8v53 oil question

[mtadamek]

I have 2 recently overhauled 8v53's in my 41' conv. It is blowing quite a bit of oil in the crap cans. These were reworked and I have 3 lines on both inboard and outboard cans. There seems to be a lot of oil blowing out of the cans breathers. No check valves, I was told naturals did not have them. I run 40wt rotella. I also don't know if the dipsticks are the correct ones, so I could be overfilling the engines with oil. I have never been able to find out the actual numerical # of quarts of oil to use in these engines on this boat. I used 2 gallons of oil on the starboard engine, and 1 gallon on the port over a 17 hour trip. No excessive smoke and about 60 hours on each engine. A lot of the oil was blown out of the cans, but I am still using too much. Engines still may not be broke in yet. Any ideas? They run great, but I think I have a combination of small problems that are responsible for excessive oil. If anybody has any numbers, I would be happy to hear them.

 

[Boatsb]

The engines should hold around 24 Qts of oil each. There is the first place to start. It is true the 8V53 has no valves on the airbox drains but they should not pass that much oil unless there is a problem.

 

[mtadamek]

Thanks, I have never been able to find the correct oil amout. When I bought the boat the engines had 2 lines dumping in the bilge, the other hole was plugged with carbon. We cleaned it out and added the third line. There seems to be an excessive amount of air coming through the lines, we may actually have created the problem by adding the 3rd line. No blow by whatsoever. Racor type air seps installed as well. No leaks except for the oil being blown out of the cans.

 

[mtadamek]

Any idea of what kind of oil consumption these engines should use over a duration of time? I have always been told that any detroit will burn some oil. But I don't know how much truth there is to that.

 

[yachtsmanbill]

The 12-71s have a cranksae breather that has a pipe up to the blower silencer... inside the housing is a steel mesh screen that accumulates the mist from the blow by and drips it back to the return... you may have one on the 53s as well. If thats plugged the air box pressure increases and hits the crap cans... The vent is way on the left side of the pic... ws

 

[DCMY #92]

I'm a little confused by your reference to 3 lines from the air box drains. My 6V53s have one drain on each side at the aft end of the air box. Maybe the 8V53 is different.

I suspect the oil you are loosing is coming from the blower. There are two rotors in the blower. Each rotor has a shaft on each end with a lip seal to prevent oil from entering the blower air path. Eventually the seals cut a groove in the rotor shaft and can leak allot of oil. Some years ago I overhauled my blowers by purchasing an oversize shaft seal kit from Detroit. The kit includes four sleeves that slip over the worn shafts to cover the grooves and 4 lip seals sized to fit the sleeves. It's not a tough job, but you have to remove and disassemble the blower to install these.

You can probably purchase overhauled blowers also, but I'm not sure about that.

 

[Boatsb]

There are 2 drains on one side and one on the other with the 8V53. I believe the side with the starter only has one if I remember correctly.

 

[mtadamek]

It is possible the blower seals are leaking. Both port and star have had them replaced, but we need to check them again. Pretty easy to check if I remember. Pull off the horn and shine a light in the blower while it is running. Not a job for a necktie.

The 8v53 has ports for a total of 6 drains. One forward on the valley, one in the back. Two more on the forward end at each bank of cylinders and two on the back end of each bank. Those are the possible places to connect, but we have them all connected. I don't how it came from the factory, but I suspect we have too many connected. Three seems like it would be correct since the engines slant toward the rear. One on the valley and one more on the rear of each bank for a total of three. This makes a lot of sense to me now and probably explains why we are blowing the oil out of the cans. The blower seals could account for the amount of oil, and the rest of the oil could be consumed during normal operation. I might even see a little increase in rpm and hp if I was not blowing all my combustion air through the cans. I am running about 2500 rpm's max with a clean bottom and props. We have adjusted the govenor and rack multiple times and it is dead on.

The cans that we have are home fabricated on the walker design. The mesh screen on the 1271 is on the 8v53, but it is not usable on the marine version. The heat exchanger tank does is mounted directly in front and does not allow it to be connected. That is what I remember during the rebuild anyway.

Does anyone have any "normal" oil consumption numbers?

Thanks for all the help. It definately gives me some things to think about and check. It is nice to have a forum to voice questions and answers.

 

[NAN-PO 41]

My 8v53's are only using 1 drain on each side, the rear ones. When I got the boat they were just dumping into the bilge so I replaced the tubes with slightly longer ones and routed them into tupperware type containers ( tubes stuck thru a small hole in the cover ) that I had filled with torn up pieces of oil absorbing blanket. That way I don't have cans filled with liquid in the bilge. So far they have worked well. I only have to clean them out once a year but am in Boston so only boat in the Summer. To answer the question about oil usage I have to say that it is minimal. You must bear in mind however that I don't run my engines very hard. We only run about 12-1500 rpm most of the time, running up about once an hour or so to clear out the engines if necessary. At 1500 they will maintain temp so that really isn't much of a problem. Oh yeah the containers are only about 1 qt in size.
Fred

 

[REBrueckner]

"I used 2 gallons of oil on the starboard engine, and 1 gallon on the port over a 17 hour trip."

At 1800 rpm, say, thats way too much too much oil use for new engine rebuilds.

Maybe if you were crusing at 2600 RPM I could understand 1 gal at 17 hours....


My 1972 8V71TI's, 435 HP, at around 1500 or 1600 RPM used about 1 gal in 22 to 25 hours running, a bit less on my rebuilt one with about 1200 hours, a bit more on the original one with about 2600 hours.

 

[SLIDELLBIGAL]

In all my tug applications we find that the 8V71 and 8V92s use about 1 gal every 24 hours on a hard push, 1800 RPM, That is without any leaks(what Detriot don't leak?) Our same horsepower Cummins NTA 855 might only use 1gal every 4 or 5 days.

Allen

 

[mtadamek]

Thanks for those consumption numbers. Looks like I am not too far off on my port engine consumption. I am going to plug the 3 drains in the front of the engine, do a full oil change and fill to 24 qts, and check for leaks on my blower seals and see what I come up with the next trip.

 

[ron6785]

Detroit Diesel prints out an oil consumption chart for their engines. I have 8v71 naturals and at hull speed about 8.8knts/ 10mph my consumption is about 1.5 quarts per 10 hrs of operation. That rate goes to 2.3 quarts at WOT. You should have some oil coming out of the air box but yours seems excessive. Almost like the rings havn't sealed or you leaking past the seal ring.