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Lars S
Samba Member
Joined: October 04, 2007
Posts: 786
Location: Sweden
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 Posted: Sat Sep 24, 2011 11:37 am Post subject: 1,7 engine cam wear? |
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Took the cam out of my spare engine and found this type of groove at the top of both of the two middle lobes (but not at the outer ones).The engine has some 150.000 km on it. The lifters looks wery fine.
Is this from wear or what ?
Should I dump this cam?
/Lars S
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raygreenwood
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Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Sep 25, 2011 8:44 am Post subject: |
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Sorry...I menat to answer you yesterday. The cam is shot. You need a new one with mathcing lifters.
This wear pattern is a normal characteristic ofmoderate to high milage stock cams. The hardening has worn through from the edge of the lifters rotating on them. It cannot readily be repaired by regrinding. Ray |
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Lars S
Samba Member
Joined: October 04, 2007
Posts: 786
Location: Sweden
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| Posted: Sun Sep 25, 2011 8:51 am Post subject: |
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Thanks Ray!
Didn't know this was a weak point at the T4 engines.
Is there a reason to why the intake lobes/lifters should wear out faster than the exhaust ones (which do not show any wear signs)?
(By the way the intake lifters do NOT look fine they are all dished).
/Lars S
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Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Sun Sep 25, 2011 11:42 am Post subject: |
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| I believe its the amount of offset contact that the intake lobes have as compared to exhaust. Ray |
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Wildthings
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Joined: March 13, 2005
Posts: 50351
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| Posted: Tue Sep 27, 2011 4:03 am Post subject: |
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This can happen to all the lopes, not just the center ones. No big deal, just normal high mileage wear. I don't think the funny wear on the cam hurts much, but the accompanying wear on the lifters is a negative. Since the lifters are no longer convex, or even flat, but concave you are loosing lift and really can't adjust the lash properly anymore.
With the engine apart I would just replace the cam and lifters, but if it were still together regrinding of the lifters would return some of your lost power, give a quieter engine, and perhaps give years of additional service life. |
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raygreenwood
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Joined: November 24, 2008
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Location: Oklahoma City
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| Posted: Tue Sep 27, 2011 11:07 am Post subject: |
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| Wildthings wrote: |
This can happen to all the lopes, not just the center ones. No big deal, just normal high mileage wear. I don't think the funny wear on the cam hurts much, but the accompanying wear on the lifters is a negative. Since the lifters are no longer convex, or even flat, but concave you are loosing lift and really can't adjust the lash properly anymore.
With the engine apart I would just replace the cam and lifters, but if it were still together regrinding of the lifters would return some of your lost power, give a quieter engine, and perhaps give years of additional service life. |
I agree....but I do know from expereince that putting in new lifters on an dimpled but clean cam will rstore quieter operation, but will greatly accelerate after that point...the wear of the cam...as a large part of the hardening at tge surface is gone and now you have fresh lifters running on it. Typically you can expect about another 20-30k miles with a lot of valve adjusting....before its time to pull the whole mess out. Ray |
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Tram
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Joined: May 02, 2003
Posts: 22728
Location: Still Feelin' the Bern- Once you've felt it you can't un- feel it.
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| Posted: Tue Sep 27, 2011 2:59 pm Post subject: |
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| raygreenwood wrote: |
| Wildthings wrote: |
This can happen to all the lopes, not just the center ones. No big deal, just normal high mileage wear. I don't think the funny wear on the cam hurts much, but the accompanying wear on the lifters is a negative. Since the lifters are no longer convex, or even flat, but concave you are loosing lift and really can't adjust the lash properly anymore.
With the engine apart I would just replace the cam and lifters, but if it were still together regrinding of the lifters would return some of your lost power, give a quieter engine, and perhaps give years of additional service life. |
I agree....but I do know from expereince that putting in new lifters on an dimpled but clean cam will rstore quieter operation, but will greatly accelerate after that point...the wear of the cam...as a large part of the hardening at tge surface is gone and now you have fresh lifters running on it. Typically you can expect about another 20-30k miles with a lot of valve adjusting....before its time to pull the whole mess out. Ray |
Yeah, I agree. the wear on the cam indicates that it needs to go, and lifters too. Regrinding the lifters might be an OK temporary fix, but seeing as the cam is already out of the case, it's foolish not replacing it.
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