For those gurus who have a good ear for impending disaster, please have a listen to this and let me know your thoughts!

Link to my noisy little engine

The engine was bought with a fairly untidy 71 Super/Baja project. We were told that the engine had been running, but had been stripped of its carby and electrics that went onto another project.

After it came home the heads were removed, inspected and cleaned up, along with the pots and pistons. All of that looked good apart from a stripped thread on a camshaft bolt. I didn't look any deeper, after all, the engine was fine, right?

After we got the engine running it developed an ominous "clack! clack! clack!" sound to it, building up gradually from an intermittent to a constant over about two to three minutes. I originally thought it was in the tinware (perhaps a rattly fan) it resonated so much. That cause was eliminated before we pulled the clutch out and tried again - same deal.

Has anyone heard this before? I understand that a shot crankshaft bearing gives a dull thud sound. The heads will come off next, and if they're ok I'll go deeper towards the core.

what have you set the valve gaps to?

I was just about to say, it's a tappet noise...

ow ow ow ow

Yeah, the video probably doesn't give the right kind of noise. It sounds a little more like hitting the fan housing with a ball pein hammer.

I haven't suspected tappets, not only because (to my ears) it doesn't sound like tappet noise, but because it started out really inconsistently.

For the record, they were set at .004", but after reading the Gregory's (probably should have done that before now) it appears that my procedure differs from what they recommend.

Maybe I'll check them again - I'm really at a loss and don't want to have to do a full pull down.

Hmmmmmmm.....

Checked clearances. They're all good.

I cranked it over again and winced at the noise once again.

"Ow, ow, ow" you say - yeah, I have to agree!

That does sound valve train (or t least top end) related in the video,
but either way you will have to start pulling down the engine till you find it....no washers fell into the ports?

How did you fix the stripped thread without getting shavings inside?

the tappets should be 0.006"

if you would like a set of engines that sound the same i'm the man ,mine had a rag in the fan really scrwed the little bliter

Busted wavy washer or clip letting a rocker arm have way too much sideplay perhaps ???

Other than that I'd be thinking something small bouncin around inside one of the combustion chambers.

Does it have an aftermarket chrome alt/generator stand? I had one once and it actually put the fan on a slightly odd angle and made it foul with the fan shroud.... try moving the generator when it is running. Just put a bit of downward pressure on it i mean. Also i think part of the problem there was the wrong fan fitted to the generator. dunno if it will help but it made a similar noise.

to eliminate the fan as a problem take the fan belt off. Start the engine, if the niose aint there anymore then you know it was the fan/generator. If its still there then its internal.

Cheers Brendan

Good point...

i've the same thing but not that loud when i start up its quite and in a couple of mins its tap tap tap and it turned out to worn valve guides. but with a sound like that i would be looking for dent in your rocker covers. are all the adjusting screws sticking out the same amount or is there one screw right out and as it opens a valve it hits the rocker cover.

good luck

Also, if it's something top end related it'll be louder on one side of the engine than the other... assuming it's only one top end that has problems of course.

Just watched the vid again, and at the end when the engine is shutdown the noise seems to stop before the engine's actually stopped spinning... weird...

Update:
Just had another REALLY good look and found one of the long studs (that hold the heads on) was not fully screwed in, and was fouling on the No. 4 exhaust rocker.
We had a eureka moment, screwed it home, replaced the valve rack, started the engine and....no change.
So:
We know it's not the fan (ran the engine with belt removed).
We know it's not tappets (checked, rechecked, readjusted, checked, rechecked).
We know it's not clutch/gearbox related (clutch is removed).
We know it's coming from the No 3/4 side (leaning towards 4).
We know our patience is wearing thin...
Tomorrow - 3/4/ head off for a look inside the pots.
Thanks for all your thoughts! We'll keep you posted!

the thread could be pulled out , check that stud again...

I say u may have dropped a tinware screw dwn the port nr 4 at some time during assembly and it is banging on the top of piston nr 4
(done it myself)
only once...nevva again!

what is the woodpecker eatin in that funny chrome cage around the fanbelt???

let him out! the noise will stop. lol

Are the pistons on the right way ie arrow to the flywheel,if they are back to front it will sound like a very noisy tappet. Try taking the plug leads off one at a time and this will also eliminate piston slap.(use chicken pliers when removing High tension leads with engine going)

Okay, so we've got the 3/4 head off. Checked it out - all looks okay. Cylinder walls all look good too.

So next we pull off No. 4 pot and give the piston a wriggle. There must have been 3 mm of movement between the conrod and crankshaft, so I imagine that somewhere in the sump are the remains of a big end bearing.

At this point we've decided to take it to a workshop for repair. All learning I guess, but I never imagined that a big end could be so loud.

G'day mate. I've been watching this thread - sorry to read about your grief...
That's a rod bearing all right! I imagined more of a clack than a click though!
Glad you found the prob, but sorry that it means at least a machined crank and reco rods...unless it did a lot of damage.
Good that everything else is good...smile :-)
Being a Vw it would have gotten you to your destination regardless....

Yeah it actually was a clack rather than a click The sound through the video camera didn't quite match it.

Thanks for your thoughts. It is actually kinda good to know what the problem is!

knowin the prob is half the ansa
fixing it and how to is the other 50%
cheers all.