Ejz675 What Do The Letters Mean ?

[m5040]

I have a 1979 RD single axle, the engine model is stamped E J Z675. The Mack book I have list the "E" stands for Mack turbocharged diesel engine, the next letter should be an "M" for maxidyne (the truck has a 2 stick 6 speed). What does the J Z mean ?

It is also stamped 672 CID, 235HP at 2100 rpm

[HK Trucking]

It's "ETZ 675", and it's a 237 Maxidyne, same thing as an ENDT675.

[m5040]

Thanks, It is difficult to see with the steel fender down. I though there might be more to it.

[Lmackattack]

I think the ETZ engines were for speced for trucks bought and owned in CA. the reason was likely for the heavy CA emission regulations? anyone recall this?? I dont know what was diffrent but im going to assume the emission control devices.

as far as the more common engine codes..ENDT675

EN= engine

D=diesel

T=turbo charged

675=maxidybe

I think yours was just built to a CA emission spec???

[vanscottbuilders]

Herb,

Is the ETZ-675 a 237 hp engine, or is it a 285 hp engine?

My ETZ-675 has the air & water intercooler with the tip turbine,

and it is completely different than any of the older 237's I've had.

The vintage mentioned here of 1979 makes sense, as my own is a 1980 engine,

and sounds like it is the same thing.

I've had a little difficulty finding much info about this particular series of engine

from Mack, as it was apparently replaced after only a fairly short production run.

Anything you might know about it would be helpful.

The rumors from the local operators are that this engine was one of Mack's best.

Thanks,

Paul Van Scott

[HK Trucking]

Herb,

Is the ETZ-675 a 237 hp engine, or is it a 285 hp engine?

My ETZ-675 has the air & water intercooler with the tip turbine,

and it is completely different than any of the older 237's I've had.

The vintage mentioned here of 1979 makes sense, as my own is a 1980 engine,

and sounds like it is the same thing.

I've had a little difficulty finding much info about this particular series of engine

from Mack, as it was apparently replaced after only a fairly short production run.

Anything you might know about it would be helpful.

The rumors from the local operators are that this engine was one of Mack's best.

Thanks,

Paul Van Scott

Hi Paul.

Is it possible that truck originally had a 676 (285), and it was replaced with a 675, but they put the intercooler and the 285 pump & injectors on the 675?

To my knowledge, any 675, no matter what the prefix, is a 237, and would be turbocharged, but not aftercooled.

What model truck is it in?

I'm sure you already know this, but the VIN suffix for a truck factory equipped with a 675 (237) would be "85", and for a 285 would be "86".

.

[David]

I'm sure you already know this, but the VIN suffix for a truck factory equipped with a 675 (237) would be "85", and for a 285 would be "86".

.

This won't apply if your truck has the long VIN.

[HK Trucking]

This won't apply if your truck has the long VIN.

In the 79 - 80 time frame Paul is referring to, they were still using the short VIN.

[m5040]

I opened the steel fender and got a better look, you are right it is ETZ675. The truck was a plow truck for the state of NY. It has the steel noze, double frame, live hyd, 10' body, 23k rear 4/1 ratio, heavy front axle (I don't know how to tell the weight on the front axles), the VIN starts with the RD685P. The engine has a small turbocharger and no aftercooling, ABosch inj pump. I am thinking about installing a Jake and a lower rear axle ratio.

[vanscottbuilders]

Herb,

I'm going to have to go check the engine stamping. I'm starting to doubt myself.

It's tough getting old! I used to be able to remember this stuff.

The engine is in my shop, and on a test stand.

I bought it from a large quarry, stone, and concrete company here.

It was one of their spare engines and has a zero mile Mack factory rebuild.

The engine data is readily available.

I don't believe the intercooler has been changed.

I'll get the info ASAP.

Unfortunately, this engine has a crack in the cooling jacket area of the block.

Apparently it was stored with water in it. No sign of any other damage, and no

water in the oil. I think it can be fixed. But I'm going to have to keep this one for

my own use. It'll make a great engine in one of my projects.

Thanks,

Paul VS

[Kav]

Hi M5040, The numbers on the blocks which were produced in the early 1980's don't necessarily mean much as Mack in Brisbane were retro-fitting intercooler kits to the ESI 237 motors to take them up to the 285 motor. They fitted the tip turbine/intercooler unit, the larger Turbocharger and changed the delivery valves and barrels in the injector pumps to take them up to around 300hp. These were done as a paid job for the customers after the intercooler units were released. It made a big difference for road-Train work. These trucks would still have all their original numbers and markings of 675 instead of 676 which the were then. There is no reason why this conversion could have been done anywhere else also. If you bought a new block from Mack they did not always have any engine numbers at all so you could stamp the original 237 number to simplify registration. Best Regards - Michael

[m5040]

I spoke to a long time Mack mechanic, he was framilure with the EZT. He said it was made in Canada and is a higher compression engine that was noted for its fuel economy. He said nozzles are very hard to get. So if you have one, keep the water out of your fuel !