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1996 E7 missing, wet stacking, no codes

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I’m working on a 1996 E7 427, no flash codes. Distinct miss at idle, heavy smoke on startup, gets better once leveled out and running.

Has tarry schmoo coming out rear half of manifold, and all other exhaust joints after that. I’m looking for advice on how to nail down which injectors to change.

I’m soaking stuff in wd40 then plan on pulling the manifold off to see what I can see.

No real consistent results from cracking fuel lines at the pump.

 

 

 

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Posted (edited)

Possibly a broken injector tip

ore a bad valve bent push rod I would pull the back valve cover first what colour is the smoke?

Edited by fjh

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Heavy grey/white starting up, light white idling. Heavy again accelerating.

I’ll check the valve train, I’ve decided to get all the injectors pop and spray tested anyhow.


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i would guess a nozzle tip problem. wont throw a code for that as there not electrical and the unit pumps cant know the difference. you could pull the ex manifold off and see if you can narrow it down to smoke out of one port. 

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Pulling the manifold will show a wet hole. Make sure you run it cold for two minutes before pulling the manifold.

Typically......check the timing to make sure you didn’t have a gear slip then buy new tips for all the injectors. Assuming you got a good service life from your injectors, they are essentially spark plugs...when it comes time for one to be replaced the others are usually not far behind. 

If your cold region consider Fred’s warning about bent tubes. It was popular on those to bend tubes, especially if you had a bad injector applying diesel-pus-super-glue to the valve stem. After a cold night sitting that crud glued the stems solid and bent the tube at start-up. Did a bunch of them from the same issue even with good injectors but driver idled too long, cool, before shutting off for cold night storage.

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5 ports were wet. Number 2 exhaust not stroking, pushrod dropped out of sight and intake rod is bent. I’m going to pull the pan and the back valve cover and have a peek up there I guess.

Anyone know a good Mack wrecker and engine compatibility across years and models? Any hp is fine. Mechanical motors are fine too. Closer to a drop in swap the better.

Thanks for the help so far folks.

Pics for your pleasure:24ddf101b4db1bcd99a737ed4a54696d.jpg8965a55f197a344176d381ea23cdb900.jpg944dc409ca9b17fbc689bd32c4e2cf57.jpg


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Well it’s better than I expected. Cam seems fine, can’t get at the followers. Any tricks on loosening a sticky valve?

With the hours on it we’ll likely put 2 new push rods in and see how it goes.


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Posted (edited)

Youch!....get a tar bucket maw, we’re reseal’in the driveway! 

Soak it with brake clean a few rounds, air bath, spray it with WD40, soak, and brass hammer(piston close to TDC).

Edited by Mack Technician

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Posted (edited)

Youch!....get a tar bucket maw, we’re reseal’in the driveway! 

Yup Agree ! OOP"S 

 IMPORTANT info -->   ( piston close to TDC) Make sure you don't knock the keepers out  beating on those valves!

Edited by fjh

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The good thing here is the new style  followers  Did not face  crack like the old days if this had happened to an E6 the cam follower and cam  would likley be done for buy now .You are sitting pretty good here for a repetitively cheap  repair!

 

Good luck with it bro!

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Posted (edited)
4 hours ago, fjh said:

The good thing here is the new style  followers  Did not face  crack like the old days if this had happened to an E6 the cam follower and cam  would likley be done for buy now .You are sitting pretty good here for a repetitively cheap  repair!

 

Good luck with it bro!

We used the cam from our spare engine last year for that exact thing. Carbide face cracks, wipes the lobe right off the camshaft. Mack doesn't make the endt676 cam any more.

Any time an engine does a hiccup I generally pull valve covers and oil pan. Valve covers will show you if you're having top end issues, oil pan shows you everything else, plus the pieces that may have dropped down.

Edited by JoeH

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26 minutes ago, JoeH said:

We used the cam from our spare engine last year for that exact thing. Carbide face cracks, wipes the lobe right off the camshaft. Mack doesn't make the endt676 cam any more.

Any time an engine does a hiccup I generally pull valve covers and oil pan. Valve covers will show you if you're having top end issues, oil pan shows you everything else, plus the pieces that may have dropped down.

FYI- if you ever get in an availability “pickle” Berry Cam Service out of Minnesota would likely fix that camshaft core. I had him build a cam for my rod decade back. He is tooled for Mack right up till E-Tech I believe. 

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Good to know for the future! I think I stuck that damaged core back in the spare motor to keep the lifters from falling into the oil pan! Now the truck we put the good cam in is retired, (split frame) so it's our spare motor lol!

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