Topic: Stopping top end oil leaks: Worth it?

[Scott S]

 I pulled my '71 CB500 out of a 28 year hibernation and got her running last year. Spent lots of time painting, polishing, detailing, etc. She runs good and looks good, too...if I do say so myself.

 I re torqued the head bolts when I was going through the engine. Still, I had a little oil weeping from around (what appears to be) the head gasket area. Last year, I could just wipe down between the fins with a paper towel every few rides or so.
 This year, it seems to be getting worse, at least on the first couple of rides. It's still not bleeding oil, but there's definitely an increase. The head/barrels are dirtier after a ride and there's a mist that is blowing back on the side covers.

 I've read a little about top end leaks and told that there are some o-rings under the head that are the likely culprit. I've also been warned of breaking head studs and a gasket change snowballing into a much larger project.

 I REALLY hate leaky bikes. I can live with a drip or two on the garage floor, but I don't like oil spewing out of places it shouldn't.

 I'm afraid I may be opening a can of worms if I go in there. The bike runs good, doesn't smoke or make funny noises. Parts to stop the leak(s) are readily available. I have a shop I trust to do the work. The work can even be done in the frame.

 Should I do it? What are some likely causes for leaks around the head gasket area? Will I REALLY break a head stud if I go in there?
 And lastly, if I'm going that far....wouldn't a nice, fat overbore kit be nice? 

[OldSchool_IsCool]

Unless your dry cleaning bill is larger than the engine rebuild bill or if the engine is needing a rebuild, I wouldn't do it.  At least, not during prime riding season. 

A lota folks will take that paper towel you mention and roll it cigarette like and jam it between the fins.  Change when saturated.  That should keep the oil weep at bay until you really do need to crack into the top end.

[bollingball]

If you are taking it to a shop quit worrying about the head bolt or anything that is why you pay someone else to do it.If you will not or can not do it yourself that is is what the money is for

I don't understand you said you re torqued the head bolts when you were (going through the engine). That is what a lot of people call a rebuild.

[Scott S]

 I didn't "go through" the engine, as in splitting any seals or cases. I got it running after sitting for nearly 30 years: adjusted valves & cam chain, spark plugs, oil & filter, cleaned/rebuilt carbs, set timing, etc. While the engine was out of the frame, I went around the head and made sure all bolts were torqued to factory spec. None were loose, FWIW.

[OldSchool_IsCool]

There are seals above the head bolts.  Look like little black rolled up condoms (only much much smaller than the ones I use  ahem, ahem )  Were those in good shape?  Might be worth a afternoon to pop the rocker cover off and replace them.  I use a very thin coating of Aviation Sealer to keep 'em in place.

[Scott S]

 I didn't remove the rocker cover. I was told those o-rings might be the source. If they are, could they cause the leak to appear to come from the head gasket? That's where it accumulates the most, anyway. I do see some oil on the head/rocker cover area, too.

[OldSchool_IsCool]

OHHHH! so the head bolts you torqued were actually the rocker cover bolts (Phillips head screws accessible external to the engine) right?  The head bolts I'm talking about are only accessible if you that the rocker cover off.  Can be done with the bike still in frame, but requires the breather cover (dome shaped upper cap) and the rocker cover (next layer of the sandwich) to come off.  You will then find 6 "pucks" or round rubber seals under there.  Those are the seal's I'm talking about.

If you peal back those seals, you will find the head bolts (actually flange nuts on studs) that hold the head and cylinder blocks to the case.  Taking out the head nuts is the point where all the fun begins, so you don't wana loosen those unless you wana go all the way down to the case. 

FYI, putting the rocker cover on requires special instructions.  Let us know if you plan to do that.

[Tugboat]

I have the same issue with my KZ400. Mid-70's models always leaked.. so much so that the factory issued a service bulletin to Kawi dealers on how to fix the leaks because they always leaked from the same places. Luckily for me I found a copy.....

But anyway, yeah. I'm not going to worry about it until the engine needs to be torn down for some other reason. Bike runs good so why mess with it? Just wipe it down after you ride it. Wouldn't hurt though to go ahead & start picking up parts for your eventual tear-down. Just my 2 cents.

[Nikkisixx]

Put a "tampon" in it and ride man.  
Tampon:  http://forums.sohc4.net/index.php?topic=70946.0

[lrutt]

On my K8, I bought some 1/4" cotton rope at Ace HW, cut some small lengths, and  stuffed them in between the fins at the head and cyl junction with a screw driver. You can't see it unless your looking, and it all but cut off the weeping. If I have to change it out each year so be it, but it sure did the trick.

[Deltarider]

Our bikes were designed to ride every day. I repeat: every day. Almost all issues I had with my 500 had to do with standing too long. I remember an article about a Dutchman who had done over 220.000 kms with his CB 500 and was still riding it... every day. That's the secret. When the bike is standing too long, seals shrink or dry out or... etc. But - and here's the dilemma - every cold start causes more wear than 100 kms of riding.
In my 30 years experience our engines leak most after the winterstop, then they'll leak too, but less. Make sure you always warm it up nice and gently. Revving to soon after hibernating is a recipe for extra leakage.
BTW, nice bike (with ridiculous handlebars).

[Scott S]

BTW, nice bike (with ridiculous handlebars).

 I have a set of 400F bars and pegs just waiting to be installed.    Also, I'm sure that sitting for almost 30 years didn't help the seals.

 I went out to the garage and cleaned up around the fins a little bit. Upon closer inspection, with a flashlight, the head to cylinders gasket seems to be fine. It appears, best I cam tell, that the valve cover and/or breather cover seem to be leaking and just running down or being blown around the fins.
  I also replaced a couple of iffy looking tappet cover o-rings and installed a couple of small "tampons" between the fins with the worst seepage.

 The breather cover is an easy one. Valve cover even not that big of a deal if we're careful, right? The odd thing is, I see a good bit of oil around/between the #2 and 3 cylinder area. Some running down one of the (I assume) head studs that is exposed between the cylinder fins and blowing back through the engine.
  If the major seepage seems to be up top, am I most likely looking at those head bolt seals, too?

[Scott S]

  The head bolts I'm talking about are only accessible if you that the rocker cover off.  Can be done with the bike still in frame, but requires the breather cover (dome shaped upper cap) and the rocker cover (next layer of the sandwich) to come off.  You will then find 6 "pucks" or round rubber seals under there.  Those are the seal's I'm talking about.

If you peal back those seals, you will find the head bolts (actually flange nuts on studs) that hold the head and cylinder blocks to the case. 

 Looking at the diagram at motogrid.com (I don't think this link will take you right to it, but... http://www.motogrid.com/pages/parts/viewbybrand/7/default.aspx  )
 I only see an 8mm flanged nut and a 14mm thrust washer. Is that thrust washer what you're referring to?

[OldSchool_IsCool]

The head nuts are #12, washers #14 and the suspect sealing rubbers are #18

[Jay B]

BTW, nice bike (with ridiculous handlebars).

I like that bike a lot. I'm going out to my shop now to paint my 550 silver.

[Scott S]

The head nuts are #12, washers #14 and the suspect sealing rubbers are #18

 Ah, thanks....I was expecting something smaller.

[Scott S]

I like that bike a lot. I'm going out to my shop now to paint my 550 silver.

 Thanks! It sure is fun to ride.

 NOTE: I also edited the poll to add a "tampon" option. 

[Mavryk03]

BTW, nice bike (with ridiculous handlebars).

 I have a set of 400F bars and pegs just waiting to be installed.    Also, I'm sure that sitting for almost 30 years didn't help the seals.

 I went out to the garage and cleaned up around the fins a little bit. Upon closer inspection, with a flashlight, the head to cylinders gasket seems to be fine. It appears, best I cam tell, that the valve cover and/or breather cover seem to be leaking and just running down or being blown around the fins.
  I also replaced a couple of iffy looking tappet cover o-rings and installed a couple of small "tampons" between the fins with the worst seepage.

 The breather cover is an easy one. Valve cover even not that big of a deal if we're careful, right? The odd thing is, I see a good bit of oil around/between the #2 and 3 cylinder area. Some running down one of the (I assume) head studs that is exposed between the cylinder fins and blowing back through the engine.
  If the major seepage seems to be up top, am I most likely looking at those head bolt seals, too?

I have the same problem a little leaking around the same area on my 75 cb550k1 going to stick a tampon in her  super absorbent and later will prob take everything apart and have the head re-milled and all that fun stuff.

[mjstone]

Mine leaks bad too. I'm going to try the cotton rope trick and leave it till I really have to go in there to fix something else.  I just can't stand the thought of having it down so long, I just gotta ride!!!

MJ

[Ryan6838]

If it was me id do the rope trick for now and start collecting parts for a big bore. That way as it gets worse or i get the time over winter Id rebuild it and have it fresh with more power for the next riding season. And i could spread the part buying out so it dont die then my wife fill me when she sees a bank statement for all parts at once. 

[Randy]

Great topic..less the tampons..i just got my CB500 runing and she started to leak oil in that very spot.. I was wondering about were it comes from.. so will be sticking rope in it..

[ak58lp]

I recently had mine do the same thing. I have been putting up with the oil mess for a long time and decided to do a top end rebuild (new head gasket, valve seals, relap valves, and all new gaskets from cylinder head on up). I had a book, posted a lot on a forum and had a friend help me take the valves out for lapping. I could likely do it much quicker now and learned a lot along the way as well as some headaches. Not that bad.

I have yet to road test mine to see if it's fixed. Here's a pic with the red arrows that point to the small O rings that leak. Found lotsa crud on the front of the engine which looks like metal filings but was just sand, grease etc.

[mjstone]

Yep, those are the oil paths from the bottom of the engine.  They provide oil under pressure for the cam shaft.  The o-rings seal that shaft at the top of the cylinder block.  There should also be some at the bottom of the cylinder block, probably in similar condition.

There are threads about blocking those  off and running external oil lines to provide oil to the cam shaft.  The idea, of course, is to never have to deal with the leaking again in the future.  There are pros and cons to this concept.  Try searching for external oil lines to check it out.

MJ

[ak58lp]

I recently had mine do the same thing. I have been putting up with the oil mess for a long time and decided to do a top end rebuild (new head gasket, valve seals, relap valves, and all new gaskets from cylinder head on up). I had a book, posted a lot on a forum and had a friend help me take the valves out for lapping. I could likely do it much quicker now and learned a lot along the way as well as some headaches. Not that bad.

I have yet to road test mine to see if it's fixed. Here's a pic with the red arrows that point to the small O rings that leak. Found lotsa crud on the front of the engine which looks like metal filings but was just sand, grease etc.

Well in my case it was not worth it. After a long winter of toiling with this project I took it out last night for a test run. It seemed to run fine but I had a noisy valve I think around 4,000 RPM, which I thought I may need to adjust again anyway. Fine, but when I pulled in the driveway my right leg was soaked with oil as it was pouring out of the head gasket area on the opposite side. The side I had the problem with before was as dry as a bone.

I made sure the head surface was clean and smooth, not gouged. New gaskets and O rings all the way to the top and all but one center head bolt was torqued to spec.  Looks like I might be parting out this bike soon as I am tired of wrenching on it.

[mjstone]

Man, what a bummer!  Maybe one of the o-rings shifted and got pinched.

MJ