Running well but burning oil... to rebuild or not to rebuild...

[riphonda]

Hey guys,

I have been thinking lately of the thanks I owe the forum- with the help of this forum and its dedicated members, I brought my old buzzard back to life and have been running it up and down reliably. Despite the reliable running she is burning some oil...

Heres the story: Engine runs great. Seems to get proper RPM, moves water freely, and runs at proper temp. I have done all sorts of upgrading and the motor now has electronic ignition, epoxy filled coil, new wires and plugs, new exhaust pipe with fire wrap, new carburetor, pcv valve crankcase air recirculator, electronic fuel pump and filter none of which existed on the engine before my ownership.

This season the engine has been super reliable and has run well. Starts within two seconds of cranking every time hot or cold. However it is burning a bunch of oil. Upon last check, Cylinder pressure was around 120 PSI on all 4 cylinders so im not sure it is rings. After about five hours of running the engine on a 20 mile trip, the engine burned half a quart. This seems like alot to me. Is it worth taking the engine all the way down this fall/ winter just for piece of mind and to get it running perfectly? Is this amount of oil within the expectation of a well running engine?

All thoughts greatly appreciated.

[hanleyclifford]

Your rate of oil consumption is indeed excessive. If you wre running the ICW or some other long trip you would be using at least a quart a day. In the long run fouling problems are sure to set in. I recommend a rebuild during the off season.

[Al Schober]

Keep in mind that there are different rings that keep the oil from coming up and from the pressure going down. You can have good compression numbers and still burn oil.
Personally, I'd live with it until plug fouling becomes a problem or you just get tired of dumping oil into it.

Al

[tenders]

Are you sure it's burning the oil and not leaking it?

If that's the only problem, I can't say I'd even take the head off for a quart of oil burnt every 20 hours...much less remove the engine...much much less tear it down.

[Dave Neptune]

Burning oil?

riphonda, you have a few different replies from different sources and different sources have different priorities. The oil consumption does sound a bit high however the most important factor to me would be reliability as the oil is cheap and easily replaced.
A couple of questions first, how do the plugs look? I f they start fouling and your constantly dropping a cylinder there are alternatives.
Does the consumption appear on all cylinders or just one? You mentioned your compression number but not by cylinder. As was stated the oil rings could be comprimised or just stuck a bit. Those can be worked loose with a little top oil like MMO although I prefer a good synthetic two stroke oil for breaking rings loose.
If all four cylinders spark plugs look evenly colored I wouldn't worry to much.
How often do you change your oil and what type are you using? Another factor could be to much oil in the crankcase, be sure the dipstick is the correct length.
Check for leaks to the bilge! My engine leaks about as much as it burns and is 40 years old and a bit tired to say the least. I use a little less than a 1/2 qt. in 25 hours and there are about 4~5 ounces in my catch basin under the rear seal.
What plugs are you using? I have recently gone back to the J8 colder plugs and am very pleased with the performance so far. I now have about 60 hours on them and they still look good. I suggest the hotter plugs in your case.
A lot of your decission will be how the engine is burning the oil~~ie if the oil is being distributed faily evenly no biggie, however if the oil is splattering and fouling the plugs it may be time to pull her and rebuild. Also at what rpm's are you cruising, cylinder load (preassure) can be a factor too.
I'd give the engine a chance by trying to reduce the consumption by freeing the oil rings if they are indeed a bit sticky~~not all that uncommon.

Dave Neptune

[hanleyclifford]

riphonda - All of Dave's suggestions are excellent and are worth trying before resorting to a rebuild. I guess I was just thinking you had already tried them. I noticed in your list of new "goodies" an oil filter was absent. Rebuild or no, I recommend it. Also make sure you change the oil faithfully every 50 hours, whether burning it or not. If the oil looks dirty even before the 50 hours, change it. Excellent idea to have an hour meter too.

[lat 64]

Keep in mind that there are different rings that keep the oil from coming up and from the pressure going down. You can have good compression numbers and still burn oil.
Personally, I'd live with it until plug fouling becomes a problem or you just get tired of dumping oil into it.

Al

This is a good point. I've seen oil-control rings stuck back in the groves in the pistons. The carbon and gunk gets pretty thick there and then the rings can't expand to scrape the oil. I think Dave has picked up the "trail". I've never used Marvel mystery oil but I think this is a good place to experiment.

Awesome that you get to enjoy your boat with that dependability.
If you only went out for a few times each season like me, then I would not worry about rebuilding but plan for a future overhaul when you can afford the time and money.

Russ

[hanleyclifford]

Russ - Only out for a few times a season?? - Follow the duck when September looms.

[riphonda]

oil and plugs...

Dave, I have actually run the motor for about ten minutes with full on mystery oil (at idle rpms) in an attempt to free up the carbon and this has had no effect on the oil burning. I understand this is a controversial thing to do... It still smokes all the same. I am running an NGK BR6 plug. Plugs are all the same, very light brown and never black and sooty. They appear dry and not wet with oil. I am using a non detergent 30 weight pennzoil oil. Should I switch?

I dont have compression numbers on hand, but I will try and get a hold of them next time I get out to the motor.

Hanley and Russ, I have been lucky that the motor is as dependable as it is, when we did the delivery there was almost no cooling water coming through due to growth in the intake scoop and the motor ran at around 210 degrees for a portion of the ride. Having no past experience with this engine, I decided that like most other gasoline engines this was within spec... maybe that did me in. But the motor was completely unreliable and got us out into long island sound and then died almost on cue (I think it was a "wow the engine seems to run well..."). After four carb cleanings only ran for a total of ten minutes more for a total of 230 miles of the trip. So Im happy with the reliability thus far after doing some upgrading and cleaning her up.

Additionally, there is no oil seepage into the bilge- i do see the transmission cover is bleeding a little bit, but not quite dripping at all so its not a significant source of oil seepage.

I am contemplating doing the swap with one of don's shortblocks but that is another idea altogether. Thank you all much for the thoughts.

[hanleyclifford]

It would be a good idea to switch to straight 30w detergent oil and give that engine a chance to clean itself. Substitute 1 quart of the MM oil during the clean up. Make sure you do your oil changes while the oil is still hot.

[Dave Neptune]

Oil and~~~

riphonda, deffinately start using a detergent oil. In your case I would try a 10-30 detregent oil. Most non-detergent oils are used for break-in purposes only. Non detergent oils do not clean at all and this could be a contributing factor to your problem. It will take time to get them un-stuck~patience saves money.
Don't go crazy with concentrations of MMO or 2-stroke oil. I wouldn't go over a 100:1 ratio and I would allow at least 15~20 gallons of fuel to be used before you recheck the numbers, as long as it runs.
What are your cruising rpm's? Cylinder load can affect oil consumption, when I went to the Indigo prop my oil use dropped a bit and is now very low. It took years for mine to get where it is~~sort of wearing back in. My lil beastie had zero, 40, 65 & 75 lbs of compression when I got it to spin after sitting for a few years frozen tight. It took days with a dead-blow hammer to get the pistons to move and that was 26 years ago. I checked my compression last week with a screw in Snap-on guage just to see what it now is. Dry and cold 90,90,110 & 110~~with a bit of oil sprayed in 110 across the board. Not bad for a forty year old motor.
Another words give it time to work, as long as it runs there is a bit of hope for improvement!
As to the heating that's also an easy fix!!!

Good luck.
Dave Neptune

[sastanley]

Check for leaks to the bilge! My engine leaks about as much as it burns and is 40 years old and a bit tired to say the least. I use a little less than a 1/2 qt. in 25 hours and there are about 4~5 ounces in my catch basin under the rear seal.

Dave Neptune

riphonda...patience is key here..sorry I have a quick hijack and nothing else to really add.

Dave, I can help you with that.

[charles@pricefarrington.c]

Oil comsumption

We just got back from a 10 day trip to the San Juan islands from Seattle with the new indigo prop. Prior to the indigo, my oil consumption was about a 1/4 quart every 10 to 15 hours and now seems to have dropped to about an 1/8 quart for the same time with the indigo. This is on a professional rebuilt motor from the PO. It was done in 06 and when I got it in 08, it only had 40 hours on the rebuild. Now, I have 400 hours. I have all the documentation on the rebuild.

With the indigo, she runs much better and fuel consumption was about 1 to 1/1/4 gallons per hour. Plugs are good and no other issues with the motor whatsoever except still no quality reverse.

The only other issue that developed on calm days was that we installed a new dodger and now with the enclosure, we get the station wagon effect when motoring and the wind is flat. Exhaust fumes seem to swirl back in the helm area.

[hanleyclifford]

Did you reach a higher rpm at cruise with the Indigo and if so do you credit this with the reduction in oil consumption?

[Dave Neptune]

Consumption

Hanley, yes I think I did see a slight reduction in oil consumption. I think that reducing the cylinder load with the Indigo allowed the weak rings to stay in better contact. I did not track the oil and still don't but I am adding it less often now, of this I am sure. Like I said though not much of a reduction, maybe 15~20% and that's a guess at best.

I saw on another thread you are looking for a 3 blade, I assume it is for a reduction trans(?).

Is it you that has the Fram F-4 filter et up?

Charles, what RPM's are you cruising at? I'm pushing a 35', 14,500 lb, 25' waterline and towing a 10' rowing dinghy at 2100 RPM's @ 7 1/2" of vac and using about .8 GPH. My reverse is vastly improved with the Indigo, however I do need to rev her up a bit in reverse.

DEave Neptune