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Sun May 26, 2013 2:53 am

Hello all,
i need some advices cause i have some troubles with my last project,
i recently built a 2542cc( oxyboxer ,and after the break-in period the engine began to produce a deep white smoke,
after the teardown ,everything looking good except barrels and pistons, there was a lot of wear all around the cylinders walls and the pistons skirts, for engine has lived 1 hour !

barrels are 4"AA products and pistons are Venolia from Pauter,

i re-honed the walls to the max Venolia specs (0.007"),there was already 0.005" before ,job done with torque plates and a true Sunnen honing head,

when i re-start engine ,same result and observations....

after some test:
leakdown test was good (under 5% ) ,
scratches of walls wear are not deep ,i don't feel them with my nail,
and compression are extremely hard to pass by hand!
barrels bottom skirts are very long(40mm), so pistons guidance is integral at BDC
rings gap still right,
and the wbx case is vented everywhere including on rear(1/3 cylinders),
valves box covers vented too ,

i don't understand where oil come and pass ?
heating problem?

so now i have no more ideas of problem cause ?
thanks in advance for your advices and ideas

Eddy

Sun May 26, 2013 3:47 am

there is something wrong with the rings.
Do you know what kind of rings they are?

Sun May 26, 2013 3:56 am

Did u check end/gap on ALL rings before installing?? Should do all and then install/mark piston where it goes, looks like rings without no gap.

Sun May 26, 2013 5:03 am

Hi,thanks for your replies,
yes all gaps have been checked (twice),i followed the instruction sheet,
rings are Total seals(Dyke style top ,gapless second) that Pauter sells with the P/Cs kit

but now ,i remember that i didn't check the piston grooves to rings gaps,
to much trust in parts....will do today

Sun May 26, 2013 5:09 am

Look at the exaust ports on the heads and see which cylinder the oil is comming from. It is probably comming from one cylinder. Examine it closely. Look at the wear pattern on the rings and check the valve guides.

Sun May 26, 2013 6:05 am

Hi,
all barrels are in this shape/state ,not only the #1,
it's clearly a general problem,

i just check the horizontal and vertical clearance of the rings in the piston grooves, and unfortunately everything is correct ,enough gaps every where ,

rings end gaps are still good ,0.018" on top and 0.014" for second,

otherwise,I could see the rings turning since their initial position

Sun May 26, 2013 6:11 am

check your valve guides on the suspicious cylinder. You may be pulling oil through them when carbs are closed and high manifold vacum exist. Check oil rings to see that expander is not overlapped.

Sun May 26, 2013 6:26 am

might be a ll obvious to suggest
and you might have done it anyways

but worth checking/mentioning

after honing
did you clean the barrels thoroughly?

i ask cuz.. some dont.. some forget..

i clean them 2-3 times and check with paper towels
and even on the 2nd and 3rd cleaning the paper towel still shows some dirt and grime..

for the most part i end up cleaning them up to 4-5times
even then... there are times the paper towel when im wiping them dry
shows a wee bit of dirt and machining debri..

my pattern :
1st - clean with mineral spirits (kerosene,lacquer thinner,gasoline)
2nd - clean with detergent (grease cutting detergent etc)
3rd - clean with mineral spritis (etc etc etc)

and so.. sometimes i have to repeat step 1 and 3 again etc...
each step includes wiping it dry with paper towel...

just wondering if you did... because u state ALL barrels are in this state

Sun May 26, 2013 7:14 am

Yeah...I agree with that last post. Because of the fine nature of the scoring....it looks like grit or dust.

Also just to ask...since you have scuffing on the skirts...what was the fit like of your piston pins? Was it a little tight? Ray

Sun May 26, 2013 8:09 am

raygreenwood wrote: Yeah...I agree with that last post. Because of the fine nature of the scoring....it looks like grit or dust.

Also just to ask...since you have scuffing on the skirts...what was the fit like of your piston pins? Was it a little tight? Ray

good eye ray...

i did post and ask.. though it might be overlooked..

i was thinking of the same view.. the scoring marks above the crosshatch pattern.. is fine scoring etc

Sun May 26, 2013 8:36 am

ditto what ralf said,but for the final clean papper towels with 10-20 engine oil in the bores real good them wipe clean. And finer hone job(400 grit,an-800 stones)just a few strokes, thats a good amount of clearance already, more than I would use.check pins& pin bore, I would dfl coat the skirts & ceramic the domes.but with that much clearance might pass on the ceramic domes.use some quick seat on the rings.
I cant see the skirt of the piston at the botom edge. it needs to be sharp!! yes sharp, yes sharp can cause some cracking, but sharp also scrapes off the oil befor the oil ring is over loaded. if the skirt has been beveled it will funnel it to the rings. I have seen some pistons with grooves to help the oil get to the pin area,does it work?? I dont know.but it does help with piston gaulding from an added lubrication stand point.
look at the skirts real good for steel or iron debris from the cylinder or rings.it will be tiny spots in the aluminum skirt. the aluminum is soft so it imbeds and just stays there and scratches the hell out of the cylinder. a very sharp pick can be used to remove all of them.(I use dential pics from the dentist to do) this. dont wory about scratching the aluminum it wont hurt squat, but that steel/iron will and does. check the oil rings for size, some race rings have a small oil ring ( my old mopar race rings had a atd oil ring on a +.060"/1.5mm bore piston, and they smoked, but made more power due to less drag) make sure the expanders are right, make sure you dont have the rails mixed up with the total seal rails.I only use total seal rings,I have for over 30 years.
check valve guides good look for oil trails.sometimes when a guide boss is removed it causes a low prossure zone behind the valve stem and that helps to pull oil through the guide. a tear drop around the guide is better than totaly removing the boss, it needs the aera behind the stem there to blend the charge back togeather so it dosent have the lower pressure zone right there. good luck.

Sun May 26, 2013 8:36 am

The pistons skirts look fine to me. Shoot, you call THAT scoring, I'll show you some scoring :lol:
total seal??? hmm, more like totally doesn't seal, I'd switch the second ring for a cast iron scraper, or just leave it out.

Sun May 26, 2013 9:46 am

Thanks for replies guys,
so in order,
raymon:
heads are new (JPM) but i checked the guides , it seems to be correct ,
0.002" between valves and guides ,and the white smoke appears when engine it's under load,not when throttles are off (which is a sign for wrong guides ,yes) ,the oil ring expanders looks good ,not broken or overlapped

Ralf:
at first ,i clean them with methanol (3 or 4 times) then i put some oil on a white rag and wiping them until the rag stay white , re-clean with methanol,
and at the end wash and dry them with a brake degreaser/cleaner
i do that on all my engines ,and no trouble until today

ray:
piston pins turns freely in pistons but it's more tight in rod bores
Mark:
piston skirts were carefully deburred ,and ring grooves too

thanks all for advices

Sun May 26, 2013 11:12 am

Do you think that a fuel excess could do that?i mean a cylinder fuel washing? Carbs are 48 trijets ,and there is no float flooding in carbs bores ,jetting is on the lean side (42vents,200,175,70, bowl level at 5.5mm), i think between 30mn and 1 hour running can't do that,but maybe?

Sun May 26, 2013 11:39 am

sometimes it can be from fuel(alky?), but rarely gasoline.
It is a shame you have honed the cylinders out so far, IMO you ruined them, but it should still work just a lot of slap. Take the second rings OFF, and throw them away, that is the cause of your problems. You have already given them TWO chances, are you going to try them a third time :shock:

Sun May 26, 2013 12:23 pm

just curious.. how long would it run bfor smoking..

without the 2nd rings? just running top ring and oil control ring?

Sun May 26, 2013 2:16 pm

I would keep the total seal rings, but you need to oil the cylinder lightly and wipe out the exsess wth a paper towel,not clean the totaly dry with solvents/meth etc, that will gauld the rings to the cylinders. a few drops of oil on the skirts then wipe it across&off with your finger & install the piston in the cylinder&on to the motor. installing the rings "dry"dosent mean totaly dry with nothing on the cylinder,it means dont oil the rings, do not flood the cylinders with oil before instaling the pistons. the quick seat will help if you have to leave them dry for some reason. total seal rings work, Ive used hundrads of sets of them. I tried the C&A zgs 1 time and had bad results.it was a stupid idea on my part to change something that worked so well.

Sun May 26, 2013 4:41 pm

Pistons do not tear up cylinders, it is rings scoring the cylinder that is making burrs and metal bits that is responsible for the scoring.
The most telling details would be looking at the top of the cylinder and look carefully at where the top ring stops, and where the second ring stops, and you can sometimes see which ring is doing the work and/or the damage, but it hasn't run very long, so there may not be enough to see.
Using a dykes top ring and a gapless second is two very strange things together.
I would not expect it to work well..............but as Mark says sometimes they do work well, but there is a lot of details that are important that I don't blame you for not knowing.
Is the top ring pre-lapped? what is it made of?
what is the second ring made of? iron? chrome? moly?
What is the recommended finish for these rings?

many ways work, and many do not.

Sun May 26, 2013 6:32 pm

steel rings are hard on cylinders. so is alcohol, thats why they make a fuel addtive for it. a good finer hone&quick seat will help in most all cases.
as far as the white smoke under load, is it fuel??moisture?

Mon May 27, 2013 12:26 am

mark tucker wrote: I would keep the total seal rings, but you need to oil the cylinder lightly and wipe out the exsess wth a paper towel,not clean the totaly dry with solvents/meth etc, that will gauld the rings to the cylinders. a few drops of oil on the skirts then wipe it across&off with your finger & install the piston in the cylinder&on to the motor. installing the rings "dry"dosent mean totaly dry with nothing on the cylinder,it means dont oil the rings, do not flood the cylinders with oil before instaling the pistons. the quick seat will help if you have to leave them dry for some reason. total seal rings work, Ive used hundrads of sets of them. I tried the C&A zgs 1 time and had bad results.it was a stupid idea on my part to change something that worked so well.

Hi Mark,
i always install rings almost like you , a bit oil on the piston skirts and very few WD40 on cylinder walls ,no oil on rings,TS instruction sheet say " if Quick seat not available put some WD40 ",
Every engine that i have built are "Total sealed" ,and i never had a problem until today ,