BEW burning oil after rebuild?

[Ryder1032]

Hey everyone. Recently rebuilt my 04 tdi with the BEW PD100 engine. Had a runaway and bent rod #4. Honed all the cylinders lightly to clean them up, and a new/used set of pistons from a local breaker with new kolbenschmidt rings and followed steps for ring placement, measured protrusion to a 2 hole head gasket. Head was sent out and decked with new guides and seals with all new valves and camshaft as well as it was also worn and time to replace. Head is totally rebuilt. All new gaskets, seals and o rings top to bottom aside from the crank seals as it wasn’t pulled. Also a new turbo.

I’ve put just over 10,000kms on it since the rebuild. Went to do an oil change the first 5000kms and before I drained, the oil was lower than the first bend on the dipstick. Maybe about 2L in the engine. Since then, I’m adding about a litre every 800-1000kms. Although all seals were replaced, it seems to be leaking at the valve cover, both ends of the PCV valve and oil cap gasket and injector harness o-ring. It looks wet around both the intake and exhaust manifold bolts but can’t tell if is just wet from the valve cover. It will also give a small puff blueish white smoke if I give a little rev when I back into the parking spot at work. Not too sure if it does it for other gears but haven’t noticed any in first or higher.

Obviously a new engine shouldn’t be consuming as much oil as this is. I really don’t know where to start looking for or for what reason it would be pushing oil out from the valve cover. If anyone has run into this issue or has any advice it would be greatly appreciated. At a complete loss and pretty disappointed this is the result of my first rebuild.

 

[Mpaw]

My sympathies - that is really not nice. Two thoughts:
Low quality gaskets?
Compression is now much higher, blowing the gaskets?. Compression test on each cylinder?
Please keep us informed.
Afterthought: piston ring failure?

 

[IndigoBlueWagon]

Blowby would pressurize things under the valve cover forcing oil out.

 

[AndyBees]

I'd give it some more time to break-in. As it breaks-in the blow-by pressure will begin to drop off. Also, at some point you probably should address the valve cover gasket again as well as some of the other gaskets/O-rings.

 

[oilhammer]

It isn't a new engine. It is a used engine with new rings. Big difference. And it is common for this to happen. As Andy says, it will likely lessen as it breaks in, but it won't ever be like a 100% brand new engine.

Also, PD valve covers don't take to new gaskets very well. They need to be replaced altogether (the new valve cover, which will be the updated version for your BEW, will come complete with a new gasket).

There is also the issue with non-OEM style cam cap bolts being used which can cause oil leaks at the back (tandem pump) end of the head. I've fixed dozens of those.

Couple other tips:

Make sure the vacuum system is intact and not leaking. The vacuum pump exhausts into the engine, and a vacuum leak (like a brake booster or any small vacuum line, or a split in the booster tube) will cause the pump to push more volume through the engine, which will in turn carry more oil vapor right back out with it... causing an oil consumption issue.

Make sure both the dipstick and dipstick tube are the correct ones for the engine, and that the tube is snapped down how it should be. If it is not, you won't get an accurate reading, and you may be overfilling the oil, which the engine will happily try and burn off and you'll think it is using more oil than it actually is.

Make sure the thermostat is in good order, and that the engine is getting up to operating temp properly. An engine running too cool will use more oil than one that is able to maintain its temp properly.

 

[IndigoBlueWagon]

There is also the issue with non-OEM style cam cap bolts being used which can cause oil leaks at the back (tandem pump) end of the head. I've fixed dozens of those.

People think they have a better answer than OE. Turns out sometimes that's not the case.

 

[BobnOH]

People think they have a better answer than OE. Turns out sometimes that's not the case.

Almost never the case. All the amateur automobile engineers make the car forums very entertaining.

 

[benshaw]

FWIW, did u use fully synthetic oil after rebuild.

 

[turbocharged798]

Did you measure the bores for taper and wear? If the bores are out of spec its been my experience that honing and new rings will make oil consumption worse.

 

[wonneber]

An engine with synthetic oil will take longer to break in.
The things turbocharged79 mentioned are the reasons.
I've seen it with the 1.5 / 1.6 vintage diesels.
I would thing 6000 miles (US) should be enough.

 

[oilhammer]

Yep, that is why I pointed out that old engine honed out with new rings is NOT the same as a new engine, and the ring seating process will take longer and will never be like it was when it left the factory.

That said, it can certainly be a good running and tolerable level of oil consumption to keep motoring the car down the road for years to come. I put new rings on used rods and pistons in my 383k mile ALH, with an obvious shiny wear mark on one cylinder. It had some pretty bad oil consumption at first, but lessened and eventually leveled off to a tolerable amount. That same engine just pushed the car past 600k miles this week still going strong.

 

[Ryder1032]

Not sure why but for whatever reason I haven’t been getting any email notifications or anything on the site showing replies to this, just thought I’d check it and I saw all the replies. Thanks to everyone that chimed in, the knowledge and experience really helps.


gaskets replaced were either OEM or Elring gaskets. Valve cover gasket was the only one that was a “Reinz” gasket which I have never used before. It was the only one avalaible aside from ordering a new valve cover itself, which will probably be a purchase in the near future.
I did a compression test on the engine, and the numbers weren’t exactly what I was hoping for. Although, the engine runs and drives and idles with no issues aside from the oil. I also did a leak down test and it passedHere are the results:

Cylinder 1: 420, leak down test 99/100psi
Cylinder 2: 400, leak down test 99/100psi
Cylinder 3: 380, leak down test 99/100psi
Cylinder 4: 420, leak down test 100/100psi

seeing the rates of compression, I wonder if I had broken in the engine wrong. Looking into breaking in specs after the rebuild I couldn’t find a direct answer. Anything on forums was either “run it hard, you want to run it at high rpm’s” and for every time I saw that I also saw “running it hard will damage a fresh build engine, drive it easy”. I then found vws stock recommendations and followed that, not revving past 2800rpms when cold and only to 3200rpms max for the first 5000km and up to max rpms for 5-10,000kms. However, if I had broken in the engine wrong, wouldn’t the compression specs be lower and wouldn’t it constantly smoke on idle and acceleration? Also would the leak down test show that there would be blowby past the rings?

i know that the engine will never be a “new engine”. But I just don’t understand why it would be loosing this much oil. Currently almost 15,000kms on the rebuild and the problem is still occurring. It has slowed down slightly I’ve noticed as you guys said the more you drive it’ll go away, it isn’t coming out of the PCV anymore but still a good leak from the oil fill cap, had it on the hoist two days ago and the bottom stud area of the exhaust manifold is soaked and oil is slightly leaking down the back of the head, and once it gets to the corner of the block between the engine and trans at the rear, it will form a dripping spot and is leaking slightly down the dogbone onto the subframe.

thanks again to everyone that has commented and put in their help, hoping to get to the bottom of this.

 

[Prairieview]

There is no way anyone here can answer your inquiries. We were not there to check bore taper. I have no idea how you non-aligned your piston rings or if you even tried. I have no idea if you fired this engine up and let it idle and allow the rings to align the gaps while it pointlessly sat there idling.

Myself, I do not put syn. oil for initial wear. I rebuild alh's and WANT those rings to grab the cylinder walls initially. NOT dance around and align their gaps while you stand there doing nothing.

I perform initial fire-up....check for leaks....and drive off. And, that can be nerve racking because you really don't know how it is ever going to go. In my life, it has gone well every time.

I obviously contend that being extremely fussy with assembly technique and practice is where it is at. Generally, THAT becomes evident with the finished product. This may well be the case.

 

[Ryder1032]

There is no way anyone here can answer your inquiries. We were not there to check bore taper. I have no idea how you non-aligned your piston rings or if you even tried. I have no idea if you fired this engine up and let it idle and allow the rings to align the gaps while it pointlessly sat there idling.

Myself, I do not put syn. oil for initial wear. I rebuild alh's and WANT those rings to grab the cylinder walls initially. NOT dance around and align their gaps while you stand there doing nothing.

I perform initial fire-up....check for leaks....and drive off. And, that can be nerve racking because you really don't know how it is ever going to go. In my life, it has gone well every time.

I obviously contend that being extremely fussy with assembly technique and practice is where it is at. Generally, THAT becomes evident with the finished product. This may well be the case.

My apologies. Completely forgot to mention from turbocharged798’s reply, but I had checked the bore taper and everything had checked out. I never wrote the results myself but my dad who has built many many engines measured them out and the pistons and said everything was in spec. Proceeded to ball hone the cylinders and install the new/used pistons. I had mentioned at the beginning of the post that I had set the ring gaps and placements to kolbenschmidt’s specs. I used liqui-moly 5w40 synthetic as it was all I was able to get at the time.