oil in cylinders

[krobbaja420]

Did a top end rebuild on my type 4 1911cc desert racer. New AA pistons/jugs (same size as old), New 1800 Hoffman heads (had stock 1700), upgraded to 914 swivel feet and solid rocker shaft. Ran really good for 20 miles then started fouling plugs. After checking compression, (85, 85, 85, 105), tore her down and found oil in my cylinders. Checked ring positions. All good. What did I do wrong? The way I see it, only two ways this could happen. blow by on rings (new), or through the valves (new). Rookie engine builder at best. Just took it apart and put it back new. How hard could it be?

[raygreenwood]

Quite hard in fact.

Taking apart qnd putting it back together is not rebuilding. This is very common in a top end rebuild.
When the whole engine has wear....and now you put in a tighter top end....it can over tax the worn bottom end. Its common.

You put on new heads. Did get rid of the head gaskets....and you should....the factory had a serb2ice bulletin out in the 80s to remove them because they have burn through issues. And if so....did you remove the cylinders and lap them to the heads?
If not you can be easily leaking compression at all four cylinder to head joints. Also.....did you check your deck and cc the chambers and set compression?

But you note low compression and oil in the cylinders....and new cylinders. Did you check them for roundness and taper and did you completely strip and clean the cylinders in hot water until no more blackness....and did you remove the rings and clean all of the ring lands.....and....what assembly lube did not use.
How did you break in the cylinders? The 20 minute run at 2000 rpm....is just for runming in the cam. Breaking in rings is a totally different operation.
And....you may need to look at this thread. Some BAD issues with AA piston rings.

https://www.thesamba.com/vw/forum/viewt ... p?t=677232

Ray

[krobbaja420]

Thank you sir for your reply. We did not use head gaskets. Appears to be no leakage at head to jug or jug to case. Deck is .060 (top of piston to top of cylinder @tdc.). Heads cc'd @ 52. With 96mm pistons; 66mm stroke; 52 cc head; .060 deck height....==8.6 compression. I THINK! Admittedly I
pulled cylinders and pistons from box and installed them directly without checking squat. Even after reading some posts as to the need for QC! You can find just as many posts that claim no issues with AA so I proceeded blindly. Also did not use any break in method other than bringing motor up to temp slowly in shop three different times before hitting road. Then just casually bringing her up to speed. In other words, I didn't just drop the jack and balls out but I followed no "routine" break in. Surely trying to make race date didn't affect that! HaHa!
So, back to the basics! Maybe someone has a link to a video for newb's on basic "top end" assembly. I may need to shop for some more pistons/jug assemblies and start over from there. Really invested a lot in new heads but I guess I may have cheaped out on Piston/jug. Or at least failed to install
correctly. I assumed they were ready to go. Buying new parts is easy, what with the internet and all. Putting them together correctly is a whole other sport. I guess that's why they call some of you guys "guru's" when comes to these air cooled puppies.
SO==== MY NEXT QUESTION ====
Do I have pistons/jugs QC'd no matter who the supplier?
Do I disassemble and reassemble after cleaning, with what lube and in what order etc..no matter who the supplier?
What is ring break in method?
What is the best I can expect for compression in cylinders?
What can I check in "bottom end" without cracking case?
And 100 other questions for newb's...
Hence maybe a video or book. I don't mind putting in the time to learn. I know you cant get everything from forums

[raygreenwood]

Oh...absolutely on the jugs and pistons....even if they are 40 year old NOS with a piece of Ferd Porsche's brain in the box.

You need to ....in my experience.....pull the rings....check the end gaps in the cylinders. I have numerous times found them off. Rarely excessive...but sometimes too small. Twice....I have found a ring upsaide down. In numerous NOS sets...I have found them frozen rock solid with dried up assembly grease.

In all sets....you will need to properly set your ring spacing and clock position. This right there could be the issue. If the ring gaps were not spaced properly....you can end up with tons of blow by.

Also....babying the engine is the worst thing for it for breaking it in. Of course you do not want to red line it.....but you need to drive some normal revs....not just highway rpms...and not just putting around rpms. The whole range. And....you need to climb some hills and on the downside let it free motor in gear up in the 2000 to 3000 rpm range. This back loads ...poor word I know....the piston rings out and changes their direction of deflection. They have to be WORN into the surface of the cylinders. Ray

[Clatter]

Always QC your Pistons and Liners - _Especially_ if Chinese, right?

The 'Cheap Junk' build in my sig covers a couple of things about P&L,
But skips most of it, because it's SOP for most all engines, not just the type 4.

Might take a look at it if you are new..

[NextGen]

Ray lets go back to he Bon Ami break in.

[Piledriver]

Not until he verifies the ring gaps... I had one P&C line up in my sons bus motor at ~50K miles, it fouled plugs in about a minute and had ~zero compression. Suppressed mosquitos well... Simply rearranged the gaps right and stuck it back together, worked great.

[krobbaja420]

ok. what is the correct gap alignment? I guess I thought it was just 180 degree off set on top two rings. not sure about the bottom ring. what does the red and green marks mean? Thanks again to all for help

[Piledriver]

180 out all 3, and if the oil ring is a 3 part style the upper and lower rails go 180 out.

What red/green marks?

Red Green marks usually come with a funny story...

Some engines spec 120 degree offset, it really doesn't matter as long as the gaps don't line up.

[sideshow]

Red green marks on the oil spreader is to make sure you don't over lap the ends, if you can see both marks you are ok (3 piece),
2 Piece oil rings don't need that.