New camshaft with signs of wear after 450 km

Hey everyone.

Small problem with my VW Polo. It has a 1.9 diesel PD engine (engine code BLT).
The well-known "Pumpe Düse" engine with 130 horsepower.

Longer background:

I bought the vehicle privately with approximately 250,000 kilometers on the odometer, which seemed "low" to me at the time.
The vehicle was handed over to me with a "chip" installed. According to the chip tuner, it should have had approximately 170 horsepower at that time. The turbocharger didn't seem to be in the best condition, as it was already starting to whistle back then. After a brief moment of hesitation in front of this seemingly indestructible engine, I drove the vehicle for about 2500 kilometers.
After a short, enjoyable drive in the Polo (returning home with a salesperson in a representative car on the open highway) ... a sudden impact, followed by a loud clattering noise.
At that time, I suspected a connecting rod bearing failure, as the vehicle was making a knocking sound synchronized with the engine's firing order, and I had unfortunately experienced that issue before.
So, we got it out of the ditch and recovered the vehicle immediately.


Back home, under the carport, the truth finally came to light. The compressor impeller had made its way into the combustion chambers...
It had destroyed the pistons, cylinder head, and some other components.

Okay, so everything has been reworked from scratch:

- New piston series and accessories.
- Head, valve seats, and guides inspected.
- New intake and exhaust valves, etc., from the accessory parts.
- Head meticulously cleaned.
- New, larger GT1752 turbocharger, upgrade turbocharger.
- Connecting rod bearing shells (after inspection, even if they were not worn).
- New camshaft with hydraulic lifters and rocker arms, installed after determining "wear." The old camshaft had 1.3mm less lift on two of the lobes. (Purchased as a set from the accessories section.)
Arp head bolts for cylinder head. (No reason, I just wanted them.)
- New oil pump.
- Charge air cooling system (new, larger, and front-mounted).
- New timing belt with water pump, new thermostat, head gasket (brand name), etc.

The ARP head bolts came with washers that were much smaller than the original washers included with the bolts. We decided to use the original washers with the ARP bolts to reduce the clamping force on the head. The nuts for the ARP bolts didn't fit under the original holes in the bearing caps. Since ARP probably had a reason for using the thinner washers, we had to chamfer the bottom of the camshaft bearing caps on the milling machine so that we could use the original U-washers.
Next homemade item...
The camshaft supplied as an accessory could not be turned even with new bearings. Therefore, it was disassembled again. Compared to the original, well-worn camshaft, the new one was a hundredth of a millimeter too large. We ground down the new camshaft so that its dimensions matched the original.
We measured it again with plastic gauges for good measure. The clearance in the bearing was between 0.025mm and 0.038mm. In relation to the diameter of the pin and, for example, the connecting rod or main bearings (roughly speaking... let's say... about 0.080mm), this seemed appropriate to us.
Now, without the hydraulic lifters, the engine could be rotated as expected with the old screws pre-installed. So, everything is assembled. We used a 0.02mm feeler gauge to check if the bearing supports were making proper contact with the cylinder head. Unfortunately, we could only achieve this on the side facing the front of the vehicle, but it fit perfectly; nothing was obstructing it.


Well, I thought, I should probably drive it for at least 1000 km to break it in.

But then things turned out differently.

After 450 km:
Looking through a small opening in the oil filler cap, I saw signs of wear on the camshaft, evidence of initial running-in on the PD camshafts, and some lifters that were partially exposed. The pattern of damage is not consistent across all camshafts and lifters. The wear marks are mainly located on the base circle or at the points where the camshaft has minimal lift.
Of course, I checked the oil level first, and it was okay.
The rocker arm shaft plugs are in place.
Oil pan removed, checked the connecting rod bearings, all OK. Therefore, the oil pressure must be present there.
Everything is put back together, and it runs without the cylinder head cover and glow plugs . Oil is reaching the head. I thought I saw a leak of diesel coming from the element of the first cylinder.
Camshaft bearing shells, all with a copper-colored finish. Sometimes more, sometimes less.

Following the extensive repairs, a suspicion arose:
The oil level remains constant due to oil dilution, but it is also being burned at the same time.
Okay, so I'm putting in a new camshaft again, re-checking the valve seats, installing a new rocker arm shaft again, replacing the hydraulic lifters again, and now assembling everything together with the PD element holders.

600 km later:
I'm just checking to be sure, and I see that it's the same. The camshaft has signs of wear.

I measured the oil pressure with a cold engine because I didn't have a way to warm it up. The oil pressure was approximately 1.8 bar at starting engine speed and approximately 4 bar at idle.
Engine oil 5W-30, VW504/507 specification.
Oil is coming into my head. In my opinion, it's definitely a case of insufficient lubrication.

Okay, here are my questions:

What are the specified values for the camshaft bearing clearance?
Where can I measure the oil pressure in the head? And will that measurement be meaningful?
Where is the oil pressure control valve located?
Wrong oil?
Could there be problems with the studs or the washers?
Will the oil pressure in the cylinder head also decrease if oil leaks out through the head bolts?
Are you familiar with occasional issues related to oil production?


There's a lot to read, but I'm grateful for any help.
Best regards,

Hello,

Please check if the plugs/stoppers at the ends of the rocker arm shafts are in place, otherwise the camshafts will not be properly lubricated.

Best regards, Rainer.

Hello Rainer,

The caps are still in place.
I even replaced the tilt lever shafts again during the second replacement because they were included in the set. In both cases, there was nothing to complain about.

Best regards,
John.

Hi,
The values for oil pressure, bearing clearance, etc., are all in the repair manual. However, the values you mentioned are likely within the acceptable range.
The lubrication of the camshaft is achieved by the oil mist that flows from under the cylinder head cover.
If the camshaft wears out on the lobes and bearings, the surface is probably worn. I would recommend using an original part.
hg
Herbert.

Hi Herbert,

Are you sure it's just oil mist? I mean, with the BRE, every camshaft was lubricated with oil.
That's a different engine (16V), and maybe I'm mistaken.

Perhaps there are videos of running 8V TDI engines without the cylinder head cover.

Best regards, Rainer.

Do you mean the oil supply to the rocker arm axle?
hg
Herbert.

Unfortunately, the images were not uploaded. I probably clicked the wrong button. I'll try again.

Hi,
Besides the signs of feeding on the northwest storage areas, I've noticed...
- The valve lifters look like they've been run for hundreds of thousands of kilometers; they're completely scrap.
- How does the oil supply reach the bearing housings? Does it come through the gap at the edge? It seems there are different designs. Please take a picture of the NW support without the bearing housing.
hg
Herbert.

Herbert wrote:

Are you referring to the oil supply of the swingarm axle (?)? hg Herbert

I don't remember the details, but it seems oil ended up on the valve lifters. Also, a 16V engine might not be comparable to an 8V engine (which uses tappet lifters).

If the valve guides are worn and have a crooked surface, this naturally has a negative effect on the surface of the camshaft lobes, as they then only make contact at specific points (especially at the edges), and that seems to be where the wear marks are.

Best regards, Rainer.

Good evening, gentlemen.

I still have pictures of the head from when I removed the valves.

Here is the second oil drilling project.

To me, it looks like oil is being forced under the bearing shells, but not into the bearings themselves. The pressure from the bearing cap is pushing against the bearing shells!
hg
Herbert.

Hello everyone.
I compared the original bearing shells with the others. The oil supply slots are the same on both. Also, they cannot be installed upside down due to the protrusions. During installation, we made sure that all the bearing shells were evenly seated in the bearing housings before inserting the camshaft.

LG
Johannes

It's hard to imagine, but if the NW storage areas were already designed like that before the repair...
Here's the translation:

"But how does the oil get between the bearing housing and the main shaft? In your last picture, I can at least see the holes for the oil supply on the side opposite the grooves in the bearing supports."
hg
Herbert.

The oil drilling rig is located in the storage lane, oriented towards the front of the vehicle or towards the PD (presumably Pressure Distribution) elements.
The bearing housings are open at the same location.
If absolutely no oil were to arrive at the storage location, I would likely have a much more severe damage situation.
I'm leaning more towards the possibility of low oil pressure in the head.

Hi,
I have marked the oil drilling hole in the bearing housing in the first image, and in the second image, I have indicated the suspected slot in the bearing shell (which can only be guessed).
If that is indeed the case, I will, of course, retract my objection.
hg
Herbert.