T673?

[Bigdogtrucker]

Engine in my "68 R611T is stamped T673. Anyone know the exact details on these?

[j hancock]

Mack Thermodyne Turbo 673 225 HP with 650 Torque.

[Brian L Blaylock]

Shouldn’t it have END stamped before the T?

[j hancock]

7 hours ago, Brian L Blaylock said:

Shouldn’t it have END stamped before the T?

I would think so but the guy stamping that shift could have been bored or feeling lazy or ???

[Bigdogtrucker]

2 hours ago, j hancock said:

I would think so but the guy stamping that shift could have been bored or feeling lazy or ???

No, this isn't the only one. I don't believe they're very common but there was a"T673".

[davehummell]

I got an odd one in my truck etz673 came out of a  mack fire truck 2100 rpm 260 hp. plate says made in 1980

[j hancock]

ETZ673

E = Mack Diesel Engine

T = Turbocharged

Z = Max 10 grams per bhp-hr emissions level

[davehummell]

Thank you for the info. Why is it still listed as a 673 when the 675s and 676s were out all ready? Would it have something to do with the torque rise of the engine?

[j hancock]

Mack used various prefixes, suffixes and numbers to identify their engines.  It does seem that the 673 designation is for a Thermodyne type engine and a narrow power band.  The 675 Maxidyne (later also with the 676) introduced in 1966 was the high torque rise engine with its wide power band.

[JoeH]

I do believe they're all 673 cu inch engines.  Even the 675/676.

[theakerstwo]

672

[Maddog13407]

I got an even weirder one in my 66 R600.... timing cover is stamped endtb675 but the rivetted tag on the block says ETAZ673T. engine came out a 1980 R612LST originally...

[j hancock]

On 5/4/2020 at 5:42 PM, Maddog13407 said:

ETAZ673T. engine came out a 1980 R612LST originally...

Hmmmm..... At least the ETAZ and 612 are a match!

[Mudman089]

Bigdogtrucker has a '68 R611T. I have a '69 R611 ST. Just wondering what the S stands for on my Mack.

Thanks. BP.

[terry]

5 hours ago, Mudman089 said:

Bigdogtrucker has a '68 R611T. I have a '69 R611 ST. Just wondering what the S stands for on my Mack.

Thanks. BP.

I believe the S is six wheel and the T is tractor.   terry

[Mudman089]

Thanks.

[doubleclutchinweasel]

I love how the number nomenclature comes up in threads every now and then!  The old Mack stuff had an elegance to the numbering system that everybody could use as a pattern.  Even individual part numbers had a system.  Then, Volvo came along and assigned random numbers to the parts, and royally screwed that up!

Anyway, it is cool to see that folks are still learning how to read the number codes on the engines, transmissions, and model numbers.  Makes me feel like I'm not such a "newbie" anymore!  I remember going through all those same exercises when I was piddling with my old R611ST.

Yes, sometimes the "END" was omitted from the engine marking (ENDT-673 for instance), because ALL the diesel engines at that time started with "END" (ENgine - Diesel).  The ENDT-673 was a turbo (T) version of the "673-series" engine.  That would have been the venerable "Thermodyne" engine.  I know they were available in at least a 250-horse version.  The END-673 would have been the normally-aspirated (non-turbo) version of the same engine.  And, yes, it was 672 cubic inches.  The "672" series was an older engine.  The "673" was used to denote the "new" engine.  Another very common version would have been the ENDT-675...the much beloved 237-horse Maxidyne (still 672 cu-in).

Remember, the model number on the truck actually hinted at the powertrain configuration (R611 = ENDT-673 Thermodyne), (R685 = ENDT-675 Maxidyne).

There were also similar numbering "clues" on the transmissions.  Lots of folks don't remember that a "0" on the end of the trans model number denoted overdrive.  Like, TRQ-7220.  This was a TRansmission - Quadruplex.  I believe the 722 indicated the torque rating or the particular gear rations used...or something.  The "0" indicated that it was "overdrive in 5th"...making it an 18-speed rather that a 20-speed.  I used to have a list of all those trans model numbers and what they meant.  I need to see if I can find that...  The attached pic shows a little of that.  Again, elegant.

 

Sorry for the rant!  I guess I just miss being a part of the conversation!!!

 

[rklahs]

i HAVE A 1978 RL685LS endt675 MACK i GUESS A Maxidyne?

[terry]

8 hours ago, rklahs said:

i HAVE A 1978 RL685LS endt675 MACK i GUESS A Maxidyne?

675 is a 237 maxidyne.   terry

[Freightrain]

19 hours ago, doubleclutchinweasel said:

I love how the number nomenclature comes up in threads every now and then!  The old Mack stuff had an elegance to the numbering system that everybody could use as a pattern.  Even individual part numbers had a system.  Then, Volvo came along and assigned random numbers to the parts, and royally screwed that up!

Anyway, it is cool to see that folks are still learning how to read the number codes on the engines, transmissions, and model numbers.  Makes me feel like I'm not such a "newbie" anymore!  I remember going through all those same exercises when I was piddling with my old R611ST.

Yes, sometimes the "END" was omitted from the engine marking (ENDT-673 for instance), because ALL the diesel engines at that time started with "END" (ENgine - Diesel).  The ENDT-673 was a turbo (T) version of the "673-series" engine.  That would have been the venerable "Thermodyne" engine.  I know they were available in at least a 250-horse version.  The END-673 would have been the normally-aspirated (non-turbo) version of the same engine.  And, yes, it was 672 cubic inches.  The "672" series was an older engine.  The "673" was used to denote the "new" engine.  Another very common version would have been the ENDT-675...the much beloved 237-horse Maxidyne (still 672 cu-in).

Remember, the model number on the truck actually hinted at the powertrain configuration (R611 = ENDT-673 Thermodyne), (R685 = ENDT-675 Maxidyne).

There were also similar numbering "clues" on the transmissions.  Lots of folks don't remember that a "0" on the end of the trans model number denoted overdrive.  Like, TRQ-7220.  This was a TRansmission - Quadruplex.  I believe the 722 indicated the torque rating or the particular gear rations used...or something.  The "0" indicated that it was "overdrive in 5th"...making it an 18-speed rather that a 20-speed.  I used to have a list of all those trans model numbers and what they meant.  I need to see if I can find that...  The attached pic shows a little of that.  Again, elegant.

 

Sorry for the rant!  I guess I just miss being a part of the conversation!!!

 

I printed out the spec sheets from here many years ago.  It lists the transmission code and gearing.