About to buy engine bearings.... - page 2 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

#15 by jtanguay on 08 Jun, 2007 20:34
I was just talking to a machine shop guy and he showed me both types of bearings... he says that the design of the all in one bearing should be superior because it has guides that hold it into place.

the only reason not to use those type of bearings is because of the way that the clutch on our dubs works right???
#16 by rallydiesel on 08 Jun, 2007 20:41
I think the reason not to use the one-piece is because the thrust bearing surface area is too small and the crankshaft gets damaged from them because of it.
#17 by Hillshy on 09 Jun, 2007 02:02
i think another reason to go for the later style big end bearing and seperate thrust bearings, these were standard on the Sb (GTD) engines which were the most evolved as Vw were already developing the 1.9's.

the Sb's have the 360 style main upgrade and seperate thrusts as standard.

hillshy
#18 by jtanguay on 09 Jun, 2007 14:55
Quote from: "libbybapa"
It is only the replacement bearings which have the integral thrust. All of the VW inline-4 engines had the separate thrust bearings from the factory.

Andrew

and they're known to last 500'000km+ so that's good enough for me.

Thanks a lot for the input guys!!!
#19 by CoolAirVw on 13 Jun, 2007 19:29
Read the 2nd post (recommend glyco & stay away from integral thrust)
http://www.vwdiesel.net/phpBB/viewtopic.php?t=8409&highlight=thrust

Read 2nd post (Never ever use integral thrust)
http://www.vwdiesel.net/phpBB/viewtopic.php?t=8072&highlight=thrust

Dr Diesel's integral thrust killed his crank
http://www.vwdiesel.net/phpBB/viewtopic.php?t=399

Pics of size difference of thrust surface
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1908&highlight=thrust

fsbGTD had a failure too
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1694&&start=37

Another guy whose bearing destroyed his crank with pics (gasser's have these problems too)
http://forums.vwvortex.com/zerothread?id=2832725&page=1

More of the same
http://www.vwdiesel.net/phpBB/viewtopic.php?t=6843&highlight=thrust
#20 by CoolAirVw on 13 Jun, 2007 19:42
Quote
I need the link to the main bearing mod that I had seen a few months back. Anyone got that? Done it? Or give me any tips or quick referance?

myke_w mentiones the Mod in this thread.
http://www.vwdiesel.net/phpBB/viewtopic.php?t=6843&highlight=thrust

myke_w started a thread with the Mod here.
(buy two sets of KB bearings or use Glyco)
http://www.vwdiesel.net/phpBB/viewtopic.php?t=3611

I spoke to myke_w on the phone and he explained the mod to me. I thought I understood what the purpose was till I looked at my block/crank/pump ect (lube system). Now I dont understand. I understand how to install the bearings but I dont understand why. As per his recommendation I got the Glyco bearings for a full 360 degree lube slot in #4 main bearing (with seperate thrust of course).
#21 by tylernt on 13 Jun, 2007 21:22
The Bentley is wrong. It's happened before ($&@*^&* Fox wiper motor instructions!!). The Bentley shows the #3 main supplying oil to the #2 rod. I sure don't think so, my crankshaft's #3 main has no oil holes! It appears that main #1 oils rod #1, main #2 oils rod #2, main #4 oils rod #3, and main #5 oils rod #4.

So... I don't get it either. Main #4 (which oils rod #3, right?) appears no different than any of the other mains. The crankshaft has two holes there just like all the others. I can see light through the passage so no matter where the crank is on its rotation, it should be getting oil from one hole or the other, right?

It would also seem that the lower main bearings take the worst beating (power stroke). Wouldn't putting a bearing shell with an oil groove there reduce the available bearing surface area by about 1/3 and accelerate wear 33%?

Further, why would a main bearing oil the head? Main saddle #4 just has one hole, how could it oil the head? Doesn't the head have it's own passage drilled into the oil galley?

I'm sure myke_w has more engine knowledge in his little finger than I could ever lay claim to, but... I don't get it. Please explain.
#22 by CoolAirVw on 15 Jun, 2007 16:21
Quote
The Bentley is wrong. It's happened before ($&@*^&* Fox wiper motor instructions!!). The Bentley shows the #3 main supplying oil to the #2 rod. I sure don't think so, my crankshaft's #3 main has no oil holes! It appears that main #1 oils rod #1, main #2 oils rod #2, main #4 oils rod #3, and main #5 oils rod #4.

Welcome to my world. Every day I swim through a sea of mis-information to diagnose cars in my job. My latest swim is figuring out if main bolts are stretch. I've found two posts that say they are but cant believe everything you read on the internet ya know.

Quote
So... I don't get it either. Main #4 (which oils rod #3, right?) appears no different than any of the other mains. The crankshaft has two holes there just like all the others. I can see light through the passage so no matter where the crank is on its rotation, it should be getting oil from one hole or the other, right?

That's what I dont understand.

Quote
It would also seem that the lower main bearings take the worst beating (power stroke). Wouldn't putting a bearing shell with an oil groove there reduce the available bearing surface area by about 1/3 and accelerate wear 33%?

Yes, kind of sort of.... the crank should "float" on a film of oil and hardly touch the bearings but I'm starting to think that stock bearings might be better also.

Quote
Further, why would a main bearing oil the head? Main saddle #4 just has one hole, how could it oil the head? Doesn't the head have it's own passage drilled into the oil galley?

Yeah! What he said.

Quote
I'm sure myke_w has more engine knowledge in his little finger than I could ever lay claim to, but... I don't get it. Please explain.

I wish he would pipe in here. I am expecting a reply back from him
#23 by CoolAirVw on 17 Jun, 2007 06:09
Tylernet said:
Quote
.... y crankshaft's #3 main has no oil holes!

My crank is like that also. Note: #3 is also the main with thrust.

More thoughts on this.

With regards to stock main bearings with the top bearing with a oil groove and bottom bearing flat (ignore #3 for now since it has no oil holes). As the crank is spinning one oil hole in the crank is in the the grooved bearing all the time and the 2nd oil hole is up against the flat bearing all the time (obviously there is a "branch" coming off the passageway between the two holes going to lube the rod bearing).

Do you think that the 2nd hole (the one not in the oil groove as the crank rotates) is providing lube to the flat bearing??

CoolAirVw said:
Quote
....the crank should "float" on a film of oil and hardly touch the bearings.....

Maybe that 2nd hole provides some oil pressure to the flat bearing to "float" the crank. Or maybe just to lube it some.

Ok using this theory lets look at the #3 journal with no holes. Top bearing still has the groove bottom bearing still is flat. Hows that flat side get lube? With stock configuration it only gets what is squeezed in from the groove through the clearance in the bearing. Take into account that the thrust bearing is surrounding this main and is lubed by the oil pressure leaking out of the bearing.

My idea is this. The Main Mod shouldn't be #4 for Rod/head lube. The Main Mod should be put the bearing with 360 degree lube channel on the #3 to improve lube to lower main bearing and to lube 360 degrees of the thrust bearing.

I'm gonna look at some of the pic of failed thrust bearings to see if they failed on the bottom or top.

Please let me know what you think.
#24 by tylernt on 17 Jun, 2007 16:49
Quote from: "CoolAirVw"
My idea is this. The Main Mod shouldn't be #4 for Rod/head lube. The Main Mod should be put the bearing with 360 degree lube channel on the #3 to improve lube to lower main bearing and to lube 360 degrees of the thrust bearing.
That sounds much more reasonable than messing with main #4.
#25 by CoolAirVw on 18 Jun, 2007 17:35
myke_w talked to his source today and I talked to myke_w on the phone. The upgrade helps during times when the oil gets aerated. He may be posting a document from VW to demonstate. I'll let him answer any questions.

My goofy theory on putting 360 degree bearing on #3 was shot down. :roll:

Richard
#26 by jtanguay on 18 Jun, 2007 20:53
well this is all about learning man. i love learning! i'm glad that this info is coming out now that i'm rebuilding my bottom end
#27 by Barry W on 18 Jun, 2007 21:56
Quote from: jtanguay
well this is all about learning man. i love learning! i'm glad that this info is coming out now that i'm rebuilding my bottom end

Agreed, i'm learning as well. :wink:
#28 by myke_w on 22 Jun, 2007 14:05
Sorry I've been AWOL... busy as I've ever been and ready for calm.

Ok, So sorry to make everybody wait.

The history of this mod-

I worked under a guy who has been turning wrenches on VW's for over 30 years (dealer and independently) and he has always pumped doctrine into my head and I don't really question it, cause he has tons of experience on VW Audi only VERY rarely wrong, and that's usually good enough for me.

This is also one of those cases, I know it's an upgrade firstly because he told me so, secondly because AFAIK every gas 4 cyl motor past 83 had it fitted. Most diesels past 83 AFAIK also have it.

This change persists all the way through the 1.8 8v gas cars, the na diesel 1.6, turbo diesel 1.6, ecodiesel, 1.9td's, ALH TDI's, 1.8t's and into the TDI-PD BEW code. In other words, they aren't doing it by chance.

So, obviously I'd like to know why he told me this so I called him up. (He's old school and doesn't really do the computer thing so I'm as close as it gets to his word). In other words, I wanted to make sure my story is right.

He says,

The story goes back to the old 1600 beetle motor. Apparently on hard cornering, the beetle would momentarily lose oil pressure even though it wasn't low on oil. (I have no I have no idea about the 1600 BTW) so they decided to use grooves in the crank itself.. This apparently helps to purge air bubbles from the oil more quickly and would preserve oil pressure. Not sure what year this happened, a blank that needs filled in obviously.

In the early diesel and gas cars (pre-83) they had a lot of the same issues, in fact they apparently were wiping out mains and #3 rod especially and putting holes in the blocks with oil still in the motor, and the mechanics at the dealers could pretty much tell how the motor died by looking at the mains. If #1 rod was trashed, then they just straight ran it out of oil (#1 rod is furthest from the pump) the low oil thing was common because they had valve seal issues then too, and the motors consumed ALOT of oil. But if #3 rod was trashed then they knew it had to be an aeration related failure. In conjunction they'd see the cam bearings all scratched to hell occasionally. Apparently this became a big deal and they were having to warranty motors right and left.

So they started adding the #4 main 360 slot.

The theory is that because #4 main lubes #3 rod, and #4 main oiling hole comes off the main galley right under where the head ooiling hole takes off from the main galley, that it would be the most affected by a pressure drop because of air or any "other reason I suppose"(it has to compete with the head for oil supply). I think this is even more true as hydraulic motors came in, because if they starved for oil at the head, you get to collapse lifter. I also think this is one of the reasons they went to the 36mm gear oil pump.

EDIT: also for those who dont have 2 holes in the #4 journal, the slot allows lubrication to #3 rod 100% of the time rather than only 50%.

So,
I'm bugging him for dealer documentation to the techs for the 83 model year that he says explains the changes in models and why they did it, this I think will put the issue (it's roots at least) to rest.

The pure fact that every car since 83 had this upgrade (with a few possible exceptions) show that it's a factory correction. It's done for a reason. To not do it, seems to undo a correction they intended.

I'm not so sure on the theory about loading the bearing too much with a slot in the bottom, these cranks are wicked stiff. Add the fact that TDI PD's are rocking 180 lb out of the gate (way more in Europe) and they have the same bearing..

Anyway, I hope to post a copy of the documentation soon.

Hope I've helped...
#29 by kamyk1122 on 22 Jun, 2007 15:41
I would suggest newbielink:http://www.autopartsway.ca [nonactive]. They have great service. I always buy my parts from them.