Cylinder Head Still Leaking

Last week I took a high RPM ride and on my way back found dripping oil while sitting at a stoplight. When I pulled into the garage it was dribbling consistently. There was no indications to this. The bike had no leaks until this ride.
The leaking clearly started during the ride.

3rd fin up at the front of the cyl. head
Not a little bit of dripping but a slow but continuous flow.
The higher the RPM's the more increase in flow.

Pulled the head to replace the head gasket and after an inspection (and not finding any outstanding issue except a hack in the HG next to the push rod opening) I installed the new HG.

After cleaning and preparing both head and cylinder faces I dropped the head back on with new HG.
Torqued new head gasket to 10lb.s and let it sit overnight. Torqued it spec the next day, let it sit overnight.
Checked the torque settings the next day and they were accurate.

Started the engine to get it hot for another round of torque setting after cool down.

In the first 90 seconds of startup oil begins to leak from the exact same spot.

I took some pics with my endoscope before pulling the head yet again trying to spot something obvious.

Below are 2 pics of the center bolt...the manual refers to it as #1.
Appears to be the leak source as the two head bolts on either side closest to it are dry.





The area below that is circled grabbed my attention...a casting flaw? Or something worse, like the bolt bottomed out or pulled through its anchor base.
There was a small amount of fine particulate/grit that I vacuumed out of the hole below. You can see what looks like a mild buildup of some sort of crap around the outside edges. Maybe a build up to something letting go?




The shots below are looking back into the CH on the 3rd fin up where the oil is flowing out. The head bolt and washer can be seen on the other side of the hole. Is that a casting flaw as well?
Maybe the source of the grit I encountered?






I am going to pull the damn head again and crawl inside of it as I should have the first time.
Once I get the head off and on the bench I will offer up some better photos...if I find anything.

The engine was really running well and this oil leak was sudden. All was clean and dry and just as quickly it the leak appeared.
It leads me to the belief that something other than a head gasket let go. I have read through the threads on this issue and its not valve covers or banjo bolts and I have a PCV valve integrated into the oil system.

Wide open to any observations.
Thanks.

I gather that you installed the cNw ARP head fastening kit; did you have the three bores in the head where the 3/8 studs live helicoiled?

Did you check that the head's gasket surface was flat? Barrel?

Is the head's oil drain clear, are the rocker spindle oil holes pointing in the correct direction?

You mentioned that you took a high RPM ride. Did you work the engine up to this or did you just go-for-it? I'm wondering if an uneven heat spike stressed/cracked some part of the head. The cNw head fastening kit comes with slightly higher torque specs, are these the ones you used?

Interesting to hear from the real experts on this.

Best.

I gather that you installed the cNw ARP head fastening kit; did you have the three bores in the head where the 3/8 studs live helicoiled?

Yes on the helicoil. (Maybe a helicoil gave out or has galled?)

I went with Matts ARP fastener package as I am a big believer in ARP products having used them in some other automobile engine rebuilds. I took the head to a local mcyl shop and he reworked it for me, he being an old timer and one time Norton dealer. All seals were renewed, valves reseated and tolerances were within spec.

Is the head's oil drain clear, are the rocker spindle oil holes pointing in the correct direction?

When I dropped the head off I mentioned the rocker spindle oil holes and he gave me his patented "look" so he was way ahead of me.
The oil drain hole...I did not check it. If I were to get really lucky could that be the source of a sudden oil flow leaving the head?
Great thought.

You mentioned that you took a high RPM ride. Did you work the engine up to this or did you just go-for-it? I'm wondering if an uneven heat spike stressed/cracked some part of the head. The cNw head fastening kit comes with slightly higher torque specs, are these the ones you used?

I never get after it after initial startup. I was taught not to take an engine over 2K until the temp gauge moves. I still practice this today. My neighborhood is full of little kids, dogs, bicyclists and moms who would chop me down in a heartbeat if they viewed me as exceeding 20mph. Plenty of warm up at lower RPM's.

I took all the torque specs 5 ft. pds. over per position.

As I mentioned this was a really sudden occurrence. I had a bit over 200 miles of shakedown after recently finishing the restoration and was starting to believe I had dumped all the bugs that always pop up after a rebuild. There was zero indication that any leakage might be in play.
Can I access the oil drain hole through the rocker box?

Thanks much RS.

I had found on my bike I was having oil leaks like you. What I did was have the head stud threads fixed with inserts cuz they pulled and the head surfaced.
On the barrel, I removed the studs and dragged a flat file across the top as the holes around the three studs were raised ever-so-slightly but enough to see metal was removed.
Then on the composite gasket I smeared sparingly RTV around the tunnels and drain on both side of the gasket. Letting the RTV dry.
No leaks. I did retorque it about 5 times though.

If you are using an automotive type PCV valve that is probably the cause of the leak.

If the breather system is not working it does not matter how well sealed the head is. It will leak.

Looks like something might be showing through the casting there?

oil drip between cylinder fins

Take a look at this thread .

Vidar

That would be this thread

https://www.accessnorton.com/NortonCommando/oil-drip-between-cylinder-fins.25124/

+1 on checking the plane of the cylinder to head surface. What's the condition of the cylinders and piston tops? Indication of excessive oil?

Head oil drain is located in the intake rocker box, partially obscured by the springs, you can check if the path is clear with a little compressed air into the drain outlet located in the timing chest. Based on your description of the flow increasing with RPM, banjo bolt leak is a likely culprit. Check that first before tearing the head off again, and if you do remove it, use some copper wire around the pushrod tunnels and oil return holes.

Good direction/ideas you guys and I thank you all.

I left the head on the engine and started tracing down the oil trail more closely. One observation that was consistently mentioned by members here and in previous threads was a leaking banjo off the upper end oil lines connecting to the head.

I broke out a small HMI (light) I hung on to from years passed and my endoscope. With big light and little camera I traced the bread crumb trail of oil back to the banjo bolt. Hard to see but it was there. I also notice there was a tiny accumulation of oil in the spark plug hole and more oil at the base of the fins on the right side. I had thoroughly cleaned the area before installing the new HG and trying to warm the engine.
That fresh oil is almost impossible to see under normal lighting but a heavy blue Kelvin temp. allows for color variations to be seen not usually visible under normal light.
Like the yellowish tint of fresh oil.

I had emailed Jim Comstock the evening before asking about head overhaul etc. and after speaking with him the next morning I headed back out with some new ideas. Jim suggested that a clogged breather may be the culprit, causing crankcase pressure to build thus causing the oil to look for a way to escape.
I have a Mikes XS breather incorporated into the circulation system. Pulling the hose connection from the crankcase I blew some compressed air into the line and heard a mild but definite "pop".
I could then clearly hear the air passing out of the oil tank breather and found some "spoo" floating on top of the oil in the tank.

I resealed the banjos and re-torqued the head to run a heat cycle.

Dry. No leak. Stayed dry too. YEEHAA!!!

Thanks again for the guidance fellas and a shout out to James Comstock for sharing his time and insight.

Guido said:

"Letting the RTV dry."

Click to expand...

That is the secret to using RTV. many people don't, and it all just squeezes back out (inside and outside the engine).

Let RTV dry before installation? Never

But then I only use it occasionally on car engines -but never on a bike motor.

I put the new composite HG in dry. I called Victor Reinz and had an interesting talk with a product rep. He told me if installed correctly, even with rough facing surfaces the gasket will do its job.

I just logged 40 miles, not a drop on the garage floor after sitting for 3 hours.

3rd gear on a Norton will set you free.

I fit composite head gaskets dry, I try to ensure the faces a scrupulously clean and follow an OCD re-torque procedure until it crushes down fully. I’ve not had one leak at all.

Can you direct me to the OCD re-torque procedure please I would like to read it, thanks.

I know what OCD is but probably not the same definition you seek...help me out...

I read up guidance on here from folk who know what they’re talking about, but I can’t find it now. Here’s my PITA / OCD procedure after starting rebuilt engine for first time. I’m not saying you should do it, but it’s what I did:

1. After first start up and run, without riding.
2. After first ride, or 50 miles
3. After 100 miles
4. After 250 miles
5. After 500 miles
6. After 750 miles
7. After 1000 miles

This is with a composite gasket, using standard torque settings. I was amazed how the gasket crushed and fasteners needed tightening. It made me realise how easy it would be to blow a gasket in this period of time.

I then learnt a tip to over torque by 5lbs for the initial tightening, this greatly reduced the crushing and subsequent ‘loosening’ of the fasteners. Although I should say that the head stud threads have UNC inserts by Comnoz. I could probably have skipped 3,4 and 6 with this method.

On the last build I used a copper gasket, and the over torqueing, and I used all waisted bolts and studs. There was very little crush evident at all this time. I could definitely have skipped 3,4 and 6 and even probably even 7 with this method.

For clarity, tightening should always be on a cold engine.

Another tip I got was to set the tappets a little slack on the initial build, you then don’t have to re-evaluate adjust them every time during the first few times.

Composite gaskets were always fitted dry, and with scrupulously clean faces. I never had any issues.

The copper gasket was fitted with contact cement and copper wire around the pushrod tunnels as advocated by Jim Schmidt. This is a very fiddly job IMHO. So far it has been fine, but I haven’t got that many miles on it yet.

I’ll also take this opportunity to recommend the ARP 12 point heads faster kit sold by cNw, this means you can bin all the dodgy box spanners and planks of wood and just use nice sockets without fuss or drama!

Keep repeating the hot re-torque until nothing moves.

I’ve read this several times on here, but have to ask. What is logic behind loosening first ? I don’t really get that.

comnoz said:

Let RTV dry before installation? Never

But then I only use it occasionally on car engines -but never on a bike motor.

Click to expand...

I can think of one specific gasket application for which I use it on certain car engines (per manufacturer instructions) and never anywhere else...except bathtubs!