79 CB 650, top end oil leak

If it's broken or just needs tweaked

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thrutheframe
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Location: Cincinnati, OH

79 CB 650, top end oil leak

Postby thrutheframe » Sat Nov 12, 2011 7:25 am

My 79 CB 650 has a top end oil leak. Its coming from above the head and I assume its leaking at the cam cover. This is one of those spots where Honda didnt use a gasket.

IMG_3865.JPG
The honda logo is dry, it seems to be seeping out from under the cam cover, back in that recess on the #2 cylinder side.
IMG_3865.JPG (117.39 KiB) Viewed 9920 times


The oil collects on the fins on the #1 cylinder and if clean it all off and start fresh I can see that it's only on the left front between the vertical fins and on the top fin by the #1 spark plug.

IMG_2796.JPG
IMG_2796.JPG (231.08 KiB) Viewed 9919 times


I took the breather cover off and retorqued all of the bolts under there but that didnt fix it.

Any ideas suggestions? Thanks.
I keep rubbin it but it still looks broken.

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Volker_P
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Re: 79 CB 650, top end oil leak

Postby Volker_P » Sat Nov 12, 2011 7:59 am

Be careful with retorquing those bolts! These threads strip quite easily.

Besides the 1.2m long O-Ring seal all around the head cover, there are six rubber coins that cover the access holes for the head bolts.
If these rubber plates are hard, oil would probably come out preferentially somewhere at the rear of the head cover.
One may replace them or reuse them but with sealant.
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forum links to common technical issues

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thrutheframe
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Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Sat Nov 12, 2011 12:03 pm

Volker_P wrote:.......Besides the 1.2m long O-Ring seal all around the head cover...


This statement just made me realize that there is indeed a gasket where I thought there wasn't one. I assumed there wasn't one there because my CB360's DO NOT have a gasket there. On the twins Honda sealed that union with Hondabond, or as many people like to do, with RTV sealant. My hard head got me on this one. As many times as I've looked at the parts fiche for this bike you think I would have seen it. I just kept looking at that union and thinking about my other bike and the way they did it on THAT bike. I have a "complete" gasket kit for the motor. When I get home later this month I'll take a look and make sure I have the right seal for this spot.
Any advice on what to watch out for on this project?

Thank you very much for looking at my project.
I keep rubbin it but it still looks broken.

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Volker_P
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Re: 79 CB 650, top end oil leak

Postby Volker_P » Sat Nov 12, 2011 12:25 pm

In fact this gasket sticks in a groove in the bottom of the the head cover so you may not notice it looking at the head. But I would asume a 3mm deep, empty groove all around the head cover bottom should catch your eye somehow.
So I don't think it is really missing, however it might be not tight, though. I'd guess the rubber coins are more suspicious, but clarify in any case. It is important to get all surfaces really clean and follow the stepwise pattern for the 22 head cover bolts. This way it should get tight with 9-10Nm. More torque typically does not help but will just cause stripped threads at some stage.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

thrutheframe
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Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Sat Nov 12, 2011 1:28 pm

Volker_P wrote:In fact this gasket sticks in a groove in the bottom of the the head cover so you may not notice it looking at the head. But I would asume a 3mm deep, empty groove all around the head cover bottom should catch your eye somehow.
So I don't think it is really missing, however it might be not tight, though. I'd guess the rubber coins are more suspicious, but clarify in any case. It is important to get all surfaces really clean and follow the stepwise pattern for the 22 head cover bolts. This way it should get tight with 9-10Nm. More torque typically does not help but will just cause stripped threads at some stage.



Again thanks, I pulled the breather cover but not the head cover. I think I would have noticed a missing seal/ empty groove.

IMG_3866.JPG
IMG_3866.JPG (163.6 KiB) Viewed 9908 times
I keep rubbin it but it still looks broken.

thrutheframe
Posts: 32
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Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Sat Jan 21, 2012 12:22 pm

I finally got a chance to take the cam cover off and take a look. The seal is hardened and smashed flush with and fouled in the groove. Here are few pics that I took of the seal and my cam etc.

IMG_0101.JPG
IMG_0101.JPG (178.66 KiB) Viewed 9779 times


IMG_0104.JPG
IMG_0104.JPG (189.53 KiB) Viewed 9779 times


IMG_0106.JPG
IMG_0106.JPG (167.95 KiB) Viewed 9779 times
I keep rubbin it but it still looks broken.

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Volker_P
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Re: 79 CB 650, top end oil leak

Postby Volker_P » Sun Jan 22, 2012 6:44 am

In case you want to make it yourself, the long "O-ring" is about 3.5x1240mm.
One may use additional sealant here and also at the rubber coins.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

thrutheframe
Posts: 32
Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Tue Jan 31, 2012 10:44 pm

It's much better but still a tiny leak down low but above the head. I am tied up working on some stuff in Indy with the Suoer Bowl related stuff. I should have taken the extra few minutes and re[placed the pucks while I was in there. I've made waaay bigger mistakes in life. I'll take the cam cover back off when I get done with all of this craziness.

Meanwhile I had my gas tank treated at the raditator shop. The chem dip tank has to be pretty brutal. I had the inside red koted, I was a little a bummed that they got the red kote on the outside but I can use it to check the durability factor.

gas tank.jpg
gas tank.jpg (111.27 KiB) Viewed 9717 times


red kote.jpg
red kote.jpg (105.6 KiB) Viewed 9717 times
I keep rubbin it but it still looks broken.

thrutheframe
Posts: 32
Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Thu Feb 09, 2012 8:13 am

I took the cam cover off the 650 last night and replaced the the head bolt seals. 5 of 6 were allowing oil to get in from the top and at least one maybe two were allowing oil to pass out the bottom.

If the seals work the way I think they do, the concave portion of the seal should be dry.

Head Bolt Seals.jpg
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It seems like a recurring theme on this bike is, flattened hard seals. I'm hoping I catch a break and that I'm done with oil leaks. I've already replaced the clutch actuator seal, the clutch cover gasket, the oil pan seal, the tach drive seal, the oil filter housing seal and the oil filter bolt with a new o-ring, the cam cover seal, and of course all six head bolt seals.

Head Bolt Seals w One Out.jpg
Head Bolt Seals w One Out.jpg (142.3 KiB) Viewed 9660 times


You can see the seal on the left is covered with oil on the bottom side, that's the one next to the #3 cylinder in the front. The dry one is from the #2 cylinder, rear position.

Dry vs Wet.jpg
Dry vs Wet.jpg (82.96 KiB) Viewed 9660 times


I have it all put back together I just have to go in today and set the valves.
I keep rubbin it but it still looks broken.

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Volker_P
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Re: 79 CB 650, top end oil leak

Postby Volker_P » Fri Feb 10, 2012 6:31 am

Good pictures.
You are right, the center bottom of all six rubber coins should be dry. If one does not replace them, one may use additional sealant at the compressed outer circle.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

thrutheframe
Posts: 32
Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Fri Feb 10, 2012 9:50 am

Thanks for taking a look. I replaced mine, I should have just pulled and replaced them when I had the cam cover off the first time. I've done alot of that on this bike.

puck on cam cover.jpg
puck on cam cover.jpg (116.02 KiB) Viewed 9645 times


pucks in place.jpg
pucks in place.jpg (117.32 KiB) Viewed 9645 times
I keep rubbin it but it still looks broken.

thrutheframe
Posts: 32
Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Sat Feb 18, 2012 9:15 pm

Its been a few days since I replaced my head bolt seals. Ive been turning the bike over with the battery and havent seen any oil since the first two when I cleaned up minute traces of oil probably already leaked out.

clean head.jpg
clean head.jpg (90.02 KiB) Viewed 9585 times
I keep rubbin it but it still looks broken.

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Volker_P
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Re: 79 CB 650, top end oil leak

Postby Volker_P » Sun Feb 19, 2012 7:13 am

That's already progress. Now the remaining question is how it will look like when the engine is hot.
Cosky's great (free) online manual: http://cosky0.tripod.com

forum links to common technical issues

If you really like this site and you would not like to see it vanish soon, have a look there: Urgent: Future of HondaCB650.com Forum

thrutheframe
Posts: 32
Joined: Fri Nov 11, 2011 10:16 pm
Location: Cincinnati, OH

Re: 79 CB 650, top end oil leak

Postby thrutheframe » Sun Feb 19, 2012 11:24 am

I'll know soon, I have a clean CB750 gas tank that I am going to put on the bike and do some charging system testing and leak testing. If the weather holds I might even pull her out on the road and get the title put in my name and some tags on her.
I keep rubbin it but it still looks broken.

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kemp2368
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Re: 79 CB 650, top end oil leak

Postby kemp2368 » Tue Feb 28, 2012 4:49 pm

good pics
i to have oil leak from i think the same place(but im really worried about re fitting the cover ,as someone before me stripped the bolts(copper washer ones) and i had to put slightly bigger ones in to get it to seal properly
how easy is it to get said washers/rubber grommets and how long to do,
or do i live with it as since i had the bike it still has not used any oil(2 years) but very annoying as its the only thing wrong with the bike
cb650z,1979


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