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replacing main bearings by fierofinder
Started on: 02-25-2008 11:12 PM
Replies: 14
Last post by: Hudini on 02-28-2008 09:50 PM
fierofinder
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Report this Post02-25-2008 11:12 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
I just pulled my engine out today. V6 '88. I believe my main bearings are bad. I believe it may be the passenger side one that gave out. After removing the oil pan I found a lot of shredded pieces of metal at the bottom and stuck to the pump strainer. Looking up in to the engine I can see metal chunks lodged between the casting on the passenger side. So my main question is how much do I have to remove to replace the main bearings. I did drive it about 50 miles after it started making the noise to get it home, would it be likely that I could have messed something else up by doing that. I just want to get it back on the road as simple as possible so that I can get the vehicle smogged than registered. Later on I plan on doing a swap. Does the drive shaft have to be completely removed to replace the bearings. And if I remove the shaft that means I have to pull the haeds and remove the pistons, or can the conecting rods be taken off the shaft and pushed up far enough out of the way? Any input helps. I'm also going to read through all the shop manuals I have for the fiero as well.
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86GT3.4DOHC
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Report this Post02-25-2008 11:33 PM Click Here to See the Profile for 86GT3.4DOHCSend a Private Message to 86GT3.4DOHCDirect Link to This Post
If you're seeing actual pieces of metal, the crank is ruined, no question about it. However im doubting you are getting actual shards of metal out of the main or rod bearings, there isnt enough clearance for even something the size of a piece of sawdust to come out of there. You might want to upload a picture of the material you found in there.

What kind of noise was it making? What kind of oil pressure

To address your other questions, if you have the engine out, you might as well pull the crank out of the block to replace bearings, but you can do it without. The only time you would really change bearings without taking out the crank is when you have the engine still in the car. But what you do is loosen all the main caps, remove one at a time and push the upper bearing out and around the crank, then roll a new one in place, then just replace the lower half.

To take the crank out, all you need to do is take off the timing cover, timing chain, and remove the main and rod caps. You dont need to mess with the heads.

If you have that much metal in the oil pan though, you probably have other signifigant damage, notably to the cam bearings and possibly the cyl walls.
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86GT3.4DOHC
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Report this Post02-25-2008 11:38 PM Click Here to See the Profile for 86GT3.4DOHCSend a Private Message to 86GT3.4DOHCDirect Link to This Post

86GT3.4DOHC

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I should probably elaborate on some main points.

If you replace one bearing, you have to replace all of them, and if you're replacing the mains, you probably should replace the rod bearings as well.

If you can see anything but a perfect polished surface on the bearing surface of the crank, you have a problem, run your fingernail across it, if you can feel even the smallest ridge, you need to have the crankshaft machined to remove material back down to a perfect finish, and get oversided bearings.

Putting new bearings on a damaged crank is a bad idea, the engine probably wont last more than a few hours.

And if you have metal pieces like that running through the engine, I can about guarentee you need to replace the oil pump, and I would pull the cam and inspect the bearings, while you're under there, look up by the pistons and check for any kind of scoring on the walls. This might be a good time to just go ahead and start a swap.
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fierofinder
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Report this Post02-25-2008 11:50 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
The sound is a clicking. It gets real louder when pressing the clutch in at idle, and also when driving. Its quieter when just idling. First thought maybe something with the clutch but everything looks fine there. I had an old post where my feed back led to main bearings. Possibly tomorrow I can get a picture, but the chunks of metal were pretty big, and ranged in size. Some were smaller and were making there way through the strainer. Hope that doesn't mess up the oil pump. So I'll remove the main shaft, I'm guessing it would probabaly be a good idea to replace the main bearings even if that isnt what went bad. And after it is removed I'll be able to see better where the metal came from.
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fierofinder
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Report this Post02-25-2008 11:58 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
The only problem is a have to have the car pass California emissions so I can get it registered before I do a swap. I have thought about just boring it to a 3.1 and rebuilding it completely.
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86GT3.4DOHC
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Report this Post02-26-2008 12:08 AM Click Here to See the Profile for 86GT3.4DOHCSend a Private Message to 86GT3.4DOHCDirect Link to This Post
If there was metal going through the oil pickup, the oil pump is damaged. In fact, potentially so is every other moving part in the engine. When the engine is cold, oil pressure is usually very high, and there is an interal oil filter bypass valve in the block. This valve prevents over pressuring of the filter, causing it to explode, but it allows unfiltered oil to go everywhere in the engine. This usually wont cause dramatic damage to everything, just anything with a direct oil feed and tight clearances, IE, rod, main, and cam bearings. If the material gets in the right places, it can damage other things, but these are the first victims.

Bottom line, if it is as you say, your best bet is to start looking for another engine, otherwise to get this one to last, you're going to have to tear it down and check every part.

Personally I wouldnt really bother with the 3.1L, its less power than you would get from just porting the exhaust manifolds and a decent tune up. The 3.1 is only good for about 10HP, and the 3.4 OHV only about 20 HP over the 2.8L If you're replacing the engine though (As you are looking at needing) its definitely a easy upgrade and worth the effort. I just dont think its worth it if someone has a good engine.
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fierofinder
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Report this Post02-26-2008 12:24 AM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
If I was to just replace it, aren't there 3.1s that are a direct swap unlike the 3.4. I would prefer to go new, So I would think it might be cheaper to replace all the internals and being able to put what i want in there than buying a new shortblock? Within the next couple of days I'll find time to start pulling stuff out and looking for damage. Thank you for all the help, and I'll let you know what I find in there.
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Report this Post02-26-2008 12:25 AM Click Here to See the Profile for uhlanstanClick Here to Email uhlanstanSend a Private Message to uhlanstanDirect Link to This Post
THis engine must be cleaned !!the metal has flowed thru the system,like a taco bell giante,grande bean burito thru my guts to the anal sphincter exhaust where a belching firey spurt makes my pinko liberal work companions act like the incomming 4.2 mortar fire alert has been given the heads need to be removed ..each day you drive this car is a gamble the engine will lock up or a piece of Detroit prime choice metal will devour a small or large chunk of something,, the large chunks of metal make for an interesting view,in the block..and add interest and adventure to each drive !!every few seconds you worry when the unopportune stop ,,screech, the rocket speed launch of rod or other parts into low nasa orbit,,if the noise becomes louder each time you drive it you are indeed an adventurer of the youthful kind..of course if this is your only earth transporter untill the mother ship calls you home you can clean out all the big pieces,strain the oil with a t- shirt and with a constant look of determination on your face continue to drive.. this will destroy the engine,, the added adventure of a locked engine at an appropiate moment can lead to the death of others,or a possible unexpected full lock up slide,extra fun on ice or on a rain slick road..inform us if any part launch occurs???
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fierofinder
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Report this Post02-26-2008 12:28 AM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
Sure, but I did say that I only drove it to get it home, and I have already pulled the engine from the vehicle.
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86GT3.4DOHC
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Report this Post02-26-2008 12:52 AM Click Here to See the Profile for 86GT3.4DOHCSend a Private Message to 86GT3.4DOHCDirect Link to This Post
The only diffrence with the 3.4OHV swap is that you have to drill starter bolt holes on the other side of the block. But like I said, if you're planning to do a swap for power, its not the way to go, not without many more mods, and I certainly wouldnt bother getting the car running again, just to swap the engine in a few more months, figure something out to get around or pass emissions, and go with it now.

If you're sticking with it, I would reccomend finding a low mileage 3.4, or if you can get a good deal, a 3.4 shortblock. Definitely dont reuse anything that has oil running through it without thourally flushing it, AND having it hot tanked at a machine shop. I think by the time you add up all you're going to have in rebuilding the motor, you wont be spending that much more for a shortblock. Im all for doing the work yourself and saving money, but only when its just rebuilding a tired motor, you have serious internal issues, and extensive metal contamination. You're going to have to have the block and heads cleaned and hot tanked, the cam bearings replaced, buy a new crank, or have the old one machined if its not too bad, buy a new cam, new piston rings, (assuiming the pistons are ok) have the valves done, and checked for damage, new timing set, new gaskets, new oil pump, it goes on.

Like I said, renbuilding a tired engine is one thing, but I wouldnt gamble on one with issues like you have, one missed piece of metal hidden in a oil passage in the block would wipe out the entire engine once its rebuilt. So much as a grain of sand can cause serious damage if it makes it into the mains.
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Report this Post02-26-2008 08:44 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
Sounds good, but I have no idea how to get passed the emissions. With whatever is the problem in there, do you think it would pass emissions okay if the engine stayed alive long enough. I'm not sure if they will fail it for the obvious noise or not. I was thinking just cleaning it out the best I can and hope for the best.
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Report this Post02-28-2008 06:18 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniDirect Link to This Post
Does anyone have a step by step for replacing the main and rod bearings with the pistons still in the engine? I too need to replace my rod and main bearings but do not want to pull the heads and pistons unless I absolutely have to.

Plus a bump for the OP and the question of will his engine pass emissions.
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Steven Snyder
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Report this Post02-28-2008 07:46 PM Click Here to See the Profile for Steven SnyderClick Here to visit Steven Snyder's HomePageClick Here to Email Steven SnyderSend a Private Message to Steven SnyderDirect Link to This Post
 
quote
Originally posted by Hudini:

Does anyone have a step by step for replacing the main and rod bearings with the pistons still in the engine? I too need to replace my rod and main bearings but do not want to pull the heads and pistons unless I absolutely have to.


Is your engine on a stand? Just flip it over, unbolt the front cover and oil pan, remove the timing chain sprockets, unbolt the oil pump, rod bearing caps, and main bearing caps... make sure you mark the caps so you can put them back exactly where you took them off from and in the same orientation.. then you can pull the crankshaft out, and replace all the bearing shells. It's a bit tricky getting the crank back in with all the rods still in there at the same time; but if you get a helper to move them around it shouldn't be too bad. Use rod boots or pieces of emission hose to cover the rod bolts so you dont scratch the crank. Make sure all surfaces are clean and dry during assembly, except before you put the crankshaft in, lube up all the installed bearing shells with assembly lube or thick motor oil. Follow the torque specs in the service manual for all the bolts.

-Steven

[This message has been edited by Steven Snyder (edited 02-28-2008).]

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fierofinder
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Report this Post02-28-2008 09:36 PM Click Here to See the Profile for fierofinderClick Here to Email fierofinderSend a Private Message to fierofinderDirect Link to This Post
Thanks for the bump, still wondering that myself. Also curious if I do the 3.4 swap will that pass emissions in place of the 2.8. I assume it would, but I believe all different vehicles have different smog specs.
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Hudini
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Report this Post02-28-2008 09:50 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniDirect Link to This Post
Thanks Steven, I was looking at it as if doing all the work myself. Having a 2nd set of hands and the hose over the rod bolts will definitely help. Just needed some advice.

Bump for the emissions question. Glad I've never had to deal with that. Wish I could help.
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