A word of caution, if you have a high mileage engine with lots of sludge build up you need to be ready to drop the oil pan.
You may inadvertenly clog your oilpick up tube with crude and then need to clean the oil pick up screen so that you do not starve your engine of oil.

 

My truck has 110000 miles on it. I don't really consider that to be high mileage but figured I'd see what you guys think.

 

110K? Are you kinding? You need to start looking for a new car! These trucks are not meant to go that long. I mean hell man, I've only got 174K on mine.

I think that you will be fine. I did not do a engine flush on mine when I bought it at 152,000. I just switched to Mobil 1 and never looked back, but my truck wasnt makeing noise either.

 

When I traded my Dodge diesel they used mileage as a reason for not giving me crap for my trade. It was a 2001 and had 113,000 miles on it. They said they could never sell the truck and make money off it which I knew was crap but wasn't in a position to argue to much since I could get a loan for a brand new truck but couldn't get a loan for a new clutch. I tried to tell the salesman that anybody that knows anything about the Cummins diesel will know that the motor is barely broken in and will ignore the mileage. Plus I had the 6-speed and heavy duty everything so the only weak point was the clutch. If I could find that truck again I'd buy it in a heartbeat, if it is still in the same condition as when I traded it.

I know these trucks will run for a really long time. I am thinking other than being an annoyance the sound is nothing that is going to damage the engine. I ran a can of seafoam through the gas system about a month ago and that seemed to help the truck quite a bit. The sound doesn't seem to effect how the track is running or its power. Still cruises on the interstate at 75 nice and smooth.

 

AK-You and I both know that "tappet" noise can go on for hundred'd of thousands of miles with no real harm to the engine.
You may have a lifter that lost its prime for some reason.
I think you said that you switched to full synthetic motor oil, that will have more detergants than dino oil and will clean your engine as you drive. If a lifter lost its prime you wont get it back.

 

Just took the rover on a short drive to work and to get dinner, about 7 miles round trip. 3 miles of that was on the interstate at 70 mph. Only once did I hear the tapping sound and that was when I got off the interstate as I was slowing down. I noticed that the sound was mainly showing up when turning corners so I checked and topped off the power steering thinking maybe the level is low enough that it is starving the power steering pump of fluid. I haven't heard the tapping since I did it so maybe I got the problem licked.

And I haven't gotten around to changing to synthetic oil yet. I asked about it but haven't had time and money to do it at the same time. I only drive the Disco about 200 miles a month here at work. The town I work in here in North Dakota is tiny so not too far to drive anywhere. Even as small as it is everything seems to be just out of comfortable walking range.

 

So it looks like you are 50 miles from Canada and what, 20 miles from Montana?

 

Dude. I have the same issue with my truck and I have 76k on it. I have had multiple threads to see if I could get some help finding the issue. As I work at a Ford Dealer, there have been 3 Master Techs that have gone through my truck and we still have not found the cause.

We have done the ATF Flush - Done - twice.
Synthetic Oil - Done
Induction Cleaning - Done - twice.
Removed the oil pan to look for shavings - Done
We did have the heads off and redone, new head bolts, new gaskets, new wires and plugs, new water pump, new belt...still have the noise. I am interested in what you find out on this one!

 

I work in the southwest corner of North Dakota, in D-i-c-kinson. At least that's where we're based. Most of our actual work is north of here about 100 miles. Fox news did a story about the town of Stanley, ND about a month ago now. Stanley is the closest town to where we do most of our work. I work on a cement crew in the oil field. It's actually 61 miles from the Montana line to here across I-94. The censor (not to be confused with sensor as I did at first) for the forum won't actually allow me to put the name of the town because it thinks it's profanity. LOL.

As to the tapping sound I was hearing. I went to O'reilly's here in town and picked up a quart of Dexron III per the owner's manual and topped off my power steering and haven't heard it since. I think the level was low enough that when the wheels were turned the power steering pump was being starved of fluid and making that sound. I don't know if that's really the case but it seems to have fixed my problem. I'd like to know how I managed to miss that the level was so low when I checked it the day before but who knows. I checked the fluids to kill time while I was waiting on someone to head to work and was probably only half awake. I'll definitely keep everyone updated as to whether the sound comes back.

Thanks for the help.

 

Can you run Dextron III in the power streering system?