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Rod bearings or Lifters?


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06-22-02, 08:32 PM   #1  
Stubborn1
Rod bearings or Lifters?

I recently installed new rod bearings and lifters into my 1978 6.6L Ford. I also had the heads done, including a couple new valves, guides and seals.

AFTER I put the motor back in the truck, a mechanic friend asked me if I bled the lifters before installing them. Like a dummy, I didn't. (wasn't thinking)

Now that I'm driving the truck again, I have an AWFUL chatter. It comes right before shifting into the next higher gear. Third gear starts chattering about 40 mph, or so.

I'm wondering if the crank was damaged by the previous owner (old bearing caps were on TIGHT!) Or if the noise is from the un-bled lifters. My mechanic friend said they would bleed themselves, but it would take a while. And the truck would not run very well until they were bled. The truck runs great, other than that God awful noise! I'm just wondering which avenue to pursue first? Bleed the lifters? Buy new lifters? Or get the crank inspected?

I'm not looking forward to pulling the motor out again, if not ABSOLUTELY necessary. Anybody know any short-cut way to diagnose where the problem lies?

 
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06-24-02, 12:52 AM   #2  
Stubborn1
C'moC'mon. Nobody's got two cents they wanna throw in?

Nobody knows how to tell if i got bad bearings or bad lifters?

Please help.

 
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06-24-02, 10:38 AM   #3  
redneck
It does sound like lifters, if it does not quit real soon then it is something else. Rod bearings or main bearings typically do not make a "chatter" noise. Have you checked oil pressure? Just finished a buddys Harley motor and the lifters made a hell of a noise for about 100miles--now the motor sounds great and runs awsome.

 
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06-24-02, 11:04 AM   #4  
Stubborn1
Thanks, redneck.

Before I started this whole mess, my oil pressure was good for about 10 minutes, then would drop. Now that the motor was worked on a little bit, I got Great oil pressure. And it holds STEADY.

Also, I forgot to mention that when the chattering is happening, it stops immediately when I let off the gas pedal. And begins again immediately when my foot goes back onto the accelerator. If it is just lifters, then I'm very happy. (No motor pulling!) I've only got about 50 miles on it, right now.

But if it is the lifters making the noise, am I doing any serious damage to them? Or anything else? Or is it just an annoyance?

Thanks again, redneck!

 
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06-24-02, 12:33 PM   #5  
Thats not lifters if it goes away when you let off.

Rod bearings make the most noise between 2k-3k and you play the rpm up and back ever so slightly. Or if very loose will make noise on accel but go away as soon as you deccel(or take load off)

If you had a direct reading mech oil gage you would see a slight drop in oil pressure when the noise occurs if it were rod bearings

Larry

 
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06-24-02, 12:49 PM   #6  
redneck
I would have to disagree with you on that--I personally had a 400 pontiac motor that had a bad rod bearing on the #2 cylinder and you would not even know it was bad until idle. It would make a "knocking" noise at idle--and no other noise while acc or decel! When I pulled it the crank was shot.

 
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06-24-02, 12:50 PM   #7  
Stubborn1
I have the factory oil pressure gauge in the instrument cluster. I put in a brand new oil pump, and oil pressure sending unit while I had the motor apart. The pressure doesn't dip when the noise occurs.

The gauge doesn't have pressure numbers on it, but when I first start the engine, the gauge goes up to about 2/3 to 3/4. After about a half an hour, it goes down to about the midle of the gauge. I'm not sure how many pounds of pressure that is, though.

 
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06-24-02, 02:19 PM   #8  
The information I gave you is base on 40 years in the automotive trade. A rod bearing will make noise at idle if all the bearing material is gone and it is using the metal backing. A slightly worn or loose bearing will not make noise at idle

Larry

As far as the oil pressure drop...it has to be a direct mech gage. The factory elec is to slow to show the change

 
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06-24-02, 05:57 PM   #9  
Stubborn1
ok.

So toyotaman, it makes no noise at idle. Just right before going into second. Then right before going into third. Then about 40 miles or so. I let off the accelerator, it's quiet. I touch the accelerator again, it's annoying.

Then, since my bearings are new, it must be that the crank was messed up by the last bearings being on so tight?

No offense, but I hope your wrong. I wanted someone to tell me it was the lifters.

Dang!

 
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06-24-02, 06:07 PM   #10  
Is your egr system working?Did you punch out the cat conv because F ord used back pressure sensing egr back then and if you punched them out big time valve rattle.

 
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06-24-02, 06:07 PM   #11  
Not to question your work, but did you measure the crank for size and if it's is round and not tapered. Did you measure the assembled oil clearance with the new bearings on all crank pins?

With out hearing your noise sure sounds like rod noise

Larry

 
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06-24-02, 06:19 PM   #12  
Stubborn1
wow.

No. EGR is disconnected. NO catalytic coverter. This thing runs lead.

Question me, toyota? You lost me. "Measure assembled oil clearance"? I brought the old bearings into AutoZone with me, and they said they looked like standard sized bearings. So I bought a new set of standard bearings. And I torqued the caps down.

Full disclosure: I never did a rod bearing job before. But I had a manual with me.

I thought for sure I did things right.

 
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06-24-02, 06:36 PM   #13  
Every bearing has a specified oil clearance. Without looking yours up should be about .002-.003". Can be measured with "plastic-gage" a thin strip of plastic laid across the bearing and crank and torqued to spec. Disassemble and match the flattened plastic to the package to get the clearance measurement.

Just because you replaced with the same part dosen't assure propper clearance. What happens if they gave you the wrong bearing. Some times you will run across a journel that was cut under size.

You said the old bearing caps were too tight. Was it apart once before? Were the old bearings worn?

 
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06-24-02, 06:43 PM   #14  
Stubborn1
I'm pretty sure the motor was opened up before me. I don't think this is even the original motor. Those bearings were shot. BUT, it didn't make nearly as much noise as it does now.

I'm starting to think this is gonna be a Pandora's Box.

grrrrr.

 
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06-24-02, 06:47 PM   #15  
Back off your timing and reconnect your egr valve,by the way if you are running leaded gas don't get caught on the street with it.

 
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06-24-02, 06:52 PM   #16  
Stubborn1
I can't buy leaded gas, but I can buy lead substitute. This thing was from the factory with no cat converter, and the big ole mouth on the fuel neck.

Back it off what? 2 degrees? 5 degrees? Play it by ear?

 
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06-24-02, 07:00 PM   #17  
Back it off 5 see what happens then let me know.

 
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06-25-02, 12:12 AM   #18  
If the crank was not checked prior to engine assembly, there are 9 journals that could be wiped, undersized, etc... If the engine was rebuilt before, it could be that you have one or more journals that are .010" to .030" undersized. If standard bearings were used, that excess clearance would be more than enough to clang away. The problem is not lifters by your description. I would say....without hearing it...that you have rod bearing or main bearing problems. Probably rod bearings.

If your timing is set correctly, leave it there. You should not have that kind of noise from advanced timing. The noise that advanced timing will make is a ping...and will be heard most when accelerating...at low rpm. The noise generally lessens when the rpm's rise.


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06-25-02, 04:28 AM   #19  
redneck
I would never tear into an engine and replace bearings without checking clearances with plastiguage--that is just asking for trouble--take it apart and do it right--cranks can be cut and/or replaced!

 
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06-25-02, 06:56 AM   #20  
Joe_F
Reading through this, it sounds like an assembly problem or mismatched parts:

1) First question is who did the work and what experience did they have (not meant to be offensive)?

2) Machine shop work should be handled by a pro with the right tools and equipment to check tolerances and parts fit. You just can't tell this stuff sitting on your back full of grease with the motor in the truck .

3) The best way to proceed is to take it out and go through it throughly. I would have a machine shop go through the whole motor and you do the R&R yourself, to save time and a headache. In this way, you will also have a warranty if something fails or you get a bad part.

My .02

 
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06-25-02, 07:36 AM   #21  
Stubborn1
grrrrrrrrrr

I appreciate all your advice, guys. I really do.

I'm just mad at myself for not taking the whole dang motor into the shop. I pulld the motor out, and took the heads into the shop. But nothing else.

I did the work, Joe. No experience on something like this. And it came back to bite me in the butt.

Well, back to square one.

P.S.
Anybody looking for a "fixer upper" Ford 3/4 Ton?

 
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06-25-02, 01:48 PM   #22  
mick4tfd
rod/lifter tap

Not the rod bearings for sure- that would only be a knock. Did you set the lifters correctly? They may be too tight/loose. Theres many ways to set them, check any book on that.
Mickey
streetrod builder

 
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06-25-02, 04:04 PM   #23  
Would be very suprised if has a good crank with properly fitted bearings

BTW Ford hydraulic lifters are not adj...they have stop nuts. If the clearance isn't correct they make different length push rods to compansate for off clearances, very rare to be needed if head work done correctly

Larry

 
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