Oil Stain under Scottish exhaust rocker cover
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Autor Thema: Oil Stain under Scottish exhaust rocker cover  (Gelesen 992 mal)

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Norrie

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Oil Stain under Scottish exhaust rocker cover
« am: 21 Juni 2017, 23:39:57 »

Fellow Einzlinder Enthusiasts
I am very happy to see that all at Edersee had a great time and I look forward to joining you one year soon.  :bike:
My 1955 R25/3 is now on the road and thanks to all on this site for encouragement and material help - it has been much appreciated.
I have now done nearly 200 miles and on the overrun or closing throttle the engine does not sound as you would expect with a banging sound not apparent under power. I wondered if it is a partially sticking exhaust valve being closed abruptly. I had trouble with the inlet valve which seized before the guide clearance was opened up a fraction. The engineering company who did the work thought the exhaust guide clearance was fine. The exhaust pipe seal to the head is good so it is not a backfire.
On to the point of this post. As you can see from the photos an oil stain is being produced directly above the hollow exhaust valve tappet adjuster on the underside of the cover. I have completely rebuilt the engine and was as careful as possible to clean out all oil ways including the holes through the pushrods. I left a solvent soaking in the hidden oil ways in the head and blew through with compressed air several times. Oil is getting up to the rockers, which were also dismantled and cleaned, with more oil appearing at the inlet than the exhaust. The exhaust tappet clearance has opened up both times I have checked since I have had the machine running.
Where is this oil stain coming from? I don't think it is from the same feed as to the rockers. It is likely coming up through the cam follower, through the hollow push rod and tappet clearance adjuster. But everything was cleaned out throughly before assembly and I don't like to think I have missed something vital. I had hoped it would clear after I had run the engine for a while.
Your thoughts would be welcome.
Best wishes :respekt:
Norrie       
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Oil Stain under Scottish exhaust rocker cover
« am: 21 Juni 2017, 23:39:57 »

Taz

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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #1 am: 22 Juni 2017, 10:45:44 »

Hello Norrie.

First of all...congratulations for bringing the bike back to its usual habitat :applaus:

As to the banging sound I have no idea, to be perfectly honest...do you own  (or can you lay hands on) a GoPro or a similar camera that might be able to record that?

Re. the cover: I have to admit that I have never checked the inside of my rocker covers for that kind of oil stains. Did I get it right...although the rockers get their oil the inside of the covers is clean as shown with the only exception being that stain that looks as if oil has been blown against it? As the rocker area is directly connected to the crankshaft housing it might be that the cover gasket wasn't all tight and allowed the pressure of the crankshaft housing to be released that way, maybe cleaning the push rod on the way....if the engine doesn't produce strange sounds from that area I would clean the cover, allow myself another test run (for scientific purposes only, of course) and see whether the stain is a permanent phenomenon or a one-time-event...and...how much did the exhaust tapped clearance open up...dramatically or just a wee bit?

All the best, Ute
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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #2 am: 22 Juni 2017, 11:10:25 »

Hi Norrie

Yes Edersee was very enjoyable and I could not have wished for a better welcome.
As Ute has suggested a recording of the noise would be helpful but could it be unburnt fuel detonating in the exhaust?

The stain looks very dirty and could be old residue freeing it's self from the internals of the engine and is not a long term problem, it certainly does not look like engine oil that has only done 200 miles.

Brian

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rolf

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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #3 am: 22 Juni 2017, 12:44:32 »

Oil stain? I think it will be oily rust...perhaps fom the rockers
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Karl

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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #4 am: 08 Januar 2019, 10:05:57 »

Hi folks

Norrie asked me to place his update here. He has some problems with attaching the images ... (pictures will follow soon)

Karl




Fellow Einzlinder Enthusiasts
Following on from the above I now believe, with fellow forum members suggestions, that the staining on the underside of the exhaust rocker cover was caused by old oil in the pushrod which I failed to clean out properly despite using solvent, a piece of wire and compressed air. As mentioned the exhaust tappet clearance was opening up significantly so I removed the head and noticed that the lower end of the push rod was breaking down and starting to collapse. I couldn’t see any debris lying on the cam follower so replaced both push rods and optimistically, as I wanted to use the machine during the beautiful 2018 summer, carried on riding :bike:.
 
Having covered approximately 1500 miles on the completed machine and feeling that all was not quite right inside the engine e.g. there were some interesting noises under load, compression was low and the oil consumption was spectacularly bad. I was never happy with the re bore I’d had done and planned on replacing the piston and barrel with parts from Germany curtesy of Taz’s courier service when she and Marie were over last August – thank you both very much.
 
On removing the barrel I discovered that I should have been far more critical in my earlier assessment and investigated further :kopfhau:.
 
Photo 1 shows the original push rod breaking up and not having removed the barrel previously meant I was unaware of the damage being done to the cam follower, presumably caused by bits of push rod (photo 2). Fitting a nice new push rod against an unnoticed, at the time, worn cam follower (photo 3) and valve adjusting screw means that the push rod takes on the shape of the worn components and wears prematurely.
 
The top piston ring was stuck in its grove and the middle piston ring was in six bits explaining the low compression and high oil consumption. 
 
The sump and oil pump have been removed, dismantled, cleaned, checked and with a new cam follower, pushrods and valve adjusting screws ordered. Once reassembled with the ‘new’ barrel and piston I am looking forward once again to flying along the road in glorious sunshine (hopefully) :schrauber:.
 
The moral of the story, for other apprentice Einzlinders like myself, is to critically check absolutely everything as some 50-60 year old components, especially if they have been lying around for years and if from an unknown source, may no longer be suitable for use.

Best wishes  :respekt:
Norrie
« Letzte Änderung: 08 Januar 2019, 10:08:17 von Karl »
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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #5 am: 08 Januar 2019, 20:49:50 »





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Morag

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Re: Oil Stain under Scottish exhaust rocker cover
« Antwort #6 am: 09 Januar 2019, 12:45:45 »

Failtè Norrie.

Thanks for sharing your findings with us. It really seems pretty dangerous to take anything for granted even if the first glance doesn't reveal any issues.

Your conclusion should be etched into every work bench surface so sloppiness doesn't get any chance.

Good luck with rebuilding the engine, Morag
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