Main Bearing Shells: Where do Grooves Go?

Mr Wizard

Veteran Member
Joined
May 12, 2010
Location
Orlando, FL
TDI
2014 Golf 1.6 TDI (EU)
Hey Guys,

Was going to put the crank in my engine and make some plastigage checks when I ran into a little problem. The seat of bearing shells that I ordered came with 6 grooved shells and 4 ungrooved. I did some searching and found two contradictory threads.

5 & 5: http://forums.tdiclub.com/showthread.php?t=215516
This is a A3/B4 post though

6 & 4: http://forums.tdiclub.com/showthread.php?t=136058
Also something pre-ALH.

The Bentley Manual Says:
Bearing Shells 1, 2, 4, and 5
- For bearing caps without oil groove
- For engine block with oil groove

Bearing Shell 3
- Bearing Cap without oil groove
- For engine block with oil groove

This seems to indicate its supposed to be 5 & 5. My engine does not have an oil groove on any of the bearing caps both engines that I have had 5 & 5.

So whats the final verdict? Should it be 5 & 5 or is something else going on?

Thanks
Christian


There is also something about sizing the bearings, but the markings that are supposed to be on the block are not there.
 

Deereman76

Veteran Member
Joined
Aug 28, 2006
Location
Southern Indiana
TDI
00 Jetta 5spd.
Markings for bearing size are on the Back of the old bearing shell, not the block. Look for something like "Std" - Standard, or ".020 US"- 20 thousands undersized crank, or a 20 thou thicker bearing.

As for the grooves, I would want to put back bearings that match what was in there. I would try to find a supplier that sold 5 and 5 sets.....
 

Ski in NC

Top Post Dawg
Joined
Jul 7, 2008
Location
Wilmington, NC USA
TDI
2001 Jetta ALH 5sp stock
Typical engine uses grooved shells on the upper half (block shell) and non grooved shells on the caps. The oil comes into the bearings from holes drilled in the block, so the shells in the block must have oil holes that line up. The shells in the caps carry the majority of the load and are typically solid.

Sounds like you got a kit with the wrong mix of shells.
 

Mr Wizard

Veteran Member
Joined
May 12, 2010
Location
Orlando, FL
TDI
2014 Golf 1.6 TDI (EU)
That is what I have come to the conclusion too also. The place I got them is supposed to be checking into this today and giving me a call. Hopefully they will make it right and send me quickly the right set. Either that maybe I can find one bearing locally.

Sucks that this going to hold me up again until the new parts arrive.
 

Mr Wizard

Veteran Member
Joined
May 12, 2010
Location
Orlando, FL
TDI
2014 Golf 1.6 TDI (EU)
Well, heard back from ID Parts and their experts are saying that the grooved bearing is supposed to go into the block on the #3 bearing. Lets hope for the best.

Christian
 

Ski in NC

Top Post Dawg
Joined
Jul 7, 2008
Location
Wilmington, NC USA
TDI
2001 Jetta ALH 5sp stock
All shells in the block should be grooved. The question is what should go on the caps. My vote is all cap shells should be solid.

Anyone else recently done a bottom end of an alh who could help out with this?
 

Mr Wizard

Veteran Member
Joined
May 12, 2010
Location
Orlando, FL
TDI
2014 Golf 1.6 TDI (EU)
That is the way that the bearings came out. I talked to some of the guys at work and the consensus was that if one of the bearings had a groove all the way around it would not matter.

I ended up putting the grooved one in the bearing cap of bearing 3. This will even out the load between the pistons. They are in now and removing them will require a new set of bolts. Unless someone tells me that this is going to destroy the motor, they are going to stay in.

Christian
 

Mr Wizard

Veteran Member
Joined
May 12, 2010
Location
Orlando, FL
TDI
2014 Golf 1.6 TDI (EU)
So far everything seems to be ok. The oil pressure is holding properly. When I called the dealer they wanted something like 40-50 for each bearing. Total of several hundred for the bearings.
 

Nutsnbolts

Vendor , w/Business number
Joined
Nov 1, 2001
Location
Weare, NH
TDI
2000 Jetta, Silver Arrow
I've done a few ALH engines with those bearings. I put the extra grooved bearing in the #3 location, because it is the only one that the Bentley describes as being different, and I think that it's because of the thrust bearing on that journal. I think that with the full groove on both the top and the bottom, the oil is more likely to bleed off uniformly and lubricate the full contact area of the thrust bearing. I've had no oil pressure issues with any of those engines to date, so you should be fine.

-Rich
 

vwdsmguy

Veteran Member
Joined
Jul 5, 2004
Location
Syracuse, NY
TDI
2002 Golf black 5-spd
grooves

It would fit together a lot better if you put the grooves on the inside, toward the crank.



You like that??
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
I'll give you the answer and why....

The extra grooved shell goes on #4 crank cap. All other bearings installed into the crank caps are solid.

The reason:
When the 1.9 TDI is run at high speeds for long durations, especially on hot days up a long grade, there is a potential for catastrophic engine failure. With virtually no warning, a rod will break and poke a hole through the block. It's usually #3 or #4 rod.

The connecting rod bearing failure is due to oil starvation. Those who work on these cars occasionally have seen this happen to a vehicles that were apparently in very good shape.

The cause and effect:
The oil flow for the crank goes from the #1 bearing to the #5 bearing. The oil for the #3 and #4 connecting rod bearings comes from the #4 crank bearing. In order to increase the oil flow through the #4 bearing, a continuous groove has been installed. This causes a steadier oil feed to the #3 and #4 rods, curing the oil starvation problem.

I hope that helps.
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Is this a running retrofit that is not present from the factory (and wasn't TSB'd?), and thus something we should be thinking about possibly doing proactively?
 

p377y7h33f

Veteran Member
Joined
Jun 24, 2011
Location
Brooklyn
TDI
2003 Jetta Wagon 5-Speed in Tornado Red
Retarded! I was assured by idparts that that the 6th grooved went into #3! And now it's too late, of course! I wish I never found out! Damn it! Ridiculous! Arrgggghhhh
 

TDIJetta99

Top Post Dawg
Joined
May 17, 2005
Location
Port Jervis, New York, USA
TDI
03... Faster than yours =]
I put mine in the #3 cap when I put mine together.. I couldn't find any real info otherwise.. 20k later on some pretty hard running on a heavily modded engine and nothing catastrophic to report.. I just returned from a 2800 mile trip where the car spent the majority of its time over 3000rpm..
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
I put mine in the #3 cap when I put mine together.. I couldn't find any real info otherwise.. 20k later on some pretty hard running on a heavily modded engine and nothing catastrophic to report.. I just returned from a 2800 mile trip where the car spent the majority of its time over 3000rpm..
Same here - only ~10k on it so far though.
 

TDIJetta99

Top Post Dawg
Joined
May 17, 2005
Location
Port Jervis, New York, USA
TDI
03... Faster than yours =]
It does make sense that it should go in the #4 from the explanation Franko6 gave.. I'm contemplating swapping the shells since I have to replace my oil pan anyway.. I have ARP main studs so it'll only take a few minutes while the pan is off..

Mine spends quite a bit of time at high rpm with pretty heavy loads so it has me a little concerned, but then again so did the engine in my 99 and the factory bearings looked just fine at 242k..
 

cevans

TDIClub Enthusiast, TDI Parts Ninja Vendor , w/Bus
Joined
Sep 24, 2002
Location
Hingham, MA
TDI
2015 Beetle Conv. TDI 6-Speed & 2006 E320 CDI
I talked with all the "TDI Gurus" we deal with daily and got a variety of responses:

1) Bentley mentions that #3 is different than the others, but doesn't specify why. Usually #3 has the thrust washers built in and has oil grooves top and bottom. Thus, traditional knowledge would suggest that #3, that has the thrust washers (separate on the ALH) would get the extra groove. Half the gurus asked supported this.

2) The extra groove gives extra oiling, so if one was concerned about oiling they could put the grooved bearing farthest from the oil pump on #5. This method was suggested by one guru's machine shop and backed up by another guru.

4) Due to crankshaft "Flex" you want flat bearings in the center, not groved ones. Therefore the bearing should be in a non-flex area, like #1. This was supported by traditional "water cooled" gasser guys.

5) Ultimately it doesn't matter - ALL gurus agreed with this statement. Any placement will give hundreds of thousands of miles. ALH motors don't fail due to main bearings alone, and if there isn't other trauma the main bearings always look pristine.

We are unaware of oil starvation issues with ALH motors. We are aware of multiple 500k (one 600k) mile engines, though.
 
Last edited:

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
I just saw this response Cevans, and I am going to say again, this is an issue we rarely see, but deadly when it happens. The whole point of what we are recommending is yet another way to extend the life expectancy of the TDI engines.

1. The reason Bentley says #3 'is different' is most likely, as you say Cevans, because bearing manufacturers like Kolbenschmidt and Mahle made the #3 bearing with the thrust washers attached to the center crank bearing. But 'thrust washered' center bearings made by KS and Mahle are made conventionally, with the top bearing radial slotted and the bottom solid. I sure wouldn't reverse them. So, we can conclude that two manufacturing companies would disagree that the #3 main cap is the right place to install a pair of radially slotted bearings. They still have the additional slotted bearing! Add VW to that number who think it is not to be located in #3, as they still make engines with 5 solid main bearings for the bottom of the crank.

2. ‘Extra Oiling’ is not exactly right. CONTINUOUS OILING would be more accurate. As the crank rotates, the oiling hole going from the crank journal to the #3 rod bearings is basically blocked by the bottom solid bearing. The whole point is that the loading and heat is greatest on #3 cylinder, therefore, improving continuous oil availability to the #3 rod overcomes a potential failure issue.

3. I guess this is a moot point…

4. I will choose to ignore #4, as I find little reason or logic in it. The cranks for the TDI’s are robust. Are your gurus grasping at straws? Who are these guys?

5. It doesn’t matter?? I think for those who we have dealt with who have #3 rods sticking through their blocks, to say "it really doesn't matter' is to put your head in the sand. It sure mattered to those guys!

I am OK to have so many unnamed 'gurus' disagree about this issue. We are not one to follow the crowd off the cliff. But if we are going to present the issue, this is NOT A MAIN BEARING FAILURE ISSUE. IT IS A ROD BEARING FAILURE ISSUE. Lets not muddle the issue.

What is more... we have seen this same issue happening in later year models of VW 5 main crank engines, for example, in the FSI engines.

Our logical solution is to add cooling and lubricating oil to the rod that is most stressed. Having the #3 rod failure is a relatively rare incident. But if it happens, and your dead engine is streaming oil and chunks of engine block onto the road, I doubt the owner of the deceased engine will be thinking how rarely this happens. And if you then realize, it happened just like I said; hot day, long climb, high rpm, broken #3 rod... the thought that there is a logical place for the 'extra' grooved bearing...Those people will surely think it does matter.
 
Last edited:

Mavrick

Veteran Member
Joined
Feb 16, 2012
Location
Ontario
TDI
2003 VW Jetta TDI
Did our ALH engines use the grooved lower bearing half, from the factory? Or is this an aftermarket improvement?
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
Mavrick,

The 'extra' slotted bearing is included in two of the aftermarket bearing manufacturers we use. We do not buy VW logo'd bearings, so we really don't know if they retro the 6th slotted bearing or not. We see the advantages and are solid with our recommendation.

As a matter of fact, for those who have or need to drop the oil pan, we offer one new slotted bearing with a pair of main cap bolts as a kit. You can check your main bearings to see how they look (bottom bearing takes the load, so it's easy enough to do...) and if the bearing appears normal, replace the bottom shell with our slotted one and torque in the new main bolts; 45 ft lbs +1/4 turn. We will also check quality of the #3 rod bearings. Any bearing showing center wear or copper at the edges is due for replacement.

This mod goes well with another development that we found several years ago, where we change out the ALH and BEW oil pump sprocket, chain and tensioner to upgrade the oil pump. All engines in the US, beginning with the BRM in '06 have a smaller gear on the pump, which increases the idle oil pressure and volume. This is a 'must' for any modified engine above 150 hp, in our opinion. Since the issue with bearings is directly related to oil pressure and volume, I feel it improves overall oiling, including rod bearings. We have a neat little kit for that, too.

One last point I did not mention earlier is that all diesel engines built by VW beginning with the BHW PD's and continuing with the CR's have larger rod journals... instead of 50.6mm big end journals as in the AHU and ALH engines, the 2.0 engines have 53.6mm rod journals. However, the crank dimensions are still the same since inception with the AHU block. So, once again, even VW recognizes the added need to improve the rods by adding additional surface area and oil pressure/ volume. We agree and then take it one more step with the #4 main cap bearing mod.
 
Last edited:

Mavrick

Veteran Member
Joined
Feb 16, 2012
Location
Ontario
TDI
2003 VW Jetta TDI
I've come across the slotted bearing when rebuilding, but did not have the info. Thanks for clearing that up. Would be a GREAT tip for the bearing manufacturer to leave a little note in the bag, as to where that slotted bearing is to be installed - for the ill informed.

Frank on disassembling the ALH short block, do you see the slotted bearing already installed from the VW factory? In other words, do you know if VW used this slotted bearing back in 2002 on the ALH engine?
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
As far as I know, all VW built engines are have 5 top bearings slotted and the 5 lower bearings solid. As I said, this is not an issue that is exclusive to the TDI.

I think VW knows of the issue, but seem to take a catatonic approach to change.
 

mtushmoo

Veteran Member
Joined
Nov 24, 2013
Location
MI
TDI
97 Passat. 99 A6 avant in process. Parting '96 Passat. Parting '01 Passat Wagon.
Buick V8's used to die for the same thing Frank describes. The fix there was to cross drill the crank to maintain constant oil film for both rod bearings and bottom half of the crank. That creates a similar effect as the fully grooved main shells, but without reducing the load carrying capability of the main.

Sounds like the main had capacity to spare, but the rods... not so much.
 
Top