Oil Fill Location - Detroit Diesel 6-71

[R1Guy]

Hello,

Purchased my boat in October and lived on it over the winter. I have twin Detroit Diesel 6-71 Naturals. Checked the oil and it needs to be topped off. I believe I know where the Oil Fill cap is, however as it doesn't clearly say "Oil" I want to make sure I am filling in the correct location. I have the old manuals from 1977 however nowhere in it could I find a picture and indicator showing where the fill cap is. Hoping someone who has one can verify I am correct.

There is a cap not too far above the dipstick. I do not see any others. Does this sound like the correct location? Attached a pic of one that looks similar to mine. I didnt take any pictures while I was down there, I should have.

99% sure this is the oil fill. But hoping someone can verify if possible with this little info.

Thanks!
Dan

[GordMay]

The 6-71 diesels hold eight gallons of lubricating oil in the sump. The dipstick is located on the port side of the engine, two thirds of the way down from the front, and directly under the exhaust manifold.
Directly at the end of the cylinder bank, on the starboard side, is a green cap roughly two inches in diameter. This is the oil fill. For every quarter inch the oil is low, approximately one half gallon of oil should be added here.

[R1Guy]

Thanks GordMay!

Followup question....

So, my engines seem to be mirror images. You stand between them to access.

On my port side engine, the dipstick is 2/3rd way down on the starboard side of the engine near the aft. About maybe 1/3rd down above it is an ~2in green cap with a T handle to turn like the pic above (although the entire engine is painted green...so not sure if thats original color). It does look like its at the end of the cylinder but on the starboard side of the engine above the dipstick.

For Starboard engine, exact same except the dipstick and cap are on the port side of the engine. Looks like placement was to make it easy to access from in between the two engines?

Other mechanical gear seem to be mirror imaged. Example is the alternators. On the port side of the port engine, on the starboard side of the starboard engine.

This sound right?

Again thanks!

[landsend]

Yes, sounds normal. Is this your first boat?

[R1Guy]

First Dual Inboards. First this big!

[R1Guy]

Originally Posted by GordMay

The 6-71 diesels hold eight gallons of lubricating oil in the sump. The dipstick is located on the port side of the engine, two thirds of the way down from the front, and directly under the exhaust manifold.
Directly at the end of the cylinder bank, on the starboard side, is a green cap roughly two inches in diameter. This is the oil fill. For every quarter inch the oil is low, approximately one half gallon of oil should be added here.

Thanks so much. Good news, those caps were indeed the oil fills! Also, the dipstick marks are exactly as you said. Both were down about 1/2 inch from high to low stamp mark and each required 1 gal to fill. Just as you had indicated. Woohoo!

One more thing about this boat learned, and hopefully better documented. Making a nice manual with pictures and more specifics for this boat than is found in the original manuals.

Thanks again!
Dan

[Jessetopp]

Hi Gord
I see you're in Ontario
As well am I. I just bought a boat with twin 671TIs.
Any concerns with these I should be looking for?
My first set of Detroit's . They have 2200 hours on them but run and fire on the first roll. Any insight is greatly appreciated

[GordMay]

Detroit Diesel Engine Series 71

Service Manual ➥ https://www.google.ca/url?sa=t&sourc...0L4I_PMSS8H0O-

Operators Manual ➥ https://www.numeralkod.com/cross/arc...9/part%201.pdf

Congratulations, on your new boat, Jessetopp!
Sorry, I don’t have any particular knowledge, beyond reputation, of larger diesel engines, like the Detroit Diesel.
The Detroit 6-71 has a long-standing reputation, as a great, reliable, and very economical engine; but, like all diesels, will have a longer life, in its Natural state.
I believe the 6-71 TIB is highly turbo'd, and has a lessor reputation, for reliability, and endurance, than the NA versions.

[skipperpete]

There’s usually a filler on the rocker cover…. See Captain Ron doing a topup on a GM in the movie. Another thing that might be useful to know about your engines is that often with twin installations they were contra rotating, of no real concern unless you need a starter motor…. Then you need to know the rotation. It’s also useful to get familiar with the emergency shutdown , GM’s have a habit of going overspeed if they get a sticky injector… and they don’t overspeed in a way that gives you time to learn how the emergency shutdown works, it happens fast. If you accidentally trigger the shutdown for any reason other than a runaway, it needs to be re set ( re latched ) or you won’t be able to restart the engine.

[Lepke]

The 671 was designed to accommodate any blower or exhaust position and either rotation. The engine can be turned 180° and puts the blower on the opposite side. Swapping the balance shaft and cam, the head can be turned around and put the exhaust on the opposite side, and more.
In WWII Detroit made a quad setup. Four 671s on a single transmission. Two quads on 2 shafts were used on some larger landing craft. Once one engine was started, the others could be started by clutching them in. After WWII a number of tugs, fishing boats had surplus quads installed. The 8v71 and 12v71 were not available until the late 1950s.