Engine Knock, maybe

[wdills]

Started working on the engine today to see how good it will run. Found one plug that wasn't firing and the timing was off a little. Correcting these got it running a lot better. Still a little rough but not too bad. Haven't looked at the points yet. I did run it in the dark to make sure the ignition wasn't arching around like a christmas tree. No evidence of archs.

Once it was running smoother I was able to hear a faint knock when I reved up the speed. I can just barely pick it out at idle. Easier to hear when revved up. Must be standing by the engine with the hood up to hear it. Can't hear it inside the car. I went over the block using a big screw driver as a stethascope. Center of the engine, I just hear valve train operation. Knocking noise is more pronounced at the front and rear of the engine.

A water hose blew out and cut my search short. When I get it running again I plan to pull the plug wires one at a time to see if I can isolate a cylinder. Is there any particular spot on the block where I should be listening to help isolate where this is coming from?

When an engine is getting ready to come apart how loud is the knocking normally? Am I chasing something I shouldn't be? I just don't want to end up with a rod poking out the side of my block.

Any advice would be appriciated.

Thanks
Wayne

[wdills]

Got the hoses replaced and car (61 Hawk) running again. I continued chasing my knock / rattle tonight. I discovered that the sound becomes obvious at about 2000 RPM. I bought a stethascope and discovered the noise is much more pronounced at the rear of the block. I pulled the plug wires one at a time and none of them had any effect on the noise.

Since it is at the back of the block I am wondering if it could be in coming from something like the flywheel, clutch, etc. Somebody did replace the original 4 spd with a 3 spd OD, so the bell housing was also replaced. It may not be related in any way, but my starter fails to engage properly about 1/2 the time.

So now I have some what if's.

What if the new bell housing wasn't centered properly.

What if the pilot bushing was left out?

Any thoughts would be appreciated.

[Milaca]

This may be a long shot, but you may want to double check that you have the spark plug wires installed correctly (for example, make sure the #1 cylinder is wired to the #1 terminal on the dist. cap). I had the wires installed incorrectly on a '64 Hawk and it ran rough until I got two of the wires swapped, then it ran great (and smooth).

[wdills]

Thanks, but that was one of the first things I checked. All plug wires are correct.

[wolfie]

Where are you hearing the knock, as in high in the block near the heads or low in the block near the crank. Lots of things can cause a knock at the rear of the engine. Since you say you have to be standing beside it with the hood up I will lean toward valve train noise. Remember theses engines are solid lift so will be noisy compared to a modern hydraulic valvetrain. A video with sound would be helpful. Steve

[wdills]

I got my Dad out to help a little today. Allwoed me to get under the car and listen while he would speed up the engine. The knock / rattle is more pronounced from the top of the block than it is at the bottom. I used the stethascope to listen around the bottom of the block and bell housing. The noise was not as loud as it was up top. I am hoping this means I am hearing a bent push-rod or really bad valve adjustment. I will try to run through the valves one day this week and see what I find.

[wdills]

Well, I couldn't wait. Checked the valves this afternoon. Some were OK, some were way loose. Adjusted everything up, things sounded better at idle. Reved up the engine and the knock was still there, more pronounced than before and seemed to start at a lower RPM. I was kinda bummed so I didn't hook up the timing light to verify the speed where the knock starts now.

Unless someone has some other suggestion, I plan to first pull the intake and valey cover so I can see the camshaft and check that everything there is tight. Next I plan to drop the trans and remove the bell housing & clutch to verify everything back there is OK. If that doesn't reveal a smoking gun, I will drop the oil pan and see what I can find inside.

Yea I know I am dancing around this thing, I just don't want to get into a $3-4K rebuild unless I am sure I need to.

[PackardV8]

Just for S&Gs, have you run a compression test?

What is the idle and 2000 RPM oil pressure?

Since you are using a stethoscope, exactly where on the top rear of the block and which cylinders are the loudest?

jack vines

[MyStude_51]

You mentioned earlier about the knock seems to be higher than the crank. You mentioned you were ruling out valve tap, but that wouldn't really produce a knock. If the sound seems to be rearward in the block as you say, and higher than the crank, it could be piston slap. This sound might be intermittent depending on how worn you piston pins are. Just a suggestion. Again, make sure you know its the problem, pulling pistons, and cranks aren't my cup of tea, unless I really need to tear things apart.

[BRUCESTUDE]

Even tho it's at the front of the engine, a worn timing gear may produce a knock too. The cam gear is made of a hard fiber type material, and is usually quiet unless it's got a bad spot.

[wdills]

I haven't done an official compression test, I would have to do a little searching to find the proper procedure. I did do a quick test where I just pulled the coil wire and then pulled the plugs one at a time and measered compression on each cylinder when cranking with the starter. All cylinders were between 115 and 120.

When the the engine is cold the idle oil pressure pegs the needle at 80. When hot the idle pressure is about 30. I have never checked it at 2000 RPM but a small speed increase to say 1000 to 1500 RPM and the hot oil pressure jumps up to about 60.

The sound seems to get progressivly louder as I move to the back of the block. No particular cylinder is noticeably louder than others. Just in general the back of the block is louder than the front. That is why I was hoping maybe it was something in the clutch / flywheel area. But the sound didn't seem to be as loud down on the bottom of the block.

Maybe I don't know what I am doing with the stethascope. This is my first time trying to use one. On the top of the engine I get the loudest knock when I listen to the exposed back edge of the block, behind where the vally cover mounts. It gets less as I move forward, listening down between the intake ports.

I have listened all around on the front where the fuel pump mounts and where ever I could get to the block between the water manifild connections. Everywhere on the front the sound was not as loud as at the back.

Down underneath I went around the bottom of the bell housing and as best I could around the rear main bearing. Again the noise wasn't as loud as it was along the top back edge of the block. I will say that underneath on the block I did most of my listening along the mounting flange of the oil pan. Wasn't thinking about it at the time, could the oil pan gasket dampen the sound where it didn't come through as being as loud.

Thanks for the help / advice
Wayne

[PackardV8]

Here's a WAG, but easily checked. Listen at the distributor shaft and body. If it is around there, pull the distributor and check for wear in the shaft bushings.

The compression is even, which is good, but seems low, which is not so good. Exactly what year and engine are we discussing? What condition - original or rebuilt?

Also, that's exceptionally high oil pressure for a Stude. What weight oil is in there now?

jack vines

[wdills]

It is a 289 in a 61 Hawk. The engine / trans is not original but according to the engine number it is from a 61. No idea of the type oil in there. I just got the car about 3 weeks ago so I am still investigating. I assume its been rebuilt, but again, I don't know all the history. The sound is most noticeable around the distributor but I never thought a distributor could kick-up that much fuss.

I will check it further this evening. Is there enough clearance to get the distributor out of a Hawk without pulling the hood? I just bought a new Mallory unit from Dave the distributor guy. (I can't remember his last name.) After looking at it, I haven't installed it yet because it looked so long I didn't think it could be done without pulling the hood.

[Milaca]

No need to remove the hood for a distributor removal. I did it this spring on my '63 Hawk. If your engine oil doesnt look clean, you may want to change that before you proceed any further. Drain it into a clean container so that you can inspect for possible pieces of metal.

[PackardV8]

1. You've got high oil pressure, which loads the cam and distributor drive gear
2. The noise is loudest around the distributor
3. You haven't changed the oil

jack vines