1978 endt 676

[Max.superliner]

My father was driving my 78 superliner yesterday with an endt 676, 10 minutes after he left the pit loaded, he said the exhaust sound changed and there was slightly less power, he though he had an exhaust leak, but when he pulled in our yard I could hear the difference in sound, almost sounds like one cylinder dynatard was on, parked it at our shop overnight, started it this morning and same sound cold, pulled the valve covers to check and every thing looks right, everything is tight, no cracked springs, started it and everything is moving(not a wiped cam). Leaning towards cracked valve or bad injector, my question is what is the best way to check the injectors before is start pulling the motor apart, thanks (last over head was ran about 8 months ago, truck runs about 3-4 days a week) 

[Max.superliner]

Here’s a video of the sound 

[br549]

can you hear a noise thru the air cleaner,  sounds like you might have a lifter head come off.  Watching the valves with the motor might not show up.  I would  go thru the valve adjustment and see if one is loose, it will make a popping sound.

[Max.superliner]

No noise coming from air cleaning, over head checks out, I pull each injector line off one by one and started it, noise goes away when #1 injector line is disconnected, working on pulling injectors now to go get them tested but they are not coming out easy, 2 out in 6 hours 

[mechohaulic]

based on days of old ;before all this electronic stuff I would go with a bad valve/ seat. no noise out air cleaner puts you down a different road (somewhat). valve might have small piece off or crack. from top side everything will look and adjust ok. bigger part of valve missing and you would know it. bad injector should have some type of smoke indication out exhaust if it's missing enough for noise.

[mechohaulic]

by '78 I would expect all the exhaust push rods have been  changed to solids. by chance did you pull #1 push rods for inspection? you state it had a dynatard sound. would think that indicates it is dynatard equipt.

[Max.superliner]

Yes truck is dynatard equipped, and it dose work, I haven’t pulled the push rod, assuming it’s straight because the lash is correct 

[Joey Mack]

Are you sure the valve lash is correct? That popping sounds like a lifter has failed or possibly a bad/bent valve. Is there anything blowing back into the air cleaner ducts? The exhaust looks ok. did you remove the rocker shaft, to just see if the valves are at the same height? I didnt see much smoke, but i'm leaning towards valve train..  it should be easy to see since it's a 2 Valve..  How about a sticking rocker arm?  

[Joey Mack]

How is the oil level?  Did you do a 'Halo' test to see if the oil is diluted?  jojo

[mechohaulic]

not sure of the internal changes on '78 engine. based on comment " engine sounds as if dynatard was working on #1 cylinder, to me that would indicate a dyna solenoid stuck . any other situation such as loose valve adjustment would give a tapping sound. design changes in exhaust solenoid must have taken place since  the valve covers no longer have expanded housing over exhaust.  is it possible for solenoid to collapse? when adjusting  early dyna's  each cyl had to be adjusted individually when on TDC, when brought up to number #1 how are the adjustments???

[mechohaulic]

On 2/15/2023 at 6:11 PM, Joey Mack said:

How is the oil level?  Did you do a 'Halo' test to see if the oil is diluted?  jojo

if the oil  was being diluted; would that not lower oil pressure ? more before changing exhaust sound.  oil school test (before high -tech heat sensor guns) was the white/ yellow crayon on each exhaust port . check which melted ; changed color // which did not. or the Polack way ::: put your finger on each cyl.🥵

[Joey Mack]

Mech.  The crayons were a way to go.. Hell I should see if i can get some..  The laser temp gun is what I use, but it can fool you too..  still a good tool..  My thought was to just see if the oil is contaminated..  Not to sound like a Dick...  but many guys don't know the older ways. Myself included. but I was taught by some old timers 30+years ago about trouble shooting. So I may ask some basic questions to stir up other ideas..  That's when YOU come along..   and that's when I KNOW that smart sh!t is about to be posted..  I use the Halo test often..  Of course I am not an oil analyzer,  But I know bad engine oil when I see it.. just sayin'..  Mech, do you agree?  Not about me just curious..  By the way.... I love Kielbasa!!!   you Polack...  jojo

[mowerman]

From what I’m hearing you might get lucky and it sounds like it’s all in one of your heads. Good luck bud. Bob

[mechohaulic]

17 hours ago, Joey Mack said:

Mech.  The crayons were a way to go.. Hell I should see if i can get some..  The laser temp gun is what I use, but it can fool you too..  still a good tool..  My thought was to just see if the oil is contaminated..  Not to sound like a Dick...  but many guys don't know the older ways. Myself included. but I was taught by some old timers 30+years ago about trouble shooting. So I may ask some basic questions to stir up other ideas..  That's when YOU come along..   and that's when I KNOW that smart sh!t is about to be posted..  I use the Halo test often..  Of course I am not an oil analyzer,  But I know bad engine oil when I see it.. just sayin'..  Mech, do you agree?  Not about me just curious..  By the way.... I love Kielbasa!!!   you Polack...  jojo

when walking down the diagnostic road , if you don't go on the side trails , you can never expand your knowledge of what could be  . oil analyzing is always a critical part of engine diagnostics. this case a noise seemingly coming from #1 cyl may be results of diluted oil in a weak exhaust solenoid .  of course I agree. my "book of knowledge " has many blank pages waiting and hoping to be filled in with updated learning from all the talent on this site.

[terry]

Just listened to that video, had 237 engines with that exact sound, was a loose exhaust seat, I know it sounds crazy but I had one do that and it ran a long time, just never know how long!  Terry

[JoeH]

Does it have Jake brake? If so, inspect the top of every exhaust valve for the disc spacer that rests on top for the Jake pistons to push down on.  Our '79 endt676 has a weak valve spring on one valve, that disc kept popping out.  We deleted the Jake brake after the second time it did it.  

I'd walk the engine round again slowly and feel for excessive valve lash. Carbide face may be missing off one lifter tappet, starting to wipe a lobe off the cam.

[JoeH]

We also had a valve seat crack and drop into a piston on the same engine, where it chunked to bits and got lodged in the piston head.  Damaged the head, ruining the core.  It's time consuming, but if you don't find anything obvious with valve lash then pull the heads. Just don't set them face down on the table, the injector tips stick down into the piston bore.

[Max.superliner]

Update, pulled all the injectors and sent them for testing, oil tested fine, I bore scoped all the cylinders, no damage to any of the pistons, everything looks good from the top. My injector guy said #1 was stuck wide open and 2 others had bad spray patterns, all 6 are getting rebuilt, should be ready by the end of the week, still not 100% confident that this is the only problem, a loose valve seat scares me, I’m having a hard time finding head gaskets, I would like to pull the head and dive deeper but I must source head gaskets first before tearing it down further. 

[mrsmackpaul]

Before pulling the head I would just bung the injectors back in and see if it's fixed 

Then maybe a compression test  

But I'm no mechanic but I do fix my own stuff 

 

Paul 

[Joey Mack]

P.A.I. has them.  I bought a pair 2 years ago for a 20 bolt ENDT. 

[mowerman]

I had the same problem on a 673 years ago sucks parts are getting scarce… Bob

[Freightrain]

I got my 237 head gaskets off Ebay.  It was a Felpro top end kit.

[mowerman]

Just a word of advice if you do discover dropped out valve seat, do yourself a favor and change all of them. Bob

[Max.superliner]

up-date. put injectors in and re ran overhead, truck was running good for about 2 months, driver pulled in the yard and sound had come back. Cylinder 1 exhaust rocker, the lash was way loose, bore scoped the lifter and the lifter is cracked and mushroomed, working on pulling cam and lifters for further inspection. my question is can I use a puller and pull the injection pump gear off and mark the gears so I don have the re time the injection pump? or do I have to take a part the adjustment for the for the injection pump? I know the lifters will have to be held up with magnets to pull the cam, is there any thing else holding the cam in?    

Edited May 31, 2023 by Max.superliner

[Max.superliner]

[Joey Mack]

I'm not as good on these as I want to be, but the few that I did, I would bring the #1 piston to TDC and make sure im up on #1 by looking at the #2 exh. rocker arm. it will be 'rocked'..  then I check the timing marks and grab a paint pen and start highlighting the marks.  as far as the injection pump gear, I match mark the gear to the pump drive gear on the cam gear, and then match mark 2 opposite pump gear bolts to the slot they are in. I mark one on the inside of the pump gear and the other on the outside on the pump gear so I dont get up+down confused..  I tend to make more marks than needed. make a match mark on the crank gear and the engine block, just in case the crank turns..  I hope Mechohaulic gets in on this one..  He's OLD!!  I mean Really OLD !!!  LIke Cranky OLD... and knows these engines much better than me..  

 

He is a wealth of knowledge,   Glenn Akers was called home this year, he would have been a great one to learn from too..  So your stuck with Mech....   and a few others.. jojo