Engine Knock

[thomas g. warner]

Arch only reason that I said main bearing is that he alluded to it going
away when the engine is speeded up. If a crank is not properly fitted
during remanufacture it can move frontwards and back in the main bearing
saddles and this is sometimes the reason that you get a knock at idle and
not at higher RPMs. Rod bearings will normally knock all the time.

One other thing. If the camshaft has a lot of wear on the front cover
(reason that Mondello makes the cam buttons), the timing could be varying so
much from idle to 2500 RPM that it could cause knock at idle if the timing
was not set correctly.

>In a message dated 10/31/1999 10:08:43 PM Central Standard Time,

>> Just my 5 cents but if you have a knock at idle it does not sound like
>> preignition. Sounds like a main bearing to me.
>>
>Tom
>
>Here we go again-----we agree. Maybe we should limit ourselves to
>things inside the engine. Now on my last rebuild it was a rod bearing.
>That was more like a ball peen hammer on the block. Since Nate says
>it is more like a sledge hammer I will even concede to you on the main
>bearing idea. I was just trying to keep it as open as possible. I sure hope
>not but I dont like the sound of this.
>
>Take Care
>Arch 76 GB IL
>
>

 

[lorry clavelli]

A friend of mine had a similar knocking in an Eldorado and it turned out to be a loose link belt and
not a loose torque converter. The link belt connects the drive sprocket on the torque converter to
the driven sprocket on the transmission input shaft. It is similar to an engine timing chain.

I dug out an old Cadillac shop manual (1977) and this is what it says under "425 Turbo Hydra-Matic
Diagnosis Procedure":

Transmission Noise - Sprocket and Link Assembly

a.) Link assembly too long. Sounds similar to pop corn popping. (there will be a rough burr along
the teeth of the drive sprocket if the assembly is too long). Replace sprocket and link assembly.

b.) Drive or Driven sprocket teeth damaged.

c.) Engine mounts worn or damaged.

HTH.

Lorry

 

[nate chase]

Hey,
Come on now... You guys are scaring the h*ll outta me! The knock is at low
idle only. Raise the idle a bit and it goes away completely. I'll check the
torque converter this weekend like Chuck and Jim advised.

Nate 75GB (a bit worried) Omaha

>

Date: Mon, 01 Nov 1999 18:24:07 -0800
From: "Steven D. Ferguson"
Subject: GMC: Engine Knocks

If she knocks coming back down get somebody to plasti-guage the lower
end. I did not want to say that.

Arch,
I think you know the inevitable................I'm glad you said it
though.
Steve Ferguson
San Diego