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Join Date: Dec 2008
Posts: 164
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What happens if you have worn out valve guides but new stem seals?
My winter project was (is) to change the valve stem seals as the engine was using a more than normal quantity of oil and I supposed (rightly) that these seals had never be changed before. I also wanted to get an idea of what has to be done in the next future to this engine.
When changing the seals, I noticed that some valves had some free play that indicates some worn guides. As the money is not there for the moment, I changed my seals as foreseen and am now reassembling the whole engine. I was just wondering what this will mean for my engine? I suppose that the oil consumption will be gone (more or less), the new seals sealing of the space between the guides and the valves even if the valves move a little bit inside the guides. Is this correct or not? What else to expect? |
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Friend of Warren
Join Date: Oct 2000
Location: Lincoln, NE
Posts: 16,484
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What happens when a valve guide gets loose and you lose heat transfer:
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Kurt V No more Porsches, but a revolving number of motorcycles. |
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Join Date: May 2004
Location: Lake Cle Elum - Eastern WA.
Posts: 8,417
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I think one of Bruce Andersons books say what Kurt told you: You lose the ability to transfer heat from the valve to the head. Worst case, head of valve breaks off and does major damage to the engine. If you can feel the play, it's pretty excessive. Measure with a dial indicator.....With the labor involved, I'd do it right the first time?
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Bob S. 73.5 911T 1969 911T Coo' pay (one owner) 1960 Mercedes 190SL 1962 XKE Roadster (sold) - 13 motorcycles |
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Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,427
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guides tend to wear more at the valve head end. so if there is slop at the spring end, there will be even more at the other end. valve stems wear also. they get tapered consideraby.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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Probably worth saving the money to just have it done. Dont want a $1500 top end to become a $5500 top end when you destroy a couple pistons/heads...
where you located?
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83 SC Targa -- 3.2SS, GT2-108 Dougherty Cams, 9.5:1 JE Pistons, Supertec Studs, PMO ITB's, MS2 EFI, SSI's, Recurved Dizzy, MSD, Backdated Dansk Sport Stainless 2 in 1 out, Elephant Polybronze, Turbo Tie Rods, Bilstein HD's, Hollow 21-27 TBs, Optima Redtop 34R, Griffiths-ZIMS AC, Seine Shifter, Elephant Racing Oil Cooling. |
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Registered
Join Date: May 2008
Posts: 723
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Oil consumption can be from a few places and if excessive you should see it on the plugs. I understand turbo seals go bad and start to suck oil. If you still have the springs of the valves see how much they move side to side.
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Registered
Join Date: Dec 2008
Posts: 164
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You're scaring me guys !
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Join Date: Jul 2008
Location: Spokane WA
Posts: 585
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Don't want to rain on your parade here but I changed my valve guide seals on my 3.2 in an attempt to defer replacing guides for a couple years. The result, in my opinion, was not worth the effort.
I replaced my seals with the engine in the car and only removed the valve springs and keepers. If you already have the heads off I would DEFINITELY do a valve job before reassembly. The money you "save" by not doing the valve job now is not worth the labor involved in doing the job over again. When all was done on my job, I was out only the price of the seals and the three specialized tools needed to remove the springs and seals. So..........$200 and two days later...........oil consumption went from 1qt/600 mi. to 1qt/800 mi. Just take your time and do it right is my advice.........sorry! |
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Grappler
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Is this correct or not? What else to expect?[/QUOTE]
Life ceases to exist as we know it..... Sorry I couldnt resist. ![]() Seriously though, I just did a top end rebuild on my 3.2 so I know what your going through. Its too big of a job to not do correctly the first time. If there is side play then more than likely the guides need to be changed and valves checked as they could be worn as well.
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Grappler Know Gi / No Gi 1976 RSR Backdate (Turbo 3.2) |
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Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
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If this is a Turbo motor, I would park it until you can do the job properly otherwise it has the potential to get FAR more expensive.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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Registered
Join Date: Dec 2008
Posts: 164
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I've listened to all the advice and decided to change the guides and valves and do everything properly. Thanks.
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