Topic: Oil leak from head, part not on Diagram.....????

[78cbfun]

Guys I have a slight oil leak on my 78 cb 550. They look like press in metal dowels or plugs in the head. 3 on each side.  I have looked at parts diagrams but no info on what they are or if they can be replaced.  Temp sensor holes maybe?? Pic attached. Newb owner btw.  Thanks. 

[bryanj]

They aint replacable and only come with a head also never seen a leak there, common leak is O rings under the end cap held on with the crosshead screw and/or the soft washers supposed to be betwwn the steel bracket the screw goes into and rocker cover

[78cbfun]

Interesting....it does leaking from the press in metal piece.  But luckily ends caps on both ends are dry! Thanks for the information

[DaveBarbier]

I have seen a couple posts of leaks from these plugs. And yeah, not sure how’d they be replaced but maybe by a machine shop. There shouldn’t be any pressure behind that so it’s possible that cleaning it as much as you can and a smear of Hondabond or something could help. Or you could find another head, they’re not that expensive on eBay used. A CB550 head from any year would fit.

[78cbfun]

I do work at a machine shop but don’t really want to start more problems by machining a new piece and maybe cause more leakage.  But I may take your advice and use extreme heat JB weld paste. 

I have seen a couple posts of leaks from these plugs. And yeah, not sure how’d they be replaced but maybe by a machine shop. There shouldn’t be any pressure behind that so it’s possible that cleaning it as much as you can and a smear of Hondabond or something could help. Or you could find another head, they’re not that expensive on eBay used. A CB550 head from any year would fit.

[trigger]

Never seen them leak from the outside ones. I remove the centre ones on each side to clean the oil way out and machine up new ones, a little smear of Honda bond and press in.

[DaveBarbier]

Never seen them leak from the outside ones. I remove the centre ones on each side to clean the oil way out and machine up new ones, a little smear of Honda bond and press in.

How do you remove them? I’d imagine drilling a hole, threading it and then using a bolt to pull it out.

[trigger]

Never seen them leak from the outside ones. I remove the centre ones on each side to clean the oil way out and machine up new ones, a little smear of Honda bond and press in.

How do you remove them? I’d imagine drilling a hole, threading it and then using a bolt to pull it out.

The outside ones can be pushed out if the head is off and the valves are out. Or you can drill in 3/4 of the depth of the slug, tap the hole and attach a slide hammer to the tap and pull it out. Measure up the old slug and make a new one on a lathe 

[DaveBarbier]

Cool, that works. Thanks

[maxheadflow]

How do you know what 3/4 the depth of the slug is?