One of my friends has a "Vocational Auto Mechanics" class and I asked him if he would be willing to change the spun bearing(s) in my Fiero and replace them with new ones, for an amount of money. He said he'd do it. The thing is, I really don't want to put a lot of money into this 2.8, because it will only be used until I can find a suitable 4.9. Even if the crankshaft is a little messed up, and all that's wrong is domewhat low oil pressure and (a) spun bearing(s), would I get a month worth of driving out of my Fiero? It doesn't knock that bad - I can't hear the knocking until the revs go past 1500-2000. Any help is appreciated.
Thanks,
Adam Smith

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Yeah Wipeout,you can get away with just replacing the one spun rod bearing esp. if it's just a temporary fix.Good luck on your swap!!

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Thanks

Do you know where I can get a single rod bearing? I was planning on ordering a full set for $50 or so.. but CHEAPER IS BETTER!!

I would just drive it until it dies. Once you open it up it is just not worth it for a temporary fix.

Once you open the bottom end up you will find the shrapnel (sp?) from the one spun rod bearing has travelled down stream (oil passages) and you will also have a nearly destroyed main bearing and journal as well, not to mention the rod journal that will be really messd up.

I just went through this with my 4.3L V6 in my boat. Just at a minimum I had to have the crank turned ($185 + $50 for one weld) which included all new main and rod bearings. I also had to get a new rod since the old on was burned and deformed. To get new rod onto the piston the head had to be removed. So all said and done I ended up spending about $400 just in parts. That doesn't include all of the labor I did and boy was it a pain trying to flush all of the metal out of the block and clean it all up.

I know Autozone sells the rods bearings one at a time, and you can replace them that way if the crank didnt get to messed up. It will not last though. I thhink just one rod bearing is like $3

The odd thing is that I changed the oil about 4 miles after it started knocking and there were no metal shavings in the oil filter or in the oil. I'm hoping that it really isn't too bad in there and I will be able to replace a rod bearing and have it last for a little while.

You see, I can get this done for free (plus a little to my friend for helping me out)

You guys don't think the $3 to buy a new rod bearing is worth it? You all know how rapidly the RPMs climb when you're going 40 or 50.. the engine doesn't sound as though it likes a knock at that RPM. If I could decrease that noise, that'd be good enough. I just don't want to throw a rod as soon as I'm on the way to school (not right away, anyway).

[This message has been edited by Wipe0ut (edited 09-04-2002).]

WipeOut,
I have *exactly* the same situation. One rod seems to rattle at 2500-3500 RPM.
My oil pressure is very good, though.
Based on some posts that I've read here, and some advice from a fellow Fiero-fiend mechanic, I'm going to try to fix mine. Hopefully this weekend.
Get your friend to use plastigage to check clearances, when he's fitting the inserts. I plan to.
If the clearances are correct, the journal is smooth and not out of round, the rod end is not out of round, and there is oil getting to it, I can't think of any reason it shouldn't work. Of course, just because *I* think so, doesn't make it true.

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Raydar

ReFormulated

[This message has been edited by Raydar (edited 09-05-2002).]

If you guys are only getting a knocking at a specific RPM, it's unlikely that you've actually spun a bearing......YET! It's important that you run the engine as little as possible.

I put some bearings in fairly recently that had left bearing material on the crankshaft which I had to get off with emory cloth cut in about 1/4" strip and looped it once around the rod journal. Then I lighly lubed the journal and applied a seesaw motion with the two ends of the emory cloth. This quickly removes the debris and also keeps everything round. Try standard bearings, without oil and plastigage them before you install each one. Pain in the butt, but necessary.

Very possible that you may not have any other damage. I didn't. Good luck

Phil

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GTDude
OVER 25 years GM experience

quote Originally posted by GTDude: If you guys are only getting a knocking at a specific RPM, it's unlikely that you've actually spun a bearing......YET! It's important that you run the engine as little as possible. I put some bearings in fairly recently that had left bearing material on the crankshaft which I had to get off with emory cloth cut in about 1/4" strip and looped it once around the rod journal. Then I lighly lubed the journal and applied a seesaw motion with the two ends of the emory cloth. This quickly removes the debris and also keeps everything round. Try standard bearings, without oil and plastigage them before you install each one. Pain in the butt, but necessary. Very possible that you may not have any other damage. I didn't. Good luck Phil

FWIW, I've always heard that the final polishing that is done to the rod journal must be done in the same direction that the rod rotates on the journal. Apparently, there are microscopic "peaks" on the metal that will erode the bearing material if they aren't polished in the same direction as the bearing rotation.
I heard that years ago.
Was it urban legend or not really necessary?

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Raydar

ReFormulated

Well that certainly is good news - if that is my case, anyway. It knocks slightly on startup (for the first second after ignition) and then it stops. It only starts to knock again when I use the gas pedal. I can idle the car around with no knocking. I talked to my friend again and he said he would get to it as soon as possible, which is hopefully in a few days. The procedure for replacing rod bearings is:
drain oil
hoist car (my school has a hoist that has two poles, and the car goes between them, lifted by "feet" that slide up the pole.. will this mess up the ground effects?)
drop oil pan
drop crankshaft
look at bearings
replace
find any stuff stuck to crankshaft
assemble
un-hoist car
put oil in

Is that all, or am I missing something?
Thank you all so much for your help. I would be very lost without this forum!

quote Originally posted by Wipe0ut: Well that certainly is good news - if that is my case, anyway. It knocks slightly on startup (for the first second after ignition) and then it stops. It only starts to knock again when I use the gas pedal. I can idle the car around with no knocking. I talked to my friend again and he said he would get to it as soon as possible, which is hopefully in a few days. The procedure for replacing rod bearings is: drain oil hoist car (my school has a hoist that has two poles, and the car goes between them, lifted by "feet" that slide up the pole.. will this mess up the ground effects?) drop oil pan drop crankshaft look at bearings replace find any stuff stuck to crankshaft assemble un-hoist car put oil in Is that all, or am I missing something? Thank you all so much for your help. I would be very lost without this forum!

Could this knock be preingintion? spun bearing are usually more consistant. you mentioned no junk in the oil also. anyways, I dont think you can actually remove the crank with the flywheel and such still on? you can still replace the rod bearings with crank in place

You can't remove the crank without taking the engine out of the car.
Actually, to remove the pan, you'll have to unbolt the front (nearest the pulleys) motor mount bracket from the car, and then remove it from the engine. In order to do that, I've heard you'll also have to remove the bottom-most bolt on the alternator bracket. Removing the mounting bracket is the only way you'll have enough clearance to slide the pan off, past the oil pickup. The pan will have to drop, and slide towards the right side of the car. You'll have to find a way to lift and support the engine while the mount is off.
You'll also have to remove the starter, in order to get to the pan bolts. Be sure to disconnect the battery first.
Good luck.

Friend of mine has done this exact job. Says it takes an entire day to do, and he's disassembled a bunch of Fieros.

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Raydar

ReFormulated

[This message has been edited by Raydar (edited 09-05-2002).]

Ok thanks; I wasn't going to lift it by the ground effects though :P just making sure nothing would get "caught".

Maybe my thinking is way off (since I've never replaced rod bearings before) but I was sure one would have to remove the crankshaft before being able to get at the rods/rod bearings.. so in other words I should not purchase a crankshaft? Does dropping the cradle require disconnecting everything from the engine? I don't want to make this too complicated (relative..).

So, somehow I could get at and replace the rod bearings without removing the crankshaft - I just have to unbolt the bottommost alternator bracket, remove the front motor mount, remove the starter, then drop the oil pan.. right?

Things seem to be a lot different in small, transaxle cars.. harder to get at.

Thanks for all the help so far!

when you have the pan off (sounds like a real mutha) why not replace the mains $21.59, 6 rods @$2.49 each $14.94, rear seal $13.62, pan gasket you have to have anyway $4.95 which comes to a grand total of $55.10 (AutoZone)+ applicable sales tax, the job sounds like a big pain in the ass to take the cheapskate route

quote Originally posted by Raydar: FWIW, I've always heard that the final polishing that is done to the rod journal must be done in the same direction that the rod rotates on the journal. Apparently, there are microscopic "peaks" on the metal that will erode the bearing material if they aren't polished in the same direction as the bearing rotation. I heard that years ago. Was it urban legend or not really necessary?

Radar.....new one on me....and my machine shop and I've rebuilt 100's of engines.

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GTDude
OVER 25 years GM experience

If you're just replacing bearings, you can leave the crank in place.

Does anybody have any pictures of a good/bad crank so I know to look for?

quote Originally posted by Wipe0ut: Does dropping the cradle require disconnecting everything from the engine? I don't want to make this too complicated (relative..). Everything has to be disconnected from the drivetrain to drop the cradle. Coolant hoses. Fuel lines. Tranny lines or clutch line. Shift cables. Throttle cable. Wiring gets unplugged from the ECM and cabin harness, and comes out with the engine and cradle. Red leads get disconnected next to the battery. Much easier that way, than disconnecting every wire from the engine. The actual cradle itself is not too bad. Support the cradle from below. Remove the dogbone. Remove four cradle bolts and three nuts at the top of each strut tower. And jack the car up off the cradle. So, somehow I could get at and replace the rod bearings without removing the crankshaft - I just have to unbolt the bottommost alternator bracket, remove the front motor mount, remove the starter, then drop the oil pan.. right? Pretty much. Although you make it sound simple. (Don't forget to drain the oil.) Once you have the pan off, you will see the crank and rods. The main caps (larger ones) hold the crank in place in the block. There are four of them, in a straight line. The bolts go straight in from the bottom. The rod caps (smaller ones) hold the rods to the crank "arms" (actually called "throws"). There are six rods on three throws, two rods per throw. They will be in different positions. You can rotate the crank to gain easier access to the bolts/nuts. The bolts can be at any angle due to the rotation of the engine. (The auto shop instructor ought to be able to point all this stuff out. That's what he's there for.) FWIW... I've heard that Fieros like to eat #3 and #4 rod bearings (the two center cylinders) for some reason. If you can take and shake the rod on the crank journal, it's definitely too loose. Things seem to be a lot different in small, transaxle cars.. harder to get at...

All GM was thinking about when they built our cars was how easy they were to assemble. They really didn't care how hard they were to fix (for the most part).

Phil, Regarding the polishing of the journals, maybe I was led astray by some outside influence, when I thought I had read that.
I was a child of the 70s.

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Raydar

ReFormulated

The rod is going to be out of round from any knocking,so a just replacing the bearing will be a very short lived fix.
These engines also have a way of losing the wrist pin bores,so it might even be that.
The rods only come out through the deck,not the bottom,so you'd need to replace all the gaskets on the intake and whichever head was removed.

Thanks for all the information. I will print it off.

Man.. engines are so darn complicated.. I should swap in an electric.......

quote Originally posted by lowCG: The rod is going to be out of round from any knocking, so just replacing the bearing will be a very short lived fix...

I swapped a few emails with Ed Parks, who told me essentially the same thing.
Gonna try it anyway, just to satisfy my masochistic tendencies. (Thank you sir! May I have another?!)
I'll try to come up with some micrometers and measure. That way I can make educated and informed mistakes.

Cheers!

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Raydar

ReFormulated

So you're saying I'll need new rods.. and to replace those I have to tear the whole damn thing apart?

If the bearing(s) has in fact 'spun', you are looking at a rebuild of the bottom end at minimum. If it is just a slight knock, from wear, you "MAY" get by with a bearing change. It all depends how long the bearing has been bad, how hard it has been pushed while the clearances were out of tolerance. The journal is going to be egg shaped as stated above; it just depends on how bad it is whether or not it will hold up. Definitly a hit or miss deal. I put 10,000 miles on an engine that started knocking. BUT, I only drove it a couple of miles at low speed before I cchanged the rod bearings, and never really pushed it hard afterwards. It was a Dodge 383 truck engine, not a Fiero.
Personally, I wouldn't change just one bearing, but that's up to you. Too much trouble to go to and not change them all. If you have ANY doubts about your oil pump-change it-with a high quality one.

And the thing about directional polishing of the journal: You heard that from someone who has worked on really old engines, back before hardened & modern material crankshafts. I've heard of it, but it has been a long, long, long time ago. Consider this. Detroit Diesel 71 series engines can be configured in a way, by using a different cam, swapping sides with the cam & balanceshaft, a few other things, and you have an engine that turns in the opposite direction. The front of the block becomes the rear etc. These are used when you have 2 engines sitting side by side, with both engines driving a transmission via a single bullgeared input. Each engine has a big gear on its output that meshes with the bull gear on the transmission- usually on marine applications. A very versatile engine.
It's been a while, but I'm pretty sure you use the same crankshaft for either direction rotation. I also worked on & operated some Faibanks engines that had no transmission at all. To get reverse, you stopped the engine, slid the cam, with a big handle & yoke, quickly restarted the engine & it would be running in the opposite direction. They were started by applying compressed air to the top of the pistons, via a special manifold.
We ran into the pier several times when the engine wouldn't restart. Thoses were the good old days!!!

[This message has been edited by maryjane (edited 09-07-2002).]

Well...
After careful consideration, and a few minutes laying on my back between the ramps, staring up at the bottom of my engine, I decided (as wiser men than I have said) "screw it".
It's a whole lot easier to replace bearings with the engine out of the car.
And if I'm going to drop the cradle, I might as well do a 3.4 (or something else) while I'm at it.
(You all see how this logic is working, don't you? )
"She who must be obeyed" has already told be to do "whatever I need to do".

The down side of this is that I'll be driving the Formula to RFTH-7 instead of the (ReFormulated) project car.
...Unless I sell the Formula first <subliminal message: check the mall. nudge, nudge>.

WipeOut, I wish you the best of luck with your endeavor. Please keep us posted.

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Raydar

ReFormulated

[This message has been edited by Raydar (edited 09-07-2002).]

I did a crankshaft kit in a 2.8 auto Jeep with the engine in the car. It cost $180 for the kit and $10 for the gasket set. The whole job took about 5 hours and it ran for 3 years with no problems. I had to replace the cranksaft becaus the old one BROKE IN HALF. You can remove the crankshaft from your Fiero to replace the bearings without pulling the engine as long as it's an automatic.

Yes it's an auto.

My father picked up a new crankshaft, rods, rod bearings, and some other stuff from Autozone. Apparently he got a good deal on the crank; it was only $100 with a $95 core charge. You say it's possible to change the crank without dropping the cradle? I'm interested.

My father loves my car (which is the reason he bought all that stuff for me). If anybody wants to trade a Fiero for a '96 Taurus, I bet he'd hear ya out

quote Originally posted by SKIDMARK: You can remove the crankshaft from your Fiero to replace the bearings without pulling the engine as long as it's an automatic.

I could see how this might be possible.

You'll have to pull the timing cover, timing chain and gears and water pump to get the crank out. Be sure to pay attention to the timing marks on the gears when you put it back together.

Here's a possible issue...
The Fiero torque converter (at least the one I removed from my 2.5) has a knob that protrudes from the "flex plate" side, that fits into the end of the crank. Sort of like a pilot shaft. I don't think that RWD cars have the same knob.
I'm trying to picture how the crank is going to come out. You can unbolt the flex plate from the torque converter, but that little knob might prevent you from removing the crank and flex plate unless the torque converter can be pushed into the tranny far enough to let the crank and flexplate fall out. And I don't think you can get to the flexplate bolts, because the torque converter is in the way.

Am I missing something?

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Raydar

I'm not the pheasant plucker.
I'm the pheasant plucker's son.
But I'll pluck pheasants
'Til the pheasant plucker comes.

Aaaaaaaaaaaaaaaaahhhhhhhhhh!!

Such a complicated job! Do you all think it would be worth it to pay a mechanic to do that?

if it's just the rod bearings, and the crank and rods are ok, and youre willing to settle for a quick and maybe temporary fix, do them in the car.

if it's more than just the rod bearings, you dont want a quick temporary fix, have knowledgable help and a decent shop, i strongly advise you to do it yourself, out of the car.

i have to re-learn (yes, the hard way) every couple of years, the "easy way" isn't.

Well..... a new twist on things. It turns out my friend won't be able to do anything with my car for at least another month. I can't afford to wait that long. If someone wants to sell/ship me a 4.9 I am still looking. As of now I have no way of changing the bearings. I can't use the school shop because I'm not in Voc. Auto.

Great....

I called around and NONE of the shops would work on a Fiero. None.

quote Originally posted by Wipe0ut: friend won't be able to do anything ... no way of changing the bearings... I can't use the school shop...NONE of the shops would work on a Fiero.

ok, youre back to square 1, forget the fancy fixes and doing it "right". drive it (gently) and hope it doesnt die, or put it up on jackstands and do the bearing(s) yourself.
i wish i could be more help, but it's a bit of a drive, ya know.

Yeah, I understand.

Now would be a great time to see a 4.9 walking down the sidwalk..........