Valve stem seals
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Tourer
Joined: Mar 2018
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From: BC
Valve stem seals
Question: My 1991 ultra runs SO well, has great compression [165/165], tons of oil pressure so I REALLY don't want to disturb anything .... but ... it uses oil. I would say a quart every 1500-2000 miles. Imo, pulling the heads means base gaskets, rings etc. The plugs don't oil foul and there does not appear to be any exhaust smoke. In the interests of leaving it alone is there any possibility of having valve seals replaced on the intake only without removing the heads? I would really like to try that.
Thanks, Frank.
Thanks, Frank.
I don't see how. How would you compress the springs, hold the valve in place, remove springs and install seal. Then reinstall every thing without taking the heads off?
At least you don't have to pull the jugs off
At least you don't have to pull the jugs off
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From: Pennsylvania
You can do it by applying air pressure to the cylinder through the spark plug hole like doing a compression check. The make fittings you can do it with. However, getting a valve spring compressor in there may be another story. You would need to be at TDC and have a constant air supply.
May be easier to pull the heads.
May be easier to pull the heads.
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Tourer
Joined: Mar 2018
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From: BC
Thanks for the replies. Replacing valve seals on an engine is a very common automotive practice using air pressure. Often the intake seal are the culprits due to that is where the suck happens. Exhaust is not so critical plus they can benefit from a bit of extra oil present. My question really is, can a valve spring compressor fit? And there may be other concerns that cold be answered by those who have done it ... if it's possible.
Last edited by 00 fxd; Sep 8, 2022 at 09:06 PM.
Road Master
Joined: Aug 2007
Posts: 942
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From: Grew up in Texas, moved to AZ
You can certainly do this job with the heads still on, if you get this tool kit. Nub Tools.
HARLEY-DAVIDSON OVERHEAD VALVE SPRING COMPRESSOR COMPLETE KIT - NUB TOOLS
HARLEY-DAVIDSON OVERHEAD VALVE SPRING COMPRESSOR COMPLETE KIT - NUB TOOLS
HDF Community Team
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From: NC USA
Intake guide bore wears out till they won't hold a seal long before the exhaust guides give out. Dead give-away is a sharp black line on the ceramic of the plug on the intake side. Mark your plugs before you pull them so you can index and you'll see what I mean.
I have the NUB tool and it works great. Having done a couple with wood blocks and prybars (monkey and football act) I'd never attempt again without that tool !
With the rockers off and all valves closed, don't try to keep pistons near TDC, waste of time. And it only takes about 60 psi to keep the valves seated. Just be sure to take the oil cap off so it can vent and when charging the front, you'll get air back up thru the drain besde the exhaust valve so don't freak out, that's just where the breather gear is closed when front piston is near BTC. When rear is near BTC, it's open and will exhaust into the cam chest and out the oil tank.
Use the James (viton) version of seals. They will seal even if the guide is worn when an OEM seal won't, plus you simply push them on with a 7/16, 12 point socket.
I have the NUB tool and it works great. Having done a couple with wood blocks and prybars (monkey and football act) I'd never attempt again without that tool !
With the rockers off and all valves closed, don't try to keep pistons near TDC, waste of time. And it only takes about 60 psi to keep the valves seated. Just be sure to take the oil cap off so it can vent and when charging the front, you'll get air back up thru the drain besde the exhaust valve so don't freak out, that's just where the breather gear is closed when front piston is near BTC. When rear is near BTC, it's open and will exhaust into the cam chest and out the oil tank.
Use the James (viton) version of seals. They will seal even if the guide is worn when an OEM seal won't, plus you simply push them on with a 7/16, 12 point socket.
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Tourer
Joined: Mar 2018
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From: BC
Daven, the NUB tool is the hint. Thanks.
Yeh, in my experience, as soon as the air pressure is introduced the/any piston goes straight to bdc, that's fine.
t150vej, Appreciate your experience and expertise on this, will do.
Changed plugs today, so had a look at them - no sharp lines, will keep in mind the marking procedure.
Still riding but looking forward to getting the 'cone off to replace/install an L grind [if theres some other cam in there, adjustable pushrods present] and new oem lifters and steel breather.
Will [like to] use non adj pushrods if I take the rocker covers off.
Now wondering if a compromised plastic breather could be causing the oil consumption because no oil fouling on plugs - maybe poor venting. Will see I guess.
Overthinking as usual :-) .......
Yeh, in my experience, as soon as the air pressure is introduced the/any piston goes straight to bdc, that's fine.
t150vej, Appreciate your experience and expertise on this, will do.
Changed plugs today, so had a look at them - no sharp lines, will keep in mind the marking procedure.
Still riding but looking forward to getting the 'cone off to replace/install an L grind [if theres some other cam in there, adjustable pushrods present] and new oem lifters and steel breather.
Will [like to] use non adj pushrods if I take the rocker covers off.
Now wondering if a compromised plastic breather could be causing the oil consumption because no oil fouling on plugs - maybe poor venting. Will see I guess.
Overthinking as usual :-) .......
Last edited by 00 fxd; Sep 9, 2022 at 12:57 AM.
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From: Poolville
How many miles? Also take a good look at the valves by removing the exhaust first. If your seals are leaking by you will see it on the valves.. If your motor was a top breather I would say a quart in 1500-2000 is not far off.. But it's a bottom breather and I'm not to familiar with bottom breathers and EPA, don't know if it's tied back into the intake or not..
Last edited by 98hotrodfatboy; Sep 9, 2022 at 06:34 AM.
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Tourer
Joined: May 2011
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From: Alberta
My evo uses a quart in about 2000 - 2300 miles, and I consider this pretty normal. Don't ask me where it goes, but plug colour is good, bike runs well, no smoke so I'm not too concerned. If it got down to a quart in a 1000, then I'd likely look at doing something. Engine has about 16000 miles on it.
I've started to let it idle for a minute or two before I shut it off as I've read about the scavenger pump needing to catch up after you come down from higher revs. Not sure if it even is an issue on these bike but easy to do and we'll see if it makes any difference.
I've started to let it idle for a minute or two before I shut it off as I've read about the scavenger pump needing to catch up after you come down from higher revs. Not sure if it even is an issue on these bike but easy to do and we'll see if it makes any difference.