Oil leak at the head?

zotz · Jan 30, 2017

I've had to deal with annoying leaks at the head gasket joint for years and haven't been able to get rid of it yet. One thing I do just to buy myself some time and control the weep without having to strip the head off is to take a bit of paper towel and fold it several times to give it some thickness and then force it between the fins at the head joint with a screwdriver. For sure not a fix, but it's invisible and it actually works quite well for me.

Mr. Rick · Jan 30, 2017

take a bit of paper towel and fold it several times to give it some thickness and then force it between the fins at the head joint

I used to do this, but I was wasting a lot of time folding the paper, so I now use those oversize firecrackers you can get from Idaho, perfect fit, no trimming or folding.
Storing the firecrackers was a problem; they'd get damp in the garage, so I discovered a warm dry space in the bottom chamber of my gas-fired water heater, and keep them there, near the pilot light.

click · Jan 31, 2017

Mr. Rick said:
take a bit of paper towel and fold it several times to give it some thickness and then force it between the fins at the head joint

I used to do this, but I was wasting a lot of time folding the paper, so I now use those oversize firecrackers you can get from Idaho, perfect fit, no trimming or folding.
Storing the firecrackers was a problem; they'd get damp in the garage, so I discovered a warm dry space in the bottom chamber of my gas-fired water heater, and keep them there, near the pilot light.

Where can I get these firecrackers, they sound like a 'really' good idea :mrgreen:

madass140 · Jan 31, 2017

well that was my laugh for today,, Click

Mr. Rick · Jan 31, 2017

Where can I get these firecrackers...

https://www.allsparkfireworks.com/produ ... W-BOX.html
We ship to all states except the following.
CA, DE, HI, MD, NJ, NV, NY, OR, RI, VT, and Washington D.C.
-Connecticut Customers may only order fountains, novelties, and accessories.
-We cannot ship to APO/FPO or P.O. Boxes.
-We do not ship outside the USA.

And, unfortunately, a $300 minimum for retail customers

It amazes me that you can buy this stuff. And as I understand it, it's illegal to actually use them in Idaho!
Sorry for the thread drift...

N0rt0nelectr@ · Feb 1, 2017

N0rt0nelectr@ said:
SteveA said:

N0rt0nelectr@ said:

Well I have found the problem. The stud hole had broken through the push rod tunnel on the right side. Now I have to figure out the best way to fix it.
I have an email in to Jim Comstock but I thought I would ask you too.
First I am going to pull the cylinders and remove the lifters so I don't drop anything on to the lifters and cam.
I'm thinking the best way to fix this is to put the stud back in with Locktite and then JB Weld the hole. Let it dry for a few days and then sand the JB Weld smooth. Anything you can see wrong with my plan?
Here is a picture of what I found. I shined a flashlight down the stud hole and you can see the 1/4" hole in the tunnel.

John in Texas

Click to expand...

John, I think it is common, which means I have one the same! I see the loctite on its own didn't work for you, but it might if you are scrupulous with the degreasing.

However, I did exactly what you proposed here, loctite on the threads, JB weld over the hole/exposed thread. It coped with 24 races in 2015!

It may have leaked a little towards the end, but that is with a copper head gasket that got nipped upa few times, and I admit I was more concerned about head gasket integrity than oil drips....racers eh!

Steve

Click to expand...

Well I found my own stupid mistake. I used the wrong grade of Loctite. I had a Loctite Quickstick 548 that a friend had given me and it is a non-hardening compound. I should have read the label a lot closer. Time to pull it down again and do it right this time.
John in Texas

I pulled the head off yesterday. Removed the stud and chased the threads with a tap and wire wheeled the stud. Picked up some high heat JB Weld and honest to god high heat Red Loctite. Stuffer a rag down the push rod tunnel and flushed the hole out with carb cleaner and used compressed air to dry out the hole The JB Weld comes in a stick which you cut off as much as you need and knead until it is the same color. Cut off a small amount and kneaded it into a pea size ball and dropped it into the stud hole then screwed the stud in. A bit of the JB Weld was forced out the hole which I removed and smoothed out the rest. The stud was easy to remove and I then applied the red Loctite and reinstalled the stud. It takes about 24 hours for the JB Weld to fully harden so later today I will put the head back on. I might use a heat gun to speed up the curing process but I have other things to do in the meantime.
Progress report to follow.
John in Texas

Fast Eddie · Feb 1, 2017

Finger crossed for you John!

texasSlick · Feb 1, 2017

Heat gun will cure Loctite in 20 minutes ..... FYI

I hope we get a good report, John.

Slick

Nater_Potater · Feb 1, 2017

No need to push the cure with heat if you have the time. I used Red Loctite on mine when performing its first top-end last year, and the studs have remained spotlessly dry since then (they did weep before).

btw, I'm only about fifteen minutes from the local fireworks stand, if you'd like me to pick up something for you...

Nathan

N0rt0nelectr@ · Feb 6, 2017

Nater_Potater said:
No need to push the cure with heat if you have the time. I used Red Loctite on mine when performing its first top-end last year, and the studs have remained spotlessly dry since then (they did weep before).

btw, I'm only about fifteen minutes from the local fireworks stand, if you'd like me to pick up something for you...

Nathan

Still got the leak, not as bad as before but it is still leaking. Damn!
OK, time to go nuclear and replace the cylinder. I have several that I have acquired over the years so I will check them all out, mic the bores and order up a set of pistons. I can only think that this is the reason the bike only has a bit over 3,000 mile on the clock. True, I'm not the first owner or even the second but the leaking issue is enough to drive a sane man crazy, fortunately I'm not sane.
Maybe it's gods way of telling me I have to much money and time on my hands (neither of which is true).
There must be a porosity problem with the cylinders. One way or another I will solve this problem!

John in Texas

lazyeye6 · Feb 6, 2017

Had the same leak from the same spot. Apparently it is quite common that when boring and tapping the bolt hole in the barrels, the hole
just barely opens up into the pushrod tunnel. Aside from the normal procedures to insure the head gasket seals the oil drain hole and the
pushrod tunnels, I gooped the bolt hole and the threads with high temp RTV. That turned a bad weep into a
VERY tiny weep. Then I installed Jim Comstock's sump reed breather which stopped all engine oil leakage immediately(valve adjustment cover gaskets, points cavity oil seal, primary crank oil seal, crank cases porosity, and of course that annoying head bolt leak)!

N0rt0nelectr@ · Feb 6, 2017

lazyeye6 said:
Had the same leak from the same spot. Apparently it is quite common that when boring and tapping the bolt hole in the barrels, the hole
just barely opens up into the pushrod tunnel. Aside from the normal procedures to insure the head gasket seals the oil drain hole and the
pushrod tunnels, I gooped the bolt hole and the threads with high temp RTV. That turned a bad weep into a
VERY tiny weep. Then I installed Jim Comstock's sump reed breather which stopped all engine oil leakage immediately(valve adjustment cover gaskets, points cavity oil seal, primary crank oil seal, crank cases porosity, and of course that annoying head bolt leak)!

I am planning on getting one in the near future.
John in Texans

Holland Norton Works · Feb 7, 2017

John, you might be looking at the wrong spot possibly the 5/16" stud/thread is not the problem but the cylinder head: the Commando 850 head is prone to crack in the front between the third and fourth fin (right behind the two front 5/16” nuts at the bottom of the recess). This crack is often caused by over tightening the two front 5/16” nuts (they need only 20 pounds instead of 30 pounds for all the other head fasteners). The problem is that there is little aluminium material from the pushrod tunnel to the recess for the 5/16” nuts.This crack is quite common and for that reason I made a special pressure tool to test 850 heads for that specific crack. This crack is hard to cure (if not impossible) I even tried to cure this crack by grinding off all involved front fins, welding the crack, welding back the fins however it lasted only a short period before the crack turned up again. But if anyone does find a cure for this crack I'd really appreciate to learn as I still have about half a dozen of these cracked 850 heads in my workshop. Btw I never experienced this crack in a 750 head.

Good luck,

Constant Trossèl
http://www.hollandnortonworks.eu

texasSlick · Feb 7, 2017

Holland Norton Works said:
John, you might be looking at the wrong spot possibly the 5/16" stud/thread is not the problem but the cylinder head: the Commando 850 head is prone to crack in the front between the third and fourth fin (right behind the two front 5/16” nuts at the bottom of the recess). This crack is often caused by over tightening the two front 5/16” nuts (they need only 20 pounds instead of 30 pounds for all the other head fasteners). The problem is that there is little aluminium material from the pushrod tunnel to the recess for the 5/16” nuts.This crack is quite common and for that reason I made a special pressure tool to test 850 heads for that specific crack. This crack is hard to cure (if not impossible) I even tried to cure this crack by grinding off all involved front fins, welding the crack, welding back the fins however it lasted only a short period before the crack turned up again. But if anyone does find a cure for this crack I'd really appreciate to learn as I still have about half a dozen of these cracked 850 heads in my workshop. Btw I never experienced this crack in a 750 head.

Good luck,

Constant Trossèl
http://www.hollandnortonworks.eu

A trick to stop the propagation of a crack, such as you describe is:

Drill a small hole (about 1 mm ) at each end of the crack, as deep as necessary or possible. Then weld.

It may not always work, but it is worth the try.

Slick

Holland Norton Works · Feb 7, 2017

texasSlick said:
Holland Norton Works said:

John, you might be looking at the wrong spot possibly the 5/16" stud/thread is not the problem but the cylinder head: the Commando 850 head is prone to crack in the front between the third and fourth fin (right behind the two front 5/16” nuts at the bottom of the recess). This crack is often caused by over tightening the two front 5/16” nuts (they need only 20 pounds instead of 30 pounds for all the other head fasteners). The problem is that there is little aluminium material from the pushrod tunnel to the recess for the 5/16” nuts.This crack is quite common and for that reason I made a special pressure tool to test 850 heads for that specific crack. This crack is hard to cure (if not impossible) I even tried to cure this crack by grinding off all involved front fins, welding the crack, welding back the fins however it lasted only a short period before the crack turned up again. But if anyone does find a cure for this crack I'd really appreciate to learn as I still have about half a dozen of these cracked 850 heads in my workshop. Btw I never experienced this crack in a 750 head.

Good luck,

Constant Trossèl
http://www.hollandnortonworks.eu

Click to expand...

A trick to stop the propagation of a crack, such as you describe is:

Drill a small hole (about 1 mm ) at each end of the crack, as deep as necessary or possible. Then weld.

It may not always work, but it is worth the try.

Slick

Slick, I didn't only drill a small hole at each end of the crack but grinded away the complete cracked area to be sure! The problem is the thin wall between the recess for the 5/16" nut and the pushrod tunnel. Extra problem is that the welded spot is always under stress from tension of the tightened 5/16" nuts in combination with alternating expansion and shrinkage due to heating and cooling.

Thanks,

Constant Trossèl
www.hollandnortonworks.eu

N0rt0nelectr@ · Feb 8, 2017

I wonder if there is an easy way to determine if there is a crack in the head? It is still off so checking shouldn't be that hard or so I hope. Is there something I should look for?
John in Texas

Holland Norton Works · Feb 8, 2017

N0rt0nelectr@ said:
I wonder if there is an easy way to determine if there is a crack in the head? It is still off so checking shouldn't be that hard or so I hope. Is there something I should look for?
John in Texas

John, you can send your head to HNW (I will only charge you shipping costs) or you can make your own pressure test 'tool' which is rather easy to do. Basically you need to block all air holes with rubber gaskets and a valve cover with an air valve (see picture below). Tighten the head to the barrel using only the two front 5/16" nuts and the 3/8" rear nut until the rubber pad is squashed air tight. Now pressurize the head to 5 bar and pour soapy water into the two front 5/16" recess holes of the head. If your head is cracked you will see air bubbles appear in the recess if not you can consider yourself a lucky man!

Constant Trossèl
www.hollandnortonworks.eu

Nater_Potater · Feb 8, 2017

With aluminum, a number of companies make dye penetrant leak checkers. You can get the general idea by watching https://www.youtube.com/watch?v=UtJTkrgvt2c which is pretty standard fare for that style of leak detection. Prices range wildly, but I think they all work pretty well. Check reviews before shelling out your cash. Expensive doesn't necessarily mean better.

Nathan

N0rt0nelectr@ · Feb 10, 2017

I got yet another new copper gasket coated it with Copper Coat spray and gave it one more try.
Started it yesterday and no leak! Hot damn, for the first time in weeks I feel like I'm not fighting a loosing battle.

Thank you all for your insight and support. Now I need to fix the wall where I have been beating my head against it, just kidding.

John in Texas

Towner · Feb 10, 2017

Holland Norton Works said:
John, you might be looking at the wrong spot possibly the 5/16" stud/thread is not the problem but the cylinder head: the Commando 850 head is prone to crack in the front between the third and fourth fin (right behind the two front 5/16” nuts at the bottom of the recess). This crack is often caused by over tightening the two front 5/16” nuts (they need only 20 pounds instead of 30 pounds for all the other head fasteners). The problem is that there is little aluminium material from the pushrod tunnel to the recess for the 5/16” nuts.This crack is quite common and for that reason I made a special pressure tool to test 850 heads for that specific crack. This crack is hard to cure (if not impossible) I even tried to cure this crack by grinding off all involved front fins, welding the crack, welding back the fins however it lasted only a short period before the crack turned up again. But if anyone does find a cure for this crack I'd really appreciate to learn as I still have about half a dozen of these cracked 850 heads in my workshop. Btw I never experienced this crack in a 750 head.

Good luck,

Constant Trossèl
http://www.hollandnortonworks.eu

Constant,

do you think that nearly all of the leaks at this nuts are caused by these cracks ? I had the problem at mine too and in the end I cured it by the XS 650 valve. A good solution and much cheaper than a new head.

Regars,
Ralf

Oil leak at the head?

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