1958 365 ticking noise

[Christian Aicher]

Hi all,

I have a 1958 Series 62 with a rebuild 365 and a rebuild transmission (approx. 2000 mls ago). Lately I noticed a ticking noise coming from the passenger side. You can only hear it when the engine is cold and under load (like accelerating from a stop). As soon as I let off the gas, the ticking disappears mostly, only to return when I push down on the accelerator again. If I rev the engine in neutral, there is no noise from the engine compartment/valve covers. First I thought it might be a sticking valve as it will go away when the engine heats up but then, shouldn't I hear the ticking also when I rev the engine in neutral or park? Is it possible that this has a connection to the transmission? It sounds like the ticking has a frequency of half the engine rpm.
My car is also equipped with a stock AC unit in great working condition - could the compressor be the source of the noise?

Thank you for any input,
Chris

[The Tassie Devil(le)]

Could it be an Exhaust leak at the Manifold?

There is no pressure when you back off the gas, but with the pedal pressed down, and leak will sound loud.

When the metal heats up, any small gap will close up.

Bruce.

[Otto Skorzeny]

I agree with Bruce. I bet the header pipe is leaking around the donut gasket at the manifold. The pipes were probably removed to facilitate the tranny removal. Thebolts probably worked themselves loose.

[35-709]

Me too.  An exhaust leak can sound just like a ticking valve.

[The Tassie Devil(le)]

Don't forget the Manifold to Head Gaskets as any leak in that area will give one "Tick" every 2 revolutions as the cylinder exhausts the fired gasses.

I have a missing bolt on my Eldo, which someone forgot to put back in place when doing some work, and that cannot be replaced till the Steering is removed, or the Manifold removed, but I will put up with that till I recondition the engine, some time in the distant future.

And, yes, it ticks till it warms up.

Bruce.

[Christian Aicher]

Thanks guys,

I feel a lot better. I was really worried about my engine or transmission. I will dive under the car this weekend and check for loose bolts and/or carbon traces around the exhaust manifolds.

Chris

[The Tassie Devil(le)]

If you don't have an Automotive Stethoscope, arm yourself with a 6 foot length of Garden Hose.

Stick one end up to your ear, and move the other end around the various places in the engine bay and you will be surprised what you can hear.

WARNING.   Don't get ant part of it caught up in the cooling fan.

Bruce.

[Christian Aicher]

Hey guys,

A quick update on this topic. I finally crawled under the Caddy this morning and the two last exhaust manifold bolts on the passenger side were loose. I was able to turn them with my fingers. So I tightened them up and the two bolts for the dougnut and... viola... the ticking is gone.
Made me feel a whole lot better.

Thanks again for your advice,
Chris

[Otto Skorzeny]

That's great. It beats an engine rebuild any day.

[DinoBob]

I would have bet the farm on the exhuast as well, because you said it only did it when cold. My ex-'74 Deville had a slight leak at one of the manifolds and did the same thing. Once it warmed up, the noise went away completely.

You also posted about a loopy idle in another post. Were I you, I would check torque on all the bolts I could get to on that engine, including the intake manifold and carb. Perhaps someone was not as diligent in tightening everything to spec during that rebuild the engine underwent.

[Ohio57-62Sedan]

You also posted about a loopy idle in another post. Were I you, I would check torque on all the bolts I could get to on that engine, including the intake manifold and carb. Perhaps someone was not as diligent in tightening everything to spec during that rebuild the engine underwent.

  Great thought Bob.. I would have never thought about that, since I'm so O.C.D. when I build stuff..