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DD 3 - 71 info

doublewide

doublewide

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I'd appreciate any info, what to look for, signs of problems on a Detroit Diesel 3 - 71. I'm thinking about checking out one this week in a street compressor and know nothing about them.

Any input would be greatly appreciated.
 
kshansen

kshansen

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Central New York, USA
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Retired Mechanic in Stone Quarry
One thing you would do well to do is use the correct oil. A straight 40 wt. oil that meets Detroit spec's. which can be a little hard to find these days, not impossible but may have to order from a good oil distributor. I can't give the spec's off the top of my head but can find it if needed.

Hope you don't have neighbors too close to where you will be running this as they can tend to play their "music" a little loud!

Clean fuel and clean oil are important in all engines and maybe a bit more in a Detroit.

And from my experience over the years with 2-stroke Detroits they don't like running at low power levels, I always found them to run better when working near their rated power. The blower pushes as much air through the engine at no load as it does at full load and that can cause the cylinders to run cold and the fuel condenses on them and just makes for a mess and stuck rings.

If this engine has not been run for sometime let us know before you try starting and we can give some suggestions on things to check.
One could write a book on those engines but I'll wait to hear more about it from your end.
 
doublewide

doublewide

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Thanks for the response there kshansen. Like I said, I have no experience with these engines ( other than my FIL’s 45’ Hatteras that had twin Detroit Diesels. What a terribly loud boat. Pure misery to be out on the water in that thing.)


I’ve always thought, that’s one engine I have no interest in owning, until I read some posts on here and did some reading on Wickipedia which piqued my interest.


The guy had this thing on CL last year and I guess no one wanted it. Maybe for a good reason.
 
R

RZucker

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kshansen said:
One thing you would do well to do is use the correct oil. A straight 40 wt. oil that meets Detroit spec's. which can be a little hard to find these days, not impossible but may have to order from a good oil distributor. I can't give the spec's off the top of my head but can find it if needed.

Hope you don't have neighbors too close to where you will be running this as they can tend to play their "music" a little loud!

Clean fuel and clean oil are important in all engines and maybe a bit more in a Detroit.

And from my experience over the years with 2-stroke Detroits they don't like running at low power levels, I always found them to run better when working near their rated power. The blower pushes as much air through the engine at no load as it does at full load and that can cause the cylinders to run cold and the fuel condenses on them and just makes for a mess and stuck rings.

If this engine has not been run for sometime let us know before you try starting and we can give some suggestions on things to check.
One could write a book on those engines but I'll wait to hear more about it from your end.
Click to expand...

Chevron Delo 100 iirc is the correct oil. And yes, give it a minute or two to warm up and throw the load to it. Cast iron pistons and liners are just about bullet proof. If you don't load it, it will just slobber unburnt fuel out the stack.
 
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B

Birken Vogt

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One main thing I would check would be cold starting. In summertime it should start super easy from dead cold without any help or clouds of smoke besides the initial puff. No knocks or extraneous noise.
 
doublewide

doublewide

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Birken Vogt said:
One main thing I would check would be cold starting. In summertime it should start super easy from dead cold without any help or clouds of smoke besides the initial puff. No knocks or extraneous noise.
Click to expand...

Good info there. Thanks Birken Vogt !
 
td25c

td25c

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You be careful looking at that 3-71 doublewide .

This gets in the blood pretty quick !

Before ya know that's all you will want to run . :)

 
R

RZucker

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Junkyard said:
Absolutely. They’re tough motors and actually quite useful in many applications. Tough as nails. They do have their quirks.....
Click to expand...
Yeah, one of those "quirks" is that the damn things will run forever with little to no maintenance.:D Sure they should have a top end tune up every so often... Nobody does that. They normally get run to death until they wont run. And then they still try to run. A customer had an 8V-71 in an old GMC Astro that needed 1/2 a can of ether to start on a 70 degree day. Once it was running it was still a puller.
 
Junkyard

Junkyard

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Claremore, OK
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RZucker said:
Yeah, one of those "quirks" is that the damn things will run forever with little to no maintenance.:D Sure they should have a top end tune up every so often... Nobody does that. They normally get run to death until they wont run. And then they still try to run. A customer had an 8V-71 in an old GMC Astro that needed 1/2 a can of ether to start on a 70 degree day. Once it was running it was still a puller.
Click to expand...

The only one I ever had issues with was a 6v-53 upper in a crane. It would run but we chased cooling issues, left to it’s own vices it would have run until it melted down I reckon. It ended up coming out and a 6-71 went in its place.

When I busted it off before I removed it from the donor truck it went to the moon until I pulled the fuel line out of the 5 gallon jug. It survived that so I figured it was good. Years later it was still chugging along when the crane was shipped to MX.
 
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