide I read said to just screw a screw into the gasket and pull it out. After several attempts I finally got it to grab, and gave it a gentle pull with the pliers. I immediately could tell something was wrong though.

Now I looked as best I could and could see the o ring, but I think it was mostly deteriorated, the screw grabbed into the metal backing and pulled it out, causing some damage to the housing itself. After cleaning up what amoubt of remaining gasket I could find, I tried to gently drive the new gasket into place. This is where my second mistake occurred, from gently tapping a socket I managed to break off the side of the housing too.

So now I have what appears to be a completely busted housing, I had to pull the valve cover to remove it and it doesn't look good.

http://i.imgur.com/FIhrFqO.jpg

http://i.imgur.com/6r75DfD.jpg

http://i.imgur.com/kssSVmG.jpg

It's hard to take pictures of it but this should show it. I'm really concerned about the torn metal backing piece. Also, I don't understand how the gasket is supposed to fit in there. I know I have the correct seal, but I push it in as far as possible and its not far enough back to work.

I'm really baffled by all of this. It doesn't seem anything like the videos I watched or the forum posts I read. It also doesn't seem like this piece is sold anywhere so I don't know how to go about replacing it.

Any and all suggestions are extremely appreciated.

 

[amc49]

Necessity is the mother of butchery they say.....................

That is a cam cap, it is part of the entire head assembly and long NLA. Your 'seal' goes in the bottom not the top. You will utterly destroy that cap trying to get it out the top and looks like you're well on the way now. The gear comes out the bottom then you remove the seal after it by punching down not lifting up.

Part still may be useable even with that chunk missing as long as it still holds the cable end in.

Look twice, do it once, look once do it twice (or break it)...................

 

[AgentMichaelScarn]

Yeah thanks to the folks over at cb750c I'm back in business with the new seal.

The thing is I watched a couple videos and read several guides online, every single one of them said to pull it out through the front with a screw, apparently one of the manuals even says to do that. I thought I did my research beforehand.

Turns out I had a metal and rubber washer (which I also didn't see mentioned anywhere until I was told on my other post) which makes this removal technique impossible.

The seal can only be removed from the top though I don't understand how you would insert or remove it from the bottom. I did remove the gear to help push it out from behind but you definitely can't insert it through the bottom...

So I have the new seal in and my missing chunk isn't hurting anything yet. But now I'm doing a valve adjustment while I'm in here, its a bit more complicated than I anticipated but I'm well on my way to resolving that too.

 

[amc49]

You can easily remove it with a proper size screwdriver in seconds. Seal may go in top or bottom, been awhile since I did one but have done plenty in the past.

My apologies.

 

[AgentMichaelScarn]

Hehe well "easily" is subjective, I wrestled with it for awhile after I took it off the bike and couldn't get it for the life of me, the seal had deteriorated a good bit so I think that was part of my issues.

There's a backing behind the seal though, you can't insert or remove it from the back. You can push through the back to push it out the front. Just in case someone else has this issue.

I ended up sliding a screw head first that barely fit behind the metal part of the seal and used plyers to pull it out while pushing against the metal ring, after a few tries it popped out and flew across the garage hehe.

 

[amc49]

Jeez, it's a simple composite metal/rubber oil seal like millions of others on all kinds of equipment. I've changed so many there is no way I could ever put a number to them other than thousands. They come out in seconds. Self tapping like sheetmetal screw of the correct size (important) and out in seconds literally after you screw it in the center hole to lock up enough to yank it.

Easily means just what it says. You spend time thinking about how to do it best then do it once and quick or rarely twice. You almost had yourself changing a head there......people often break that entire cap in two doing what you did in the wrong fashion. The head pretty much becomes scrap when it happens.

 

[AgentMichaelScarn]

Alright well thanks for your "help" I think I'll stick to the cb750c forums from now on.

 

[amc49]

I post there as well and thanks for the 'complement'.

Don't ask for help if you cannot accept that the helper might know more than you to hurt your feelings. You seem to want to wallow in your lack of knowledge about simple seals and that does not help you at all; and looking for others to back that unquestioned says you don't want to move any further forward. That's self-limiting behavior pal.

 

[AgentMichaelScarn]

In the time it took you to tell me "its easy" and like "millions of other seals" the members over there were helpful and explained it to me kindly and thoroughly. My problem was solved.

You gave me incorrect advice (it can't be pulled out the rear, despite what you keep saying) and didn't offer anything helpful or constructive besides saying to do my research. If you'd read my post youd see I did plenty of research before attempting it, but nowhere did I read that there was a metal backed seal, and my replacement was rubber so I was just confused as to what I was dealing with.

I think you're the one getting your feelings hurt. But thanks anyway for trying I guess. Now I'm not surprised why this place is so dead.

 

[amc49]

I just started here too so don't blame me.

You win, I should have not answered at all since your lacking of skills was easy enough to spot. Normally I stay away from those, they give the most trouble and in hindsight I was right. I shouldn't be surprised.

Post #8 is still cast in concrete for you.