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06-08-2015, 07:08 PM | #1 |
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Model A Lower end
For the first time I am going to pull the pan on my 28 Model A and see what condition the bottom end is in. I am doing this for 2 reasons. At higher engine speeds I get a terrible vibration and it feels like engine is going to come apart. Also I have a bad rear seal leak. My compression is ok and the car runs ok but I think it is time I see what condition it is in. Any ideas on what I should look for when I get the pan pulled. Should I check for extreme looseness in the rods or use plastigage? Thanks for any help.
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06-08-2015, 07:21 PM | #2 |
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Re: Model A Lower end
ck for crankshaft end play
this can be done with the pan on |
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06-08-2015, 07:57 PM | #3 |
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Re: Model A Lower end
Thanks Mitch what will that tell me how much is too much.
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06-08-2015, 08:17 PM | #4 |
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Re: Model A Lower end
i believe the spec is .003-.008
to much end play can contribute to a rear main oil leak and vibration. of course many other things can cause that also. |
06-09-2015, 12:18 AM | #5 |
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Re: Model A Lower end
Usually the center main is the first to go, so I'd check that one first.
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06-09-2015, 06:46 AM | #6 |
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Re: Model A Lower end
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06-09-2015, 07:56 AM | #7 |
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Re: Model A Lower end
Some average, completely stock Model A's, many time has vibrations/rattles, that sounds as if you're "tearing" up the engine, usually above 45 MPH. Many small things can cause "disastrous" sounding noises. Minerva had a bad noise for about a week, once! The locking knob for the windshield slide bar was NOT TIGHT enough. The tail pipe hanger can cause BAD noises sometimes. If you rig up a rubber hanger on the pipe, it helps a lot.
On crankshaft end play, it helps prevent some wear on the bearing thrust area, IF when you're waiting at LOOOONG stop lights, put it in neutral & let the clutch out. With the clutch pushed in, it puts a LOT of pressure on the thrust area of the MAIN BEARING & causes extra wear. You can get a FAIR idea of lower end bearing condition, by holding the idle to about 900 to 1100 RPM & "feather" the speed, UP & DOWN, slightly & listen for KNOCKING type sounds. A rod knock can be narrowed down by grounding out 1 cylinder at a time. If you SUSPECT a loose CENTER MAIN, usually it quiets down SOME, when you ground out # 2 or # 3 & will quiet down completely, when you ground out # 2 & # 3, AT THE SAME TIME, while "feathering" the throttle. Claude, (RIP) our REAL GURU, had a rebuilt engine with a center main knock, SOMEONE FORGOT TO ADJUST THE CENTER MAIN!! The shim pack was TOTALLY undisturbed!!! After adjusting it, the engine sounded "PRIMO"!!! Bill W.
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06-09-2015, 05:22 PM | #8 |
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Re: Model A Lower end
Correct me if I'm wrong, but I don't think a bad bearing will cause a vibration. Or at least a loud knock way before that? Has this engine ever run smooth? I think the vibration is u joint, out of balance crank/rods or pressure plate ect.
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06-09-2015, 05:35 PM | #9 | |
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Re: Model A Lower end
Quote:
What does high engine speed mean ? And, does this vibration happen while sitting still in neutral or only when driving ? |
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06-09-2015, 06:31 PM | #10 |
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Re: Model A Lower end
I always sit at a light with my foot off the clutch, also helps me from getting T boned people like to run red lights hear. also I start up the motor with my foot off the clutch, I like to get some oil in there before I step on it
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06-09-2015, 08:30 PM | #11 |
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Re: Model A Lower end
the vibration is the same in neutral or driving. It starts at mid throttle. I think my laymen thoughts are it is in the rods?
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06-09-2015, 08:43 PM | #12 |
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Re: Model A Lower end
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06-09-2015, 09:48 PM | #13 | |
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Re: Model A Lower end
Quote:
Bill W.
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