The Stovebolt Site Forums The Shop Area Engine Shop Engine rattles

Hello Everyone,
I am just about at my wits end with this problem and hope someone can help me.
I have an original 55 series II pick up with 76,800 miles on it. It starts well, doesn't smoke, idles well, has good oil pressure and doesn't overheat. Performance is also OK.
Over the Easter weekend I checked valve lash, timing and even dropped the pan to have a look at the rod bearings. Everything was in order.
Here's why I took it apart.
At about 1800 RPM when the engine is warm it starts to rattle. At about 2800 RPM the rattle goes away. I can't hear it anymore. When the engine is cold, there is no rattle. At least I can't hear anything. Also no rattle on a cold start.I have an oil tester that tells me there are no metal contaminants or water or anti freeze in my oil. Just normal soot from running a little rich.
I swear, it sounds like a con rod is about to break loose and come out the side of the block. During all this, oil pressure remains steady and everything else is OK. It has gotten to the point where I am afraid to drive anywhere for fear that the engine will blow up!! If I can't sort this out I think I'll pull the engine and drop a V8 in. Been struggling with this for a couple of years and have tried every suggestion but am not getting anywhere.
Many Thanks in advance for any and all suggestions. I don't want to give up but I am really frustrated....

It could be the fuel pump

Is this rattle while under a load? At 1800rpm the vacuum advance may be active, at 2800 maybe not so much. Perhaps the ignition timing is a bit fast and causing the rattle you hear.

Also, had one rattling a while back and found the water pump had a bad bearing. Would rattle a bit at one speed and then go away while either above or below that speed.

If it is happening under load it sounds like Ping, pre-ignition or detonation. All the same thing, cylinders firing too early, but from different causes. Timing too far advanced, carbon deposits, even a too hot spark plug.

Piston wrist pin?

I bought a '70 El Camino cheap because it had a bad "rattle". Barely audible at idle, got very loud as rpms increased, then died down at higher rpms. I used a length of pipe to isolate the sound. Turned out it was the fuel pump, as Don Stocker mentioned.

These old trucks like to make noises and when you are able to trace it down it's usually something simple.

A simple test for the water pump. when it is warm and making noise shut it down and try to rock the fan towards the engine and away from the engine. If the fan is cracked it will flex and click. If the bearing is bad you will feel it move.

do like my kids use to do, turn up the music..

at least checking replacing the fuel pump would not cost much,
neither with the water pump, if one or the other does not fix the problem you will still have them for later on... and later on would come sooner or later.. I have never heard either one rattle but........the only thing that I heard close to that was in a 55 chevy, I thought the thing was going to come apart, turned out to be one lose bolt in my fly wheel cover that was moving around..

let us know what you find out

Try it for a short time with the fan belt off.

You may want to look at the heat riser to be sure it is not rattling.

Does it have hydraulic lifters? If so sounds like one is failing, not pumping up completely so the connecting rod is not firm up against the rocker arm. Explains the no rattle when cold (oil is thicker) and at higher RPM its cycling so fast your ear can't pick up the noise as well. Had it happen to me last year.

Thanks to all!
Checked the easy things. Now know it's not the fan or waterpump. Could be the fuel pump. I have a new one and will exchange.
Rattle is definately under load. Nothing heard when coasting.
Sounds to me like a rod or wristpin. I have an endoscope and will
pull the plugs and have a look at the cylinder walls.
Heat riser was one of my first checks. It's now fixed - OPEN.
Rattle is very hard like a rod or wrist pin. Sounds too loud to be something simple BUT you never know. I'll try everything and anything as I want to keep the truck original.
Seems to me like we've covered everything but if there are more ideas out there please let me have them.
Many Thanks

It's a truck and has solid lifters. At first I thought maybe I had a hydraulic lifter problem as the noise is similar but checked and they are definately solids.
Thanks

Did you try retarding the timing and driving it?

If you think it is just a single rod/wrist pin making noise. Disconnect one spark plug at a time and run it under load. At least you will isolate the problem to one cylinder. Using my internet stethoscope it sounds like a broken/cracked piston, if not the wrist pin. Good luck.

SimS

I just found a rattle in my 53 today. The PO installed a 235 a couple years ago and replaced the clutch and put it in backwards. It had ground down the heads of the flywheel bolts and I was darn lucky to be able to get them off. I've had the truck about a year and just started the resto, seems like everything the PO touched he screwed up, I'm finding.

Many Thanks to all for the new suggestions.
Changed the fuel pump yesterday and readjusted the timing (retarded to service manual spec).
Hope to drive it over the weekend. Weather here is thunder
& showers. Will wait for a dry spell.
My endoscope inspection did not turn up anything new. Cylinder walls look good. No gouges as if I had a wrist pin problem.
Compression is also good. All 6 @ 150#'s. No deviation. Of course, this doesn't preclude a cracked piston.
Will also disconnect one plug at a time and drive it under load. This sounds like a good idea...
Replaced the rear main seal and the clutch last year. My helper DID NOT install. the new flywheel bolts I gave him. Been bothering me that maybe one or more have come loose.
I'll let you all know what I come up with...
Thanks!

Good News!
Not sure if it was the new fuel pump or resetting the ignition timing but the "rattle" has been reduced to about 10% of what is was.
In order to hear it at all the engine has to be very warm like after a high speed run on the highway. Even then the rattle is barely discernable.
Am very happy with it as it is and have decided to enjoy my truck and drive it as it is. If it gets louder or suddenly comes back real loud, I'll have a look at the flywheel bolts. Rechecked my compression and it's so good that I can't believe there is anything wrong with the pistons or valves.
Many Thanks to All !!

Hi Folks,
Seems like I've lived with my engine rattles problem forever! It's been a couple of years and every drive was full of worries that maybe I wouldn't make it home.
Guess that's why I haven't driven more that 100 miles in the last two years. Even then, I kept the engine speed out of the "rattle" zone. Didn't enjoy those rides at all.
Over the Easter Weekend, I finally bit the bullet and adjusted my valves. Never did them all by myself but have had the sneaky suspicion all along that they were incorrect.
I took my time and adjusted them correctly. Guess what? The rattles are GONE! Most of the valves were a bit tight. Three of them had no clearance whatsoever. Not sure why they clattered. Can only think that maybe when things warmed up the valves were touching the pistons. Compression is OK so I guess no damage was done. Anyway, I just wanted to say THANKS to all of the Bolters who helped me with this Problem.
Now I just want to fill the tank and go for a long ride......