900 RPM roughness (running) 93 7.3 F350

[Titojeep]

man this is why I love this forum so much I appreciate all of the input and will take your advice on checking the injectors. to answer a couple of the questions the injectors and fuel system only have 62000 miles and yes the vibration or roughness goes away above 900 rpm or below so in other words yes when I rev up it goes away. I'll actually try the thermal imaging test first as I have access to a nice $20000.00 camera at work and I'm level 1 certified. I should have thought about that first.Then I'll do the crack test this weekend.

 

[Brad S.]

Did you try the "hold your hand on the top of each injector/line..???"
If theres any noticeable temp difference among all the injectors, start with the injector that has the temp difference..????
IIRC if a injector is stuck closed it gets really hot, but your pickup runs to good to be a stuck injector.
Maybe pull a Glow Plug or two, look if theres a noticeable difference in color/burn pattern etc, then start with that injector...????

 

[helidiesel]

The more I read this post I'm wondering more and more about your harmonic balancer. If it's the stock unit that's a lot of miles. Does not hurt to do simple paint line test. You paint one solid line from a point at the center of the balancer out to the out circle edge and run the motor through the rpm range the shut down and look at the line, if the line is disturbed (broken) in anyway between the inner and out ring replacement is due. The job of the harmonic balancer is to absorb vibration. So it makes sense to me to test it for sure. How's the rubber ring look?

 

[helidiesel]

man this is why I love this forum so much I appreciate all of the input and will take your advice on checking the injectors. to answer a couple of the questions the injectors and fuel system only have 62000 miles and yes the vibration or roughness goes away above 900 rpm or below so in other words yes when I rev up it goes away. I'll actually try the thermal imaging test first as I have access to a nice $20000.00 camera at work and I'm level 1 certified. I should have thought about that first.Then I'll do the crack test this weekend.

I was thinking something like a rayteck gun!!

 

[Zxmazza]

If it was the harmonic balancer it would vibrate continuously, if starting to go probably not noticeable at low rpm and wld progressively get worse as Rpms rise, but it wldnt cause smoke so I cld understand it thinking.


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[Titojeep]

So thought I'd post a quick update. Just came in from outside checking the temperature as suggested above. Very quickly I noticed that my fan was not moving correctly. I turned off the engine, grabbed the fan, and discovered my water pump bearing is bad although not leaking yet. I can move that whole thing a lot. Going to replace it right away by this weekend and then see if that is the source of the roughness I've described above. I'll post my findings afterwards. Again, I appreciate all of the input and help. I'll be back.

 

[Zxmazza]

Could make sense, nvr wld have thought of that. Awaiting ur findings.


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[helidiesel]

Nice find!! It's a start in the right direction!!

 

[icanfixall]

Wow... No matter what. Replacing the water pump is the correct thing to do at this time. Check the fan clutch on the radiator side for wetness or dirt buildup around the thermo spring or the seal to the shaft. Once they leak they are shot and you need another one. A stuck injector that closed will be cold but a stuck open injector will be blistering hot so be careful touching the injector or the lines. Some stuck open injectors get so hot they burn thru the return line caps from the hot compression gas blowing them apart.

 

[Titojeep]

UPDATE - UPDATE - UPDATE - RESOLVED PROBLEM 4/19/14 - 900RPM roughness. Replaced water pump, and she's back to normal. No more vibration / roughness. As it turned out, that bad bearing on the water pump would allow the pulley to move just enough to induce the vibration / roughness I felt. To my surprise, although I could literally move the fan up and down, the impeller had not yet scraped the inside of the pump housing. Hell it wasn't even leaking yet. Another interesting observation is that although the initial discovery was at 900 rpm while gently moving through bumper to bumper traffic, the rest of the rpm range must have had a slight vibration that wasn't obvious to me. I say this because now that the pump is replaced the motor is so much smoother all the way up the rpm range. Literally feels like I put a new motor in with new motor mounts. So thanks again guys, and hopefully this will help someone else in the future.

 

[Zxmazza]

Thts awesome great job!


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[icanfixall]

Wow.. sure happy you got it figured out. You do know how lucky you were that the pump didn't leak or break off the fan and send it thru the radiator. Enjoy the ride now because the engine makes a soothing sound when its rattling along..