IanM

Hey guys, I posted this yesterday in the 12v engine and drivetrain, but its getting progressively worse everytime I get in it.

A few days ago I started hearing a grinding/buzzing noise coming from the drivers side of the motor. It happens between 1200-1700 RPM cruising/mild acceleration. At WOT or decceleration it's gone. Its the same when i pull the throttle cable too. It's not a steady noise, but intermittent throughout that RPM range. I can't pin point it to a specific part of the motor, but when it happens, its loud enough to make people on the sidewalk turn their heads. I've done a few different searches, but can't find any posts with similar symptoms.
My lift pump is ticking away, and I've learned that means it is almost time for a new one...could the IP be getting starved of fuel? The only thing I can think of is that this noise may be related to lack of lubrication in the IP....I just can't afford to have the stupid thing grenade on me if I can source it out....everything seems to be breaking at once here

Thanks in advance for your help!!

Mexstan

As I was reading your post a wild thought came to mind. Could your starter bendix somehow be intermittently touching the ring gear? Next time the noise happens, check the volt meter.

This is a 2WD isn't it?

IanM

This would be a 4x4. I'm not sure what a bendix is, but it could be related to the starter...I just had it rebuilt, so its a possibility. Actually, there have been a few times where I've gone through a drive-through, put the truck in neutral and turned off the motor and had the starter not engage when I tried turning it back on...made a similar noise.

Mexstan

The bendix is the gizmo in the starter that engages the ring gear when you turn the key.
So did the noise start soon after you had the starter rebuilt?

IanM

Yes, actually. It was rebuilt about a week and a half ago...

Mexstan

A connection then .........????

infidel

Have you ever had the engine continue to run when you turn the key off?
This usually indicates a Bendix that isn't disengaging due to sticking starter contacts.

GMathews

I had that noise on my 2003. It ended up being the flex plate going. It'd make noise from idle to 1300 and go away after words. then it finally let loose.

IanM

No issues with "dieseling" when I shut the key off...
GMathews, was the noise you heard sporatic throughout the RPM range, or consistent? What exactly is a flex plate?

I have to wait until next week to bring my truck into the guy that rebuilt my starter...it doesn't seem like anyone thinks its the P7100 dying, so thats positive.

Thanks for everyone's response.

Mexstan

In very simple terms, the flex plate is a plate that connects the crankshaft on the engine to the torque converter, which in turn is connected to the transmission. The ring gear for the starter is also mounted on the flex plate.

When you finally get the problem rectified, please don't forget to post the solution back here so that we can all learn.

GMathews

It was sporadic at first then constant. When the noise started and continued I could've sworn it was up front in the motor its self. I have a video that I posted but can't link due to me being on my phone currently.

GMathews

Here is the video - http://www.youtube.com/embed/OeC5Zompb2w

IanM

Well, I finally got some time to get it looked at. Pulled the starter off, the Bendix had lots of tension on it, and looked more or less brand new. So I doubt it is the problem.

Took a look at the ring gear, and it looked alright...there were a cluster of teeth that had wear on them, but the tranny shop said that is kind of expected seeing as the truck has 400k + on it. The guys said from what they could see, it most likely isn't the ring gear or the flex plate.

Poking around a bit more, it looks like the bearing on the tensioner pulley is shot, so I'm going to replace it this weekend and see if it solves the problem...

I'm tempted to post a thread listing all of the noodle-scratchers I've had on this truck, with the sources of the problems listed as I've systematically gone through with the intention of helping other newbies like myself.

Thanks again for all the help guys, you have no idea how much I appreciate it! This site is unbelievable!

Cheers,

Ian