Oil leak at exhaust port?

RoadScholar

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Bad news!!! Less than 100 miles and looks like a cracked guide or guide hole!!! Wet oil in exhaust track and you can see the green oil all around the guide!! Thanks all ...time to make a phone call

And no exhaust smoking?

Best
 

baz

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Bad news!!! Less than 100 miles and looks like a cracked guide or guide hole!!! Wet oil in exhaust track and you can see the green oil all around the guide!! Thanks all ...time to make a phone call
That's a sure sign of a loose valve guide
Unfortunately that's also a sure sign of amateurs
Anyone can change a valve guide but it needs to be done properly!
I wouldn't use that shop again if I were you
Sorry
 
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And no exhaust smoking?

Best
Mine had cracks around the exhaust guides and oil leaking into the exhaust port, the bike didn't smoke and no oil on the plugs just oil from the exhaust flange that was 2 weeks after being back on the road from the rebuild back in the early 80s.
 

concours

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Yes new guides were put in along with new valves/springs etc. no porting though.
You need to ask if the head was heated during the guide replacement procedure. Watch for the blank stare as you ask. It may only last for a split second, or maybe more.
 
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To repair you need the cracks laser welded, Norman White uses these guys but best you go through Norman to finish off the job with properly fitted exhaust guides.


The issue with guide removal and reinsertion knowledge being lost is best avoided by lining the old guides so they are undisturbed.
 
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The issue with guide removal and reinsertion knowledge being lost is best avoided by lining the old guides so they are undisturbed.
good on an 850 but not so much on a 750 as IMHO and that of comstock the 750 guides become to thin and are prone to breaking
 

RoadScholar

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Mine had cracks around the exhaust guides and oil leaking into the exhaust port, the bike didn't smoke and no oil on the plugs just oil from the exhaust flange that was 2 weeks after being back on the road from the rebuild back in the early 80s

I still don't understand how oil leaking into the exhaust port wouldn't produce visible smoking from the silencers, but you and the OP have both provided "testimony" supporting this. I also don't understand why the OP's leak, expressed on the exhaust nut, didn't start a fire.

Years ago I made arrangements to have Leo Goff freshen up a Mk3 head. I told him that I had the Norton valve guide tool and that I would save him some time and punch out the guides. Absolutely not he said, we machine them out and measure/machine the new guides for the factory specified fit, for each hole.

Thanks for the correction to you and the OP.

Best.
 
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Well I talked to the builder...he said that he would like me to run the bike for a couple more weeks and periodically check the exhaust port. He said that they would correct any issues if it was done by them. He went on to tell me that some of those heads are very pourus and maybe when pressing in the guide it aggravated a possible anomaly? They did heat the head when putting in the guides...his Machinist is local to him and specializes in Brit bikes.

I’m not going to name because I respect the business and “NOT “saying any negative remarks since they have been honest and helpful.

I’m going to run it and see what happens.

and yes....seriously no smoke on start up? Plugs are clean and pipes has grayish exhaust soot in it.
 

concours

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" They did heat the head when putting in the guides..."

Did they heat it before removing the old ones?
 
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I still don't understand how oil leaking into the exhaust port wouldn't produce visible smoking from the silencers, but you and the OP have both provided "testimony" supporting this. I also don't understand why the OP's leak, expressed on the exhaust nut, didn't start a fire.

Years ago I made arrangements to have Leo Goff freshen up a Mk3 head. I told him that I had the Norton valve guide tool and that I would save him some time and punch out the guides. Absolutely not he said, we machine them out and measure/machine the new guides for the factory specified fit, for each hole.

Thanks for the correction to you and the OP.

Best.
The oil didn't piss out it was more just a slight leak from both cracks and took its time to show from the exhaust flanges but after two weeks it started to pool at the flanges, at first thought its was a blown head gasket but after cleaning and following the leak it was from the exhaust ports then removing the exhaust and headers and a close inspection I could see the oil and small cracks, the way the oil traveled through the valve it didn't pool in the area or near the spark plug and reason no smoke or oil on plugs, who knows, maybe riding it longer it might have but the head came off and sent to another head rebuilder who knew his stuff after showing the damage to the original rebuilder and he admitted he stuffed up and he told me it was his first Norton head.

Ashley
 

baz

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Well I talked to the builder...he said that he would like me to run the bike for a couple more weeks and periodically check the exhaust port. He said that they would correct any issues if it was done by them. He went on to tell me that some of those heads are very pourus and maybe when pressing in the guide it aggravated a possible anomaly? They did heat the head when putting in the guides...his Machinist is local to him and specializes in Brit bikes.

I’m not going to name because I respect the business and “NOT “saying any negative remarks since they have been honest and helpful.

I’m going to run it and see what happens.

and yes....seriously no smoke on start up? Plugs are clean and pipes has grayish exhaust soot in it.
I'm wondering why he wants you to run it for another couple of weeks? If it's a loose guide it'll make matters worse
If it's porosity it will have always done it from new
If it cracked it's been cracked by someone
I'm guessing it's a loose guide
I did once have a problem with some 750 guides they were wider at the bottom than the top where they fitted in the head
So although they went in tight they were letting oil seep down
I took the guides back to the dealer and went through a box of guides with my micrometer to find 4 parrelel machined guides
I always check them before fitting nowadays
 
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I’m just going try his advice and see what happens? If it’s bad it’s bad. I won’t run it hard just a few miles here and there and see what happens and give him the feedback....sh-t it only has about 75 miles since rebuild.
If anyone want a to PM me their phone number, I can send my pics and you can upload for me?
 
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My 2 cents worth. I went through almost the same thing. Re did the head, same problem. Sent in head again and nothing wrong. It turned out after 2500 miles the rings never seated.
 
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how long they have been doing it don't mean they know how to do it right. I did 2 engines a year ago and used a machine that has been in business since the late 40s and both valve jobs was pure crap.
 
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