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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> very slight scaring on exhaust rocker arm. why? /cgi-bin/YaBB.pl?num=1241808378 Message started by DocNeedles on 05/08/09 at 11:46:18 |
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Title: very slight scaring on exhaust rocker arm. why? Post by DocNeedles on 05/08/09 at 11:46:18 I have a slight scaring on the exhaust rocker arm surface. Initially I thought it was just discolouration but it is slightly etched. A friend suggested putting the bike together minus the head cover and start it running to ensure that oil is circulating properly. I don't feel I want to replace the rocker arm now, doesn't seem to be any wear on the cam as far as I can see, and maybe save this for the winter project. Could it be since I have had a head oil leak that not enough oil was getting there, and hopefully will be fixed when I retorque the head? Feedback appreciated. DocNeedles |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by Yonuh Adisi on 05/08/09 at 11:59:15 The problem with that is the head cover is where the rocker arms are attached. You can't run the engine even for tests without the head cover. |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by marshall13 on 05/08/09 at 12:26:48 are you sure its etching, and not just a buildup of fried oil residue? that exhaust rocker is going to be pretty hot in running conditions... edit: just noticed you live in BC... way humid spot... the vent hose could be drawing atmospheric moisture into your head... between that, the acids produced in the combustion process, and the high heat of the part, you have a pretty good answer... if you have the cover off still, pull the rocker and inspect its wear surfaces... pivot, contact face with cam, tip of the adjuster screws.... see any galling, scarring, peening, etc? if not, i'd be willing to bet dollars against donuts that the oil flow is fine... lack of lube will show as worn out wear surfaces, not a general surface corrosion... dont know if you're the first owner of the bike or not... could a PO have used a caustic to clean the rocker at some point, and have done a lousy job of rinsing? |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by Oldfeller on 05/08/09 at 17:49:29 You folks need to do some research using search. What he describes is well understood and it will happen to every person who uses plain 10w40 current modern car oils in their Savage. You have plain tappets (your rocker arms) and they require ZDDP additives to keep from spauling or gauling. This has been known to the elder members here for years but seems to require re-discovery each year by each new crop of new members. You need to type ZDDP or ZDP or zinc phosphorus into your search engine and also on the list search function and then review the oil war information that search digs up. Recommendation - use Shell Rotella T oil (dino or synthetic) to get what you need at an affordable price. Happy oil war to you all ..... Oldfeller |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by Phelonius on 05/09/09 at 09:32:36 I am puzzled. How do you frighten rocker arms? Phelonius |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by PTRider on 05/09/09 at 10:55:25 I think-- Spauling means Spalling, "Spall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ball bearing). Spalling and spallation both describe the process of surface failure in which spall is shed." Gauling means Galling, "Galling, according to ASTM standard G40 (2006), is: “a form of surface damage arising between sliding solids, distinguished by microscopic, usually localized, roughening and creation of protrusions (i.e., lumps) above the original surface”. In other words galling is material transfer from one metallic surface to another caused by movement and plastic deformation. Galling usually refers to adhesive wear and transfer of material between metallic surfaces." Frighten might mean Fretting, "Fretting refers to wear and sometimes corrosion damage at the asperities of contact surfaces. This damage is induced under load and in the presence of repeated relative surface motion, as induced for example by vibration." All definitions from Wikipedia. I'm say the wear is probably galling, but in any case, Oldfeller might have the answer. No, don't add a ZDDP additive to oil. Buy better oil. The latest gasoline engine oil standard, ILSAC GF-4 has the phosphorus reduced to a max of 0.8% to reduce phosphorus poisoning of the catalytic converter. Diesel engine oil can have up to 1.2% phosphorus, which comes from the zinc dialkyldithiophosphate or related antiwear compounds he mentions. (The upcoming spec, GF-5, will retain the 0.8% P, but further reduce P getting to the catcon by requiring reduced volatility of the oil.) ZDDP is a very effective anti wear and antioxidation agent, and very cheap. Other chemicals work as well but cost more for the blender to put into the oil. As Oldfeller says, use a dual-rated diesel & gasoline engine oil or a motorcycle oil. Shell's Rotella-T line, either conventional or synthetic is perfectly OK and nothing special. Among conventional 15W-40 oils, Conoco/Phillips/76/Kendall's new diesel/gasoline engine oil with their "Liquid Titanium" is the best of the bunch currently. The standard engine tests for valve train wear show less wear with this oil and actual deposition of titanium on parts. Nothing will rebuild the worn parts, but better oil might slow additional wear. In any case, if you don't want to replace the parts, I'd hand-stone any high rough areas smooth very carefully with a very fine sharpening stone, clean all the grit away thoroughly, then keep running the engine with more robust oil than a 10W-40. |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by marshall13 on 05/09/09 at 12:44:36 ok, explain to me how galling, spalling, or fretting will effect the non-contact surfaces of a part.... if the entire part appears "etched", i have a hard time grasping how that could be the effect of chemically inadequate lub.... and if so, why would it only happen to the exhaust rocker, and not the intake, nor leave any evidence on the cam lobe? |
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Title: Re: very slight scaring on exhaust rocker arm. why Post by DocNeedles on 05/09/09 at 15:22:05 6E5859425F76535E445E370 wrote:
Of course!! Of course!!! my Moma didn't raise no dummie!! I would have figured that out the 2nd. or 3rd. time I tried pushing the starter button!! Thanks for pointing that out. DocNeedles |
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