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Detroit Diesel inline 71 Series model number breakdown PLEASE READ

jimg4652

Contributing Member
"I have seen a few threads sta

"I have seen a few threads started asking what that persons particular model number means. I dug through some service manuals at work and found model number break-downs for 53, in-line 71, V-92, and 149 Series engines. This break down is for the inline 71 Series engine only.

All rotations are found with you standing in front of the engine, looking at the crank pulley. If the pulley rotates counter-clockwise, it's a left-hand rotation. If it turns clockwise, it's right-hand.

Bank determination (Left bank, Right Bank) and accessory placement (blower, exh. mani) is with you standing at the back of the engine looking at the flywheel. I know in-lines have no "left bank, right bank" but I will use those words to describe which side the blower or exhaust mani. mount.


First digit in the model number determines what Series your engine is. 1000-0000

5 = 53 Series
1 = In-line 71 Series
8 = V-92 Series
9 = 149 Series


0230-0000: 2nd and 3rd digit determine how many cylinders the engine has.

02 = 2 cylinders
03 = 3 cylinders
04 = 4 cylinders
06 = 6 cylinders
08 = 8 cylinders
12 = 12 cylinders
16 = 16 cylinders


0004-0000: 4th digit determines "Application Designation"

2 = Marine
3 = Industrial
4 = Power-Base
5 = Generator
7 = Vehicle
8 = Vehicle


0000-5000: 5th digit determines the "Basic Engine Arrangement and Rotation"

1 = Engine is left-hand rotation, blower is mounted on the "left bank", exhaust manifold is mounted on the "right bank"

2 = LH rotation, blower and exhaust manifold both mounted on the "left bank"

3 = LH rotation, blower mounted on "right bank" exhaust manifold mounted on "left bank"

4 = LH rotation, blower and exhaust manifold both mounted on "right bank"

5 = Right Hand rotation, blower on "left bank", exhaust manifold on "right bank"

6 = RH rotation, blower and exhaust manifold both mounted on "left bank"

7 = RH rotation, blower on "right bank" exhaust manifold mounted on "left bank"

8 = RH rotation, blower and exhaust manifold both mounted on "right bank"



0000-0600: 6th digit determines the "Design Variation"

0 = 4 valve cylinder head ("N" Engine)
1 = 2 valve cylinder head
2 = 4 Valve cylinder head ("E" Engine)
3 = Turbocharged engine
5 = Customer Spec. Engine
7 = Constant Horsepower


0000-0078: 7th and 8th digits are the specific model number.

Remember, the model number on your block determines the way your engine came from the FACTORY. Anything could have changed by others who have rebuilt your engine."
 
Jimmy my 671 has this stamped

Jimmy my 671 has this stamped on the block 6a256017
ra6055m
do you know how to brake fitst 4 down
 
"Serial number 6a256017: 6A i

"Serial number 6a256017: 6A is the Suffix for 6-71, all 6-71's will have "6A" as the first two digits.
According to my Field Service Data book, serial number 248936 started in 1972, and serial number 272037 started in 1973. So your serial number of 256017 means your engine was built in 1972.

As far as your ra6055m number, to be honest, I have no idea. I will try to look it up in the Service Manual at work on Monday and see if I can find anything on it."
 
"I have a 6 71 and don't k

"I have a 6 71 and don't know the model. The boat was built in 1961. It says Gray Marine and from old paper work, the s/n is 67178342. I want to get the correct manual for it. I have a few manuals but don't know which one to use. From researching this, the s/n I have may not be correct. Where can I find mod and s/n on this engine so I can get the correct manual?"
 
"Model and Serial number shoul

"Model and Serial number should be stamped on the block right behind the governor.

On the old Gray Marine engines, the s/n usually did start with "671" like yours, so you probably have the correct number. I don't have the literature available to give me any more information though, so I apologize.

I think they didn't start using the "6A" prefix on the s/n's until the late 60's - early 70's."
 
"Jimmy.......

Thank you so


"Jimmy.......

Thank you so much. I will look and see what I can find. Do I need to get the correct Model # in order to get the manual? Or can I get a manual from the serial number? Thanks again for your help, Bud"
 
You should just need the seria

You should just need the serial number. The correct manual should cover all models of your engine.
 
I was told the two Detroit engines in an old boat I recently purchased were 371 marine models. The numbers I found stamped on the block are:

5032-A600
3D57015

Can anyone help me determine what these numbers represent?

Thanks

SM
 
Hi iscottmcleod,

I am certainly no authority on the Detroit Diesel Marine engines. I'm just an old Bus and Truck mechanic with a love of boats that TRIES to help out here once in a while.
I have LOTS of experience with all manner of Detroit V engines and NEWER inline 4 cycles but not a bit with the inline 71 or ANY 53 engines of "yore".

So, having given you my disclaimer....

I did a quick look online and it would seem that you have at least one, if not a couple of, 3 cylinder series 53 Detroit Diesel engines that were manufactured in 1968.

Other than that, I really can't give you more info. I have included links to the web pages that gave what I would describe as a "partial break down" of the numbers you listed from your block.

Other than that, I can tell you that the series 53 is STILL a popular engine for guys to put in pickup trucks and there are a couple of forums that some of them are on that you may be able to get more info from. One of those groups is likely to be able to provide you with technical tips and parts sourcing that you may find useful. I'm sorry, but I don't remember the names of any of them but if you hunt around on the web I think you will probably stumble across one as I did some time back.

I hope this helps you in some way and good luck.

http://engine.od.ua/ufiles/DETROIT-Model-Serial-number.pdf

http://igor.chudov.com/manuals/Detr...s-53/Detroit-Diesel-Engine-Serial-Numbers.pdf

http://www.volvodemort.com/technical/detroit.html
 
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Hello, I have read thru this thread and have looked at my engines for the model numbers with no luck. I have 2 671's on a 1953 boat I just bought and need to determine what my engines are exactly. 2 valve or 4. I found what appears to be a casting number on the main case, 6 digits they are 511434 and 518328. looked at the governor area and any other possible places. any help is greatly appreciated. Bryan
 
According to the link below...which I have provided for you to look at for yourself...ALL inline 71 engine serial AND model numbers are stamped HIGH UP on the RIGHT FRONT of the cylinder block. You must stand at the REAR of the engine and face forward to determine RIGHT from LEFT. This guide shows the SERIAL number to be the TOP number and the MODEL number (what you will need to determine valve arrangement etc.) to be the BOTTOM stamping.

The 71 series SERIAL numbers always begin with "1" followed by the number of cylinders...IE "06" in your case.

The numbers you provided above may be, as you have indicated, what are lovingly known as "casting numbers". Casting numbers are put on pieces that are poured into a mold and are there for the foundry to reference if any issues pop up with the casting during machining of the product. Casting numbers have caused confusion for mechanics ever since the process was started....ARRRGH! I don't think that they will do you much good.

http://engine.od.ua/ufiles/DETROIT-Model-Serial-number.pdf

If you simply want to know how many valves the head has, pull the valve cover and count 'em up.

I hope this helps you and good luck.
 
Thanks for the info, I was trying to avoid taking anything else apart, but ya gotta do what ya gotta do. hopefully I can get the serial and model numbers tonight. These engines have not run in about 6 years. the left engine has the cyl. head missing, gone, who knows. so I need to buy a complete re-built head.
 
Well, it should be a lot easier to find the numbers on the block with no head. But, you're probably gonna pass out when you get the quote on a replacement head. There are probably thousands of these old girls lying about the countryside.....the problem is finding them.

Again,
Good luck.
 
Ok, I searched both engines last night and the only number I found stamped on either was 6A45222. it was on the left side at the rear of the cyl. head on the block. the other engine at the same location was blank. the same pad was there but nothing on it. according to the S?N chart you posted its a 1986 model. well its a start.
 
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