Valve Sticking? Bad Injection Pump? Going Mental?

[DirtyRed7.3]

Ook so sadly im back again, i want to thank everyone for their help last time but i arise another problem. recently my 7.3 has started to get a chuffing noise in the exhaust again, i know its not the injector even they they are miss matched. i don't have hard starts, a little blue smoke but thats always been there, no intake chuffing only oit the exhaust. now i really want to get to the bottom of this, ive read many and many a post about this similar issue to no avail. so lets make this the one that goes over all possibilities.

So boys were do i start?

 

[DirtyRed7.3]

No one has any ideas?

 

[OLDBULL8]

Patience Patience.
First pull the valve covers and check for broken valve springs, loose rockers, bent push rods, if them are all OK, could be a broken valve. To determine which cyl., pull the GP's and put air into each cyl., make sure both valves are closed on that cyl. use only about 50-60 lbs air or you'll push the piston down, bad intake valve, air comes out the intake horn, bad exhaust valve, air out the exhaust. Go from there.

 

[cpdenton]

You can also find exhaust valve problems by seeing soot around the rockers under the valve covers.

The guide wears causing the valve to not sit straight up and down and soot leaks into the valve area.

Might be a dead giveaway.

 

[BDCarrillo]

Use a spring compressor (two claw with screw type) to take the spring tension off the suspect valve, with piston near tdc. Then wiggle it to check for end play. You'll know a bad guide when you can move the valve around 1/8"+

As advised, look for soot/goo, leakdown test, and then check endplay. You'll know for darn sure with a three pronged approach.

 

[DirtyRed7.3]

ok guys, im gona go through the steps listed when i get the chance (probably this friday) and see whats going on. i just wan to go and address all possibilities even if its somthing simple so therefore when another person comes asking the same question we can shoot them to this thread.

 

[BDCarrillo]

If the valves all come out OK, suspect the injectors.

While you have the glowplugs out, that'd be a good time to run a compression test. I have a diy in my signature for the cheap harbor freight kit.

 

[stealth13777]

If you have one, take a mechanics stethoscope while the engine is running and listen around each cylinder. Should be able to narrow the noise down to one or two that way and then work from there.

Personally I would listen first (and even if you don't have one, stethoscopes aren't super expensive). Then I would swap the injector(s) at the suspect cylinder(s) and see if the noise moves. If it did, problem solved. If it didn't, I would then do what is listed above.

If you are 100% certain it's not the injectors, skip that step. Imo it would still help to know where you should be looking by narrowing the noise down. Trying to save ya some work. Just my technique though, neither right nor wrong either way


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[IDIoit]

worst case, get yourself a extra set of heads in the machine shop.

if you get the right products, your rig will be reliable.

 

[DirtyRed7.3]

well i started to think and im pretty sure when i had this noise prior (before swapping injectors) it was for the same issue at hand (still unknown as to what it is) i was running a muffler for a while but when towing the EGT's kinda scared me so i took it off and the noise was back (it never left, i just was muffled) and so i gave it a good drive to listen and there is for sure a noise coming from the motor like a ticking sound leading me to believe either a broken spring or stuck valve. so with an empty wallet and a lack of sanity i started my exploration, haven't found anything yet and the lights gone from the sky so il be back on her tomorrow afternoon... looks like the old 86 Ford ranger is getting back to her contract working days for tomorrow

 

[Zaggnutt]

I have an ongoing issue with a chuff in my N/A '89. All my research led me to a bad valve so I had a used set of heads partially rebuilt (just the exhaust valves and one bad guide, one bad seat). Cost me roughly $600 for the machine shop work on them. Add in new headbolts ($50/head) and gaskets ($90) + Valley pan ($50). I also bought a torque wrench ($75), thread chaser and handle ($25)

Compression test yielded one low cylinder on the driver side. When I pulled valve covers driver side had a lot of soot build up around cylinder 6 rockers / valve springs. Passenger side looked like it was dipped in honey. I pulled driver side head and replaced it with rebuilt. Chuff is still there. I am looking at replacing injectors next because they are definitely spent.

 

[OLDBULL8]

DirtyRed7.3
Well, Friday has come and gone. What was/is the results? Did you do the procedure I suggested above?

Patiently awaiting your response.

 

[Waystro]

X2 looking forward to see what ya find

 

[DirtyRed7.3]

Ok sorry guys, work to priority for a few days. so i had looked all over at my springs and everything, no soot, np bent rods or snapped springs. i swapped injectors around and it keeps coming from the same side (drivers bank) so i think im going to get reman heads when i get the $$$ the highest psi i had was 441 and the lowest was 426 so i think my compression is well in spec. im guessing a broken valve or bad seat. sorry to not have much interesting

 

[OLDBULL8]

With that hi of compression, I wouldn't think any valve would be bad, a bad valve would/should lower the compression considerable on that cyl. Mysterrious.