Topic: oil leak cylinder head

[GordonFraser]

Short story 1976 motor. Oil leak above the head gasket at No 1 cylinder. Runs onto outside of 3rd fin down and also fills up around spark plug. I suspect it is the oil disc seal that sits under the camshaft holder. Any thoughts from the gurus?

Long story: this will be the 6th time I have removed the engine fixing stuff. At least I have developed a method to remove the motor by myself in a couple of hours. And putting it back in in about 3 hours.

removal #1. rebore, new pistons valves. t chain tensioner. elect ignition. Also replace carb jets. = runs rough
removal #2. check valve timing = Ok still runs rough. Spark plug oiling up.
removal #3. try a new head gasket and all the rubber head seals = runs rough. plug oiling up
take bike to guru. He says he won't touch it unless it has original air box. Find air box. install.(presumably it had been jetted for pods and bought the new but wrong jets) runs much better. plug still oils up.
removal #4. get 2nd hand head, move new valve gear from existing head. head skimmed by pro engineering shop. Now plug does not oil up but leaks above the head gasket line,
removal #5. I think a head stud is stretched and protruding and stopping cam shaft carrier from sealing the rubber disc. Angle grinder on cam shaft carrier. Lots of goo on rubber disc.= still peeing oil
removal #6.  wtf do I do now?

Work also done. rechrome forks and new springs set up by a guru. new wiring loom. respray.brake pads. battery. rectifier. when bought had new tyres chain and sprockets.I bought absolutely cruddy 4 into one exhaust that started rusting as I bolted it on. Market value = 1/3rd of costs to date.

[mystic_1]

I was with you right up until number 5, what made you suspect that one of the camshaft holder studs with stretched, and what exactly did you do with an angle grinder there?

Also, will be wanting some pictures eventually, but since you are new you need to build up a few posts before you will be able to attach pictures directly. If you have a Photobucket or Flickr account, you can post the photos there and then post the image links here, otherwise just chit-chat with us a little bit more and when you have 5 post you will be able to attach photos.

Welcome aboard.
mystic_1

[flybox1]

cam tower studs
were they ever removed, and if so, did they get some good sealant on them when they went back in?

[flybox1]

any of your head studs require a brass crush washer under a nut/acorn which was reused before annealing?

[GordonFraser]

thanks guys for thoughts. Found the problem. The cylinder head recon engineer helicoiled the cam shaft holder stud hole. It is supposed to have a blocked end. He drilled all the way through. (and charged me $100 for the pleasure.) So now oil runs down the bolt, through the helicoil and out the bottom. Lord knows why so much oil can get through here. I tested this by syringing oil down the bolt hole. it comes straight out the bottom.

Question now is.... what gunk do I stuff down the bolt hole to seal off the leak ?

FYI.. I angle grinded about 1mm off cam shaft holder so there was a visible gap to the head stud.

[PeWe]

Thread sealer high temp version. Like this:
http://www.permatex.com/products-2/product-categories/thread-compounds/thread-sealants/permatex-high-temperature-thread-sealant-detail
My CB750 head has holes all the way to spark plug compartments.

[flybox1]

Thread sealer high temp version. Like this:
http://www.permatex.com/products-2/product-categories/thread-compounds/thread-sealants/permatex-high-temperature-thread-sealant-detail
My CB750 head has holes all the way to spark plug compartments.

The cam tower stud holes are thru holes from Honda.
Always need to re-seal them if they are removed.

[700504]

Flybox1: I know where you're coming from, fresh rebuild on one of my motors and it was leaking like there was no tomorrow. I was crushed until I took the valve cover off and started checking everything; suspected the rubber pucks and yadadada, turned out I forgot to put thread sealer on the cam tower studs. doh, at least I didn't take the head off trying to chase a leak that was at the top of the top end.

[Davidov]

Thread sealer high temp version. Like this:
http://www.permatex.com/products-2/product-categories/thread-compounds/thread-sealants/permatex-high-temperature-thread-sealant-detail
My CB750 head has holes all the way to spark plug compartments.

I used the same product

http://forums.sohc4.net/index.php/topic,139737.msg1582180.html#msg1582180

Similar problem

[PeWe]

I had an oil leak dripping oil from front, between 1-2 somewhere. I had thoughts about the threads in head for valve cover. Some of them hole all the way thru the head. Maybe after drilling/threading deeper to fix the threads. I need to seal those this spring and fix the threads with timesert thread fix. (cam tower stud ends were dry)

I made a mistake to seal the head gasket (Cometic fiber 65.5mm) with copper spray. Fiber gasket should not have any additional sealer, the graphite should seal dry. The gasket before had no leaks or sealer. My local tuner that tuned CB750's in early 70's-80's (street,racers and drag racers), still in business tuning/reapairing engines said that NO sealer on these gaskets. My experience veryfy his words, I have never  before had such leak. I had thoughts about not flat head and cyl that were OK when checking them.