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Re: DeWalt D55170 oil pumping ,scored cyls. Can a hone...
It is possible to hone the cylinders and replace the rings to save the pump but don't remove too much metal as there are no oversized rings available for this type of piston/cylinder set. Also make sure to find out what caused the scoring in the first place and remedy that or you'll be replacing the cylinders and pistons next time.
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Usually, oil in the discharge air indicates too much oil in the pump or oil too thin (in hot climate use oil treatment). If oil level is known to be correct and oil not to thin, indicates worn cyl /rings. Easy to check. Remove bolts holding cylinder to body/base of pump. Pull off cylinder with head attached to examine piston and rings. Replace parts as needed.
If the motor is working OK but pressure won't go over 20psi you may have an air leak but most probably have damaged piston rings or cylinder or the valve plate is damaged. Check to make sure the tank drain valve isn't open or that you don't have leaks in any of the air lines. If that's OK, you will have to remove the head from the cylinder to check the valve plate and piston/cylinder assembly. The reeds on the valve plate should be flat and not overly discolored (black or blued) from heat. If they are they can warp or get brittle and break. Since your compressor is oil lubricated it is rare for the piston/rings/cylinder to get damaged unless it's run with no oil so check those areas for scoring or damage like broken rings. Replace whatever is damaged and keep the oil full.
If you are getting oil from the air pump in your hoses and tools your problem is in the cylinder/piston area. The piston on air pumps is very much like a car piston, depending on what model you have it has compression rings and oil scraper rings. If any of these are damaged or if your cylinder(s) is badly scored oil will get by the piston and be forced out with the compressed air to your tools. The only repair is to take the head and valve plate off and find out what parts you need to replace. If the cylinders are lightly scored they can be honed out but you can't machine them out as Campbell Hausfeld doesn't make oversized rings or pistons.
Piston rings may be broken or cylinder bore scored. These will allow oil to pass at a fast enough rate to cause problems for painting or media blasting, but slow enough to not register on sight glass or filler plug.
Very rare to have problems with rings. Blow-by would produce high pulsating pressure in the crankcase causing oil to blow out the oil filler plug/ dipstick. If normal crank pressure, suspect problem with valves or gaskets. Remove air filter cover and check for air blowing out of intake or very hot head or air discharge tube. Leaking valves or blown gasket will cause low volume/ low pressure and hot discharge air. Remove the in-tank checkvalve and look for carbon deposits /debris build-up. If the checkvalve and the interior or discharge hose are coated with oil deposits /carbon, most likely problem is valve plate/ gaskets /head. Good luck with your repair.
It sounds like your fault could be worn rings on the compressor pistons causing slow pressure buildup and excessive oil in tank. Replacing rings, checking poppet valves for proper sealing and having cylinder bores honed should fix problem.
Most late modle MX & enduro (from about 1990 on plus some even earlier)
have what is called an electrofusion bore.
This is a very thin plating on the alloy cylinder. They use this so as to allow heat to dissipate quicker & can run tighter piston cylinder tolerances for improved performance.
To answer your questions,
No, they can't be re-bored(like the older style steel sleeved bore bikes could)
Yes, they can be honed but it requires a special type of hone(finger type bottle brush style hone).
Pistons are available increasing in size by much smaller incriments than the old style & are usually marked A,B,C,D(as the coating is much thinner than steel sleeve).
If it is scored very badly & you can see alluminum spots/scores anywhere on the cylinder surface there are several ways to deal with this.
Here in Australia there is a company(electrocill) that can re-cote the cylinder which is much cheaper(plus thicker & stronger) than replacing the barrel
If you have a cylinder re-coated It has to have all studs, seals & power valve assemblys removed.
You would also need to supply(or have them supply) a new piston in order for them to set the correct clearance.
Also here in Australia you can have most of the common models fitted with a sleeve & this gives you the abillity to rebore in the future.
In the U.S this company is known as Wisco(serco in Aust.)
It is worthy of noting that the piston rings are not interchangable between an electrofusion & steel type cylinder.(so if you opt for a re-sleeveing any spare rings from your spares kit ar of no use).
If you need a lead on how & if these services are available in your country(if your not in Australia) I suggest taking a look in the classified section of your local dirt bike magazine.
The trick is to undertake regular srevicing of your air filter(this is A MUST),oiling it properly with propper foam filter oil, useing a top quality 2stroke oil(motul,syn-lube for eg)
& regularly inspect & replace rings/piston as needed to get the best life from electrofusion or steel type bores
Hope this explains it all for you
Regards Andrew Porrelli
your ring on the piston or your cylinder is scored. you'll need to have or do it your self and have the cylender hone and new rings installed. check to make sure your cylinder is not to Fardamaged. good luck
At the web address below you will find a parts list of your compressor. The most likely problem areas are the tube seal and the piston/cylinder. The tube seal seals the discharge tube to the head of the compressor. It will fail over time and cause the problem that you have. (only costs a few dollars) The other problem that you could have is a worn cylinder. Your compressor is oil free thus the piston ring is made of silicone vinyl and wears depending on conditions at the job site. Heavy dust/ dirt will shorten the life of the unit. With unit unpluged and covers removed, push the piston to top of stroke and examine upper portion of cylinder. If you see groves/scratches install cylinder kit. (cost around 39 dollars) In most cases I would replace both the seal and cyl kit. These parts are also available at your local dewalt service center or on line at dewalt.com. The folks at dewalt are very helpfull. Good luck with your repair and email if you have more questions.