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Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: bigbry13 on September 22, 2021, 10:21:38 PM

Title: 1958 Cadillac 365 knocking?
Post by: bigbry13 on September 22, 2021, 10:21:38 PM
Hi all
looking at possibly buying a 58 Cadillac that has been off the road for a while and wondering if you think this engine is possibly knocking. here is a link to the video. Its hard to tell by a video I know but perhaps someone can help me out.

https://www.youtube.com/watch?v=nqc1eQ-x_OA
Bryan
Title: Re: 1958 Cadillac 365 knocking?
Post by: Hillbillycat on September 23, 2021, 03:54:56 AM
Well, I´m hunting down a knock on my ´56 right now (see other thread).
Listening to your video I hear two noises when the engine almost idles. A high pitch clicking noise and a low pitched, dull one.
The lower, dull knock is what my 365 sounds like when hot.

So yes, I´d say it does knock.
Title: Re: 1958 Cadillac 365 knocking?
Post by: dn010 on September 23, 2021, 09:37:20 AM
I can hear a noise that shouldn't be there. Is the exhaust hooked up? If it has sat for years, like my 57, I had lifter noise that finally went away after an oil change and routing starting/running.
Title: Re: 1958 Cadillac 365 knocking?
Post by: Cadillac Jack 82 on September 23, 2021, 11:59:35 AM

Sounds like a stuck or gummed up lifter.  Put some Marvel Mystery Oil in there and that should help.
Title: Re: 1958 Cadillac 365 knocking?
Post by: Michael Petti on September 23, 2021, 05:43:14 PM
Sounds like a dry upper end to me. Change the oil. If you want to try mystery oil. Drive it a little and see if it goes away. I did not hear a rod knock.
Title: Re: 1958 Cadillac 365 knocking?
Post by: fishnjim on September 23, 2021, 08:42:06 PM
Probably should have prepped that motor/car before you started it up.   More damage that can be avoided.   It's loud because the air cleaner is off.   Shouldn't rev them up cold like that, until they warm up.   Common mistake.   There's a definite lifter noise on the driver side when the camera moves that way.   Run a compression test on it and see if you can isolate cylinders.   Could be some ancillary noises from the belts and pulleys, etc.   
They sit for a reason, and may have something to do with all that.   
I put $5K into my '58 motor to rebuild it plus another $2K for the 3x2 carb swop.   So just in case you're negotiating price, what kind of money you're looking at.   You can probably get by for $3.5-4K minimum, if it doesn't need the fully monty.   But parts and labor are more expensive now.
Title: Re: 1958 Cadillac 365 knocking?
Post by: bigbry13 on September 24, 2021, 09:58:06 AM
Quote from: fishnjim on September 23, 2021, 08:42:06 PM
Probably should have prepped that motor/car before you started it up.   More damage that can be avoided.   It's loud because the air cleaner is off.   Shouldn't rev them up cold like that, until they warm up.   Common mistake.   There's a definite lifter noise on the driver side when the camera moves that way.   Run a compression test on it and see if you can isolate cylinders.   Could be some ancillary noises from the belts and pulleys, etc.   
They sit for a reason, and may have something to do with all that.   
I put $5K into my '58 motor to rebuild it plus another $2K for the 3x2 carb swop.   So just in case you're negotiating price, what kind of money you're looking at.   You can probably get by for $3.5-4K minimum, if it doesn't need the fully monty.   But parts and labor are more expensive now.

i havent seen the car yet, just a video that was sent to me. im kind of antipating having to rebuild the motor, but would definitely be nice if i can get away with saving this one for the time being. I will for want to run a compression test when i am with the car in person. i honestly dont think ive ever conducted a compression test myself. isnt it usually a good idea to have the car at operating temp when doing it to get a more accurate reading? should i do it wet and dry? any tips? thanks!
Title: Re: 1958 Cadillac 365 knocking?
Post by: Hillbillycat on September 27, 2021, 03:34:52 AM
From what I heard a leak down test is the most interesting value. These testers run cheap on ebay.
Title: Re: 1958 Cadillac 365 knocking?
Post by: V63 on September 27, 2021, 05:31:52 AM
I have seen 'push  in'  style compression testers and never saw the value in those🙄, I prefer the 'thread in' versions to insure a good seal and reading. Maybe verify a fresh oil change?
Title: Re: 1958 Cadillac 365 knocking?
Post by: Michael Petti on September 28, 2021, 11:06:41 AM
Check the water pump. A worn bearing or dry pump can sound like this. When you get to the car take off the belt and see if the engine still makes the sound. Also make sure there is coolant on the water pump and cooling system. it's just a thought.