Main Bearing replacement how to ?

Is there a how to on this forum for Main bearing replacement without removing crankshaft?

I searched and can't find one. I might snap some pics and write one up as i do mine. But I have a few lingering questions.

How do people get the top bearing off? Rotate engine while pushing on bearing?

Also, where can you get the main bearing cap bolts?

If a main cap is a bit scored-- like where the bearing rubbed rubbed a 1/16th inch wide channel in it, can you reuse it?

Thanks for any help.

Update. BTW, This is a 98 Beetle with ALH engine. The PO hit a curb with oil pan and that did the damage to the main bearing. No WVO has ever been in this car.

So this is not going so well. My car is still on ramps. I have a spare engine that i am ready to drop in but I was hoping to get this was running again and drive it til it died.

Anyway, So I'm stuck at getting #5 cap off. One of the bolts is so tight against the block that I can't get anything on it. I grinded down a socket as thin as i could and got it on but then it split.

How do people do this. I have heard of people removing crank with engine in car. Is there a how to on that? Cant seem to find anything on search. In fact, searching for main bearing replacement didn't even bring up this post.

Thanks for any help.

You'd have to remove the transmission, clutch and flywheel (manual), driveplate (automatic), rear main seal, timing belt, crank belt pulley, front seal flange and oil pump (plus its drive chain) in order to remove the crank.

I've also seen a broken crankshaft from a blow to the belly. Actually it ran for a long time before the crankshaft fatally fractured. Was the crank hit by blow?

You need to remove the transmission, remove the clutch/flywheel, remove the rear main sealing flange, remove the front sealing flange, the oil pump chain/tensioner, the oil pump. Then everything is right there.

You will want to check/replace the rod bearings too. And the rod cap bolts will need to be replaced. If you want, you can do the mains one at a time, but to be honest at that point it is just as easy to lower the crank out.

I am doing one now on a BHW engine (B5 Passat) which is the same basic engine but turned longways and it also has a subframe in the way.

DOH! MOGolf beat me!

To my knowledge you can't remove the crank while everything is in place on any vehicle I ever seen, but what the old-timers would do back in the very early days of bearing lasting under 50K miles was to remove the caps and the bearing shells attached to them, then put a new bearing on the journal and rotate it to the top while the old bearing comes out. If the journal was scored, they would remove the upper bearing and clean the journal with crocus cloth. There were even electric power tools that could undercut the journal while everything is in place. Work like this isn't done anymore... or is it? I would only do it the correct way.

You both beat me although I click "reply" before there were any replies. It happens when one watches "House" while internet'n.

Thank you all. I was thinking you all were the same person for a minute. I just read that post on the B5 with broken chain.

Sounds easier for me and my car ramps to remove engine and work on it. So there is no way to do the main caps with out removing crank? I tried squeezing the top bearing in and just bent the bearing. They are very soft.

If there is no way to do it without taking the crank out I'm just gonna pull it and rebuild in spare time.

Half the #1 main was shaved off and inch long x 1/16" splinters were in the oil pump screen. The number one main cap has a oil groove worn in it from the spun bearing. do you think the crank is foobared? Do i need to replace the cap? The dealer said the caps are matched to the crank. Do i need to get a new crank and caps to match?

thanks

Duster408, you beat me. It is definitely tough getting those top mains in with crank in place.

Caps are part of the connecting rods.

Main bearing caps are with the block.

MOGolf said:

Caps are part of the connecting rods.

Main bearing caps are with the block.

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MoGolf, are you saying that if i need a new Main Cap, then i have to get a new block?

If you are replacing just a main cap you should get the block align bored thru the mains to make sure you are true. You might be better off installing the spare engine and doing a complete rebuild. Now would be a good time to upgrade the rods, too.

The main caps are part of the block as they are machined together from the factory. If the main cap is that trashed, then the block probably is too. However, from the last tooefed BHW I had, that spun the center main as it had welded the bearing to the crank, I was able to clean out the bearing saddle in the block and the cap and was able to reuse with a new bearing and crankshaft. It just depends on how bad it is.

It is still easier to leave the engine in the car and drop the crank from underneath. The trans will need to come out either way, so...

Any possibility for photos so we can see what you see?

main cap and crank pics

MOGolf said:

Any possibility for photos so we can see what you see?

Click to expand...

Yep here are some pics. Thanks for clarifications everyone. I'm sure the dealer said the caps were part of block not crank. My mistake.


Main Cap # 1. -- scored . The bearing was have shaved away , length wise, so it still protected the crank. Wish i had a pick of it.


The crank under #1 -- looks good and I cannot feel any grooves in it. I also pulled the #1 rod bearing and it seemed ok. No feel-able grooves. I plastigauged it and it was within specs. Put new bearing and bolts on anyway


The crank -- all felt ok to me.


Main Cap #5 -- the bolt i could not get out.


What do you think of the pics?

I think I'm ready to just swap engine at this point and rebuild or sell this engine if its repairable. I have a friend that could use an engine. I was hoping for a quick fix to my oil pressure problem but not gonna be. The car ran so good and was so peppy. I'd much rather work on this on the stand where i can take my time and enjoy the work on my own time and check everything out good.
There are 215,000 on this engine so there may be other things like rings which it would be worth replacing.

thanks

bump posted pics

It does not look very good,specially if you cant get that bolt out. It is probably melt that. . I would go with other engine or rebuild this one.

thanks jetta 97. i've made up my mind to do the swap.

I think you might be able to put a main bearing on the crank and rotate it in

Interesting that the main caps have bearing surfaces machined into them. Do a lot of manufacturers do this now?

MayorDJQ said:

Interesting that the main caps have bearing surfaces machined into them. Do a lot of manufacturers do this now?

Click to expand...

Um, what? The bottom end of these engines is pretty textbook, nothing strange.

TurboBugger said:

I think you might be able to put a main bearing on the crank and rotate it in

Click to expand...

Once the main caps have been removed you can use a trimmed flexible plastic putty knife to push out old main bearings and then push in new ones with the crank still in the car. A bit of assembly lube and the entire job takes about 5 minutes. I did it under emergency situations one weekend where the car had to be back in service within 48 hours.

Having said that, I'd highly *not* recommend it for anything other than extreme circumstances. You're hoping all clearances are fine, the crank journals don't need polish, etc, and in particular if there's any metal floating around in the engine a full tear-down is a much much better approach.

biopete said:

thanks jetta 97. i've made up my mind to do the swap.

Click to expand...

I used the below instructions from user QuickTD(?).


To change the crank bearings you will need:

Rod bearing shells std size
main bearing shells std size
thrust bearings
rod bolts
main cap bolts
torque wrench
service manual
Lots of time and patience, this is critical

The rod bearings can be replaced without much trouble with the engine in the car. Rotate the crank so that the rod you are working on is at BDC. Do them one at a time and make sure the caps go back on in the correctorientation.

Mark the installed position if they are not already clearly marked. Use care to avoid nicking the crank journals. Lubricate the shells thoroughly with clean engine oil. Use new bolts and torque them to spec. Keep everything is spotlessly clean.

The main bearings will be somewhat more difficult. It is possible to very slightly loosen all the main caps and the crank will drop far enough (you only need a few thousanths of an inch) to ease the removal of the main bearing shells. Again, only remove one cap at a time and make sure to reinstall it in the correct orientation. The main caps are a light press fit into the block, it will take some wiggling to get them out. The #3 main is particularly nasty because it carries the thrust washers and has very little wiggle room.

The term "rolling in" refers to the method of installing the upper bearing shells. To do this you must fabricate a tool to insert into the oil hole in the crank. The "head" of the tool must be large enough that is does not fall into the oil hole completely, that would be extremely bad, but low enough that it can fit between the crank and the block. An aluminum roofing nail can be fashioned into a suitable tool, and is non-scratching to boot. The tool is inserted into the oil hole and the crank is rotated with a wrench (remove glow plugs to make it easier) to to push to old bearing shell out.
The new shell is then laid on the crank journal and rolled as far as possible into the block. It is then pushed to its final position with the tool. Be careful. If anthing binds up stop and back up. You don't want to shear off your tool in the oil hole or bend a bearing shell.

The rearmost bearing shell cannot be removed/replaced in this manner as it does not have an oil hole in the journal. This shell must be pushed out using a non scratching flexible sheet metal strip. Aluminum sheet about 3/4" wide and .040" thick works well. The aluminum strip method may also work for some of the other bearings, YMMV. You may have to fab up more "special tools" as you work. There are no off the shelf tools for this job. The shells can be stubborn and it can be very difficult to get the locating tabs in the shells to align properly with the grooves in the block. Try to start the bearings as centered as possible as this will help with final alignment.
When you are doing this kind of work be prepared to spend a couple of days at it. Rent a car if you need to. It is very frustrating work. Be prepared to walk away from it a few times to cool off.... I'll admit it, it is sometimes easier just to pull the motor. If you have never changed bearings on an engine, I wouldn't recommend you attempt the job for the first time on an engine installed in the car.

Cleanliness is of the utmost importance. Have plenty of clean rags and solvent (brake clean) available in case something gets dropped and needs cleaning. Dip the new shells in clean engine oil before installing them and crank the engine for at least 30 seconds with the fuel cutoff solenoid disconnected to prime the oil system once the work is complete.

Do an internet search for "main bearing replacement" and "rod bearing replacement" and you may find some additional info. I'm a little afraid of what you might find when you get in there. The overlay metal on the bearings is very thin. If the overlay wears through the crankshaft journal will be tore up. If this is the case you will need to pull the motor and either get the crank reground and undersize bearings installed or just get a new engine, which would probably be the easier route to take. New bearings will not last on rough crank journals. Even worse, one or more of the bearings could have stuck to the crank and spun in the rods or in the block. If this has happened you will need a new engine for sure.

oilhammer said:

Um, what? The bottom end of these engines is pretty textbook, nothing strange.

Click to expand...

I guess I'm just misunderstanding this:

The main caps are part of the block as they are machined together from the factory. If the main cap is that trashed, then the block probably is too

Click to expand...

So a TDI engine main cap has bearing halves like engines have had for years?

mine are

You will have to remove the engine to install main bearings which are like onion peels. After removing the engine, turn it upside down. You need not remove the head, but you will need to remove timing belt and other items as you see necessary. There are many machine shops who can polish and balance your crankshaft. I have done this engine reassembly on 1.6 diesel and turbo diesel. Frankly, it is messy job and involves lifiting, so make sure your back is good. The easy way to handle this project is to remove the head, transmission etc., so that you are left with the short block that would weight 50-70 lbs. Place the car on ramp and you should be able to drop the short block on ground on a heap of newspapers and then drag it out. Or you may use a cherry picker. Harbor Tools sells 1ton cherry picker for about $149 that in sale goes for $99 (I have one and can lend you but you are not near). The machine shop can provide you matching bearings. If you take your short block shell and crank, the machine shop can make necessary bore measurments (so find out wheher it need reboaring to accomodate next size pistons), deglazing, bore align, etc for about $300 (this includes cost for bearings set, but not pistons if required).

Unless, I missed it in one of the posts, don't the main bearing halves on the "block side" have dowel pins?

I've never seen an engine that doesn't have dowel pins on the block side of the main bearings!

Edit: Well, after a quick look in the Bentley, it appears there are no dowels ....... refers to "retaining lugs."

Nope, no dowel pins.

Push on the side opposite the retaining lug, out she rolls.

Dowel pins vs retaining lugs

Vince Waldon said:

Nope, no dowel pins.

Push on the side opposite the retaining lug, out she rolls.

Click to expand...

Well, that's pretty much the same design as the rod bearings?

Wow!

No need to remove the engine, the bearings can be rotated out of each of the locations.

Remove all the main bearing caps.

Each bearing has a shear tab that prevents it from rotating in the journal and is also designed to shear in the event of oil starvation to prevent damage to the crank.

The best way to rotate them out is to use another bearing (non-tabbed end) to push the bearing then grab the old one with plyers and extract in a rotational motion until removed.

Lubricate the new one with engine oil (Mobil 1 Turbo Diesel truck 5w40, just like the factory NEVER use an assembly lube) Rotate the new one in the same way.