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Discussion Starter · #1 ·
I have a 64 289 the oil pressure is lower after the engine warms up but no lifter noise I have a slight knock at idle. Doesn't use any oil and has great power. I'm thinking I have a weak main bearing. Question is
Do I have to pull the heads and pistons to change main bearings? I believe I have to if I'm changing rod bearing. It was rebuilt in the early 80's and has maybe 20,000 miles on it. Runs great and always starts right up.
 

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Discussion Starter · #3 ·
I'm going to pull the pan but can I change them without removing the pistons?
I'm taking the motor out and putting a c4 in and thought I would check and change the bearings while I have it out. I know the top of the engine is in great shape.


<font size=-1>[ This Message was edited by: btaillon on 3/14/06 11:24am ]</font>
 

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Oh yahh no problem and id recommend it. Just at the very least get some plastigauge and check the clearances before you button it up.
You also may have to get the crank polished while its out. Cheap to have that done.
Just dont rush the job and pay attetion to detail here ,cleanliness etc.
Good luck
 

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As mentioned above, you don't need to pull heads or pistons. Just unbolt the rods from the crank and push all of the pistons to the top of the cylinders (with spark plugs removed). You have to rotate the crank some to get the rod's big end to clear the crank throws/cylinder skirts.
 

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You don't need to pull the crank unless it's damaged (which is likely to a small degree) and you don't need to pull the plugs and push the pistons to the top, you can do one rod at a time if you wish, and if it's a crank bearing and there's only 20K on the motor go with the same size bearings that are currently in it. If you go to an oversize bearing without having hte crank milled you could wipe out all the bearings on the first start. Use lots of Oil and or EAS lube, and keep everything clean.
 

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Define "low oil pressure". Can't hurt to change the bearings - there is an old service bulletin that lists a knock in the front main caused by accessory belt load.
 

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Save youself alot of hassel and pull the motor out, put it on a stand and disassemble the bottom end. At the very least mic the crank....... if its worth doing, its worth doing it right !!!
 

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Discussion Starter · #10 ·
I'm going to pull the motor anyway I want to fix an oil leak on the front of the motor and put a new tranny in and paint the engine compartment as well and paint the motor. as ez as it is to pull the motor thats what I'm going to do. I just want to check and change the bearings while I have the motor out of the car. I had a guy tell me that you can't pull the crankshaft out without pulling the heads and pulling the pistons. I thought I could pull the crank and check the crank bearings and the rod bearings without tearing down the whole motor. I did not want to pull the heads and lifters as they are in great shape. As for the knock it sounds like it is in the lower part of the motor but can't pin point it. When I turn the AC on you can hear it more but it draws the motor idle down. It sounds like a sewing machine at idle. it's hard to tell where it is coming from I have had guys look at it and they just say if it runs good and has been doing it for so long just keep running it. So i don't think it is something that is going to gernada the motor I joust thought I would check into it while I had the motor out of the car.
Thanks
Brett

<font size=-1>[ This Message was edited by: btaillon on 3/15/06 2:22am ]</font>
 

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Sound like a sound plan. You can pull the crank out without pulling the heads off. Are you sure you don't have an exhaust leak or something simple?
 

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Discussion Starter · #12 ·
Yep it sound like a sewing machine at idle. Sounds great from the back of the car the duel exhaust is loud enough to cover the engine noise.
This is going to be my summer project. I did not think I would have to pull the heards off but a guy said that you can't change rod and main bearings without pull it all apart.
Well I guess it's time to get a how to build your small block ford book and start from there.
Thanks
Brett

My Daily Driver
 

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I can't count the times I've layed under a car, pulled the pan, replaced ALL the bearings, and had it running...in just a few hours. Even did a few overhauls with the block still in the car. Granted, the crank didn't come out, but it didnt need to be out just for ring/bearing job.

The one that sticks out in my mind is doing an overhaul on an Altered (small block chevy) with the motor still in the frame, at the track and in between rounds. Detonation (nitrous car) burned 2 pistons and pounded the rod bearings pretty good. Took probably an hour & a half, IIRC.

Most times you can just take the caps off, spin the bearings out and spin the new bearing in...without ever moving the rod/piston or crankshaft. 'Course if the crank's gouged, it's gotta come out anyway, but it might save a little trouble if you can just spin some new bearings in and let 'er rip.

_________________
"it is better to appear ignorant than to open your mouth and remove all doubt"--Mark Twain

<font size=-1>[ This Message was edited by: mavman on 3/15/06 11:04am ]</font>
 

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HMMM you know what i thought of??
I had a bad flexplate once that was cracked around the bolt pattern. Sounded Just like a knocking rod. You might want to check that out.
being dumb and getting some bad advice i pulled the rebuilt engine that i got from someone and sent it out to be rebuilt again. They told me that there was nothing wrong with it. I then told them to just do it anyways.
I buttoned it all back together at 2 am and DAM if it didnt knock just like the old engine.!!!
I spent 600 on a short block and it endend up being a $75 flexplate.
Lesson learned.
So id check it out even though your going to put a c4 in it.
 
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