New Engine Knock

[PeacesVW]

I know I may be opening up myself for abuse but here goes,

Because of time restraints, lack of confidence, knowledge and tools I decided to go with a prebuilt engine. From the builder: All our Turn Key Engines are Pre-set, cam break in, and run for a minimum of 1 hour before leaving our build shop.

The video below shows my first start after cranking the engine, without fuel, for a time to build up enough oil pressure to turn off and keep off the oil warning light. Could my light revs have doomed my engine? What does this sound like to you?

https://youtu.be/wMVkDfUVAm4
The knock comes at the end of the video.

1914cc
AMS break in oil within normal level.
New 94 case
New internals, some German.

I've got a message in with the builder.

Thanks for your advice. [/url]

[mikedjames]

If you are to believe the builder, anything loose in their build should have shown up in the burn-in run that they did.

Did you count all the nuts and washers when you put the carburettors and manifolds on the engine? Are your carburettors still intact ?

I dont think that noise has anything to do with your initial treatment of the engine.

Perhaps a small loose foreign object was dislodged and fell down into a cylinder as you revved the engine.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[PeacesVW]

I did make double and triple sure all nuts were accounted for. In the video my wife was joking about finding a missing nut I also took the standard caution of putting new and clean rags into the open ports as a deterrent to unnoticed debris falling in the engine. But you do bring up a good point - something related to the build theoretically should of shown up when they ran it.

But now, of course, my paranoia is going to force me to quadruple check nuts and sockets.

I was also concerned this sounded like a rod or rocker arm. I hadn't opened it up yet. Quite frankly I was so defeated and it was late I just needed to walk away from the whole car before I released my frustration upon it.

Thanks for the suggestion.

[modok]

The rattle seems to be quite fast, maybe 2x rpm so it's probably a loose fan or loose pulley.


It could be a loose flywheel or broken crank, but if the engine hasn't been under load yet then I can't see how that could happen.

[bsairhead]

Pull the belt first. That is the easiest and and can narrow down a lot of things.

[mukluk]

First thing I'd do is pop the valve covers off and have a look at the rocker assemblies.
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[RandyV]

[jbbugs]

Possibly just a loose valve adjuster jam but.
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[PeacesVW]

Thanks for the ideas. It's nice to have people who know aircooled engines, whose advice has weight. I've had a lot of keyboard mechanics, unfamiliar with VW, offering abuse or incorrect information elsewhere.

Unfortunately I haven't had time to tear into it yet, wife and kids keeping me busy. I'm getting into it sometime this week.

I do appreciate your opinions, hopefully I won't find something catastrophic. Waiting to hear from builder.

[nsracing]

Sounds valvetrain - lifters, rockers, pushrods.

if the shop ran it for 1 hour, then this should have been heard. Pop the rocker covers and see what is going on. But-there are clatter sounds coming from somewhere.

What cam and rockers are in there?

And the motor should not take that long to run. Seems to me your timing is off too.

AFter a squirt of fuel in there should fire within a second of turning. But not all engines are built the same. You get what you pay for.

[Dusty1]

It sounds like shit just cranking. You shouldn't have to crank it that long to get it started.

.
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[PeacesVW]

The motor cranked so long because the fuel lines were completely dry when I started cranking. New tanks, new lines, I had just put a gallon of fuel in the tank and the engine hadn't been run yet. The engine was starving, It took that long for the fuel to reach the pump and the carbs. The stance of the car wasn't helping either as I lowered the front and raised the rear for that 70s muscle car look.

I spoke to the builder, first thing to eliminate was the fan as builder and bsairhead suggested. Not the problem. That's as far as I got because I only had a half hour to dabble with it (kids, man). Next suggestion is to eliminate the possibility of any errant bolts. I've done that but a second look won't hurt. Next, valve covers come off and check valve assemblies.

Asking for opinions here, one thing several people have noticed is that the engine's idle doesn't seem to change when the noise starts. If it were valve problems shouldn't I expect backfires or misses? Someone here may have a better ear than me and hear a change in the engine's sound, let me know if you do or if I'm wrong in my assumptions.

Another thing I noticed is it doesn't make the noise when the engine is turning only by the starter. Not sure if that's relevant.

There is one thing that I hadn't considered to be related to the noise, and that's my throwout bearing. Being a 70, the throw out bearing is held on with those two small clips. Now, after I installed the engine but before I ran it, during a test of the clutch the cable snapped and caused the broken part of the cable to shoot as if from a gun and the clutch arm and forks slapped back into the bellhousing hard. I've got to check it no matter what, but what are the odds that we're hearing that bearing bouncing around in the bellhousing?

I'll keep you guys posted with what I find, it may be a few days. Meanwhile I'll keep checking this post to see what other suggestions arise.

Thanks again, I appreciate this community.

[raygreenwood]

I think you have something ...bolt..nut...rock..rattling around in the bell housing or down under the pulley. Ray

[modok]

If your throw out bearing fell off it could make a noise like that, maybe...but I'm not totally sure. Sounds plausible.

So ... The clutch cable is broke, but you started it up anyway just to see it run....is that right?

So you don't know if it fell off or not?

[PeacesVW]

modok, yes that is correct. The cable broke a few weeks ago and the possibility that it could've fallen off hadn't occurred to me until having to consider all possible causes for the noise. Now that the idea had come to me, as late as it is, I have no choice but check, no other option.

I admit I ain't always the swiftest.

While the engine is out, I'll take the time to inspect the valve trains and try eliminate any possibility of debris in the cylinders and that should rule out all possibilities of the noise coming from the top end. Then, back to the builders.

[bsairhead]

[bsairhead]

I guess I missed that last part.

[nsracing]

If it is not lifter/s, or cam lobe, could be a rod bearing going...is my guess. Maybe someone forgot a circlip? It happens.

At any rate, all that clatter is not gonna go away. I will just take it apart before she throws an arm thru the roof. It is only labor - fix it now or fix it later. Later is much worse.

[PeacesVW]

Alright guys. (And girls?)

During disassembly I've noted the following:

1 The original fuel line is worse that I thought, even though I thought I cleaned wel enougj it with compressed air, it still allowed rust into the fuel, I need a new line and filter.
2 My left lower mounting nut was loose.
3 My throttle cable tube, see video.

https://youtu.be/2xcGatuQybQ

My valve train appears ordinary and tight. Nothing unusual with my pushrods. Running my finger along the inside of my head I found around 10 metallic flakes, the size of dust particles but I imagine that's normal.

I'm going to continue to give the engine more scrutiny but I think I may have already found my problem. What do you think?

[67rustavenger]

Well that's a first!
Since you have the engine out. Keep checking, just to make sure that the throttle tube, really is making that awful racket.

Link

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