Chevy six

[oiler]

Last weekend i put a newly rebuild ,I was told when i bougt it, 1956 215 cu.in sixer in my 1955 Bedford TA fire engine.

Now the engine i running very sweet and quiet at low idle no knoking at all, but as rpm's go up kncking gets worse. At about 2000 rpm it sounds like a diesel. I've tried to retard it and i've also tried to listen to all bearing as good as possible but they all sound as they should.......

Any ideas?

[BioHazard]

Piston slap? I just to have a Jeep with a six and the piston slap was so bad I had more than one person convinced it was a diesel....

[DanG]

215 was the new OHV six was offered for the 1952 F-series? Solid lifters? If the motor bottom is tight you could need tappet adjustments or have weak springs?

My 1999 F150 5.4L had Ford replacing a bunch of their Canadian short blocks on warranty from piston slap, occurs on start up only while cold, fades with RPM increase. Motor sounds like a diesel for 20 seconds on start up. Ford claimed no harm, 136,000 miles on mine and so far so good...

[SteveU.]

Wrist pin or pins with excessive wear clearances likly. Expensive to correct on a "rebuild" so often not done except on a quality "remanufactured" with new pistons and wrist pins. These parts are probably unavailable on this age and limited production of an engine. Will drive you nuts figuring out as you get a double knock high up and then low down in the block. Had this on a 292 I-6 Chevy and lived with it for 100K+ miles. Corrected this on an original Euro spec 250SE Mercedes with believe it or not Allis Chalmers road grader wrist pins length ground and the piston and connecting rod holes reamed/fitted to these larger OD pins. Kinnda' expensive. Not a problem any oil additive can fix.
Hope I am wrong about this.
Other possibilities ARE piston/pistons slapping due to loose fitting or misassemble with the wrist pin offsets 180 degrees on the wrong side.
Camshaft bearing/gear/chain noises?? I cannot quite hear from here. If so, these will fail quickly and the problem be apparent then.
Any recourse with the "rebuilder"?

Regard
Steve Unruh

Steve Unruh

[oiler]

Thank you all for your help. It seems I've been lucky this time. I drove it home from my frieds barn yesterday, and after a few km's it sounded quite different and now i purrs like a kitten


Perfect, now on Saturday i can pick up my firefighter collegue and drive him to church.
Poor guy is getting married

[Carlb]

sounds to me like it had a stuck lifter.