BRM Cam Failure

[aNUT]

First I've seen of the BRMs having valve train issues. The car in question is an '06 w/ 100K miles; Castrol TXT and SLX its whole life w/ 10K mile OCI.

The worst of the wear is on the #3 exhaust lobe. All other lobes are worn as well, though not to the degree #3E is. They all have a distinct edge on the trailing face of the lobe. They are wearing from parabolic to trapezoidal in shape.

The exhausts are worse than the intakes due to the increased pressure. The injector lobe on #3 has a pretty good divot in it, though all rollers are in good shape, including #3. Lifters all appear to be in OK shape, though all will be replaced when the cam goes in. The cam bearing shells are all fine.

The car as making a 'bupping' sound with no performance issues when it was brought to me. Upon removing the upper intake pipe @ the EGR, it was apparent that exhaust was getting blown back into the intake and making the noise. I believe that #3 was not fully emptying on the exhaust stroke because of the decreased valve lift. This gas remained traped until the intake valve opened on the intake stroke; at which point it vented into the intake.

Now the pics...Full sized images available by clicking the pic.

#3 exhaust lobe from above


#3 injector lobe


Another angle on #3E


EDIT 2.27.09 There are many more pictures on page 3.

EDIT 2.15.09 for ease of reference, torque specs and parts list have been moved to the first post.

BRM cam R&R parts list:

1x Cam - 038 109 101AH
8x Followers - 038 109 309 C
1x Valve cover gasket - 03G 103 483 D
1x Camshaft Seal - 038 103 085 C
10x Bearing - 038 103 673 B GLB
10x Journal cap bolt - 038 103 714
1x Tandem pump gasket - 038 145 215
8x Injector rocker bolts - 038 103 714 A
1x Oil cooler* - 068 117 021B
1x lower cooler gasket* - 038 117 070
1x upper cooler gasket* - 038 117 070 A
*These part numbers are for the ALH cooler which is identical from everything I can tell, but much cheaper than the BRM
1x Oil filter 071 115 562A
5l Oil
2l coolant ZVW 237 G12


It's a good idea to R&R and clean the oil pan as well. Also a good idea to remove the oil from the pools at the front of the head.

The above list does not include rockers, as these were not worn in my case.

Pertinent torque specs for a BRM cam R&R:
All torques are in ftlbs unless otherwise noted.

Always replace bolts are bold.

Oil pan: 11; seal pan with a thin bead of RTV.
Oil pan to tranny: 44
Oil cooler cap: 18
Journal Cap: 71inlbs + 90deg.
Rocker arm axle: 15 + 90deg.
Timing belt tensioner nut: 15 + 45deg.
Large tandem pump to head: 15
Small tandem pump to head: 7
Valve cover: 7

Valve cover tightening sequence:
___10__ 5___ 4___ 8___
1___________________2
13_________________12
9___7___3___6______11

Cam hub to cam: 74
*it is essential that the taper fitting is clean and deburred. Brake cleaner and a rag works well.
Cam sprocket to hub: 18

If I left something out, PM me, and I'll look it up and edit this post.
__________________

 

[kcfoxie]

I'll be the first to ask.

Did they use Biodiesel?

 

[TDI 4 RD]

Similar question: What typically causes something like this? If the correct oil was used, then does mean the excessive wear is a manufacturing issue? Thanks.

 

[oilhammer]

I think slowly the truth is coming out that the PD's skinny cam lobes needed to make room for the injector rockers' lobes is just a weak design.

I will say that I just did a cam and lifters in a BHW that had 244k miles on it, and it had less wear than the engine shown above but the nature is similar. It also had its worst wear on that same lobe, #3 exhaust. It had .075" or so worn off, the rest had .015" to .020" worn off, with only one at .006".

In contrast, at its SIXTH timing belt changeout at 360k miles, I measured my Jetta's cam lobes and found less than .002" wear in comparison to a brand new one.

So clearly the skinny lobes are not good.

FWIW, the new lifters are a different finish...kind of a blackened finish like you see on gun barrels. Not sure if that will help or not. I would have thought the BRMs would have already been equipped that way...guess not?

 

[kcfoxie]

The bigger question is, are there suitable after market replacements for when this happens?

 

[OsirisTDI]

Are you able to measure the PD injector cam lobe during the timing belt change?

 

[oilhammer]

Are you able to measure the PD injector cam lobe during the timing belt change?

On the BEW and BRM it is easy to get the valve cover off. Not so on the BHW. Only way I have found to get the BHW's cover off it to remove the cam sprocket, and even then it is pretty tight against the intake.

However, during a timing belt service it is not difficult to remove the cam sprocket of course.

 

[airwolf]

Did they use Biodiesel?

Other than contamination of the oil with Biodiesel, I do not understand how using Bio would cause this as certified B5 is supposed to be okay to use in these cars.

The car in question is an '06 w/ 100K miles; Castrol TXT and SLX its whole life w/ 10K mile OCI.

Where was the main place of service for the car. Not to jump on the dealer bandwagon, but if it was serviced at a dealer, how can you really be sure that the correct oil was used?

I guess just for peace of mind and insurance, it would be a good idea to pull the valve cover when changing the timing belt to see what the extent is of the wear on the lifters/cam for all PD's.

 

[OsirisTDI]

If my air filter looks like this at 31k miles, should I worry about cam lobe wear, or, just keep driving it? I've had Castrol SLX OCI @ 5k, 10k, 20k and 30k.

 

[VeeDubTDI]

What does a properly functioning air filter have to do with cam wear?

 

[OsirisTDI]

It looks like soot over the filter. If there were an issue with exhaust valve timing, would there be soot in the photo from the EGR?

 

[meganuke]

Stop drafting city buses and you wouldn't have so much "soot" on your air filter.

 

[VeeDubTDI]

Perhaps you shouldn't tailgate your local city buses.

 

[BlueCTTDi]

soot on the air filter?

Is there some kind of performance mod I don't know about that involves connecting the exhaust pipe to the intake snorkel?

 

[kcfoxie]

Other than contamination of the oil with Biodiesel, I do not understand how using Bio would cause this as certified B5 is supposed to be okay to use in these cars.


Where was the main place of service for the car. Not to jump on the dealer bandwagon, but if it was serviced at a dealer, how can you really be sure that the correct oil was used?

I guess just for peace of mind and insurance, it would be a good idea to pull the valve cover when changing the timing belt to see what the extent is of the wear on the lifters/cam for all PD's.

Well, it seems to be just heralded as fact that anything over B5 is going to cause premature lobe wear due to oil dilution. Hence why I wanted to be the first to ask, do they use high concentrations of biodiesel?

(Come one, dude, I ran B100 for 60k miles in mine and only due to cost have switched back to petrol, I'm asking to either verify or debunk the myth).

 

[Bob_Fout]

soot on the air filter?

Is there some kind of performance mod I don't know about that involves connecting the exhaust pipe to the intake snorkel?

Hot air intakes improve MPG

 

[aNUT]

I hope to have more of this this evening after I get the cam out, and chat with the customer a bit more...hopefully I'll have some pricing info for him. BRM valvetrain parts are tough to track down for a reasonable price.

Oilhammer - I chatted with frank06 yesterday...man that guy likes to talk! He told me about the new blackened lifters, stating that my price through WorldPAC was the incorrect part, despite the part numbers matching. I did a bit of digging, and I was able to uncover this technical bulliten from Federal-Mogul. It won't help me get them any cheaper, but at least I know what I'm looking for.

I'm disappointed in the A5 Bentley, as it lacks any machining specs or limits. (valvetrain, head, block, or otherwise.) As such, I won't be able to quantify how much wear we're looking at on the lobes until I have a new camshaft to measure against.

I'll ask about biodiesel. I suspect not, and he was on diesel when he came in, but we'll see. Also, not to get off track, but BD is prohibitively expensive for most here; $4.50/B20, $6.70/B100.

The owner did all his own maintenace, with the exception of a few things he did not have the equipment for. He did he own TB properly, brake pads & fluid, trans oil, etc. It looks like a very well taken care of car otherwise.

 

[VeeDubTDI]

soot on the air filter?

Is there some kind of performance mod I don't know about that involves connecting the exhaust pipe to the intake snorkel?

That's the new EGR upgrade for fewer emissions. Unfortunately, it seems to destroy the cam.

 

[BlueCTTDi]

maybe i missed it from reading up above, but was the car chipped or otherwise modded?

 

[VeeDubTDI]

Well, it seems to be just heralded as fact that anything over B5 is going to cause premature lobe wear due to oil dilution. Hence why I wanted to be the first to ask, do they use high concentrations of biodiesel?

(Come one, dude, I ran B10 for 60k miles in mine and only due to cost have switched back to petrol, I'm asking to either verify or debunk the myth).

Oil dilution causing poor lubrication!? That's impossible!! Biodiesel has superior lubricity!

 

[kcfoxie]

I'll ask about biodiesel. I suspect not, and he was on diesel when he came in, but we'll see. Also, not to get off track, but BD is prohibitively expensive for most here; $4.50/B20, $6.70/B100.

4.50 isn't a bad price, but if D2 is $4 I can understand not wanting to throw the extra money behind it. Do ask tho, as I'm keenly interested in seeing how paranoid VW is in their dilution testing.

Oil dilution causing poor lubrication!? That's impossible!! Biodiesel has superior lubricity!

I didn't say impossible, I said I don't believe that it causes THAT much freaking wear over the course of the life of Good Oil (not that my car has seen Castrol since it left the factory, Motul or Elf exclusively for my little gem).

However, if this failure is from a never used B-anything other than the B5 the car shipped with from Mexico... well, looks as if one way or another the cams will fail and using Bio won't necessarily increase that risk. We'll see, I'm nearing 100k.

I'll listen for a 'bupping' noise and have Gerich @ ApexTuning yank the valve cover off the car at 100k (5 months out?) when the belt gets replaced and compare it to this. I ran B100 for 60k of 66k miles thus far, so the comparison should be interesting.

 

[oilhammer]

Is there a date on that FM TSB? I did not see one. If this update happened post 2006 model year, then maybe ALL PDs could benefit from an upgraded part at some point and time.

I have to say though, as of right now the only source for these is through Volkswagen, and they are NOT cheap. You also need cam bearings, and all the stretch bolts for the cam caps as well as the injector rocker mounts, and the tandem pump gasket. And of course the cam, which as I understand may be available for the BEWs aftermarket, but not for the BHW (and they are different). Unsure about the BRM.

 

[dieseldorf]

and I was able to uncover this technical bulliten from Federal-Mogul.

a, this is an interesting find. It begs the question: how many others will have near-term failure with the original lifter

 

[aNUT]

The car in question is completely stock.

BioD has superior lubricity compared to ULSD; but is a far cry from that of a special semi-synth 5w40/30 oil. Fuel dilution is real...but I'm not curious enough to pay for his UOA. The owner might, but then again his wallet is about to cough up a $500 cam and a $300 set of lifters; (unless on of the 10 or so people I have tracking this stuff down really surprises me).

I'm in favor or pulling valve covers on these engines. The reason people noticed the '02 ALH cam casting flaw was because the VC was being removed at 80K. It's nice not to have to pull the VC to do the TB, but it allows problems to fester unnoticed.

Make sure you have the replacement gasket on hand.
The part number is: 03G 103 483G.
Also, despite this iteration of the Bently lacking significant information, it does at least have a torque spec and tightening sequence:

___10__ 5___ 4___ 8___
1___________________2
13_________________12
9___7___3___6______11

10 Nm/7 ftlb

The car in questions' valve cover had not been removed previously. For some reason all bolts were uniformly pretty loose ~2 ftlb; they came out with a nut driver, not a wrench.

 

[airwolf]

The car in questions' valve cover had not been removed previously. For some reason all bolts were uniformly pretty loose ~2 ftlb; they came out with a nut driver, not a wrench.

This has been posted about often on here. There are few people that have noted that their valve covers have been seeping oil, and they find that several of the bolts are less that finger tight.

After reading about it, I checked mine, and also found a couple that were not very tight!

 

[oilhammer]

I snug PD valve cover bolts all the time. They are loose. So are the A5's Torx bolts on the insides of the doors

 

[Bob_Fout]

This has been posted about often on here. There are few people that have noted that their valve covers have been seeping oil, and they find that several of the bolts are less that finger tight.

After reading about it, I checked mine, and also found a couple there were not very tight!

Toof's in yer cylinder head stealing your oilz

 

[airwolf]

I snug PD valve cover bolts all the time. They are loose. So are the A5's Torx bolts on the insides of the doors

Yup, lost a couple of them already. Notice it when the door skin starts flapping in the in the wind.

 

[aNUT]

No date on the FM TSB.

The cam bearing shells actually look brand new. The bolts and tandem pump gasket are also on the shopping list. Thanks.

Also, please don't wait until your car is bupping to have it looked at. I'm gonna throw 80K miles out there as a suggested inspection interval. Hopefully any wear will be apparent at this point, but not so much that you'll be in danger of sticking a lifter.

Keep in mind that the car only bupped because wear was on an exhaust lobe. While slightly less likely, the same wear on an intake lobe would not have had any signs of problems until it completely eroded a lifter and it jammed in the head.

It's hard to say if UOAs would have caught this. All that have come back thus far show the PD kicking out lots of metal...that's why the Dieselgeek By-pass filter is boarder line imperative IMHO on these cars.

 

[aNUT]

This has been posted about often on here.

Thanks. I'll shut up about it then. Me and my old ass A4 don't spend too much time over here with you folks.