Oil dripping between exaust valve guide and head.

DanT

DanT

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Jun 23, 2025
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The problem is that the hole where the exaust valve guide is insert has a thinny crak. Then the oil pass throught this crak and end in the exaust pipe and exaust seal.
My mecanic told me my cylinder head is scrap... The cannot weld alu in this hole. An other one told me to spread locktite green in the hole and insert the valve guide. My own idea was to use JB weld hi temp instead.
Please any other advice. That's only problem with this head. Valve seal seal very well. 135 psi compression.
 
The risk is that the guide comes loose. I don't think any Loctite will survive the heat in this location. The JB Weld would probably survive better. People use it in cylinder bores. I have a head damaged by an idiot machine shop pounding the guides in cold and I cured the smoking by putting high-heat silicone under the spring insulator washers. Thousands of miles and no problems. If the guide is not loose now, I wouldn't remove it to try to fix it.
 
DanT said:
The problem is that the hole where the exaust valve guide is insert has a thinny crak. Then the oil pass throught this crak and end in the exaust pipe and exaust seal.
My mecanic told me my cylinder head is scrap... The cannot weld alu in this hole. An other one told me to spread locktite green in the hole and insert the valve guide. My own idea was to use JB weld hi temp instead.
Please any other advice. That's only problem with this head. Valve seal seal very well. 135 psi compression.
Click to expand...
Take it apart, you might just need an oversize guide fitted by an Automachinist then cut the seat etc.
 
Back in 1982 a so call motorcycle head expert replaced my guides in my Commando head and after 2 weeks on the road I had the same problem you have took it to another head repairer where the guides were pulled out as there was a crack on each side of the front guides he was able to weld the cracks and replace the guides and sent the other so call expert the bill for the repairs, he admitted when he pushed them in cold, well the head was welded up and reported, I am still using this head to this day with the original valves and has well over 140k mile since this repair.
They can be welded so the head is not junk, in the 49+ years of ownership the guides have been replace 3 times, 2x when this so called expert stuffed it up and again about 20 years ago when doing some more work on my motor, I do all my own work on my motor since that major fu ck up, not all MC experts are experts with Norton's.
So your head can be saved, just finding the right person who does know what he is doing, I was lucky after this big stuff up in 82 I got a job working at a Tec College (TAFE) and was a T/A to the maintenance fitters as well the motorcycle section had 2 teachers one was a old school British bike owner/builder and the Kiwi teacher work as a Norton race team mechanic when he was in NZ and I had full access to all the machines and worked under a very good fitter who knew his stuff, I learned a lot while there for 31 years.
Get it fixed properly don't do a bodge job on it.

Ashley
 
ashman said:
Back in 1982 a so call motorcycle head expert replaced my guides in my Commando head and after 2 weeks on the road I had the same problem you have took it to another head repairer where the guides were pulled out as there was a crack on each side of the front guides he was able to weld the cracks and replace the guides and sent the other so call expert the bill for the repairs, he admitted when he pushed them in cold, well the head was welded up and reported, I am still using this head to this day with the original valves and has well over 140k mile since this repair.
They can be welded so the head is not junk, in the 49+ years of ownership the guides have been replace 3 times, 2x when this so called expert stuffed it up and again about 20 years ago when doing some more work on my motor, I do all my own work on my motor since that major fu ck up, not all MC experts are experts with Norton's.
So your head can be saved, just finding the right person who does know what he is doing, I was lucky after this big stuff up in 82 I got a job working at a Tec College (TAFE) and was a T/A to the maintenance fitters as well the motorcycle section had 2 teachers one was a old school British bike owner/builder and the Kiwi teacher work as a Norton race team mechanic when he was in NZ and I had full access to all the machines and worked under a very good fitter who knew his stuff, I learned a lot while there for 31 years.
Get it fixed properly don't do a bodge job on it.

Ashley
Click to expand...
OK thanks Ashley, I will consult a guy of high expertise in welding alu... I realise that we all have to consult a lot of people before finding the good one. I'll keep you inform in a couple of weeks.
 
hhh said:
The risk is that the guide comes loose. I don't think any Loctite will survive the heat in this location. The JB Weld would probably survive better. People use it in cylinder bores. I have a head damaged by an idiot machine shop pounding the guides in cold and I cured the smoking by putting high-heat silicone under the spring insulator washers. Thousands of miles and no problems. If the guide is not loose now, I wouldn't remove it to try to fix it.
Click to expand...
Its not so much about the guide coming lose (wouldn't help) but oil coming out of the cracks and dripping out into the exhaust rose as what was happening with mine on both guides on each side was dripping oil from the cracks, the guides have to come out, the cracks grinded open then welded, a bit of porting and new guides put in as my guides were still tight, pushing the guides in cold caused the damage.
 
ashman said:
Its not so much about the guide coming lose (wouldn't help) but oil coming out of the cracks and dripping out into the exhaust rose as what was happening with mine on both guides on each side was dripping oil from the cracks, the guides have to come out, the cracks grinded open then welded, a bit of porting and new guides put in as my guides were still tight, pushing the guides in cold caused the damage.
Click to expand...
Thanks to answer, this will help me. I heated the whole head at 200 f. And the guides was very easy to come off... too easy I guess.
 
DanT

You can purchase kibblewhite phosphor bronze guides +0.002 over from BCS.
shop.kpmi.us

Guide, C674, Intake, Norton®, 750, 1968-1973

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
shop.kpmi.us

Guide, C674, Exhaust, Norton®, 750, 1968-1973

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
Not sure if you stated your engine size 750 or 850
shop.kpmi.us

Guide, C674, Exhaust, Norton®, 850, 1973-1977

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
There Black Diamond Valves are top notch as well.
Good starting point!
Cheers,
P.S, welcome to the forum.:)
 
Last edited:
Heating the head and around where the guides go in make the guides come out easy as the metal expands and pushing the new guides in when hot, the cooling down the metal retracts should make the guides a tight fit same with putting new main bearing in the cases heat the cases the old bearings drop out and dropping the new bearings in straight away while still hot, heat is a fitters/mechanics best friend.
 
Laser welding is used in the UK by Norman Hyde to fix these cracks, before the head was usually scrap.

jseng1

Thread 'Cracked valve guide bore head repair - is it for real?'

LASER WELDING

Anyone else have any experience with this? Can it be done in the US?

"EMP in Havant Hampshire can laser weld inside a valve guide bore... an elongated and cracked valve guide bore was successfully welded and remachined."

http://www.e-m-p.biz/laser-welding/classic-cars/

If this really works it'd be a great way to save all those cracked heads.
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Oil dripping between exaust valve guide and head.
Oil dripping between exaust valve guide and head.
Oil dripping between exaust valve guide and head.
Oil dripping between exaust valve guide and head.
 
CanukNortonNut said:
DanT

You can purchase kibblewhite phosphor bronze guides +0.002 over from BCS.
shop.kpmi.us

Guide, C674, Intake, Norton®, 750, 1968-1973

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
shop.kpmi.us

Guide, C674, Exhaust, Norton®, 750, 1968-1973

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
Not sure if you stated your engine size 750 or 850
shop.kpmi.us

Guide, C674, Exhaust, Norton®, 850, 1973-1977

These Engine Builder valve guides have been designed with the price conscious builder in mind. Expect the same exacting KPMI® tolerances, but with a reduced toughness / wear-ability when compared to premium C630 Nickel Aluminum Bronze valve guides. The softer Manganese guides are easily reamed...
shop.kpmi.us shop.kpmi.us
There Black Diamond Valves are top notch as well.
Good starting point!
Cheers,
P.S, welcome to the forum.:)
Click to expand...
Thanks, I did't know there was over size for these guide.
 

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