1969 m-52-a1

Hi All,
My friend has a M-52 with a Mack engine.
It will start on either and run all day but shut it off
and it will not start.Even trying to start it 10 seconds later. We have gone thru all the filters and fuel lines
but still no change.This gets me because it doesn't run the filters dry.
Any advice would be nice.
Thank you for your time.

zeb781 said:

Hi All,
My friend has a M-52 with a Mack engine.
It will start on either and run all day but shut it off
and it will not start.Even trying to start it 10 seconds later. We have gone thru all the filters and fuel lines
but still no change.This gets me because it doesn't run the filters dry.
Any advice would be nice.
Thank you for your time.

Click to expand...

How’s the compression?

It ran good till he ran it out of fuel.
So I did not consider this or a pump problem.

I had a ragged out 7.3 that would run decent, but no matter what couldn’t start without help. Finally checked compression numbers and they were so low it couldn’t build up enough heat to light the Diesel on its own. I’m sure the Mack knowledgeable folks will chime in with more helpful info

I'm not sure how often AMGeneral stops by on here but he knows the Mack ENDT-673 engines very well. I will send him a text to let him know his expertise is welcome on this thread! I'm pretty sure my buddy Elijah95 hit the nail on the head, if the truck runs well once started it might have compression issues across all 6 cylinders. One problem with the Mack that I learned from AMGeneral is it runs a flat tappet camshaft drivetrain which is very much incompatible with the current oils that got rid of alot of the Zinc that was once in motor oil. A flat spotted lobe or 6 on the intake side of the camshaft will cause the issues you are having. Let's see what the Zen Master's input is. He may offer something that even I didn't see to look for and all I will do is learn something else to pass along!

Thanks.

Text message sent, all I can do is sit back and eat popcorn at this point. He's a good guy though, search AMGeneral and you'll see what I already know, he loves the Macks! I've met him personally a few times at a local get together and he's always had solid advice.

I would have been here earlier, but work hours have been long as of late.


Interesting problem.

I do have a few questions first,

Does it smoke white or gray while trying to start it cold or even after it has been run for a time?

When it does run, does it miss or idle roughly?

At what RPM does it idle at?, It should be 550 to 625 RPM.

Did it run and start correctly before it ran out of fuel the first time?

Have you tried pumping the hand primer pump before starting the engine, if so, did it seem to build pressure or " free flow" no matter how long it was pumped?

zeb781, you are in good hands now! I'm just an amateur but AMGeneral knows the Macks as well as most anything else Diesel powered! I'm going to stand back and learn.

Hi AM,
1st No white or gray smoke.
No it runs smooth and fine.
It idles around 600 rpm's
Yes there were no problems before running out of fuel.
He has another fuel pump and is going to change it today and let me know what happens.

Ok,standing by

Sorry All,
I injured my back and have been in bed.
He said there were no changes with a new fuel pump.
I will be heading back there hopefully on Saturday and will check it out more.
Thanks