Tapping noise
 

About 3 weeks ago I was doing some local deliveries. Lots of idling, starting and stopping. During this and leaving one of the establishments, I start hearing a loud tapping noise. The engine runs fine. No change in performance, idle or anything else. Just the noise. It sounds like one of the lifters had come out of adjustment. You can hear it really good if you are driving by a curb, another car or a building. I can only hear it while I am accelerating and the noise seems to only be there between 1500 to 2200 RPM. Cruising along at normal speeds it is not audible at all. Only while accelerating.

So, a week went by and I had some time to work on it. I checked and adjusted all the valves (cold). They were all right on the money. No problems there. I saw no unusual wear or anything that looked out of place on the cam or any of the valve train.

Something else... Right before all the deliveries I did an oil change and switched from Rotella to Delo because I found it cheaper. I cannot imagine this causing any problems. I'm sure the additive packages are a little different.

Could this be the vacuum pump? If so is there a way to check?

Any other input is appreciated.

is there any black goo in your vac lines? I'd get a vacuum line filter and install it close to the pump. My 617 had one and it was a good thing to have. Even though I had a new pump on it.

also, I ran my 617 on mobile delvac 1300 and never noticed any loud tapping.

Thanks Joe... I'll check that tomorrow. I have the filter I pulled off when I removed the EGR crap. I'll put that inline somewhere and see what I get.

Is there another way to check the pump besides noticing the residue?

Can you listen and try to identify where it's coming from? Listen around the vacuum pump and the injectors with a length of hose and see if you can pin down the location.

pray its not a rod knock...this was my former love, a ford 150 5.4L until it developed this sound.
http://www.youtube.com/watch?v=po47c0uz8lY&feature=email

That is the problem. The noise is only under load while accelerating and only in a certain RPM Range.

At idle or cruise speed it is all business as usual.

I can check it again with "the stick" tomorrow. But, I could not identify any specific spot that had more noise than another around the valve cover or the vacuum pump?

Not even close to that. And there is no noise at idle until 1500 RPM. Then the noise is gone again around 2200 RPM.

It sounds just like a loose rocker arm.

I'll do some more searching in the AM.

It could be an injector knocking, that would be worse under load. Does it sound like someone hitting metal with a hammer?

it would have been a real shame for you and your car if it was. get us a video of the noise.

I was thinking maybe something got through the fuel filter and clogged an injector. Are you familiar with the "nailing" injector sound?

you see the thread where I just installed 2 filters?

http://www.peachparts.com/shopforum/diesel-discussion/265761-vacuum-line-filter.html


Charlie

Ok... This stupid noise came back today for the first time since it appeared. When this happened before I rebuilt the vacuum pump with the kit from Phil but did not replace the bearing. Also, I adjusted the valves and changed the oil. After doing these things (all at once) the noise went away. I'm thinking that it was a loose rocker arm. I seem to remember them all being in spec. But, I honestly cannot remember.

Like before, the idle is perfect. No nailing or strange noises. The car has plenty of power and cruises nice. Under light or moderate throttle I can hear the tapping. I have to be driving by a curb or a concrete wall to be able to hear it. Under idle or full throttle conditions, it sounds completely normal.

I plan to pull the valve cover in the morning and have a look. Is a worn cam lobe on these engines obvious/common?


FYI.... I just changed the oil and both the fuel filters yesterday.:rolleyes: Go figure.... I switched from Rotella 5/40 to Rotella 15/40 last oil change (1.5 months ago). I went with Rotella 15/40 again with a Mahle oil filter. The primary fuel filter is a Meyle "Clear" and the secondary is a Mahle. Also, I have not used BioDiesel in a while I have been running it in a blend for 2 weeks. Starting off with a little and working up to B99. Right now I am at about a 50% blend. This is the reason for the fuel filter change.

Right now the car sees between 700 to 900 miles per week. So, I'm trying to keep everything tip top.


Anything else to check?

Nevermind.... I did a valve adjustment today and the noise is gone. There was a couple that were a tad loose.:rolleyes: