Myriad issues on my car

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
I’ve determined my engine is on its last legs… here are my symptoms:
  • Oil in the vacuum lines
  • Oil in intercooler tubing
  • Blue smoke on startup
  • Leaks from block seals
  • Strange buzz when I get to full boost
  • Low oil pressure
The engine has always leaked but the symptoms have gotten much worse after this summer’s low oil pressure fiasco. My guess is that my turbo finally is giving up the ghost.

What exactly is going on here? I’ve never had such excessive oil leaks until now. Is there a way for the turbo to pressurize the vacuum system and pass oil into it?

There doesn’t appear to be any particularly bad blow by on this engine but that doesn’t explain the oil in the vacuum system. Is there a chance the vacuum system has a leak that is causing too much crankcase pressure?

Not really sure where to start here.
 
Last edited:

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
Oil in the cooler tubing doesn't surprise me...then again it depends on how much. Have you ever removed and drained the lower hose at the cooler itself? That's typically where the bulk of the oil will sit if you're not running some kind of external CCV system. I yearly check and drain of the cooler hose might be a good idea.

My 1Z in the 97 JIII leaks and was slated to have a major seal / gasket replacement that hasn't yet happened except for the oil pan gasket which did happen last oil change. But there's a slew of other gaskets that need changing as well.

The rubber seals get hard after a while and no longer seal the way they should. My pan gasket was so brittle but it was clear that oil was seeping past it.

If you can I would gently wash the engine to get rid of what you can and so you can observe what is actually leaking. There aren't that many points that can be leaking unless something is causing pressure to push oil out through the seals.

Good luck
Steve A
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
I had another go at it today.

I pulled the timing circuit all apart yesterday and found that the intermediate shaft seal was leaking, which was flowing back off the back of the block and hitting the axle which then flung the oil everywhere. It seemed like a ton of oil for that seal to be leaking but thankfully the other seals appeared to be dry.

The cause of the leak? I had tried a PTFE seal for the I-shaft… bad idea as I discovered several noticeable grooves in the shaft, probably from previous seals, which would probably never seal. I sanded down the sealing surface as best I could with fine grit sandpaper and fine steel wool and it’s definitely smoother. I then replaced the seal with a spring-type seal and all appears OK.

While I had the timing belt off I looked at the intermediate shaft bearing. It had a little visible wear at the typical places but zero play in any radial direction. The fit of the bearing was definitely not super tight but it was good enough for me to not feel the bearing is shot.

I have rod bearings and plastigage in hand, and will be replacing the rod bearings probably tonight. I still suspect the turbo is done, but I want to test and verify the oil pressure change before/after rod bearings. I will also test vacuum performance as it appears a leak can increase crank case pressure.
 

PassatLife

Well-known member
Joined
Jun 27, 2019
Location
Coquitlam, BC
TDI
1996 Passat Tdi Wagon
Intermediate shaft bearing is what killed the original motor in my B4 a few days after I bought it lol. It was the first thing I replaced on the donor AHU I swapped in. Cheap insurance, especially if you already have it apart. It's a ***** to do otherwise
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
Intermediate shaft bearing is what killed the original motor in my B4 a few days after I bought it lol. It was the first thing I replaced on the donor AHU I swapped in. Cheap insurance, especially if you already have it apart. It's a ***** to do otherwise
Did you pull your engine or trans to do yours? I have seen the one write-up that shows the process of removing the rear engine mount and tilting it down enough to extract the shaft. I am down to pull the engine but generally try to avoid making myself experience extra unnecessary pain.

Even so, it would only allow for replacement of the outer bearing. Inner bearing requires full tear down.
 

PassatLife

Well-known member
Joined
Jun 27, 2019
Location
Coquitlam, BC
TDI
1996 Passat Tdi Wagon
Did you pull your engine or trans to do yours? I have seen the one write-up that shows the process of removing the rear engine mount and tilting it down enough to extract the shaft. I am down to pull the engine but generally try to avoid making myself experience extra unnecessary pain.

Even so, it would only allow for replacement of the outer bearing. Inner bearing requires full tear down.
The motor came from a donor A3 so it had to come out regardless. Yeah I think that's the only way to do it with the motor in the car, the shaft basically goes right into the frame rail as it sits normally. AHUs are pretty easy to pull, not many things to disconnect.
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
One other thing that may or may not be of note is that there was visible wear, about the size of a pinky nail where the IMS had contacted the seal plate and worn a bit of the paint away. I'm not sure if that is normal or something questionable.
 

PassatLife

Well-known member
Joined
Jun 27, 2019
Location
Coquitlam, BC
TDI
1996 Passat Tdi Wagon
One other thing that may or may not be of note is that there was visible wear, about the size of a pinky nail where the IMS had contacted the seal plate and worn a bit of the paint away. I'm not sure if that is normal or something questionable.
That might point to play in the inner race/bearing, which as you mentioned requires a full tear down to access. I would install a new outer bearing as theyre cheap and take a few min to install. Check the shaft play with the new bearing and seal installed and go from there
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
Does it make sense to replace all the main bearings and leave the pistons/rings alone? I am not really sure if I want to go to the length of tearing the whole block down. I don't have reason to believe the rings are bad. The head is also functionally fine, if definitely worn.

As of now, my plan is to pull the engine, put it on the stand, pull the crank, replace / plastigage all the bearings on the rotating assemblies, and reinstall, basically. Is that a bad idea?
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
I‘ve seen people replace just bearings, with good results.

Not sure how much work would be saved, if you leave the engine in the car. Other than lowering just the right side, to pull the IM shaft, that’d be the worst part.

-Todd
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
I‘ve seen people replace just bearings, with good results.

Not sure how much work would be saved, if you leave the engine in the car. Other than lowering just the right side, to pull the IM shaft, that’d be the worst part.

-Todd
I considered that, however that would make it impossible to replace the inner IMS bearing. On the plus side it’s not hard to pull these engines.
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
Inner one doesn’t usually see much wear. Doing the work on your feet, does sound better, though…

-Todd
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
I see the inner bearing for the intermediate shaft is more culprit than the outer. I have to disagree, to only replace the outer Intermediate shaft bearing, as the inner bearing is the passthrough to the head for oil pressure. Besides, the bearings come in pairs. Don't throw away the inner!

You can lose a lot of oil pressure to the head from marginal wear on the inner bearing. Generally, the gear driven oil pump has enough problems without items like loose bearings adding to the problem. I have removed the shaft without removing the engine, but getting the bearings installed correctly becomes a real challenge. It's hard enough to get it done correctly on a stand.

I believe it was from VWVortex, there were some 1.8 20v rally enthusiasts (That engine also has a intermediate shaft) that modified the inner bearing with a radial slot. The idea is to get oil penetration in the bearing and improve the passthrough oiling. Although that does remove some bearing support material, it seems to improve life expectancy. It's a narrow bearing slot they cut. It does improve cylinder head oiling.

The outer bearing will wear, seemingly more, but I think it's just harder to measure the deflection for the inner bearing. Lack of oil pressure to the head is more telling measure of the inner bearing.

There is another place where an older engine will lose oil pressure; the cam caps. When rebuilding a cylinder head, one of the 'unknown improvements' we make is to check each cam cap for clearance. The valve springs push the cam up into the caps and although the head is durable, the cap will eventually, wear egg-shaped. The deflection can be measured with a dial indicator by installing the cam without lifters and cleaned of any oil, and pulling up on the cam. Our clearance goal is .0015"-.002". But my 'redneck technique', we use our bench belt sander to carefully sand the base of the cap in an 'X' pattern. Cross-hatch. When you can't feel any clearance when a single cap is bolted on at a time, and the cam spins freely, that is good. Advance carefully, as you can bind the cam. That trick alone raises oil pressure perceptibly.

Smoke at startup is most likely worn valve guides, if it's only a matter of a few seconds. If you blow blue for 15 minutes, it's likely rings. You haven't mentioned the mileage, but TDI's eat valve guides. They also don't suck oil through them, they just leak down the stem when shut off. You'll get that 'puff of blue' that generally clears up quickly.

As for rods and mains, we check before we dive in. But mileage is a big factor. Usually, a well maintained engine's rings will last 350-400k. The rod bearings, especially on the AHU's seem more fragile: 250k. Mains, same as rings. But each engine is different. Pull the #4 main and the #3 rod to check. Both main and rod bearings are TTY and not to be reused. I don't know the mileage of your engine, but that is another important factor. Check clearance between piston and cylinder wall and the end gap for rings. VW usually allows more than we think is reasonable. Max piston/ cylinder clearance: .0035". Max end gap: .024", and that's stretching it. New: .016" top ring.

My opinion of Plastigage... I don't use it. Journal bearings today are so accurate, they are measured in .00001". Measure the rod's big end diameter. Measure the mains. Measure the diameter of the rod and main journals. If your crank is shiny and smooth, it's most likely good. They are built like a diesel truck crank. Most of the time, we just check deflection and polish them. Be sure to clean out the crank's cross-drilled holes if you remove it.

We have all that stuff in stock. Can loan the seal driver, if you don't have one. We also offer some upgrade pistons, sized and balanced for incremental ring sizing. Audi makes a 79.51mm ring set. It's almost .003" larger. Hone to remove taper and out-of-round, and sometimes, the 'wear limit' rings fit. No boring necessary. We coat pistons up to .010", first oversize and match rings to fit.

My usual thought when rebuilding: "Where do I quit?" It's usually when everything is touched.

'Do It Once and Do It Right'
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
I see the inner bearing for the intermediate shaft is more culprit than the outer. I have to disagree, to only replace the outer Intermediate shaft bearing, as the inner bearing is the passthrough to the head for oil pressure. Besides, the bearings come in pairs. Don't throw away the inner!

You can lose a lot of oil pressure to the head from marginal wear on the inner bearing. Generally, the gear driven oil pump has enough problems without items like loose bearings adding to the problem. I have removed the shaft without removing the engine, but getting the bearings installed correctly becomes a real challenge. It's hard enough to get it done correctly on a stand.

I believe it was from VWVortex, there were some 1.8 20v rally enthusiasts (That engine also has a intermediate shaft) that modified the inner bearing with a radial slot. The idea is to get oil penetration in the bearing and improve the passthrough oiling. Although that does remove some bearing support material, it seems to improve life expectancy. It's a narrow bearing slot they cut. It does improve cylinder head oiling.

The outer bearing will wear, seemingly more, but I think it's just harder to measure the deflection for the inner bearing. Lack of oil pressure to the head is more telling measure of the inner bearing.

There is another place where an older engine will lose oil pressure; the cam caps. When rebuilding a cylinder head, one of the 'unknown improvements' we make is to check each cam cap for clearance. The valve springs push the cam up into the caps and although the head is durable, the cap will eventually, wear egg-shaped. The deflection can be measured with a dial indicator by installing the cam without lifters and cleaned of any oil, and pulling up on the cam. Our clearance goal is .0015"-.002". But my 'redneck technique', we use our bench belt sander to carefully sand the base of the cap in an 'X' pattern. Cross-hatch. When you can't feel any clearance when a single cap is bolted on at a time, and the cam spins freely, that is good. Advance carefully, as you can bind the cam. That trick alone raises oil pressure perceptibly.

Smoke at startup is most likely worn valve guides, if it's only a matter of a few seconds. If you blow blue for 15 minutes, it's likely rings. You haven't mentioned the mileage, but TDI's eat valve guides. They also don't suck oil through them, they just leak down the stem when shut off. You'll get that 'puff of blue' that generally clears up quickly.

As for rods and mains, we check before we dive in. But mileage is a big factor. Usually, a well maintained engine's rings will last 350-400k. The rod bearings, especially on the AHU's seem more fragile: 250k.
Unfortunately I don’t know the exact mileage as the cluster was swapped, but I estimate the engine has 400-450k based on the carfax, chassis and my arithmetic. I am surprised to hear that an AHU could eat its rod bearings in only 250k. That seems rather soon.

Valve guides definitely worn… puff of blue on startup but honestly the biggest concern was the oil leaks under boost. To me that could be rings starting to go.

Either way, engine is coming out this weekend and I’ll assess further what to do. @Franko6 I will reach out to you for the head work as it definitely is due.
 
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