chirping noise

[chitwnvw]

So my cries of hallelujah became muted this afternoon, when after a year plus, the Troutmobile roared to life. A year ago, the number 3 cylinder showed 0 psi compression and prompted me to remove it and send it to a machinist. While looking at the dirty engine compartment, piece after piece of tin and any thing else in the engine compartment was removed, cleaned and painted. On assembly there were a few missteps, but finally this afternoon, he roared to life...only to be accompanied by this tinny chirping sound that can be heard here:

http://youtu.be/GsiFok9PVYoff

I can't hear it when just cranking the starter, it only can be heard when running, and if I pull the spark plug wire to number 3 it also goes silent.

[Amskeptic]

So my cries of hallelujah became muted this afternoon, when after a year plus, the Troutmobile roared to life. A year ago, the number 3 cylinder showed 0 psi compression and prompted me to remove it and send it to a machinist. While looking at the dirty engine compartment, piece after piece of tin and any thing else in the engine compartment was removed, cleaned and painted. On assembly there were a few missteps, but finally this afternoon, he roared to life...only to be accompanied by this tinny chirping sound that can be heard here:

http://youtu.be/GsiFok9PVYoff

I can't hear it when just cranking the starter, it only can be heard when running, and if I pull the spark plug wire to number 3 it also goes silent.

That might be the famous nasty head leak chirp if it is an air sound versus a twittering piece of sheetmetal:
Loose (or defective new) spark plug,
Possible leak at exhaust manifold, but usually exhaust will be noisier when you goose the throttle,
Damaged head sealing surface or out-of-position sealing ring if you used one

It may go away if you let the engine warm up. If it does, drive it. Let the engine get warm. You are hoping that surfaces may settle in.
If it is as bad the next morning when cold, head comes off.
Colin

[chitwnvw]

No luck getting things to settle in, it was as chirpy warm as it was cold, maybe even more so. The engine dies when I pull the spark plug wire to 1 or 2 with no change if I pull number 4 wire, which leads me to believe 1 and 2 are doing all the work...

Looks like I have a project for tomorrow...

[Amskeptic]

No luck getting things to settle in, it was as chirpy warm as it was cold, maybe even more so. The engine dies when I pull the spark plug wire to 1 or 2 with no change if I pull number 4 wire, which leads me to believe 1 and 2 are doing all the work...

Looks like I have a project for tomorrow...

I still can't shake that photograph of head removal in the snow ...
Colin

[chitwnvw]

Iconic imagery!

Tomorrow...today, is supposed to be close to 50, it'll be a walk in the park.

[Amskeptic]

Iconic imagery!
Tomorrow...today, is supposed to be close to 50, it'll be a walk in the park.

That one. Excruciating. I can feel the wet socks, the snow creeping down my neck, the oily cold clumsy fingers, the dead engine with little greasy nuts and bolts dropping on the cold damp ground under the car, the shirt that has become untucked as you scrooch under the oily engine, it is terrible.
Colin

[chitwnvw]

Looks like the sealing rings were leaking.




The sealing rings are looking a little wavy washer-esque, is it ok to put it back together reusing these rings?

[Amskeptic]

Looks like the sealing rings were leaking.
ok to put it back together reusing these rings?

Find out why. Fix.

No.

Colin

(I think you may need to do a very light flycut on the head spigots.)

[chitwnvw]

This lip is measuring .305 inches.


This is measuring .270 inches.



Sealing ring is .029 giving me a couple thousandths of an inch of a gap.

Is it acceptable to take a grinder to this area:



And shave off a couple of hundredths?

[satchmo]

Yes, you can.

[72Hardtop]

Iconic imagery!

Tomorrow...today, is supposed to be close to 50, it'll be a walk in the park.

That head has been overheated more than once (coking of the oil). Which led to the failure of the head gasket that shouldn't have been used in the first place. Time to rebuild both heads. Just remember...skimp and you'll be doing it twice and doubling the price.

[Amskeptic]

That head has been overheated more than once (coking of the oil).
Which led to the failure of the head gasket that shouldn't have been used in the first place.
Time to rebuild both heads.
Just remember...skimp and you'll be doing it twice and doubling the price.

There are many "conventional wisdoms" in VW Land that I am devoted to challenging.

The engine in the snow photograph was from (a couple?) years ago. Different file.

Chitwnvw nailed the cause of his current leak, too deep of a flycut. Sealing rings are mandatory.
Though pricey, chi, Air-Cooled.Net has good solid copper rings that will work well without having to file away the surface as seen in satchmo's photograph.

The TSB recommending the deletion of the sealing rings had to do with a different issue than some unusual sensitivity to failure experienced by these rings. They were deleted to improve the immediate heat conduction from the heads to the barrels under transient loads to prevent a rash of 94 piston scuff/seizures in the 2.0 engines due to too rapid expansion of the aluminum. Every point in that bulletin was exactly devoted to warming barrels and cooling pistons > notching the connecting rods)
Colin

[satchmo]

Chitwnvw nailed the cause of his current leak, too deep of a flycut. Sealing rings are mandatory.
Though pricey, chi, Air-Cooled.Net has good solid copper rings that will work well without having to file away the surface as seen in satchmo's photograph.

Colin

Yes, but...if the initial problem was caused by premature contact between the head and some cylinder fin cast flashing or something, wouldn't it be easier to deal with the contact spot rather than getting new thicker sealing rings, re-figuring the deck height and the compression ratio, and finding new barrel spacers to make it all like it was supposed to be? Just wondering.


Tim

[Amskeptic]

Chitwnvw nailed the cause of his current leak, too deep of a flycut. Sealing rings are mandatory.
Though pricey, chi, Air-Cooled.Net has good solid copper rings that will work well without having to file away the surface as seen in satchmo's photograph.

Colin

Yes, but...if the initial problem was caused by premature contact between the head and some cylinder fin cast flashing or something, wouldn't it be easier to deal with the contact spot rather than getting new thicker sealing rings, re-figuring the deck height and the compression ratio, and finding new barrel spacers to make it all like it was supposed to be? Just wondering.


Tim

I personally would do some simple math, like the factory .028" - .030" sealing rings missed by .005" - .007" with chi's above numbers, so get some .040"s and clean the edges of the head spigots with a razor blade. Then, you have dropped the compression ratio a teensie bit in the safer direction, slap that sucker back together and hit the road. This with an actual road history with the car, which I think chitwnvw has from driving it across the country. If some other symptom is known about the engine, that would be entered into the decision-making. Chitwnvw, if you had stinky heat that you just couldn't resolve, here is your reason. Who did headwork on this engine last?