UNCHAINED 2005 Passat TDI lost oil pressure?

Hello all,

I just walked in the door from a 120 mile tow truck ride.

Our 2005 TDI Passat wagon has 140K on the clock, and received the gear drive upgrade at 90K. I am religious about my oil changes and other maintenance.

I was driving home from a weekend in central Oregon, when the "OIL PRESSURE" warning announced itself on the display. We pulled over and checked the oil, which was right about where it normally is on the stick.

The engine gave no other indications of low oil pressure (knocking or valve train noise). HWY 97 in Bend doesn't have full-width shoulders, so I drove it about a mile further to the next exit and called AAA for a tow. While I was exiting, the STOP warning appeared and the car suddenly seemed to go into limp mode. We had almost no power, and it acted like the wastegate on the turbo was stuck open. Am I correct in assuming that there is a limp mode?

Once the tow truck arrived, I had to move the car to an adjacent lot where he had room to load us up. The car now behaved normally, with no indication of low oil pressure or limp mode.

Has anyone with an un-chained TDI experienced this? Is it possible that the oil pressure sensor could be suspect?

The only way to check is to remove the sensor and screw in a pressure gauge. Could also be the hex drive shaft on the oil pump.

Good luck.

1854sailor said:

The only way to check is to remove the sensor and screw in a pressure gauge. Could also be the hex drive shaft on the oil pump.

Good luck.

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Thanks. I was hoping that the gear-drive mod took care of this. I have a call in to my TDI guru.

They still have hex shafts in them

JFettig said:

They still have hex shafts in them

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Isn't this only an issue if the lash isn't set correctly?

Sorry to hear about that Dave. Same thing happened to me this time last year, except I didn't get a limp mode. And I had 56-57k miles on my geared BSM.

Mine happened one morning on the way to drop the kids off at preschool. The alarms didn't start beeping until several seconds after start-up - long enough that I was already out of the driveway. I think someone here suggested there is a 10-15 second delay upon start-up for system checks before the ECU will throw the alarm about no oil-pressure, so that might be what happened when you re-started the car to move it for the tow-truck.

Rather than shut-down immediately, as I should have, I drove about 6-7 houses before I could safely turn around, and then I drove back home and even thought ahead enough to reverse into the garage to make tow-truck job easier. After having it towed to my local 'guru', he ran it briefly a time or two again to get pressure gauges on it to confirm it wasn't a sensor issue. I now have 13k on it after balance shaft delete and apparently no harm/no foul having run it a little while after the OIL PRESSURE and STOP warnings. I feel I dodged a huge bullet there.

After reviewing the geared BSM upon removal, the hex shaft was indeed worn. A couple of the hex corners were sheared so about half of it was rounded smooth and the other side still had the corners.

The last time I drove it the day before, I ran a 13 mile errand and as I was exiting down the highway ramp and turning left at the green light I got a jolt that felt like I hit a pot hole in my front-right. Went back a few weeks later and there was no pothole or uneven pavement there. Not sure if that was when the BSM moved or the hex shaft finally sheared so the oil pump would spin freely, or any other correlation. Odd thing though was I continued a mile or so to the store, and then a 13-15 mile circuitous ride back home with one more brief stop on the way, and got no oil pressure warnings during that time. So perhaps the jolt/pot-hole is a totally unrelated issue. I just mention it for the knowledge bank here.

Hope it works out for you. If no damage from running it without oil pressure, I highly recommend the BSM delete option. It will put your mind at ease, add some MPGs, and your car will be peppier too. And a tune (if you don't have one) will compensate some for any added vibes, and makes it a lot more fun to drive.

newlitemotorist said:

Isn't this only an issue if the lash isn't set correctly?

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That is one theory for the hex shaft on the geared BSM when installed. But keep in mind that the hex shaft was the original problem on the original chain driven BSM, before the chain & tensioner problems started to surface after about 80k miles. I think those hex shaft failures on the original chain driven BSMs also started showing up around 50k miles.

The jolt was not the shearing of the pump shaft and driving it without oil pressure, even for a very shirt time, is a very bad idea. When an oil pump fails, you have about 30second ay highway speed before the engine destroys itest. The damage starts amlost instantly when the preasure goes away. I guarantee there is wear on those connecting rod bearings, even if it was only driven 6-7 houses. Maybe not enough to make the engine knock but is sure dectrased its life by a lot.

newlitemotorist said:

Isn't this only an issue if the lash isn't set correctly?

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You are correct!
A hex pin will wear out if it is fed by a pulsing power source whether it be loose chain or loose idler gear!
Anything pulsing like that will wear out something like an impact socket does!

Probably a less than a year after I purchased the car and probably 170K miles prior to going chainless, I once had the oil pressure and stop warning message come on while making a sharp turn on a highway ramp.

It was so long ago I can't remember if the message went away prior to pulling over and shutting off the engine. I'm thinking that it must have gone away on its own as I don't think I would have turned the car on again after that kind of message.

I do remember taking it to the dealer and they didn't find anything. It never happened again before or after the balance shaft delete so I'd say a false alarm is possible. Loose or corroded contact at the sender maybe?

imo000 said:

The jolt was not the shearing of the pump shaft and driving it without oil pressure, even for a very shirt time, is a very bad idea. When an oil pump fails, you have about 30second ay highway speed before the engine destroys itest. The damage starts amlost instantly when the preasure goes away. I guarantee there is wear on those connecting rod bearings, even if it was only driven 6-7 houses. Maybe not enough to make the engine knock but is sure dectrased its life by a lot.

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I have to disagree. At low speeds and loads a couple drops of oil lasts along time. It will be the sitting and restart that will cause the wear as the oil is now totally lost.

Thanks for the input, everyone.

I'm betting on a stripped hex drive, as oil pressure at idle seems fine.

It's heading to Portland via flatbed, to our local TDI Guru.

I'll post updates as I receive them.

Whispers...


"Delete"

Windex said:

Whispers...


"Delete"

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Just Whispers ....?

So here's the question: Do we have people who don't know what they are doing, replacing BSMs and not adjusting gear lash, or is there something else going on? In the last couple of weeks its become aparent to me that there seem to be a number (presently unknown) who haven't been able to get a lot more than 50,000 on a geared BSM.

the instructions seem pretty clear. When I did mine, I had my son use a wood block to push the gears together. There was enough force that tension was reduced on my engine support bracket and the engine moved up a few inches. I'm now at 115,000 post BSM, so i guess I did it right. ( I hope)

johnboy00 said:

So here's the question: Do we have people who don't know what they are doing, replacing BSMs and not adjusting gear lash, or is there something else going on?

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Well that's the million dollar question, and it's been discussed with no clear answer (that I'm aware of anyway).

Some here think the only way the hex shaft can fail on geared BSM is if gear lash is set wrong on installation.

In other threads, other folks here have opined that the hex shaft design itself has always been flawed and the hex shaft can fail irrespective of gear lash on installation (i.e., wrongly set gear lash can cause hex failure, but it can still fail even when gear lash is set correctly).

As I recall from other threads, the hex shafts were failing around 50k on the OE chained BSMs before the issues began popping up with the chain stretching, sprocket, tensioner, etc. that caused people to switch to the geared BSM. Same pesky hex shaft design.

Seems reasonable to me that a properly installed geared BSM could still experience a hex shaft failure. Parts do fail in real life, even if installed properly.

Would love for any of the 'gurus' here who know for sure a geared BSM was installed correctly to say unequivocally whether they have/have not seen a hex shaft failure.

Backlash: http://en.wikipedia.org/wiki/Backlash_%28engineering%29
I learned something today.

Thanks for all of the replies.

Still waiting on our TDI guru to call us back whenever he gets it apart.

I'll give updates as more information becomes available.

Ther is a good chance it is the oil pressure switch gone bad.

I've heard of (but not seen personally) of hex shaft failures on CBEA engines, which were geared from the factory. The "upgrade" to the BHW is essentially just installing CBEA-type parts. So I guess, technically, even if it was installed correctly, there is a potential for failure.

However, I've not had any that I have done fail that I am aware of, and some of these have already been back through here 100k miles later for timing belts. I've had a couple that have been back for another timing belt just this year. One is nearing 350k miles, the other has got to be well past 400k miles by now, and I think that one I dechained around 160k when it's tensioner blew apart.

I get the preload on the intermediate gear TIGHT, as tight as I can push it, I push so hard the engine wants to shift to the side so I have taken the extra step to wedge a block of wood between it and the body rail on the side by the turbo.

You can buy just the hex shaft by itself, and you can swap this easily enough once the oil pan is down (you don't even need to disturb the timing belt, oil pump, or BSM). There is a tiny little circlip in front, and the inside of the hex shaft has a threaded hole you can use to screw something into to get a grip to pull it straight out the front. Then just slip a new one in. However, if the inside (female) part of the hex in the #2 balance shaft is badly rounded out, a new hex shaft won't buy you much time, if any. And unfortunately, the only way you can buy a #2 balance shaft is part of the whole assembly.

If I see one that does, this, though, I am going to try and weld the hex into the balance shaft, which will require a bit more disassembly but I think I can do it.

Any news OP?

Welding the shaft into the shaft sounds like a thought but it may need the little movement in order not to shear or crack the weld. I used a product about 15 years ago on a damaged camshaft to repair the drive gear rather than replace it saving about 3 grand. Its still running fine today. Check out their site...

http://www.belzona.com/en/products/1000.aspx

thundershorts said:

Welding the shaft into the shaft sounds like a thought but it may need the little movement in order not to shear or crack the weld. I used a product about 15 years ago on a damaged camshaft to repair the drive gear rather than replace it saving about 3 grand. Its still running fine today. Check out their site...

http://www.belzona.com/en/products/1000.aspx

Click to expand...

I agree very good product!
Comes to turn into like iron that you can drill or tap
I think the long end of a high quality 6mm allen key would be the real fix!

oilhammer said:

I've heard of (but not seen personally) of hex shaft failures on CBEA engines, which were geared from the factory. The "upgrade" to the BHW is essentially just installing CBEA-type parts. So I guess, technically, even if it was installed correctly, there is a potential for failure.

However, I've not had any that I have done fail that I am aware of, and some of these have already been back through here 100k miles later for timing belts. I've had a couple that have been back for another timing belt just this year. One is nearing 350k miles, the other has got to be well past 400k miles by now, and I think that one I dechained around 160k when it's tensioner blew apart.

I get the preload on the intermediate gear TIGHT, as tight as I can push it, I push so hard the engine wants to shift to the side so I have taken the extra step to wedge a block of wood between it and the body rail on the side by the turbo.

You can buy just the hex shaft by itself, and you can swap this easily enough once the oil pan is down (you don't even need to disturb the timing belt, oil pump, or BSM). There is a tiny little circlip in front, and the inside of the hex shaft has a threaded hole you can use to screw something into to get a grip to pull it straight out the front. Then just slip a new one in. However, if the inside (female) part of the hex in the #2 balance shaft is badly rounded out, a new hex shaft won't buy you much time, if any. And unfortunately, the only way you can buy a #2 balance shaft is part of the whole assembly.

If I see one that does, this, though, I am going to try and weld the hex into the balance shaft, which will require a bit more disassembly but I think I can do it.

Click to expand...

when I done mine I pushed and jacked till I was blue in the face
Always found some slack in the gears very frustrating!
Wound up snugging the idler bolt up some and then tapping it sideways with a stick and hammer until I achieved 0 backlash and then torqued the bolt
Would the #2 balance shaft from a chain unit not fit a geared unit?

This thread makes me glad I got a geared unit with a reinforced hex shaft socket from Powermaxx engineering. It must be a common problem on these 2.0 engines with balance shaft modules, otherwise I find it hard to believe that a machine shop would spend the time and effort on tooling for a project that was not a common concern. Deleting it seems like an option, but not one I liked,as my tool and die making father told me, vibrations can do nefarious things. From what I have ascertained, four cylinder engines need balance shaft units from 2 liters on, as the 2nd order vibrations are to harsh. Honestly though, I am just a nursing student, not a mechanical engineer.

I remember i used a C clamp of some sort to hold the gear in place while tightening as I felt it was a more positive method than the push technique. Also checking after tightening to have zero clearance is a good idea as well.

oilhammer said:

I've heard of (but not seen personally) of hex shaft failures on CBEA engines, which were geared from the factory. The "upgrade" to the BHW is essentially just installing CBEA-type parts. So I guess, technically, even if it was installed correctly, there is a potential for failure.

However, I've not had any that I have done fail that I am aware of, and some of these have already been back through here 100k miles later for timing belts. I've had a couple that have been back for another timing belt just this year. One is nearing 350k miles, the other has got to be well past 400k miles by now, and I think that one I dechained around 160k when it's tensioner blew apart.

I get the preload on the intermediate gear TIGHT, as tight as I can push it, I push so hard the engine wants to shift to the side so I have taken the extra step to wedge a block of wood between it and the body rail on the side by the turbo.

You can buy just the hex shaft by itself, and you can swap this easily enough once the oil pan is down (you don't even need to disturb the timing belt, oil pump, or BSM). There is a tiny little circlip in front, and the inside of the hex shaft has a threaded hole you can use to screw something into to get a grip to pull it straight out the front. Then just slip a new one in. However, if the inside (female) part of the hex in the #2 balance shaft is badly rounded out, a new hex shaft won't buy you much time, if any. And unfortunately, the only way you can buy a #2 balance shaft is part of the whole assembly.

If I see one that does, this, though, I am going to try and weld the hex into the balance shaft, which will require a bit more disassembly but I think I can do it.

Click to expand...

Oil Hammer - You did my chainless conversion in December of 2009, and I have put 98,000 miles on mine. Two days ago my oil pressure warning came on along with the STOP warning. It would only come on above 1500 rpm. During evaluation, I found that the turbo is probably toast, as it barely is able to turn by hand. It is good to hear that just the hex shaft can be replaced, as I had thought that one could replace just the oil pump, now finding out that is not the case? I would have to replace the whole BSM assembly? What a poor design. Any info on the BSM delete option?
After I drop the pan and pull the hex shaft, I will post pictures .

Thanks for any info you can provide!

Just to update everyone who has helped thus far - The hex shaft in the geared BSM did get rounded off, hence the oil starvation to the rest of the engine. Fortunately, I did not run it long and the only thing that is toast is the Turbo. Now to order the delete kit and an upgraded turbo...

rksiewert, dont recall ever seeing other TDI wagons in the area, have you had been in the area for a while? I possibly have a customer for your take off parts if the only damage is to the oil pump driveshaft

So did the shaft destroy the BSM. What I'm wondering if the shaft wore on the BSM side. I'm in the process now of changing mine and got a BSM from Ireland with a re-done hardened hex slot in the BSM side. Hope I explained this well.

oops, wrong thread... I meant to reply to your other thread...