Well it seems when I fix one problem another mysteriously pops up. Had this reman IP installed last summer and the truck has been kinda quiet. Noticed over the last couple of weeks it has gotten more rattle to it but really no loss of power. Last night after first start of the day with outside temps in the 20's drove it to the store and while accelerating she was making a god awful clattering. After I got up to speed it would just clear up and go back to the normal rattling sound. This happened a few times and after driving a while sound stayed normal. I have no idea what the h*ll this sound was. I'm bout ready to put a for sale sign in the window.

 

whatsparkplug,
Welcome to FTE and the IDI diesel forum.

There is a switch located down by the thermostat housing that advances the timing and kicks the idle speed up if the water temp is below 115 degrees when it is working correctly.
It is easy to dislodge the wire from the switch and never know you did so.
Changing an IP would be an easy way to dislodge the wire since the wire goes to the switch and then straight to the IP.
Possibly the switch is failing or the wire is only making contact sometimes.
Since the throttle linkage on the IP has a lever that retards the timing as you apply more throttle, when you are going faster the timing advace is overridden and the engine sounds normal.
Did you notice a change in idle speed when this happened?


Another possibility is the reman IP is failing.
When my IP failed the timing was all over the place, changing all by it's self while driving.

The rear wire on the drivers side of the IP is the timing advance wire.
If it starts like that again, unhook the wire and see if it makes a difference.

I have my timing advanced far enough that I have a definite Power Stroke rattle while the timing advace is on, as soon as the water temp comes up enough to kick the advance off it sounds like normal. I like the way it runs timed like that.

 

Thanks for the reply. First crank of the day this morning high speed idle is working fine but truck is definately rattling a little more than a couple of weeks ago. While idling I took the back wire off and no change in sound or running. Drove around the block and when rpms got up just prior to changing gears got that really loud clangy rattle just like last night. Truck has 126k miles with original injectors so is it possible some are bad and causing a timing change issue? Last summer after IP change averaged around 12 mpg pulling my 7000# trailer on a trip and I don't think it got 9mpg last week on that same camping drive. Since it got louder I've noticed a serious drop in fuel mileage.

 

Weak springs in the injectors can cause them to fire early before the line pressure builds to the point they were supposed to pop.

IP failure can cause the same thing.

Another thing to consider, winter fuel drops my MPG about 2.5 to 3 MPG below what I get with summer fuel. Winter fuel and weak injectors could be your problem.

You can also loosen the IP mounting nuts and turn the IP top to the drivers side about the width of the timing mark to retard the IP timing a couple degrees.
That should stop the rattling.
If it returns in a couple days or less, I think the IP is at fault.
When it was rebuilt, they may have used some parts the looked OK but should have been replaced.

Do you have any warranty on the reman pump?

 

As for warranty I'll have to check my receipt. Got the pump and had it installed at Dieselcare in Memphis Tn. This sound is almost like there's no oil at all going to the top of motor when rpms get above about 2000. After it reaches operating temp noise will stop. Taking off from a start truck sounds decent up to a certain rpm and then all of a sudden like shaking a coffee can half full of nuts and bolts. At this point I'm just hoping there's no serious motor problems. Again, thanks for the replies.

 

i have about the same problem so i am replacing my injectors to see if that fixs the problem my mpg is less the 10 empty