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fl59bug
Samba Member
Joined: November 23, 2005
Posts: 1976
Location: North Carolina
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 Posted: Mon Apr 06, 2020 9:11 am Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| Are all the pushrods straight, none of them bent? You can roll them on a flat surface to double check. |
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Who.Me? 
Samba Member
Joined: July 14, 2014
Posts: 2206
Location: UK (South)
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| Posted: Mon Apr 06, 2020 1:08 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| sjbartnik wrote: |
Your sound reminds me of what my engine was doing before teardown:
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Hmm. It does sound worryingly similar.
| sjbartnik wrote: |
When I pulled the engine apart the camshaft gear had CRAZY backlash with the crank timing gear - it wasn't even all the way around (due to tight spot or bent-ness) but at the worst part of the cam gear I measured it at .017"!!!
The engine ran fine but sounded like a diesel - kind of a deep rattly sound from inside the case due presumably to the cam gear slapping around in there.
I think you're in for a teardown to see what's going on - maybe you have a main bearing not seated properly or something is bent.
How many places around the circumference of the cam gear did you check backlash? |
I checked it in four places. I got three 0.01mm results and one 0.03mm. It ran smoothly when I used the rods to turn the crank. There was barely any play and it didn't jump out of the bearings.
| fl59bug wrote: |
| Are all the pushrods straight, none of them bent? You can roll them on a flat surface to double check. |
They weren't bent when they went in. I'll check them again though.
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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GARRICK.CLARK
Samba Member
Joined: June 30, 2012
Posts: 1267
Location: Lancashire UK
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| Posted: Mon Apr 06, 2020 2:37 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| Cam thrust bearing doesn't look right |
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Clatter
Samba Member
Joined: September 24, 2003
Posts: 7537
Location: Santa Cruz
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| Posted: Mon Apr 06, 2020 6:23 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| andy198712 wrote: |
| dizzy drive installed now yh?with dizzy in place? |
^^^That's my call^^^
Do NOT ever turn the motor over with the distributor drive in place with no distributor.
Especially Especially with no flywheel..
-Never- have the distributor drive in without a flywheel on, even if you don't turn it over.
If that soft brass helical distributor drive gear gets dinged at all (much less mangled) it will forever make your timing scatter-y, and beat the shit out of your distributor, opening up the end-play.
I'd be pulling the thing apart just to inspect the brass gear.
If it doesn't have oil in it yet,
it's a no brainer.
Good luck!
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Bus Motor Build
What’s That Noise?!? |
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Who.Me?
Samba Member
Joined: July 14, 2014
Posts: 2206
Location: UK (South)
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| Posted: Tue Apr 07, 2020 10:15 am Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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Well, I'm pretty certain that I now know what the problem is - it seems to be the cam backlash.
This is the first engine that I've built. I think my technique must have been off and the cam and crank weren't seated in the right position forward or back in the case when I measured the lash.
I just pulled the pump body out completely and, reaching through the hole, I can rock the cam back and forth about 1mm and there's a distinct 'clack'.  
I'm guessing that torqueing the gland nut has pulled the crank in to position and the lash is much higher than it was when I measured it.
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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Who.Me?
Samba Member
Joined: July 14, 2014
Posts: 2206
Location: UK (South)
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| Posted: Thu Jun 18, 2020 12:19 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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Just finished reassembling the engine with a NOS +3 camshaft, but it turns out that the cause of the noise wasn't cam lash.
Turning the engine over by hand, the noise reappeared when I bolted down the rocker assemblies. Took me ages to spot the problem. This slo-mo video shows it pretty clearly though. If you can't see it at first, watch the video full screen in YouTube...
Link
I'd backed the valve adjusters right back so they were inside the rocker arms during assembly. The lash cap snagged in the adjuster hole on this valve before snapping loose, causing the knock. When I set the valve lash, the lash cap couldn't snag anymore and the noise went away.
I'm glad I stripped the engine down though, even though the cam wasn't the problem. I had screwed up the cam backlash measurement. It was huge.
I bought some scrap cams with different sized gears and worked out that I needed one with a +3 gear.
Comparing the Kuhltech cam I'd fitted to the scrap cams, I reckon its gear was roughly -2 !
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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raydog
Samba Member
Joined: February 09, 2006
Posts: 1163
Location: Cape Cod
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| Posted: Thu Jun 18, 2020 1:27 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| So you didn't set you side clearance between your rockers? |
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9462
Location: NOVA
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| Posted: Thu Jun 18, 2020 9:57 pm Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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Oh for fucks sakes - your tips are not even on the valve stems. So the hollow is on the tip of the valves and it is not tracking properly. See the video and see where the rocker slams on the side of the rocker stands.
Use a lighter spring so you can observe its entirety. If you have to back off that much on the adjusters tells me your pushrods are too damn long!
get you an adjustable pushrod to check. |
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Who.Me?
Samba Member
Joined: July 14, 2014
Posts: 2206
Location: UK (South)
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| Posted: Fri Jun 19, 2020 12:44 am Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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They're standard rocker arms, not solid ones. There isn't any side to side adjustment. They just have the standard spring washers.
I checked the rocker geometry and the wipe marks of the actual adjusters on the lash caps seems OK, although that was on #2 and #4 exhaust.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9290501#9290501
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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RWK
Samba Member
Joined: June 24, 2009
Posts: 1348
Location: S.W. MI
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| Posted: Fri Jun 19, 2020 5:42 am Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| Clatter wrote: |
| andy198712 wrote: |
| dizzy drive installed now yh?with dizzy in place? |
^^^That's my call^^^
Do NOT ever turn the motor over with the distributor drive in place with no distributor.
Especially Especially with no flywheel..
-Never- have the distributor drive in without a flywheel on, even if you don't turn it over.
If that soft brass helical distributor drive gear gets dinged at all (much less mangled) it will forever make your timing scatter-y, and beat the shit out of your distributor, opening up the end-play.
I'd be pulling the thing apart just to inspect the brass gear.
If it doesn't have oil in it yet,
it's a no brainer.
Good luck! |
What Clatter said,found this T4 engine literally in the woods,over 30 years ago, it would only turn over about a 1/4 turn, no flywheel or dist. in it, figured it was junk, got it apart and found ground up dist drive gear, all else was perfect less some rust dist. gear was stuck part way up its hole due to corrosion,binding crank
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Who.Me?
Samba Member
Joined: July 14, 2014
Posts: 2206
Location: UK (South)
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| Posted: Fri Jun 19, 2020 6:30 am Post subject: Re: Double knock turning newly rebuilt engine over by hand |
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| RWK wrote: |
| Clatter wrote: |
| andy198712 wrote: |
| dizzy drive installed now yh?with dizzy in place? |
^^^That's my call^^^
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What Clatter said, |
The distributor drive gear was fine.
It was that rocker arm snagging on the edge of the lash cap when the adjuster was wound out so far that it left a socket.
Stock rocker assemblies fitted in new EMPI 1600 dual port heads. The assemblies were built with new shafts and the best OG VW rocker arms, shims and washers that I had from a couple of sets that I had, and new adjusters.
Geometry checked during assembly https://www.thesamba.com/vw/forum/viewtopic.php?p=9290501#9290501
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Andy
Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786 |
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