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engine knock
Posted: Tue Apr 09, 2019 4:59 pm
by wilfbrad
1915 T, getting knock when engine cold, just at thrust and drag power setting and after engine gets hot, no knock.. Is this a sign of center main bearing??
Wilf
Re: engine knock
Posted: Wed Apr 10, 2019 11:57 am
by Russ T Fender
Sounds like it might be a wrist pin. Does the knock get softer or go away when you retard the spark while the engine is still cold?
Re: engine knock
Posted: Wed Apr 10, 2019 12:01 pm
by Shane Lach
Piston slap potentially.
Re: engine knock
Posted: Wed Apr 10, 2019 12:14 pm
by Ruxstel24
I'm with Shane.
Do you know if the pistons are iron or aluminum ?
Most anything else will not quiet up when warm.
Re: engine knock
Posted: Wed Apr 10, 2019 3:17 pm
by Adam
Sounds like the typical noise you start to get from aluminum pistons when clearance gets to be a bit too wide (generally over .006”). If you drive for an hour on a 70-80 degree day and the sound gradually becomes unnoticeable, that’s probably the issue. If that is the issue; it won’t hurt anything and likely won’t get much worse very fast as long as there is no contamination in your engine, you change your oil regularly, and don’t drive much over 30. You might be able to get several years off it depending on how much you drive. Knurling the existing pistons or boring & honing the block to the next oversize with new pistons and rings are the only 2 fixes.