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High oil consumption?

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ricmey1

Well-known member
Well here is the problem. I have new cylinders,rings,pistons installed on my 220 gpu. I still have high oil consumption, so I pulled everything off again. I noticed a lot of oil in the cylinders around the piston skirts and under the pistons. So I'm thinking about oil spraying from the rod bearing is getting into the back of the cylinders. This could be causing the cylinders to be drowning in oil, something the rings can't handle. So I pulled the rod's and I have .008 of play, I think it should only be about .001. Now just to cover any questions everything has been checked and double checked (tolerences) on the cylinders,pistons,rings ect. Now anyone have any thoughts on this? help me please.......... my head hurts!

Rick
 
I don't have my GPU book here right now, but the manual for a 520 claims .006 min. to .010 max. on the connecting rod on crankpin end clearancewith new parts, and a .016 service limit.

Larry
 
How many hours are on the motor since you rebuilt the top end, and how much oil are you using? My dads GPU seems to be starting to use less oil after it hit the 50 hour mark since the new rings, these things can take a while to break in.

Larry
 
Larry, I have about 40 hours on it and it smokes at idle and you don't notice it when runnig. It uses about 4 qts in a 3 hour run.
 
Smoking at idle sounds like an intake valve guide problem, at idle you have a high vacuum level in the intake tract and its trying to suck anything it into it. Any excessive clearance causes oil to come past the valves. Did you have the guides replaced when the top end was overhauled? You can usually see oil in the intake tubes if it has an intake valve guide problem, sometimes it even leaks out from the flange onto the head.

Larry
 
does any body no if to much gas thins oil and ads to oil lose i was told that to much gas will wash the cilenders and wear the rings but does it thin the oil and cause oil lose gator season comin 38 more days :twisted:
 
Hogen - I run the 0-540 on full rich and never use the lean control unless it is to clean fouled plugs or kill the motor at times. She uses about 1/2 quart or less per 20-30 gallons at cruise. If I stand push the throttle more, the oil use increases to about 1 quart every 15 gallons.

I know if you leak fuel through the manuel fuel pump, it dumps into the crankcase and the gas in the oil with trash a set of rings and bearings.
 
What type of crank case evacuation do you run. Also do a leak down test to check the condition of your rings if you have valve seals and good ring seal I bet your getting a positive pressure in your crank case this will cause allot of oil to pass your rings and enter your combustion chamber. A leak down will tell you everything! Also I have seen allot of people run chrome rings in a chrome bore that will cause a massive oil consumption problem.
 
its cause your mains are all wore out. best is r&r them and polish the
crank. u can also try not running but 5 quarts of oil.
also been told to plug off the cam oiler hole on the rod cap.
i gunna do that on mine as it is tore down now.i will let ya know
when i try it.
 
Richmey1 I have seen this problem ten or so times with 220’s. I know of three people when they rebuild a 220 they do not smoke a bit. Myself being one of them. It sounds like you have had a hundred suggestions. Simply your problem is coming from oil entering the combustion chamber there is only three way’s this can happen one poor ring seal (due to a bad bore or finish or rings) 2nd our your crank case if being pressurized causing your rings to flutter or lift 3rd oil is coming thru a valve guide. I think you said you installed valve seals. I do this on all 220’s because from the factory they don’t come with seals so I crossed over the valve guide and stem diameters to a caterpillar diesel motor so I can buy bran new P/C Teflon seals for 25 cents each. I know most people like running the older aircraft ones for $15 a piece. I like the newer Teflon style myself let alone the fact their better and cheaper. You need to control the oil consumption but don’t do it by limiting oil to your camshaft. 90% of the time I have found the problem to be in the rings and bore. What rings did you install in the motor. Chrome molly, cast iron or plasma molly. Were the rings from Superior or Ducarr aviation. Also what finish did you put in the bore as in what grit. Also were the bores re tapered when they were honed? If I’m annoying you just tell me I’m only trying to help!
 
Waterthunder, No your not annoying! To answer your questions, yes I installed new valve guides and later installed valve seals. I bought new gpu pistons and cut the ring grooves to accept Total Seal gapless rings.The cylinders are new also and I rehoned them with the correct cross hatch and removed most of the taper. The pistons would hang up in the bore just where the the threads started, kinda had a hump there. After honing and cleaning the pistons slid in the bore real nice! Now here is my plan: install new pistons with gpu rings, replace rod bearings and put her back together. If it still uses oil I will finish the season out and tear her all the way down this winter. I also cut the jugs for dual plugs.
Thanks everybody for the help, it's amazing how we airboaters stick together and help each other.
Ricmey1
 
just a thought how is your oil cooler lines installed ?
most gpu engines are plumed for engine destruction.
if yours is plumed from the back those tapered plugged holes
which are there from the factory then you get 100 hours and the mains are fried. this is what it sounds like to me if your rod bearings have worne 10 thousands in only 30 hours somthing has starved them.
if the mains are worn 10 then massive oil is being sprayed everywhere
this is why i said to plug the rod cap holes. there is so much oil
already being sprayed from the mains.
 
Swamproot, The bearing are the original ones when I bought the boat.
They did not wear out in 30 hours, just thought I would clarify myself!
I have ordered new rod bearings and bushings, and will do a total rebuild at a later date. Thanks,
 
Waterthunder, Would you please specify what valve seals - part #, size - that cross over from a diesel engine. Do you do this kind of installation service?
 
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