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Discussion Starter · #1 ·
As I've been making the intermediate shaft bearing tool for some time now, I've also been looking closely at the VW oil system that supplies oil to the intermediate shaft bearings. An often overlooked part, that I've found well worn out in several examples, is the upper oil pump shaft bushing. (Pull out the vacuum pump and look down....it has the horizontal line across it, which is used to line up the oil port with the oil port in the block. This bearing/bushing gets oil before the oil gets to the filter.....if it is worn out, pressure will be quite low. A quick check is to remove the oil pump and look at the shaft. If it's scored/scratched near the end, the bushing is worse. It's a fast change.

The other issue I've found is the intermediate shafts themselves. They are cast into a mold and machined as needed. Between the bearing journals, you'll note a very rough finish and yes...the cam lobe for the mechanical fuel pump on the early Rabbits. (Same shaft as the gas engine, just a different gear on the end.) The disturbing thing is these shafts are not even close to being balanced. The cam lobe for the fuel pump was still part of the mold some 10+ years after they quit using a mechanical pump!

I'm working on another 1.6 diesel build, and will be putting an intermediate shaft on the lathe to remove the outdated cam lobe for a gas fuel pump. I'm looking to balance the shaft perfectly,a nd leave it with a polished surface the entire length....not just the bearing journals. I'll post some pics when it's done. PM me or post here if anyone wants a similar shaft made for them. I think a balanced shaft will add a lot more miles to the bearings....which admittedly will last 200,000 miles anyway, as long as the timing belt isn't too tight and proper maintenance is taken care of. But there's no substitute for doing it right.....
 

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i doubt the balanced IM shaft will have ANY affect on bearings.. you said it yourself, they often go 200k miles without issue..

OVER TIGHTENING the timing belt is WAY HARDER on the bearings than an unbalanced IM shaft.

a balanced/lightened IMshaft is in no way a bad thing. but its not going to be a very large gain either.. that shaft spins 3000 revs TOPS. cause our engines only turn 6k rpms. im sure it will help, no question. but how much?
 

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Discussion Starter · #4 ·
Part number is in the picture below....

As for benefits of balancing, I'll post results here. I'm wondering about engine vibration, and thinking th eintermediate shaft in stock condition may constribute significantly. An interesting point in this discussion, is that if you look at a Porsche intermediate shaft, it is completely finished/polished the entire length, and balanced. The VW one is obviously a case of cutting corners to save money and make the car more affordable...our camshafts are in the same boat, look between the journals and lobes. Rough and unfinished.

 

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Discussion Starter · #5 ·
and speaking of cost cutting.....if you look at the flywheel side of the block, just under where the vacuum pump or distributer in a gas version mounts, you'll see where the oil port was drilled in the block to supply the above bushing. They plugged the hole with a pop rivet. Never seen a manufacturer do that. Usually a pressed in steel ball, or tap it and screw a plug in. But this one is out of sight, out of mind???

I think the factory build can be improved.....
 

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I've rebuilt many of these engines and have found that wear of the oil pump bushing is very rare.

I think the unfinished quality of the intermediate shaft is due to the relatively low rotational speed. It might rotate 3000 rpms at most. I recently pulled an ABA intermediate shaft and it was milled smooth without any lobe. I may swap the gear and use it on a diesel, but I doubt I'll notice the difference.
 

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Discussion Starter · #9 ·
I've seen several diesels at around 200,000 miles, that had regular service intervals, where the intermediate shaft bearings were worn excessively. I suspect that at a minimum, a properly balanced shaft would let the bearings go for 300,000-500,000 miles with normal oil changes done properly.

As for the oil pump shafts and the bushing....below is a pic of an oil pump I just pulled out of a 1987 VW Golf, 1.6 NA diesel, engine code ME. 144,000 miles, previous owner was the wife of a VW dealership owner. (Maintained by the dealer, by the way, glove box had all documents going back to day one.) Vehicle was used for mainly city driving it's entire life. Note the oil pump shaft is well worn at the bushing, and scored fairly well. The bushing I have yet to pull out, but from what I can see it is toasted. This car recently had the oil pressure warning buzzer going off at a hot idle. I usually find such wear is normal on engines at the 220,000 mile + range.

 

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Discussion Starter · #10 ·
I'm a bit amazed about the comment regarding 3000 rpms at most.....so suggesting that balancing isn't likely important? A diesel truck engine these days red lines around 2100 rpm, yet balancing the rotating assembly is mandatory in the manufacturing process. By doing so, Detroit Diesel and Cat can recommend swapping the main and rod bearings at mileages like 500,000 miles, and doing a complete inframe at 1 million miles....or more.

Vw made these engines as conversions from their gas counterparts, and keeping the production cost down was imperative. To keep these cars going another 25 years, I think it would be prudent to build them right when they are rebuilt. Ever weigh the pistons on one and discover they are a couple ounces different? The engineering Germans were noted for simply isn't here. They know how to do it, but the idea was to make the car affordbale, and yet last long enough for the average car buyer. The rivet blocking the oil port is an amazing example of this. You wouldn't find that on a Porsche 930 Turbo from the same era. Or how about a cam not riding in bearings, but raw aluminum? (1972 Honda motorcyles used that method...and they were known to be the weak spot in their engine!)

A smuch as I lik ethese engines, they are basically defective from th efactory and there is a lot of room to do it right. My 1986 1.6 diesel with a balanced rotating asembly never ran so smooth as it does now. In fact, I thought something was wrong after the rebuild because the dash didn't shake at a slow idle. First one I have ever seen not do that.....
 

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What is the mic difference on that pump shaft between the worn and unworn area? Regardless I've got a crate full of high mileage oil pumps that look better than that one. There is no side load on the oil pump shaft and the radial play with old vs. new bushing is usually not measurably different.

I was not saying that balancing the intermediate shaft was a bad idea just that the effect on overall engine performance will be negligible. Even with the gross lobe and unfinished surface, the fact that the imbalance is so close to the center of the shaft and the shaft spins at 1/2 crank speed means that the imbalance will have several magnitudes less effect than an imbalance in the rods or pistons. The effect of balancing the crank rotating assembly would have a far, far more significant effect on overall engine vibration. Balancing the injector pop pressure to within 5 or 10 psi will also have a significantly greater effect on engine vibration as opposed to just swapping stock shims to get within 71 psi. All that said, there's only benefit to be had. If you've got the time/skills/money then have at. Good luck with your project.
 

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Discussion Starter · #12 ·
My daily driver is completely balanced......injector pop's as well.....it's a completely different engine. I actually did it simply because I found the pistons so different in weights, and had time to play with getting it right. Really opened my eye's to how these engines 'should' run. As I mentioned, the dash doesn't vibrate even at a slow idle, and it's just plain smooth.

The oil pump shaft.....I suspect a bad vacuum pump is the cause, or else too many cold/dry starts. That shaft gets oil almost immediately. (Supplied with oil pressure before the oil gets to the fliter flange.) There's also the lower shaft bushing, which usually looks goog and doesn't do much. It's lubed only by the oil splash, or oil running down the shaft. Both are a simple 5 minute swap once the oil pump is out, so I always do them both.

Low oil pressure issues are not always the intermediate shaft bearings.....I find it is often a case of both the shaft bearings as well as this upper shaft bushing, as well as the vacuum pump oil seal. (Usually a worn vacuum pump....wobbling a bit.)
 

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Diesel and gas intermediate shafts

I was wondering if I can take an intermediate shaft from a ABA engine, change the gear on the end and use it on my TDI? I have a 97 jetta TDI AHU and I'm in desperate need for an intermediate shaft. Any suggestions?
 

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Discussion Starter · #14 ·
Not sure...I'd have to look at a TDI intermediate shaft. If it's the same dimensions as the earlier ones, then you could just press the gear off the older style and press on your gear.

Also, if yours doesn't have the extra lobe on the shaft like the earlier ones did....a throw back to the early gas engines that used the lobe for a mechanical fuel pump.....you might have to have that machined off for clearance.

Post a picture of your shaft here, and measure the overall length, plus the diameters of the bearing journals. Also measure thelength of the area on the shaft the gear takes up.

If the bearing journals are the same as the older style (Distance betweeen them) and the overall length is the same or longer, it is a possible retrofit. If the bearing journals are larger on the older style, they can be machined down easily enough.

It would be far cheaper to obtain one from a VW salvage yard....you might call Parts Place at 248-373-2300 and see what they have.
 

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Discussion Starter · #15 ·
If your part number on the shaft is 028115017E, I found it here: http://www.jimellisvwparts.com/products/Intermediate-shaft/5145217/028115017E.html

Wow....$439.00!

The good news.....it shows on that page the applications it fits. Scroll down and it shows it fits the 1995-1999 1.9 TDI engines as well, including the AHU. If that is correct, it is the same shaft as the older 1.5/1.6 and 1.9 AAZ engines. That would suggest the oil pump gear is the same and it should be a perfect fit. Double check by measuring what you have.....I have a used shaft here well within factory specs on the journals. The journals are within .001" of the factory maximum diameter, and so they are like new. $75 + $10 shipping if you want it. I can machine off the lobe that VW left on these earlier modles for $20 extra.
 

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I cut the lobe off the IM shaft before my last build. I didn't notice a difference. The thing I worried about was with close to 100psi cold when I first rebuilt before everything wore in was, cutting it to balance it was also taking away material that is driving the oil pump. It was broken in by winter so I didn't see to crazy high oil pressure. I think it stayed around 80psi...I forget. But to drive the thick oil I didn't cut much off that IM shaft. I will find a pic somewhere, it has been 4 or 5 years ago.

My machinist told me that every VW rotating assembly he has ever balanced was +- 5 grams stock. On the flipside, he said most SBC he balances are +-40 grams...last week he had one that was 60 grams off nuetral.

The dealer told me those bushings were NLA, when I asked him last year??? I will have to ask again.

Found them:

 

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Discussion Starter · #17 ·
I think the biggest noticeable difference will be in the life of the bearings...

The intermediate shaft itself is way past 60 grams out of balance, until you get rid of the useless lobe. It should have been originally built with some weight to counter it. And I wouldn't worry about reducing any strength....the oil pump shaft itself is only 14.25 mm's in diameter.

Oil pressure...you should get 100 psi + at a cold start. Particularly on a 40 degree morning, you should see 100-120 psi. That's why we don't use those orange filters.....or other cheap versions. They can inflate and pop.

I see the largest out-of-balance engines coming from the 1980-1992 engines, particularly the rods. What's frustrating, is you will find 3 pistons perfect....then the fourth one is a couple grams lighter than the other three. Crankshafts have been really good. The worst is the intermediate shaft followed by the rods.

SBC's.....usually far worse than a VW, but the GM 151 engines are incredibly close. I haven't done a comparison over German built vs Brazil or anywhere else....I suspect therein lies the differences. I have noticed very different casting qualities on the supposedly same parts.
 

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I think the biggest noticeable difference will be in the life of the bearings...

The intermediate shaft itself is way past 60 grams out of balance, until you get rid of the useless lobe. It should have been originally built with some weight to counter it. And I wouldn't worry about reducing any strength....the oil pump shaft itself is only 14.25 mm's in diameter.

Oil pressure...you should get 100 psi + at a cold start. Particularly on a 40 degree morning, you should see 100-120 psi. That's why we don't use those orange filters.....or other cheap versions. They can inflate and pop.

I see the largest out-of-balance engines coming from the 1980-1992 engines, particularly the rods. What's frustrating, is you will find 3 pistons perfect....then the fourth one is a couple grams lighter than the other three. Crankshafts have been really good. The worst is the intermediate shaft followed by the rods.

SBC's.....usually far worse than a VW, but the GM 151 engines are incredibly close. I haven't done a comparison over German built vs Brazil or anywhere else....I suspect therein lies the differences. I have noticed very different casting qualities on the supposedly same parts.
GM 151? the famous 3.0L 4 cylinder? the UPDATED iron duke? those things run SMOOTH for a HUGE 4 cylinder...
 

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Yes I know the oil pump shaft is roughly 14mm and so was the cast section of my IM shaft when done. I can still see the casting numbers in it as I didn't cut it much. BUT the oil pump is made of steel and probably a high carbon steel... and the IM shaft looks like ductile iron and for sure it is cast, so it will be the weaker of the parts being driven. I could mic them both as I have them out if anyone is curious. It wasn't a problem last engine, but I wouldn't want to make it a problem I guess is what I was trying to convey. No big deal, just something else to think about before cutting it down to nothing and having it snap on a cold winter day.
 

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Discussion Starter · #20 ·
I think you're correct....the weak point is likely the cast iron shaft. (Or the gear at the end of the vacuum pump, or distributer in the gas models) I've never seen one break. I doin't think even the turbo diesel makes enough power to worry about it. Keep in mind it's the same shaft on the 16 valve gas engines, with what....double the horsepower? 14 mm should still be plenty strong for those cold mornings with 100psi+. I never drive off till the oil gets warm enough and drops down to 80 psi, and then I still keep the rpms down until it gets fully warmed up.
 
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