Porous cylinder head

Clean all the old oil off (I find brushing it off with white spirit best because it leaves no residue). Warm the head with a hot air blower and then brush all round the suspect area with locktite 290. It is a penetrating locktite and is also used for sealing porous castings. Because the air flow moves the oil around in some strange ways don't rule out the usual place for porositywhich is thepush rod tubes at the front of the head.

It worked for me and was recommended to me by 2 highly respected NortonINOA members, both excellentengineers in the USA (Jim Comstock and Alan Goldwater) both of whom hadprevious successes with it.

Quite a lot of Dommie heads leak through the casting near the oil return from the inlet rocker area. I have even seen a head where the metal has completely fragmented, in this region, between the fins and left a most unwelcome hole.

JB Weld was used ,in this case ,to plug the hole but the patch was a bit unsightly. However, it did the trick. A good degreasing before application is vital.

Plan B which worked on another head, that was porous, was the use of Araldite smeared over the metal after the area had been heated. The heat seemed to thin the glue which then diappeared into the pores of the metal. Afterwards, the head was left for 24 hours for the glue to harden.

Result!!!

I had the same problem with an 850 Commando, after building it from boxes of bits, & spending a small fortune, oil literally poured from the head & would be dripping off the front of the head after about 10 miles, there was no way the bike could have been used like this, oil would blow back down the sides of the bike & all over my legs, but I really didnât want to have to tear it all apart again without getting at least a few miles on it. I looked at all the options I could find, but they all meant removing the head to do a half reasonable job. Clutching at straws, I decided to incorporate a mod I had installed on my roadster years ago, & added a breather outlet to the inlet rocker cover, teeâd into the original breather going to the oil tank. My hope was that it would stem the flow a bit so I could at least get some miles under itâs wheels, then pull it apart over the winter & sort it properly. To my surprise, the leak dried to the point where I just had a weep that dried off as quickly as it escaped, so all I had was a bit of staining. That was four years & about 5000 miles ago, & Iâm still running it like that. It seems to have sealed itâs self completely now, as I have washed the stains off & they havenât returned. Simply releasing the pressure from the head stopped it forcing the oil out & I guess carbon deposits or similar have now plugged the porosity. Iâm not going to remove the breather mod to find out, but I sometimes wonder if it would be ok now without it.

Regards, Tim

I have contemplated using the dishwasher for this (the mechanical one not me) but haven't mustered up the courage to try it yet. I reckon the detergent will degrease and the heat will dry the casting nicely. Life expectancy (mine) afterwards is another matter though.

Previously david_evans wrote:

I have contemplated using the dishwasher for this (the mechanical one not me) but haven't mustered up the courage to try it yet. I reckon the detergent will degrease and the heat will dry the casting nicely. Life expectancy (mine) afterwards is another matter though.

I cleaned a barrel and head in the dishwasher a few months ago. It stunk, and I had to run another three cycles using a whole bottle of rinse aid before it was back to normal. Thank heavens my wife works nights...

best thing for cleaning cylinder heads is a mild acid like Rhubarb deuce and to find cracks or porous metal use engineers blue. its can be thinned down with white spirit , and you can use engineers blue to see if the cylinder head is warped and its as its uses when fitting valves and lapping in valves that if any of you know what engineers blue is, your anna j

Anna, I have a suspicion that most people on the forum know what engineer's blue is, in much the same way as most people know what a Manxman is. Incidentally, many if not most dentists use engineer's blue to check bite clearances when a tooth has been filled or capped.

P.S. Don't use caustic soda to clean your cylinder head. An aquaintance of mine did (as a lad) and found he was left with valve guides and valve seat inserts the next morning. 'Twas only a Tiger Cub but even so...

Anna, I have a suspicion that most people on the forum know what engineer's blue is, in much the same way as most people know what a Manxman is. Incidentally, many if not most dentists use engineer's blue to check bite clearances when a tooth has been filled or capped.

P.S. Don't use caustic soda to clean your cylinder head. An acquaintance of mine did (as a lad) and found he was left with valve guides and valve seat inserts the next morning. 'Twas only a Tiger Cub but even so...

anna j

Of course we all know whatengineer's blue is. It's the colour my fingers go when working outside on a Norton in cold winter weather.

It's also the colour that the air goes when engineers skin their knuckles or find a bit on the floor that should be inside a rebuilt motor.

It's also probably the correct name for the colour used on the first Manxman Nortons.

I bet there are lots of other variations around. Suggestions welcome?

Varicose vein blue?

Another thing to watch out for when using the dishwasher for cleaning parts is that most of them use salt in the cleaning process which (certainly in ours) turns some aluminium parts black; and they look far worse when they come out to when they went in.

Of course we all know whatengineer's blue is. It's the colour my fingers go when working outside on a Norton in cold winter weather.

It's also the colour that the air goes when engineers skin their knuckles or find a bit on the floor that should be inside a rebuilt motor.

It's also probably the correct name for the colour used on the first Manxman Nortons.

I bet there are lots of other variations around. Suggestions welcome?

Norton Manxmans are in Metallic pacific Blue , and engineers blue is not a metallic and its a darker blue , dose your hands Phil go metallic in the cold weather, I will not even think about working in the cold, with engineers blue thinned down and run round inside the cylinder head you find where you have a porous patch then you can clean things up a treat it,