TheSamba.com :: View topic - connecting rod bearings

Mon Feb 03, 2014 7:51 am

I'm down the rabbit hole of a head gasket job, for a compression leak, rather than typical dripping. The sleeve was stuck to the head, so, the piston rings popped out, and down the hole we went.

I am now in the part where the connecting rod comes off (to avoid the #1/#3 wrist pin pull). That went well and was much easier than removing the pins on #2 and #4.

I'm not sure the term is rod bearing or journal bearing, but I'm talking about these things: http://www.van-cafe.com/home/van/page_258_268/rod-bearings-standard.html

Question 1: Is it a good idea (ie, worth the $ and more waiting for parts) to replace these bearings while I am here? One of them had a visible wear marks (in the middle/half way down the bearing) but they seem reasonably thick and the notches are not worn. How does one go about measuring the wear on them and/or the crank? I am working in my driveway with limited tools (although I have a basic digital calliper)

Question 2: Any tips on reinstalling these bearings and seating them in the rods? My first attempt was to wipe them then smear oil on them. I then attempted to place the bearings on the crank first, and then the rod and cap after. The oiled bearings promptly slid around and dropped off before I could get the rod and cap on. In my next attempt, I used some thick brake calliper grease, which stuck them into place nicely (is that ok?) and again put the bearings on, followed by the rods. I got one side on and it seems ok (rod flops down, albeit a bit slower than before - I presume because of the grease) and the bolts seem tight, but on the other side the rod does not move freely and I'm worried the bearing is not seated correctly (I did note the notches). I'm going to remove that one and try again.

Details: 1.9 with at least 130k miles, new heads in the past 10 years.

Mon Feb 03, 2014 9:38 am

I was taught...... Back in the old days..........

Never reuse used bearings........
They are so cheap, so available, such good insurance against future failure.

Unless.......

You are stuck in nowhere ville and you are making temporary repairs to get back to civilization.
After you are back, pull the engine, put in new bearings.

Even with new bearings, get some plastigage and check clearances. Too tight..... Engine ruined...... Too loose..... Engine ruined.

It's difficult working in those holes, be careful, install them correctly.

Dave

Mon Feb 03, 2014 9:52 am

The bearing shells should have nothing on the back side when installed into the cap and rod. If the rods are sized properly, the shells should snap into both ends and stay put while you assemble them to the crank. Snap might not be the correct term, but they are snug. If yours are flopping around, I would be inclined to replace them or at least compare the fit of new vs used.
If new shells are loose, I'd go ahead and have the rods checked for sizing.

Certainly limited tools and a driveway are not the most ideal conditions and may dictate how carried away you get.

Mon Feb 03, 2014 9:56 am

If the sleeve was stuck to the head inspect the sealing surface in the bore for the green ORing very carefully for pitting and decay.

If it is badly pitted, the ORing will have trouble sealing and you will need a new head/s.

Dave

Mon Feb 03, 2014 10:32 am

Thanks guys. I'll look in to ordering some and figuring out if I need undersized ones or not. My understanding is you only use undersized ones if your cam has been machined, otherwise, stick to the stock size.

Quote:
The bearing shells should have nothing on the back side when installed into the cap and rod. If the rods are sized properly, the shells should snap into both ends and stay put while you assemble them to the crank. Snap might not be the correct term, but they are snug. If yours are flopping around, I would be inclined to replace them or at least compare the fit of new vs used.
If new shells are loose, I'd go ahead and have the rods checked for sizing.

They seemed snug, but getting them to stay put, especially when putting the rod cap on was tricky. Oil didn't help matters any for sure. I was working alone so perhaps I need some extra hands to hold things in place while getting the rod & cap on.

I'm reading from your comment that having a wodge of grease under there is possibly bad news (I presume back side means between the cam and the bearing)

Quote: If the sleeve was stuck to the head inspect the sealing surface in the bore for the green ORing very carefully for pitting and decay.

If it is badly pitted, the ORing will have trouble sealing and you will need a new head/s.

Yeah, I'm pretty sure the stuck one was the one that had the compression leak, but that is just a guess. It only leaked under load/when hot - not during a leakdown test. Heads and valves were tested, all ok there.

The head seems in good shape, no pitting, but I'll give it more scrutiny. Perhaps under-tightened? Still considering if I should use some goop to help seal the compression gaskets, eg blue hylomar or something like it.

Mon Feb 03, 2014 10:38 am

Hmm, re-reading this, I think definitely installed these the wrong way. I put both bearings on the crank, and then put the rod cap over the bearing, then attached the rod. This made me then worry about the bearing being seated correctly in the rod...

Mon Feb 03, 2014 10:41 am

Anything under the backside of the bearing would not be a good thing. With new bearings, I actually "shine" the backside of the bearing with some red scotch brite. I have found new bearings to be tight when installed to stock worn cranks, but clearance comes back after shining the back side. Grease could affect the clearance. I use Royal Purple assembly lube on the wear surfaces though. Most of my boxer engine building experience is on air cooled engines which probably have more room for your hands when installing rods etc with the case together.

Mon Feb 03, 2014 10:56 am

so, backside meaning the side that faces the rod? or the other?

i can see how working on an aircooled would be more fun than these wassenstein beasts. the waterjacket was a clever engineering hack. no wonder conversions are popular.

Mon Feb 03, 2014 10:59 am

Looking at area in heads where sealing ring(flat one) contacts, if u have any compression leak u will see a dark stain looking area of the leak. All i've seen were areas between holes 4 head studs. i Mark cyls so they go back where they were. If a compression leak seen i take cyl 4 that position in head and with some very fine valve lapping compound lapped the cyl to head so a clean complete even area all around. Actually after 1st wbx eng i do ALL cyls to head 4 max sealing. DON'T re-use the sealing rings, use new and i do a light enuf coating of lube on seal so it sticks to head, this is enuf, no silicone goop type stuff. Rod brngs already covered, i always use new, type ones used anyway. Not a fan ofonly doing top end if rods show wear, i always found more wear on mains 4 some reason, changed these also, just my 2-cts, no warranty offered at this time.

Mon Feb 03, 2014 11:55 am

hehe. no money back guarantee on free advice morymob? :) i appreciate the words.

there seemed to more carbon around the lip/head of the suspected problem cylinder. i have no lapping machinery in my driveway and have have been cautious about wearing any surface down without some level of precision. are you saying you could do it by hand, eg, just gently rub till it shines and hope it is smooth enough?

i had taken the heads to a machine shop to be tested (and remove one bloody broken bolt) and asked them about machining the surface area. although they seemed a decent machine shop, they were afraid to that on a vanagon head as they were not sure of the process, so they referred me elsewhere, but i did not follow up on that. so far, heads have just been cleaned by hand by me with no abrasive stuff. i understand it is good to rough up the water jacket gasket area, but i was not sure if the same goes for the compression seal.

all new gaskets ready to go. just wondering what stuff to do before i start closing it up. and i know i could go on for ever, but spring is coming and i want it back on the road before i am broke.

Mon Feb 03, 2014 12:06 pm

Ben's place oozes information!

Get a cup of coffee and start reading, you be better for it!

If you find it helpful, consider donating to him, he carries this site himself and it would be great to help keep it up and available!

http://www.benplace.com/vw2.htm

Dave

Mon Feb 03, 2014 12:24 pm

The backside of the bearing refers to the surface that does not face the crank journal. It is extremely important that the tang of the bearing shell inserts into the cut out in the rod and the rod cap. If not, it will pinch the crank and fail quickly.

So to recap, bearing shell into the rod cap, engine assembly lube of your choice on the face and the journal. Make sure the rod cap is in the correct orientation. There is a wrong and right way. Slip the cap onto the crank with the shell and carefully walk it around the journal. You can rig a coat hanger or something to hold it in place while you attach the rod with the piston assembly. That seems like a total pain to do with the piston and cylinder attached, carefully install the nuts and tighten to torque.

Mon Feb 03, 2014 1:23 pm

@djkeev - yes, ben's stuff is great. i've watched a many of his videos and read lots of his posts. also, time here and on the vanagon list - very much appreciate all the knowledge shared.

thanks so much @rsxsr - this stuff probably seems obvious so i appreciate your patience. the piston and cylinder are off, so it shouldn't be too bad - it was mostly the tricky part of holding the cap in the right place while getting the rod installed that was getting me. i will seek coat hanger/etc or extra hands from the other side of the case.

Mon Feb 03, 2014 1:50 pm

atomatom wrote: @djkeev - yes, ben's stuff is great. i've watched a many of his videos and read lots of his posts. also, time here and on the vanagon list - very much appreciate all the knowledge shared.

thanks so much @rsxsr - this stuff probably seems obvious so i appreciate your patience. the piston and cylinder are off, so it shouldn't be too bad - it was mostly the tricky part of holding the cap in the right place while getting the rod installed that was getting me. i will seek coat hanger/etc or extra hands from the other side of the case.

If you have small children, grandchildren..... Those tiny little hands can get into amazing places!

Dave

Mon Feb 03, 2014 1:50 pm

Then when assembled, the rod should drop on it's own weight when released even with assembly lube. If it hangs in space, something is wrong. Use something to hold the nuts into the socket. Some putty or tape. Tape the socket to the extension too. Dropping something into the case sucks.

Mon Feb 03, 2014 1:55 pm

do not presume that the factory sent out "standard" sized journals.
they could have been machined 1 or 2 thousands to fit at the factory.
I've made this costly assumption before.

Mon Feb 03, 2014 2:11 pm

@djkeev - hehe, yes, i have two girls 4&7. they have a tight grip, but they're a bit worried about the grease. i may have to make a candy offer although they want the bus back on the road as well.

@rsxsr - i used the grease-in-socket trick that tencent mentioned on some thread. that held the nuts in the socket nicely when removing them. i just went nuts with that idea when re-installing, then had doubts.

i've already fished a circlip out of the case - what are the chances the one flying circlip would fly in that direction - hello murphy. and yes, i put towels in the holes every other time. got it out within a minute thankfully.

@danfromsyr - good point. never trust a factory - and likewise, i have no idea if my crank has been machined.

Mon Feb 03, 2014 2:32 pm

The backs of the bearings should have markings to indicate their size. If OE, I think you need the Bentley manual to determine. If they are oversize, they are marked. .25 mm .50mm or unlikely but .75mm I believe. You should look for the markings though on the ones you took out.

Mon Feb 03, 2014 3:07 pm

On the back is a part number, that number will tell you the size.
Most likely you have standards.........
These in the photo are standards...........

Dave

Mon Feb 03, 2014 4:38 pm

Thanks Dave, part number much appreciated. Same seen on mine.

Looks like these should be replaced for sure anyway. It is worn to a nearly bronze color on the edge. Is that a typical wear pattern? I'm surprised to see it veer to one side (the worn side is the toward the front of the van). This is from cylinder #4, on the rod cap side. On the rod side it looks like less wear and it is in the centre of the bearing.