What's causing this?
 

Continuing on in repair of a minor oil leak at my cam tower, I removed the heads and was looking everything over. My engine is a 3.4 conversion single plug wedge dome, Mahle Motorsport 98mm P's and C's with Goetz rings, brand new outta the box, cylinders came from Mahle bored to 98mm, not refurbs.

1,800 miles on this build. Getting the occasional smoke puff on startup, but this looks like way to much oil up top. Plugs looked o.k, cylinders look fine (they were brand new), break in procedures followed when first run in, rings look fine to me.

Gaps at install were 1st and 2nd ring= .004" to .006", Oil ring=.013" to .016

Pistons (I actually wiped some carbon/oil/whatever away on this one)
http://forums.pelicanparts.com/uploa...1389585795.jpg

Heads:

http://forums.pelicanparts.com/uploa...1389585824.jpg

Cylinders (wiped down and cleaned up)

http://forums.pelicanparts.com/uploa...1389585886.jpg

As I stated all parts were new and supposedly in spec. Is this what it looks like when rings don't seat? And if so, what can I do about it? All pistons and head etc. look the same as shown.

Thanks

Yes, this is blow by. You can tell because there are fewer deposits around the perimeter of the piston. This is because compression gases are leaking past the rings and creating a velocity of gas over the edge as the piston rises in the compression stroke which strips deposits from forming and keeping it clean. Use non-synthetic oil for break in and be sure not to be too gentle on it. Load the engine and allow it to vacuum break after pulls. Avoid freeways and city traffic where you would idle for extended periods of time.

What fuel are you using? Techron additive actually does work to reduce clustering of deposits. Might be worth using during the break in while there's more oil in the chamber.

Those ring gaps sound way to small to me. I think they should be at least .012 inches. If it were me, I'd make sure the gaps are right, put it together with wd-40 instead of engine oil and try another break in.

-Andy

I am in agreement with Andy,

You may get away with .009, but if temps climb you could see ring gap related issues.

About .012 gives you enough safety margin.

Is it pretty typical then to have to file ring end gaps on a brand new set of Goetz rings supplied by Mahle for a set like this?

Lapkritis is right on about seating the rings. Load then coast and repeat. A good routine for seating rings was developed decades ago and I've had good success with it with numerous cars. You need a clear road so you can accelerate at full throttle in a high gear from about 2,000 rpm up to 4,000 or 5,000 and then coast with the throttle closed back down to 2,000 rpm and then repeat the full throttle run back up to 4 or 5 thousand then coast back down. I try to do this at least 10 times but if I have time and an open road I will do it many more times. 4th gear works well, but you have to work within your local roads and speed limits. Try to use the highest gear possible as the differential in the load on the rings between the acceleration and coasting phases will be the greatest and you will have the best opportunity to seat the rings.

On my 92mm bore with iron cylinder(grows less so tightens up more than aluminum cylinder) I'm pretty sure I went .016 top, .024 middle and .018 oil. Proper break procedure is important but yeah, i agree that .004 gap on 98mm bore is way too small. The larger circumference ring, the more expansion so the larger the gap than a similar circumference smaller ring.

Yes, always check gap on rings when replacing them. It only takes a few minutes and you can do it with a $10 feeler gauge set from Autozone. If you need to open the gap a bit then ring files aren't too bad either.

Thanks, checked all the gaps during the build and checked them thoroughly, just didn't have specs to check against...

Any recommendations on a tool for filing these? Looks like lots of options out there.

Just a quick question...what oil are you using?
If the oil has something like STP or another friction reducing agent...the break-in can be very long if at all.
I like to use something like straight 40W or 50W for the first engine start....then change after 20 minutes (or first warm up to running temp)...then the same oil for the first 200 - 400 miles....then put in the oil you will use for the rest of the engine's life.
Bob

Is this your standard practice, or just for special cases? I've heard of this technique, but only rarely.

Before we go too far astray...

Any recommendations on a ring end gap file...what works best, etc?

What do you guys look at for ring end gap specs and where do you find them? Nothing came with my Mahle set and Mahle Tech Service did not have the ring end gaps.

Jegs sells a piston ring filer which is what I use. 80514. The host here may sell something similar and I would support Wayne and team first considering the resource they provide.

I did it on an Alusil rebuild with new rings. It was the recommendation of the ring manufacturer. I had a special top ring made due to a non standard top ring groove size. I think they were from total seal but not sure. Normally I lightly oil them with a cheap 10-30 oil like I use on my work car. I suggested a more aggressive approach due to the difficulty he is having.

-Andy

Isn't straight mineral oil used for break-in for air cooled engines?

I used Joe Gibbs Drives "BR" (break-in) for the first 1,000 miles and did the loaded throttle approach that Lapkritis and RedCoupe speak of.

Oil recommended by Mahle was non synthetic Brad Penn break in or Joe Gibbs BR.

Based on what?

Non detergent is used so that there is no possible detergent types reacting with one another