Rebuilt Perkins 4-108 Oil Consumption-Is this Normal

[jpendoley]

Hoping some Perkins users can offer some experience. My recently rebuilt Perkins consumes lots of oil-but leaks almost none.  I motored for eight hours yesterday and consumed three cups of oil. Is this normal? Is it just paet of the break in process? I've puit a few hundred miles on the engine and it has lots of oomph and good oil pressure. Barely a leak of oil anywhere.  Curious to hear others thoughts-valves maybe?
Jim

[Dale Tanski]

Jim,
Oil consumption can be a result of many items.  First... If I had a recently rebuilt engine and it consumed that much oil, (actually any oil) I too would be concerned. 

The first question I must ask is what does "recently rebuilt mean"?  Recent as in 1000 hours ago?  5 years ago? The next question I would have to ask is what does rebuilt mean?  Many a "rebuilt" engine consists of a degrease and a coat of paint.  Other rebuilds consist of the crankshaft seal replacement and a handful of gaskets fixing the leak problems.  Some are just a recalibration of the injector pump and work on the injectors and/or the replacement of the injectors.  The next step perhaps would be the top end rebuild which typically consist of re-lapping the valves and new valve stem seals, maybe even a truing of the head surface.  Then we get into a rebuild that consists of the re-honing of the cylinders and the installation of new piston rings.  Perhaps the installation of new cylinder sleeves and pistons depending on engine and finally crankshaft bearings and rod bearings. 

So... what does rebuilt mean?  Was it honed of sleeved?  Top end done? The difference can be hundreds and hundreds of dollars, additional usable hours and if it will continue to consume oil or not. 

The oil itself is a major variable.  I am a big believer in synthetic oil.  I use it in everything I own... almost.  The difference between a synthetic oil and conventional oil engine when you open that engine up is substantial.  I have tried synthetic oil in my 107 Perkins and it ate it like it was going out of style, very close to your consumption numbers. How much is a cup by the way?  I went back to a traditional oil rated for diesels and my consumption issue went away. 

In terms of "break-in", it all depends on what was done to the motor.  Oil consumption of the nature you are talking about is not a normal break-in consumption.  "Normal" consumption would be perhaps a fluid ounce over hundreds of hours. 

Does it smoke?  Blue in color?  Especially at cold start up?  These are all tell tails that indicate high hours and the rebuild was nothing more than a paint job.  If smoke is present then it could be valve seals, it also could be rings and cylinder condition.  Remember a diesel engine runs in access of 300 pounds per square inch of compression pressure approximately three times what your gasoline engine in your car runs at. 300 plus pounds is a real incentive for hot engine oil to escape and be incinerated in the exhaust.

So... I have raised lots more questions than provided solid answers.  Unless you have deep pockets and want that engine back to spec, try changing the oil and running a 15W-40 viscosity rating in a great brand like Rotella and see what happens. 

In the words of Captain Ron, Diesels love their oil like sailors love their rum!

Dale

[jpendoley]

Dale-thanks for your reply. I did the rebuild with the help of Hanson Marine doing the machine shop work-they are a long time Perkins/Westerbeke shop. They trued the head very slightly, pressed new sleeves and honed them. New rings and valve seals and seats, new pistons, bearings,crank seals etc. I did all the reassembly. I think the only thing that was not machined or replaced was the crank.

Its been used lightly since it went in June of last years. 2-300 hours of break in at most. Some experienced folks have suggested it needs to be run under heavy load for five or ten minutes. I ran under wide open throttle yesterday for about three minutes-heat stayed under 200 and oil prerssure was great. Engine lifted the bow and pushed a fully loaded 365 with full fuel and water at 7 plus knots.  Smoke almost not noticeable-except there was a lot of soot visible on the stern when we got into port.  I chickened out on running at WOT for longer than three minutes because it just makes me nervous to push it that hard.  I think I'm still in a breakin period.
Two very experienced folks have suggested a teaspoon of abrasive of some sort be entered into the air intake to facilitate ring seating. Apparently that;s a not uncommon "bush" remedy to remove cylinder glazing. If running under WOT makes me nervous you can imagine how I feel about introducing an abrasive into my air intake...
In all respects the engine runs well, its tight with loads of power and zero smoke at startup or under load. There is  a small remaining rear seal leak that migh account for some of the oil loss-but a very small proportion oif the overall loss. Ging to track it very closely on my return to Mass which is about a 200 mile trip.

[Alan E Skeldon]

Was the block and head dye tested or pressure tested for cracks? My diesel truck motor blows black smoke all the time and it's covered in soot but burns no oil. I pity the fools behind me when that black soot covers their car when i smash the pedal 

-Alan

[Dale Tanski]

All sounds good...
What weight oil are you running?
I would not add an abrasive to the inlet.  The new sleeves as you indicated have been honed and crosshatched from the as they would have from the manufacture as well. That would have caused the new rings to seat during break in.  Break in happens for the most part in the first few hundred revolutions.  They always recommend you vary RPM's across the board of course but even that is a guess.  Seems like you did everything right.   Could be a leak issue through a casting.  Remember leaking to the outside is the path of least resistance but it could be going into the combustion chamber. That of course would mean smoke.  Hummm?

Dale

[Alan E Skeldon]

Another problem would be if the rings turned during handling installation and now there are slots aligned instead of off-set.

[jpendoley]

Was the block and head dye tested or pressure tested for cracks? My diesel truck motor blows black smoke all the time and it's covered in soot but burns no oil. I pity the fools behind me when that black soot covers their car when i smash the pedal 

-Alan

Alan, It was at least magnafluxed, but yes it was tested. As I said, I have tons of power-like it raises the bow when I go wide open-

[jpendoley]

Another problem would be if the rings turned during handling installation and now there are slots aligned instead of off-set.

I installed the rings and believe I got them right-at least I know I staggered them. Worse comes to worse I'll  pull the engine and bring it home this winter.  Just can't leave well enough alone. I may also try a heavier weight oil. I'm obviously burning some oil based on consumption and the evidence on the stern. You'd think it would show as a haze in the air, but it really does not. Nor does it stink.

[Alan E Skeldon]

do a cylinder leak-down test for compression. you may also see if one cylinder is oily. that will provide more pieces to the puzzle.

[jpendoley]

I'm going to live with it for the season. One interesting possibility came up as I was reading Nigel Calders diesel handbook-prop overloading.  I cruise easily at 6knots and 2000 RPMs.  No staining on the stern. Bump it up to 2300 or as far as 2900 (WOT on my boat) and I get the smear of oil on my stern.  I have a big three blade prop. The speed increases by about 1Kt.
Going to take off the valve cover for a look and will report back.
jim

[S/V Deo Volente]

That sounds like you are proped about right. If you are overloading you should see a lot of black diesel soot on the boat, but it shouldn't be burning lube oil. Are you sure of your dipstick fill level? You say you burned 3 cups of oil, so I wonder will it hold at that level or will it continue?

[jpendoley]

Thats a good question, but Im afraid to find out.  The difference between the hi and low mark on the dipstick is 4 cups-I'm afraid to go below the low mark for fear of damaging a newly rebuilt engine. Again., virtually no discernable smoke in the exhaust. In the picture attached you can see the exhaust staining-but this only happens when I go above 2300 RPM-below that I get no staining and no smoke, but the oil still dissapears...

[S/V Deo Volente]

I wouldn't go below the mark, but if you are down 3cups I'd wait to see if it continued to 4. While I have a BMC 1.8 my dipstick reads almost 1 quart difference from one side to the other because of the angle. Did you check ring gaps when assembling? They should also be 120° apart. You should run it fairly hard to break it in, 2300 is not too high.

[jpendoley]

I ran it at 2800 RPMs in short bursts of 3 to 5 minutes or so. And one time we almost had it up to 3000 RPMs in any case, I did run it at wide-open throttle. The rings were definitely spaced 120° apart. I'm leaning towards a valve stem seal, but will have to get the cover off to check. And yes the dipstick reading is very imprecise. I will take some pictures of the valve train as soon as I get the cover off and we can compare notes.