Morning Boys, I have a 97 F350. A couple days ago she got a nasty knock. It sounds like there is a whole other PSD under the hood. But, give it a couple hundred RPM and she smooths right out again. And then it starts to come back, maybe at around 1800-2000 RPM.

My my first thought was that it was the turbo. The sound seems like it is coming from that general area. I pulled the intake off the turbo, and I'm not convinced that is it.

I have only had the rig for about a year, so I'm pretty new to the PSD world. This has me stumped. Any direction would be really appreciated.

Thsnks fellas, this forum never disappoints!

 

Is it always there no matter whether at first startup or warm engine? And is the 1800-2000 rpm issue the same knock or is it the engine stumbling and making it hard to get past 2000 rpm?

 

It is there as soon as I start the tuck, and doesn't go away. I noticed also, that when I was idling and decelerating, before turning off the highway, I couldn't hear it.

I'm not positive, but I would say the truck might be lacking power. I've been trying not to drive it though.

 

You should check your fuel pressure first. There is a Schrader valve on the drivers side of the fuel filter housing. 20psi cranking and 50 running.

 

Sure, I'll check it out right now. What effects would low fuel pressure have?

And, at this test port, am I checking the pressure after the filter?

 

Sounds like you have and injector knock. Normal causes are low fuel psi or loose injector hold down bolt that has let the injector lift

 

Makes sense, on my way to the shop right now. Does anybody permanently install fuel pressure gauges? And where do you plumb them into?

I work this truck everyday, towing and plowing snow. I live in Canada, and haul an air track around. Drill and trailer is about 16,000lbs. I miss her when she is sick...
She loves it! Had to put the tire chains on this day!
Truck, trailer and Drill.
Drilling pipes through the ice to build a boathouse.
I have a 2006 F350 gasser. She pulls in a pinch, but the 7.3 likes it a lot better!

 

Where are you at? A few of us in the lower main land...

 

I live in Kenora, Ontario, Canada. About two hours north of Minnesota.

 

So... I checked the fuel pressure. The gauge is liquid filled so it was a little slow to respond while cranking, but I'm running 48lbs at idle. The fuel filter is about a year old, so I will replace it anyways. All that being said, it sounds like I should look for loose injectors. I've never been into the heart of the beast before, so what am I looking for? I'll pull the valve covers, I'm assuming it is the back left side that is loose. I'll check all of them while I am in there. What kind of torque should I be cranking them down to?

Thanks crew, seriously, this site is great!

 

Lower inj bolts to 120 inch pounds.
48 psi at idle is good

 

60 at idle is optimal.

I'd pop the VC and check the hold down bolts

 

Unplug one uvch at a time and start the truck. When the knock goes away then you know what bank it's on

 

When you have the covers off run the engine and check the oil flow out of the injectors. Little spits of oil is good.

 

Well boys, so hear it is. I think the problem was a loose wiring harness, outside the valve cover. Somebody has been dinkin around in there before and the plastic retaining clip is broken off. I took the valve cover off anyway, and everything seemed tight. I let it idle with the cover off and each injector is spitting oil. When I pulled the harness back during idle, it made the same knock, so there you have it.

I also checked the glow plugs while I was in there, and they are all reading high, over 7 ohms. From what I can see that is to high. So I'm going to grab a handful of them in the morning and throw some new ones in. Around here, glow plugs are a big deal!!

Thanks again boys, I learned a ton reading through this forum this weekend. Everytime you learn something new, you find out how little you actually know! And now, I want to tweak her out more, injectors maybe... and I probably need a chip... and then there is the exhaust... My wife is going to be so excited!!