Ok, I have to replace the main bearings in my 88 4cyl. My question is. What else beside the main bearings should I replace? ie Rings, pistons, crank stuff like that. And, where would be the best source for fiero parts?

Are you going to pull the motor?

Yes I was going to pull the motor. Unless you know some cool tricks??

It sounds like one of those since-you-was-at-it moments. I'd replace the rod bearings and oil pump as well. If you support the passenger side of the motor you can drop the oil pan and do this while the motor is in the car. I've done this before to a V6 car and see no reason why the L4 can't be done as well.

If you're going to pull the motor, you might as well get a re-ring kit. Then get the head done. Then replace the freeze plugs, and the oil pump...

You might as well just rebuild the whole mess. It won't cost a whole lot if the block is in good shape.

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"Its a Fiero thing... Heck, even I don't understand!"

Timothy E. Smith
1986 SE V6 BACK ON THE ROAD AGAIN!!!!
1984 Coupe
1996 Ford Probe GT
1999 Chevrolet Silverado Z71
1975 Chevrolet ElCamino SS

I'm with Tim here, once its out and opened up you may as well go for it and do everything. I'd even say have the block honed too for proper ring seating. I was in the same boat 3 years ago with a rod knock, I yanked it out and redid the whole shortblock myself, including the honing, no problems to date. It was not that hard just messy and kinda a pain.
A tip if you're going to put the pistons back into the bores yourself. DON'T do this with the motor on a stand. Your fighting gravity and even with rubber boots on the rod bolts you stand more of a risk of dmamging the crank(ask me how I know). Place the block on a solid bench on the bellhousing end upright. My engine builder showed me this trick and it works great. The rods won't walk all over on you while you tap the pistons in. They pretty much stay put.
Damn gravity.......hehe

There is a way to change the main berring without takeing the motor out, i can post how if your going to go that route , i'll check back in a bit.

That's where I was going, the mains and rods can be done without pulling the motor.

Id just do a rebuild while your at it. If you have bad bearings, the metal went somewhere. If you do just the bearing, about 2 months down the road your gonna find where.

Thats the really major point in fact that if metal has been removed from a bearing or crank surface its gone "somewhere". Having tried to change rod bearings(engine still in car) once when the new bearing spun 5 mins after getting it all back together I for one would not recommend the effort in doing this.
Not to mention I can't imagine doing the mains in this way being very pretty at all. How do you get the crank off the block to change the lower one? In any case I doubt its very fun!

Alright, thanks to all for the info, here is were I stand. I can't afford to do the entire rebuild on the engine(School Tuition and what not). But I don't want to **** it up worse in a couple months. I hate to have to do it like this, but oh well. If I replace Main/rod bearings, get my block preped, and replace the piston rings. Would that fix my problem and not mess up the car later on down the road?

P.S.
wouldn't i have to take the cyl head off also to change the bearings without pulling the engine? In that case, it sounds like a pain in the ass to do on a Fiero(not much room to work).

No you do not have to take the head off. The bearings will slide out. Replace them one at a time and use a torque wrench. I did this back in 1997 while in school and I got another 60,000 or so miles out of the engine before it had to be rebuilt; also replaced the oil pump with a high-volume.

I recommend you pull a main and a rod bearing to see what size is currently in the engine. Buy replacments to fit. When installing these it is VERY IMPORTANT to keep things clean. Coat only the side of the bearing facing the crank with some engine assembly lubricant. Dirt or installing a cap backwards will lead to a VERY quick failure.

Make sure the rods move side to side freely - this is a very small amount. Also check that the crank rotates easily before reinstalling the oil pan; remove all the spark plugs.

Luck!

How many miles on it?
My experience with high milage iron duke re-ringing only on the has been very unsuccessful because of the way they have a nasty habit of really hogging out the upper part of the cylinder.

But doing the rod and mains can be done in the car without pulling any of the upper end apart. Just drop the oil pan and replace the bearings. Just a word of caution ,GM occasionally put under size bearings on rods or mains from the factory. It's easy to check drop the pan ,remove one of each, look on the back side of the bearing it will be marked with the size.
I got bit once by ordering in advance of the job thinking it WILL be STD. but the rods were 010. under .OOps!

In all honesty.... find another L4... Unless you are doing a complete build up, it's not worth rebuilding it.

The vin R version motor was used in 87-88 Olds Cutlass Calais and Grand Am.

I'm not 100% sure yet, but the U vin version of the motor looks interchangable. This motor was available in Olds Cutlass Calaise thru 91.

To use a FWD motor you need to change brackets and pulleys but the rest is the same for Vin R.

For Vin U I think there are some differances but nothing that should keep it from bolting in. You would want ot keep track of the original car info just in case you have to buy parts.

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11-Sept-01, The day the world as we knew it ended.

what makes you believe it needs mains? Knock, oil pressure.
The reason I ask is the cylinder,upper wear can get so bad that it sounds like rod knock. but it's really piston slap! My first rebuild on my '83 Olds Ciera REQUIRED a .060 oversize piston. I was suprised that something could get that bad and still run. Although a bit down on power and alot of blowby.

I'm with theogre........get an engine if you need a rebuild......it's not worth it.

theogre got his letter mixed up....lol
The U engine was used in all 4cyl grand ams, calais, skylarks until 91. The R engine was used in the 6000, celebrity, ciera, skylark.

I believe, like theogre, that the U engine will work, but not 100% sure either, however the R is a direct replacement.

Phil

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GTDude
25 years GM experience

If you really need crank bearings, you need the crank reworked or replaced. New bearings on a sh_tty crank will not last long.

Also, this being an 88... Are you sure it's not the bloody balancer unit? that thing failing could sound like a crank problem. it could even cause a crank problem.

Price wise,,, a good used motor runs between $200-300 in this area. Shop around and pick one carefully.

Even if you want a motor to build up, you can probably find a better one to build up that doesn't have major problems to start with.

Well, there is no rod knocks of any kind. Just low oil pressure and a high pitched buzz that rises with rpm's. A guy I know (works on cars) said to just replace the oil pump with a high volume and check the bearings(main and rod), and replace if need be and I would be on the road again no problem. what do you guys think?

I'd do it , I've had some motors that (if the crank is ok) just replaced the bearings with very good results.. If your really short on money , Its' a cheap way out.. Just make sure to check the bearing size first. Most bearings are special order.
Do you have a Micrometer or Vernier caliper? If not just look for obvious wear like large rings(scratches)on the crank.
Bob

How did you determine the main bearings were bad?

Main brgs. usualy last forever. ( short of running out of oil)

My 86 2.5 is currently opened up for rings, #4 cyl 85 lbs. dry & 135 wet, and rod bearings. I'm doing the job w/ engine in car.
When the pistons are out I will install new rod bearings.

As well as a visual inspection, to guage the remaining life, get some plasti-guage to check the clearance of the old bearings

Main bearings can be checked w/ plasti-guage also.

Good luck

Johnny Fiero

Ps. the 86 has a Tech 4 engine totally different than an old iron duke.