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blow by? just reringed engine and still oil blowing out dips
by
ameen
on 01 May, 2006 10:53
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i just spent some hard earned money honing the cylinders, reringing, new rod and main bearings and all new gaskets. Car should run great!!
it does run great!! but it is still blowing some oil out the dipstick.
is this due to the rings not seated yet?
how long should i allow for the rings to seat?
any help or suggestions would be greatly appreciated>
someone suggested cleaning the valve pan cover with wd40...IS THIS A GOOD IDEA?
IS THERE ANYTHING THAT COULD CAUSE THIS?
PLEASE PLEASE HELP...
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#1
by
chrissev
on 01 May, 2006 18:32
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i just spent some hard earned money honing the cylinders, reringing, new rod and main bearings and all new gaskets. Car should run great!!
it does run great!! but it is still blowing some oil out the dipstick.
is this due to the rings not seated yet?
how long should i allow for the rings to seat?
any help or suggestions would be greatly appreciated>
someone suggested cleaning the valve pan cover with wd40...IS THIS A GOOD IDEA?
IS THERE ANYTHING THAT COULD CAUSE THIS?
PLEASE PLEASE HELP...
did you check that the cylinders were round?
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#2
by
jtanguay
on 01 May, 2006 19:24
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even if they were round, would the rings seat, just take longer? or are we talking a permanent blowby situation here?
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#3
by
ameen
on 01 May, 2006 21:15
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thats what im asking....how much oil should if any it should blow before the rings seat.........how long should i allow this to go on before i get worried....im worried now...but dont know what to do or what to expect...this is my first diesel and i drove it witht the blow by for 3 months before i decided to do the rings and bearings and all belts and gaskets and stuff.
will the blow by continue...is this normal, or will it stop when rings seat and how long for them to seat...ive driven it 306 miles since the rering.
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#4
by
chrissev
on 02 May, 2006 17:38
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even if they were round, would the rings seat, just take longer? or are we talking a permanent blowby situation here?
well if the cylinders weren't round, then the rings wouldn't matter much. That is why I am wondering. People often check the cylinder walls side to side, from West to East sort of thing, and never remember to check them from North to South. And they seem quite good still, because they don't wear West to East. So they glaze bust them, fit new rings, and then put everything back together. Then they get excessive blow by. Because the cylinders wear North South. West to East never wears out, always tight as a drum.
So yeah if they aren't round he's screwed. But assuming that in an 18 year old engine with a zillion miles on it, with worn out piston rings and excessive blowby, the cylinders WERE still perfectly round, then yes you would need more than 300 odd KM to seat the rings. You would need around 1000. So do that then get back to us if it is still blowing by excessively.
Chris
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#5
by
ameen
on 02 May, 2006 21:35
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400 miles, should have 1000 by sunday eve. should i refrain from wvo until my problem ceases?
hope the 1000 mile marker takes care of the problem...my fuel mileage has risen considerably, my last tank before the rebuild lasted almost 400 miles, i had 97 miles in on the tank when it went in for work and just filled it up this eve at 450 miles, i anticipate over 500 miles on this tank so i should hit the 1000 mark by sunday.
love my diesel, though, ive had many, many other vw, and i have never grinned so much in the drivers seat of any car as much as i do this one.
bought my first new car last year, and the excitement lasted maybe 3 wks, this car is 17 years old and has almost no acceleration, but still gets up and goes, and makes me grin like a chicken; hahahaha
thanks for the advice!!
additional advice welcome
ill get back at the 1000 mile mark.
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#6
by
BigAndy
on 02 May, 2006 22:06
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My 85 Jetta n/a had 240,000 km and I took the head off to replace the head gasket. Figured I was in this far, may as well take the pistons out. #1 and #4 had broken #2 compression rings. All cylinders #1 compression rings had about 1 cm gap.
This explained the hard starting and blowby.
I borrowed a bore dial guage to measure the cylinders. North/South - slightly out of round - .04mm. I believe wear tolerance is .08mm - any more and the block must be bored.
East/West - minimal. That's right at the top of the cylinder at #1 compression ring height at TDC. About 1" down, basically to spec all around. At the bottom of the stroke - to spec.
I gently honed the cylinders using a 3 leg 'hone' with 220 grit. And when i say gently, it was very very light using ATF as a lubricant.
I then used the 'ultra fine' scotch brite pad on a drill to 'polish' the cylinder.
Rings go in this weekend and we'll see how we did.
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#7
by
fspGTD
on 02 May, 2006 22:24
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The stock VW Diesel piston rings have hard chrome plate facings where they wear. This chrome needs to wear into the cross-hatch pattern in the cylinder walls you added when you deglazed the walls.
So... keep driving her. Don't give up on the break in until you've logged at least 10k. Hopefully your mileage will come up, blowby and oil consumption will go down. Stay far, far away from synthetic oil during break in!
You said oil or blow-by gas pressure was coming out of the dipstick tube... are you sure your crankcase vent system isn't just plugged up? I know a retired VW engine builder who cut the blowby baffles inside the valve covers open, cleaned them out thoroughly, and welded them back up. Old varnished oil residue here could easily clog the crankcase vent system up here and cause pressure build-up inside your crankcase (and behind the dipstick.) If you removed your valve cover, you could test to see how restrictive the blowby vent is by blowing air into it.
Other things that you could consider doing next re-ring to help quicken ring seating (but granted, probably too late this time around)...
* You made sure the piston rings were installed in proper orientation? (2nd compression ring has a "top" and a "bottom". Also, staggering the gaps is recommended.)
* You used a suitable deglazing tool I assume, such as a dingleberry hone, and got the proper angle on the cross hatch? The grit needs to be right too.
* Were there any damaged areas in the cylinder walls noted? (IE: any gouges in the bores, etc)
* Did you clean the carbon out of the piston ring lands? New rings could be thicker than used ones, and you want them able to move around in the rings lands freely to be able to conform to the bores. You should be able to push any properly fitting ring back behind the "face" of the piston.
* Did you check your piston-ring land clearance with new rings installed? Bentley gives specs, and it's easy for shade tree mechanic to do (just need a feeler gauge set.) Too much clearance can supposedly let gas blow around the rings.
* I have heard some engine builders prefer to use super thin/light oils (such as WD-40) on the rings/bores during assembly instead of motor oil. I've even heard of some mildly abraisive material being applied to the rings and bores during assembly (I may be off here, but have heard of some using boraxo, and/or some honing compound comes to mind.) The theory is it helps the rings wear in qucikly, and breaks down quickly, and gets flushed out when you change the break in oil out a few times.
* I know of some engine builders with a preference for nondetergent oil for break-in, which is also very light.
* The most recent widely recommended ring break in procedure is to let the engine warm up, then drive it hard - load it up a lot, and vary the RPMs to get the rings broken in. The gas pressure in the cylinders press the rings harder into the cylinder walls. Some believe that if an engine isn't properly broken in very early on, it will never properly and completely break in.
Another train of though (which seems to be more outdated) is to "baby" the engine to get a more gradual break in and to reduce the risk of gauling or seizing.
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#8
by
wyldman
on 03 May, 2006 06:48
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Leave the cylinders rough after honing.220 grit stones are perfect,but use varsol,not ATF or any oil,as it won't cut well.Do not polish with anything afterwards,or the rings will take longer to seat.
Drive the snot out of it during break-in,to seat the rings quicker.If you baby it,it will take forever.
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#9
by
commuter boy
on 06 May, 2006 10:22
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Drive the snot out of it during break-in,to seat the rings quicker.If you baby it,it will take forever.
Yes, drive it hard, but also warm the engine up before hammering it.
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#10
by
hillfolk'r
on 07 May, 2006 12:09
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i had awesome results with ring seating using total seal's dry film cylinder lube,and their ring lube,hey if "dry" is good enough for a topfueler,its good enough for me..............
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#11
by
ameen
on 07 May, 2006 17:41
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cool...still running it...up to 730 miles since the rering.......still blow by....gonna try swaping out the valve pan cover...we think the baffles may be gunked up.
we clened them 3 times with no reduction of blow by...once before the work...once really really good during the re ring...and yesterday.
anyone had any successs with this?