20 mile engine; is this a rod knock?

Sigurd

I hope you guys can help me diagnose an engine sound. First, the details:

1915cc
L5 heads (ported, 40 x 35)
Engle 120/1.25/solid shafts
Scat SLR NON-Lubealobe
8.7:1 CR
40 Dells
1.5" A1 Sidewinder
Full flow and deep sump - Brad Penn break-in 30W
AC.N SVDA w/ Computronix set to 32 total
All parts are new
Full tin, flaps and thermostat
I built it

I'm out in the garage yesterday trying to sync the carbs with the snail gauge. Linkage is disconnected on both sides. The engine is idling happily at about 1100 and responding to the changes I'm making on the throttle stop screws. I dial it down to about 800, but it stumbles, so I'm on the way up. It starts to run slower and slower as I dial it up, like it's starving for fuel. A quick blip on the throttles brings it back up. Then I hear it....knockknockknockknockknockknockknock...and then I shut it off. It was rhythmic and started soft and slowly got louder. After sitting about 5 minutes, I restarted it, it still knocked, and I shut it down right away.

Head temp was just over 250 on my compensated Aircraft Spruce gauge and I had about 20psi of oil pressure. Oil temp was just over 120, probably not even warmed up yet. This engine has about 20 miles on it which was a few trips around the block after I broke it in and a trip to the grocery store. I haven't dug into it yet, but I'm hoping a rocker shaft just came loose. Could I have thrown a rod or spun a bearing at 800 rpm? Was that too slow to push oil around? Shattered a lifter?

I'll be pulling the valve covers off tonight when I get home, but does this sound familiar to any of you?

Glenn · Posted: Thu Aug 13, 2009 8:41 am Post subject:

Try pulling a spark plug wire and see if the sound lessens. That should be the cylinder in question.

I hope it's something simple.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

Ellis' Bug · Posted: Thu Aug 13, 2009 8:55 am Post subject:

When that happened to me, it was a rocker coming apart. Quick fix but it sure makes you panic for a while.

sturgeongeneral · Posted: Thu Aug 13, 2009 9:06 am Post subject:

I hope it is a rocker shaft or something simple like that. I hate to hear stories of anything worse....
_________________
Street legal fiberglass rocket ship
2005 Lotus Elise supercharged
1974 Chevy Corvette
My fiberglass car collection!

In honor of bowtie56jw:Another victim of the nasty "C" Praying for ya Jeff!

My exwife said if I towed home one more bug she would leave me. You know, every once in a while I miss her

Sigurd · Posted: Thu Aug 13, 2009 10:22 am Post subject:

Yeah, especially because this thing has been heated up only about 5 times since I broke it in. Glenn, I thought that the plug wire test was only for electrical or fuel delivery problems. Do that work for mechanical things too?

Glenn · Posted: Thu Aug 13, 2009 11:03 am Post subject:

thetravman · Posted: Thu Aug 13, 2009 11:18 am Post subject:

That's interesting. My engine when it was on the first few times that I started it, the rockers on BOTH heads popped loose from the rocker blocks and they were tightened fine. I tightened them up and never had a problem again.
_________________
Have your car serviced at your local aircooled repair shop today.
/=O=\ good ole swing axles

Sigurd · Posted: Thu Aug 13, 2009 11:37 am Post subject:

Duhh. No fire, no pressure on the piston. Rolling Eyes

Thanks for the help. I hope it's something simple and non-destructive. Or at least quickly repairable.

a-train · Posted: Thu Aug 13, 2009 11:41 am Post subject:

could have sucked a washer or nut down one of the carbs.....it's happened to me before. just a thought.
_________________
I like VWs

Marv [UK] · Posted: Thu Aug 13, 2009 12:56 pm Post subject:

could potentially be a loose flywheel

nextgen · Posted: Thu Aug 13, 2009 1:23 pm Post subject:

Hey you are way ahead of the game. Last time I heard a noise like that a rod came out of my block and left me on a highway in 3 feet of snow. Miles from home. No cell phone.

But the time before that it was a rocker arm, ha!!!
_________________
email: [email protected]
The TYPE IV UPRIGHT CONVERSION MANUAL
BEETLE MAGNETIC DEFLECTOR SHIELDS
LETS TALK DUBS https://www.youtube.com/results?search_query=joe+cali+ghia https://letstalkdubs.libsyn.com/ep-200-joe-cali-ty...qI3xJTCzjs

Sigurd · Posted: Thu Aug 13, 2009 6:42 pm Post subject:

#3 intake is stuck open. Think

Looks like I'm pulling it tomorrow.

Image may have been reduced in size. Click image to view fullscreen.

Glenn · Posted: Thu Aug 13, 2009 6:46 pm Post subject:

69 Jim · Posted: Thu Aug 13, 2009 7:42 pm Post subject:

I wonder if you can see a foreign object in there via the intake port.

stealth67vw · Posted: Thu Aug 13, 2009 8:03 pm Post subject:

The Noof · Samba Member Joined: January 25, 2005 Posts: 4346

Jimmy111 · Posted: Thu Aug 13, 2009 8:48 pm Post subject:

Bent a valve..
Not good...

miniman82 · Posted: Thu Aug 13, 2009 9:01 pm Post subject:

Guessin' there was no clay involved in this build?
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747

kielbasa · Posted: Thu Aug 13, 2009 11:19 pm Post subject:

ouch that blows
_________________
Gotta give my props to:
Wolfsburg Motorsports
Dubbers Toy Box
Jeff's VW Speed and Fab
4inbore.com
Kielbasa Industries

thetravman · Posted: Fri Aug 14, 2009 12:58 am Post subject:


Hello! Log in or Register \| Help \| Donate \| Buy Shirts	See all banner ads \| Advertise on TheSamba.com

Forum Index -> Performance/Engines/Transmissions		Share:
		Print View

	Forum Index -> Performance/Engines/Transmissions	All times are Mountain Standard Time/Pacific Daylight Savings Time Page: 1, 2 Next
Page 1 of 2