CAT Gas Engine Oil Consumption Problem

If there aren't major oil slicks on the floor, check the color of your exhaust. Maybe a ring job is in order.

You say this is a Cat gasoline engine, Your sure its not diesel? If it is diesel I would remove the intake next to turbo and see if the tube is clean and free of oil. Sometimes we cut the cost of rebuilds by not rebuilding accessories. This is one area of major oil leak, other wise you may have to do a tear down and check for broken rings.

I might ask if the unit has a Cat engine monitor on it. If so you maybe able to run diagnostic's and find issue.

As has been said, check the exhaust. A blue color indicates worn rings. Do I understand you correctly when you say you change the oil every 2000 hours? I think you might be adding a 0 on that schedule. Does the engine service specifications say to go this long? What is the condition of the air cleaner? And if it is indeed a gas engine be sure to check your pcv valve, and check for vacuum leaks. These things will cause oil consumption.

Another fault easely overlooked: If the engine has a "lift pump" on the side of the engine, pumping feul from the feul tank, the diafragm of the pump could be leaking feul into the crank case, diluting the engine oil and causing oil level rising and oil use.

If it is bad enough the engine will also use more feul than expected.

Lets see the reasons for oil to be finished up anomalous

- Leakages to any oil system,

Check for leakages, i believe you might have already try that, if your engine part are much compacted it might not be easy to realize the leaks, so you can concentrate to the sensitive parts of the oil system that are likely to get affected, chekk the piping close to turbo.

If it is a Gasoline engine look at the valve guides in the head. They may be leaking oil into the combustion chamber as well.

Where is the make-up oil being added, into fuel or crank case?

On car engines, both diesel and petrol types, when dismantling the engine, the places where oil is being used is often very apparent, did the mechanic(s) who did the job notice anything? Ask them.

Blindly dismantling and rebuilding is not a professional way to do such a job.....

There is of course the possibility that oil consumption before the strip down was actually less than it is now, is that the case here?

If yes, then you (your engine) may be suffering from "Glazed Bores", which probably means that new piston rings (and maybe pistons too!) were installed, but the bores were still good and left untouched - FAILURE!!

They must be "unglazed", it used to be done with a tool that looked like a small tree with balls of special stone on the ends of each branch would be put into an electric drill, to slightly roughen the surface of the bores. This slight roughness produced would allow the rings to bed in quickly and seal properly within a short time.....

If that is what was forgotten, they will eventually bed in, but it will take a long time.

How long? Sorry, no idea.....You will have to work out what is cheaper, using oil till they finally bed in, or stripping down and taking the glaze off.......? Again no idea for the price difference......sorry.

If the engine has a Turbo(s), they have been known to burn oil when the bearings get worn, but there is usually ample evidence of that when you look inside the turbo!!!! Were the turbos refitted completely or not?

A good old German saying, which may be applicable here is:- "He saves money no matter what it costs!"

Best wishes.....

This most be a natural gas gen set. Maybe it would be a good idea to re-visit the numbers you have stated. To me none appear to correct. It is true that natural gas engines burn extremely clean so any color in the exhaust would indicate some oil loss through the rings as already mentioned.

There are many reasons when engine uses excessive amount of lube oil-:

Defect crank- shaft end oil seals,defective turbochargers seals,cracked crankcase

cracked piston crowns,loose or defect lube oil piping system,leaking gaskets

defect oil scraper rings,perforated lubricating oil cooler,

Glazed liners,wrong grade of lubricant used

Excessive blow by,worn valve guide,make up lubricating oil added unnecessary.

Please check with the breathing pipe. The crank case may getting over pressure.

A correctly overhauled engine will not use 1500 liters of oil in 2000 hours. Ensuring that the engine operates correctly is part of a good overhaul. Have someone competent redo the overhaul. As others have suggested, there are many causes of excess oil consumption -- but all those should have been addressed in the overhaul.

Overhauling was screwed up, or not done at all. Do you still have warranty? Check if the pressure sensor is sealed! Sometimes an angry "friend" of the man who had overhauled the engine loosen up the sensor and the leak consumes oil! Also oil if consumed it is because the cylinder bore is oval or piston rings broke. There is no cure for sabotage! You just must have anger somebody under your supervision. My advise is, if you want to save your ass, to treat those under your supervision with respect. Also if you can recall anything from the past as your dis-respectful behavior to anybody, including floor sweeper, to approach him and apologize. That might work better than hiring an expert.

Maybe they left off or didn't replace the oil rings. Maybe the cylinders are out of round. Valve guides and valve seals are also a suspect. How much do you trust the mechanics who did the overhaul? Does it use more oil or less than before the repair?

You don't state what the engine is used for. If it has an air compressor on it, it is possible for the compressor to suck some of the lubricating oil into the compression chamber(s) Check the air tanks, if so equipped. Good luck

Lots of good ideas here. I would add, before tearing it apart, do a compression check on the cylinders. This should reveal a lot. In addition, hold a piece of paper up to the exhaust, about 1" away for a couple of minutes while running. Is the residue oily?

Whoever did your overhaul either forgot or skipped something important.

Dear Mr.rajrao,

The figure 2000 Hrs, as stated by you appears to be very high. In my opinion, a duration of 200 Hrs. is O.K. or at the maximum - 220 Hrs. For 2000 Hrs, the oil could have lost its character. Since you are using (or have used) 1500 Litrs, you did not feel the pinch or severe mechanical damage.

Now the question is "Why Excess Oil Consumption.? "

The reasons can be as follows.

1. Damaged Oil Scrapper Rings.

2. High Clearance between Oil Scrapper Ring and the liner.

3. Burn out of oil is more than permissible.

4. Oil Pumping is defective.

5. Oil Scrapper Ring will not be perfect circle.

DHAYANANDHAN.S