Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 10-13-2020, 07:02 PM   #1
jack wingard
Senior Member
 
Join Date: Oct 2019
Location: Stoneboro PA
Posts: 120
Default Knocking on start up

On a cold start up there is a 30 second engine knock briefly. Where should I start to look?
jack wingard is offline   Reply With Quote
Old 10-13-2020, 07:44 PM   #2
40 Deluxe
Senior Member
 
Join Date: May 2010
Location: now Kuna, Idaho
Posts: 3,774
Default Re: Knocking on start up

Drop the pan and check for a worn rod or main bearing. They knock worse on start up until they get oil. Sometimes a worn/cracked piston will rattle for awhile until it warms up a little and expands.
40 Deluxe is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 10-13-2020, 07:48 PM   #3
Synchro909
Senior Member
 
Synchro909's Avatar
 
Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 7,472
Default Re: Knocking on start up

Quote:
Originally Posted by jack wingard View Post
On a cold start up there is a 30 second engine knock briefly. Where should I start to look?
I'd start with a check of the main bearings, The rods get oil from the first revolution, not after 30 seconds which is about right for loose main bearings. Adjust them to 0.0015" and you'll be on your way for many more miles.
__________________
I'm part of the only ever generation with an analogue childhood and a digital adulthood.
Synchro909 is offline   Reply With Quote
Old 10-14-2020, 10:11 AM   #4
katy
Senior Member
 
katy's Avatar
 
Join Date: Jun 2015
Location: Red Deer, Alberta
Posts: 5,011
Default Re: Knocking on start up

I once had a 302 engine that knocked like that for a few seconds. The fellow at the machine shop told me it was piston slap until the pistons warmed up and expanded. I dropped the pan, replaced all the rod shells with .001" undersize (oversize?) shells, knock went away.
__________________
If you don't hear a rumor by 10 AM, start one!.
Got my education out behind the barn!

Last edited by katy; 10-15-2020 at 09:51 AM.
katy is offline   Reply With Quote
Old 10-14-2020, 10:36 AM   #5
WHN
Senior Member
 
Join Date: Mar 2017
Location: Connecticut Shoreline
Posts: 1,815
Default Re: Knocking on start up

I’m not a big fan of rushing in and taking things apart. If the engine runs good, isn’t smoking or using any oil, and is quite after 30 seconds?

I would do one thing first. Change the oil. Put in 20w-50 HD and one blue bottle of STP.

I have saved a couple of engines over the years from what some people felt needed a major overhaul, to many more happy miles. These cars are not as quite as your Ford Escape or your neighbor’s BMW.

Please no negative comments, this is just my opinion. Advice is free.

Enjoy.
WHN is offline   Reply With Quote
Old 10-14-2020, 10:49 AM   #6
jb-ob
Senior Member
 
Join Date: Jun 2010
Posts: 631
Default Re: Knocking on start up

Sponsored Links (Register now to hide all advertisements)
WHN 2X

I'll add to WHN, with the ignition key off, step on the starter for 10 - 15 seconds. Listen carefully as the engine sound will change as the oil from the pan is pumped up to bearings etc.. Then turn on ignition & start normally.

Diagnose from simple (cheap) to complex (expensive).
jb-ob is offline   Reply With Quote
Old 10-14-2020, 10:50 AM   #7
Jim Brierley
Senior Member
 
Join Date: Jun 2010
Location: Temecula, CA
Posts: 4,066
Default Re: Knocking on start up

It's probably loose main bearings as Syncro909 says. I had an engine that did that, and leaked out the rear main like you wouldn't believe. It may be time for a complete rebuild.
Jim Brierley is offline   Reply With Quote
Old 10-14-2020, 11:20 AM   #8
Y-Blockhead
Senior Member
 
Y-Blockhead's Avatar
 
Join Date: Jul 2011
Location: Redondo Beach, CA
Posts: 5,817
Default Re: Knocking on start up

A couple of years ago the engine in my Town Sedan started knocking at start up. I pulled the pan and found this lovely site. Not saying you lost a bearing but you may consider checking. All the "parts" were in the dipper tray so nothing showed in the oil.



Y-Blockhead is offline   Reply With Quote
Old 10-14-2020, 04:45 PM   #9
jg61hawk
Senior Member
 
Join Date: Oct 2014
Location: Central New Jersey
Posts: 395
Default Re: Knocking on start up

WHN hit the nail on the head....rebuild an engine for what...to drive 400 miles a year?? Is this a daily driver.... up the oil viscosity, STP added and live with it for years and years I'll bet.
jg61hawk is offline   Reply With Quote
Old 10-14-2020, 09:28 PM   #10
eagle
Senior Member
 
eagle's Avatar
 
Join Date: Aug 2011
Location: Eagle Bend, MN
Posts: 2,025
Default Re: Knocking on start up

Its a simple matter to pull the pan and check it out. Should be done once in a while anyways. The bearings have wafer thin shims that you take out to tighten.
__________________
"There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool."
eagle is offline   Reply With Quote
Old 10-15-2020, 05:50 AM   #11
jack wingard
Senior Member
 
Join Date: Oct 2019
Location: Stoneboro PA
Posts: 120
Default Re: Knocking on start up

Thanks for all the advise. Over the winter I'll probably pull the pan and check things out.
jack wingard is offline   Reply With Quote
Old 10-19-2020, 11:52 PM   #12
AZ_Nick
Junior Member
 
Join Date: Jan 2016
Posts: 17
Default Re: Knocking on start up

Quote:
Originally Posted by eagle View Post
Its a simple matter to pull the pan and check it out. Should be done once in a while anyways. The bearings have wafer thin shims that you take out to tighten.
Exactly. We're not talking about rebuilding the engine, just adjust the shim stack to spec and off you go.
AZ_Nick is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 05:48 PM.