Replace Pistons/Rings or the whole vehicle?

[vishnu333]

I have a 2003 A4 1.8T Q5M Avant with 150k miles. I put a FrankenTurbo F4L turbo in it along with many supporting mods. But I'm STILL burning lots of oil in my exhaust. My mechanic says it's rings. Should I pay my mechanic to replace the pistons/rings and rods while they are at it? Or should I sell the whole vehicle and start over with used 2.0T A4? I have about 5k$ of mods into it. I assume I could sell it as is, smoking, for about 3-4k$. A used Audi A4 Avant worth considering would cost me 15-20k$ + whatever I want to upgrade on it...

Any recommendations from experience with bad rings and how the rebuilt engine lasted/performed? I would hate to sink another 3-4 grand into it now and then have other major failures (aside from clutch) in the next 5 years.

[Matt Devo]

did your mechanic do a compression test and/or a leak down test to confirm leaky rings, or is he just speculating based on the symptoms and your mileage?

[vishnu333]

He did do a compression test last week and said it passed. The leak down test he did on Friday. Not sure the results. I plan to talk to him Monday about the diagnosis. I wonder how much of his diagnosis on friday was his speculation. He was going to give me quotes for parts and labor on Monday as well. Anything in particular I should be asking him about from those two tests? Could it be valves instead?

[cpu77]

I will say this I pulled my intake manifold for something and looking at the last two cylinders.... They are went sludgy and the other two are clean... My car only has 47k on the clock! I would see how the compression check went.

If it were my car and a toy I would just redo the engine... maybe stroke it. If its your DD. Then part it out cut your losses move on. You could keep it as your toy cause in the grand scheme of things 3k is nothing! Hell if you lived closer I would give you that for it right now!

[vishnu333]

compression results: greater than 170 on all 4 cylinders. Leak down test: less than 10% across all cylinders.... but the car still smokes. Could it still be the oil seal piston ring? Or valve guides or stem seals?

[Audi Skate Snow]

compression results: greater than 170 on all 4 cylinders. Leak down test: less than 10% across all cylinders.... but the car still smokes. Could it still be the oil seal piston ring? Or valve guides or stem seals?

Could be your turbo seals leaking oil.

[Wet0willy01]

Agreed. Especially if it just started since the FT install.

[vishnu333]

I highly doubt it is the turbo. Oil smoke in exhaust started last year with stock K03s. Beginning of this year I put in an RP k04-15 which didn't fix it. Then I put in the FT since I didn't trust the RP turbo after all the problems people had. Still didn't fix it. (Also, IC piping doesn't have any build up of oil. But I guess it could be leaking through the exhaust side of the turbo.) I should have clarified when the smoke started. I will edit the original post.

[drjonez]

compression results: greater than 170 on all 4 cylinders. Leak down test: less than 10% across all cylinders.... but the car still smokes. Could it still be the oil seal piston ring? Or valve guides or stem seals?

With those results, it is not the rings.

Done anything with your PCV system lately? What did the exhaust side of the turbos you removed look like?

[vishnu333]

in hopes of not removing the head, I replaced all the PCV system, new hoses and new PCV. still smokes after that. So if not piston rings, maybe valve stem seals? Is it worth the cost to have the head rebuilt and see if that fixes it? My thought was, head is off, engine is old, might as well do new rings and forged con rods.

[IVRINGS]

How much oil are you losing per oil change or is it to the point you have to add a few times before the change?

[vishnu333]

honestly, I haven't exactly measured the amount being consumed. I would say somewhere around 1 qt per 1000 miles. My problem with it is not the cost or time of refilling the oil, but more the annoyance of smoke when sitting in traffic or hammering hard on the accelerator. I also wonder if it would pass my next smog/DEQ check next fall.

[diagnosticator]

In addition to the usual wear items, leaking valve guide seals are often the cause for excessive oil consumption and exhaust smoking. Since the compression and leak-down tests pass good, I predict the cause for the smoking and oil consumption is leaking valve guide seals. You can replace the valve guide seals without removing the cylinder head, but a cylinder re-bore to 1st oversize with a re ring job with new forged pistons and con rods and a cylinder head rebuild, would extend the useful life span of the engine/car a lot. Without reboring the cylinders oversize, a re-ring job has limited practical merit extending the engine life span to less than the total extension possible with a re-bore, with compromised results due to the wear in the cylinder walls. If the cylinders will not be rebored oversize, then I recommend only replacing the valve guide seals, and reevaluating the situation after that.

[rowdyaudijeffy]

im rebuilding my 1.8t amb auto 138k(no sludge)right now and i had the same problem it started smoking only on kick down and then progressed to a side melt down on #2 piston.(daughter ran her hot @ 90mph until she blew)well anyway.all techs never seen anything like it and still cant figure it out.dont want to scrare you but its worth the rebuild.

[Bische]

In addition to the usual wear items, leaking valve guide seals are often the cause for excessive oil consumption and exhaust smoking. Since the compression and leak-down tests pass good, I predict the cause for the smoking and oil consumption is leaking valve guide seals. You can replace the valve guide seals without removing the cylinder head, but a cylinder re-bore to 1st oversize with a re ring job with new forged pistons and con rods and a cylinder head rebuild, would extend the useful life span of the engine/car a lot. Without reboring the cylinders oversize, a re-ring job has limited practical merit extending the engine life span to less than the total extension possible with a re-bore, with compromised results due to the wear in the cylinder walls. If the cylinders are not also rebored oversize, then I recommend only replacing the valve guide seals, and reevaluating the situation after that.

Damn, i just got new glasses and the text's are not floating as much.
I just love to read D's posts, i cant imagine how he is able to put everything so well.

It feels like a full long chapter of information, but youre only reading a few rows!

[vishnu333]

If the cylinders will not be rebored oversize, then I recommend only replacing the valve guide seals, and reevaluating the situation after that.

Interesting advice. I was thinking honing the cylinder walls and putting in new std size rings on my old pistons and new forged con rods with calico rod bearings would extend the life. At least it would toughen the bottom end in case I get a real GTRS elim turbo after I get bored with the F4L. But sounds like it might not help the longevity of the engine. In such case, I could save alot by just doing the head since I'm paying my mechanic for labor. Can the bore be increased while the block is in the vehicle or are we talking pulling the motor?

One more question, if I get the head rebuilt, is it worth putting in the Supertech valves that are just SS with nitride coating? I didn't think I needed the Inconel ones but maybe then I don't even to replace the stock ones if I don't plan on going over 7200 rpm (Revo Stg 2 rev limit).

[diagnosticator]

Honing the cylinders will allow the new rings to wear in somewhat, but most likely won't seal as well as the rings in the engine now. The actual results of hand honing, especially with the ball type hones, most often only makes the cylinders larger and less straight/less round. Unless the rings are actually worn out, or damaged, or the cylinder walls scored while also not worn much and are nominally straight and round, (not likely with 140k miles wear,) is re ringing with just a light hand hone worthwhile. In your case I think you are better off leaving the existing rings in service, since the rings are working OK. Unless you are going to re bore the cylinders 1st oversize, IMO, spending money on performance parts is not justified and won't provide the desired end results. The engine must be removed from the chassis and disassembled to bore the cylinders. Unless this is done, the money is better spent on other maintainence and repairs. Rebuilding the cylinder head, is the most I can recommend without boring the cylinders 1st oversize also. If you want to build up the engine for higher power levels, then a complete engine rebuild with cylinders bored also, is the way to go.

If you just have the valve guide seals replaced, then you can sell the car for thousands more, and get a newer car to build up. Or, after considering things for awhile decide to rebuild this A4 and build it up instead. BTW, a late model 2.0T with the Valve Lift head, has a lot more hp and torque compared to the stock 1.8T, and is the equal or better performance compared to most 1st stage/bigger turbo setups on a 1.8T. A tuned ECU and a larger turbo on the late model 2.0l TFSI, has a lot more bang for the buck too.

[cpu77]

Is there a DIY to replace valve seals with out removing head?

[diagnosticator]

Is there a DIY to replace valve seals with out removing head?

I don't know of any DIY for that job. The procedure requires the following steps.

1 Position crankshaft for #1 cylinder at TDC compression stroke, then turn cranshaft 180 degrees further in the normal rotation direction, CCW facing the engine from the front, to place piston at BDC, at the end of the power stroke.

2 Remove camshafts and cam followers. Set the cam followers aside in order so that they can easily be replaced into the original locations.

3 Using a spark plug hole adapter, and an air pressure regulator, pressurize the cylinder with compressed air, setting the regulator output pressure to ~100 psig.

4 With the air pressure holding the valves closed, use a valve spring compressor and remove the keepers and valve spring on 1 intake or exhaust valve.

5 Using long nose plyers, pull the valve stem seal off of the valve guide. Next, use the protector sleeve over the keeper grooves, and slide a new seal onto the valve stem and press/tap the seal onto the valve guide. Measure the distance from the valve stem tip, to the seal lip before removing one of the old seals so you know when the new seals are installed onto the valve guides all the way. Measure both intake and exhaust seal distances, as they may be different.

6 Replace valve spring and keepers,

7 Replace the other valve guide seals in the other intake and exhaust valves, one at a time.

8 After replacing all the valve guide seals in cylinder #1, replace the valve guide seals in cylinder #4, then after #4 cylinder is done, rotate the crankshaft 180 degrees and replace the valve guide seals for cylinders #2 and #3.

9 After replacing all the valve guide seals in all four cylinders, re install the bucket cam followers, then re install the camshafts.

[cpu77]

Wow thank you! I really appreciate it. Thats should be a sticky by its self! How long does something like this take? I seem to have some leaking seals... Might give this a try.

[vishnu333]

@diagnosticator : Good writeup for stem seal replacement without removing the head. I would use that procedure if I didn't want to do valve guides at the same time.

My current plan to fix my whole problem is: to pull the head, replace valve guides and stem seals, lap the stock valves and put the head back in with a new head gasket. I don't think I'll bother with Supertech SS exhaust valves since I'm not trying to build a high rev'ing head. Just trying to keep my DD for another couple years. Eventually I'll buy a late model 2.0TFSI to build up. My only hope is that my current smoke problem isn't caused by a damaged oil seal piston ring. I've heard people with good compression and leak down numbers that still have a bad oil seal ring. Thanks all for the advice on this thread. I'll let you know the outcome later next week.

[diagnosticator]

I think your plan makes sense. While it is possible for the oil scraper rings to be weak with the compresssion rings still in good condition, that is a very rare situation. Since the compression rings are working good, the condition of the oil scraper rings are most likely also in good working condition. The chances that the oil scraper rings are allowing oil to pump into the cylinders, to be burned, is practically none. The evidence and symptoms don't support the worry that the oil scraper rings are weak.

[A4SoftWalker]

Honing the cylinders will allow the new rings to wear in somewhat, but most likely won't seal as well as the rings in the engine now. The actual results of hand honing, especially with the ball type hones, most often only makes the cylinders larger and less straight/less round. Unless the rings are actually worn out, or damaged, or the cylinder walls scored while also not worn much and are nominally straight and round, (not likely with 140k miles wear,) is re ringing with just a light hand hone worthwhile.

I really want to clarify this statement from diagnosticator bcs I am in the process of purchasing a cylinder honing tool for my JE piston/ring install.

Using this video - long considered a bible to 1.8t engine rebuilding I am now at odds with what to do:::

Which honing tool and which grit to get?
Flex Hone 180 grit from the video OR Integrated Engineering states 320 grit = approx 240 grit Flex Hone? OR none at all.
I can still see the original factory honing marks...
SORRY forgot to add in that its at 4:27 in the video

[diagnosticator]

I really want to clarify this statement from diagnosticator bcs I am in the process of purchasing a cylinder honing tool for my JE piston/ring install.

Using this video - long considered a bible to 1.8t engine rebuilding I am now at odds with what to do:::

Which honing tool and which grit to get?
Flex Hone 180 grit from the video OR Integrated Engineering states 320 grit = approx 240 grit Flex Hone? OR none at all.
I can still see the original factory honing marks.

The type of hone that will do the best job, and help straighten the cylinder bore instead of making it more out of round and less straight, is the 3 (or 4) stone parallel type, that holds the straight stones parallel to each other, and cuts a lot straighter. The accurate cutting parallel stone hones are a lot more expensive than the flex ball hones, for good reason. The Ball type Flex hones, will follow the out of round and tapered cylinder walls and make the problem worse. The balls will also bounce with rotation of the hone, and cut the cylinder walls making them wavy. The grit to use depends on the type of piston ring facing, Iron, moly steel, or chrome, and the width of the ring faces. The hone manufacturer has advise on what grit stones to use per ring type. The wear ridge at the top limit of the upper piston ring travel, must be cut down using a ridge reamer tool, before honing also, or the new upper ring will collide with the wear ridge and break the new rings. If the cylinder walls are in perfect condition, then honing is not nessessarily required, but the new rings will take longer to seat in with the cylinder walls, without at least a light hone to re cross hatch the cylinder walls. The wear ridge must be cut down regardless.

[vishnu333]

So the head is being recondition and reinstalled by my mechanic right now. I'll get the car back on Monday. They said there was oil residue in the head in the air passages so we believe this will fix it. Crossing my fingers until Monday.

[vishnu333]

Got the car back. Has about 1000 miles on it since head rebuild. Everything seems great regarding the exhaust smoke. It runs better than ever. The exhaust smell is as you would expect from a new car. Now I have to smog the car in California so the real test is about to occur.

[DBM]

Good luck!

[Audi Team Steeg]

Cool! Great to hear Vishnu333!

Could you please get a list of what the mechanic done??

I want to start planning the same as I'm having alittle smoke too

To Diagnosticator!
Great replys!!
Really love your insight and advise!
Its legen dary!

Karl