Topic: CB400F -- Cam tower Pucks?

[vames]

Hi -- I've done some searching and don't come up with much. My '75 CB400f leaks some oil right around the spark plug hole in the fins on the left side (when sitting on the bike). It's above the head gasket so I don't think that's it, and it seems like it could be the cam tower pucks that a lot of people talk about with the 550 and 750 engines. Do these same pucks exist with the 400F? Do they sit under the cylinder head cover? Can they be bought separately and replaced?

I'm in the process of disassembling and cleaning a lot of the bike, and I'd love to see if I can fix this when I take off the head cover to clean and polish. I'd like to order parts before I do it, though I'd sooner live with the leak than take off the entire head right now. I want to ride and the season is almost here!

Any information is greatly appreciated. Here's the diagram I'm looking at, but I don't see anything resembling rubber pucks:

[Tim2005]

There's no such pucks on the 400. Most common 400 oil leak source is the seals that sit in the head gasket, but as yours is above maybe it's just running down from the rocker cover gasket. Best to clean it right up then see if you can see where it's starting from- some people have had success by covering the area with talc as that shows the leak easier.

[vames]

Thanks -- I guess that's why I didn't see them in the diagram. I will replace the cylinder head cover seal regardless, and while it's open, make sure all the head bolts are properly torqued. Then if I'm still leaking once I'm all cleaned up and running in a few weeks, I can try and pinpoint where the leak is coming from. At very worst, it'll be paper towels stuffed into those fins for the summer then I can think about it again next winter.

Any other good things to inspect/replace when I take the head cover off?   

[Kanticoy]

You might check the crush washers under the acorn nuts on the rocker arm shafts too. They are known to leak.

[vames]

Would those crush washers be #241 in the diagram above? If they leak, is there a path where oil could make it out to the fins around the head?

Thanks for the help.

[bryanj]

The other leak is via the washers under the head nuts as they are "coppered" and suposed to be changed but rarely are

[vames]

Sounds like bryanj and Kanticoy are talking about the same copper washers under the head nuts (#241 in the picture). Is it possible that I can replace them and retorque the nuts one at a time without disturbing how the head gasket is sealing? Is there an order I should do it in?

At the same time, I'll replace the valve cover gasket. Hopefully I'll have a dry engine after that.

[jessezm]

Watching for an answer to the question above with much curiosity!!!  I've got a head gasket leak after a top-end rebuild and have re-torqued the heads but failed to replace the copper washers.  Heads are still weeping a little.  So I just ordered new copper washers (though the two washers with seals--#242--are on back-order everywhere), and was planning to replace all the washers with fresh ones then re-torque.   So would it be best to do them one at a time, from inside to outside in the normal, zig-zag order, in order to avoid any further issues with the head gasket?

[jessezm]

Sounds like bryanj and Kanticoy are talking about the same copper washers under the head nuts (#241 in the picture). Is it possible that I can replace them and retorque the nuts one at a time without disturbing how the head gasket is sealing? Is there an order I should do it in?

At the same time, I'll replace the valve cover gasket. Hopefully I'll have a dry engine after that.

Actually, I think Kanitcoy is talking about the washers under the acorn nuts for the rocker arm shafts, which go into the valve cover from the side, and are not in the heads--they are not pictured in the diagram

[vames]

OK I see what Kanticoy is talking about now. Definitely not where the oil is coming from, but good to know. I just ordered 10 of the sealing washers for the head nuts at hondaparts-direct.com for $2.70 a piece. I found generic M8 crush washers for as little as $0.25 a piece, but I figured I'd better get genuine Honda ones.

jessezm, keep me informed on how it goes when you replace and I'll do the same. It'll be a couple more weeks before I get to that, but I'd be really excited if it dries up the front top fins.

[jessezm]

Yeah, I will definitely report back here.  Also might be a few weeks though--I want to replace those #242's as well, which are on back-order...

[vames]

hondaparts-direct.com seems to have the #242 washers -- at least on their website it suggests they do.
http://hondaparts-direct.com/fiche_section_detail.asp?section=121649&category=MOTORCYCLES&make=HONDA&year=1975&fveh=2911]
[url]http://hondaparts-direct.com/fiche_section_detail.asp?section=121649&category=MOTORCYCLES&make=HONDA&year=1975&fveh=2911[/url]

[jessezm]

Thanks, will check it out.  Service Honda told me they were on backorder from Honda nationwide, but maybe Hondaparts has some in stock?  Usually you don't find out something is backordered until after you pay for it though!

[fmctm1sw]

I'm definately watching.  After close scrutiny, it appears my leak is coming from the middle somewhere; right where those studs come down through.  I drew up a crude picture of where the leak appears to be.  I did the top end gaskets a few years ago but never did anything with those copper washers.  It leaks so bad I've only ridden it once or twice in the last month or so.  I had the valve cover off last weekend and retorqued all the head nuts with no change.  I'm intertested to see what effect those washers have...

[vames]

Thanks, will check it out.  Service Honda told me they were on backorder from Honda nationwide, but maybe Hondaparts has some in stock?  Usually you don't find out something is backordered until after you pay for it though!

You're right -- I tried to order those #242s but hondaparts-direct said they're backordered until mid-May, so I'll just be replacing those 10 crush washers.

I'm definately watching.  After close scrutiny, it appears my leak is coming from the middle somewhere; right where those studs come down through.  I drew up a crude picture of where the leak appears to be.  I did the top end gaskets a few years ago but never did anything with those copper washers.  It leaks so bad I've only ridden it once or twice in the last month or so.  I had the valve cover off last weekend and retorqued all the head nuts with no change.  I'm intertested to see what effect those washers have...

That's way lower than where I'm leaking -- my leaks are upstairs in the fins around the exhaust.

[vames]

For those that were following this thread, I don't have any answers yet about whether replacing the 10 copper crush washers under the head bolts and retorquing will end my oil leak.

But do know that Honda is now supplying the two other sealing washers (#242 in the diagram and part# 90442-377-000) after having them on backorder for a while. Just got mine in the mail from Hondaparts-direct.com.