Strange Start-Up Noise and Idle

[aberrant]

I have a intermittent start-up noise after the truck has been sitting overnight. It sounds as if it's being over cranked and only lasts for a second. It's the same kinda sound if you were to keeping turning the key after the engine has turned over. Really strange. Seemed to start doing this after I replaced the fuel pump. I'm thinking the starter, but really have no clue.

Also, the truck will often idle strangely. And this is intermittent as well.This does not seem to affect drivability. I don't think it's the timing chain as I've heard what failing ones sound like. Recorded a video and posted it below.

Thanks for any help.

 

[aberrant]

Here is a link to a video showing the idling noise. Any ideas?

 

[Thev6thatcould]

Yea that's your timing chain. $1900 or more to fix.

 

[RandomNerd2000]

Timing chains, common SOHC issue. Not worth it if you don't do your own work, not especially worth it if you do, depends mostly on year and miles

 

[Thev6thatcould]

I dropped in a junkyard motor with 83k miles on it. If u want to keep your truck, that's the route to take. Start looking now before the chain completely snaps and blasts thru your valve cover.

 

[aberrant]

Crap, that's not good. Was planning on doing a long road trip. It doesn't always sound like this, only once in awhile, so not sure how long I have left. Truck has about 135k on it and was always well taken care of with regular oil changes and maintenance. This is really disappointing. I think I'll just take the risk and run it as-is till it finally gives out.

 

[NolaGio]

Crap, that's not good. Was planning on doing a long road trip. It doesn't always sound like this, only once in awhile, so not sure how long I have left. Truck has about 135k on it and was always well taken care of with regular oil changes and maintenance. This is really disappointing. I think I'll just take the risk and run it as-is till it finally gives out.

Mine does the same thing at idle, and intermittently, i.e. it can not happen for a week, then it happens one day on start up, and then later in the day it doesn't happen. I've found that it happens more as the oil ages, i.e. gets thicker. For the first few hundred to about a thousand or so miles after an oil changes, mine doesn't do it. I have 194k miles on mine, and it's been making this sound for at least 10k miles.

 

[aberrant]

Hmmm, wondering if an oil change every 2000 miles would help? I usually do it at 3k.

Also, another weird thing that's been happening is when idling and cold, the RPMs usually sit just a hair above 500. When this happens, there is a noticeable vibration in the floorboard and I can hear the exhaust vibrating as well. With some research I've narrowed it down to plugs and wires, or possibly a bad crankshaft pulleys/balancer. It doesn't do this all the time and abruptly stops once the RPMs are raised to 1000 or they come back down to right at 500. Really weird. Any ideas on this one?

 

[Tech By Trade]

Oil changes wont help. you could try changing your tensioners if you are in a bind, but there is a real good chance it will completely destroy the cassettes. Other option is to pop the valve covers off and inspect the cassettes first and see how bad of shape they are in. The rattle you feel is probably the chains too. Mind did that, I thought it was a loose cat but it was the cassettes. You will probably hear a rattle between 2500rpm and 3000rpm.

 

[RandomNerd2000]

Your balance shaft is out of time, mine started that recently, and also picked up a slight rattle, pulled the plugs off both banks and they're perfect in wear at 5,500K miles so I concluded the balance shaft had slipped time.

 

[Tech By Trade]

Your balance shaft is out of time, mine started that recently, and also picked up a slight rattle, pulled the plugs off both banks and they're perfect in wear at 5,500K miles so I concluded the balance shaft had slipped time.

Not likely. you pretty much have to remove the balance shaft to get the chain to move. The tensioner sucks down there, but even if it isn on the gear there still isnt enough room for it to jump a tooth. Pulling the tensioners will tell you nothing about cassette wear either, the chain runs on the cassettes, all the tensioners do is hold the cassette tight. You need to pull the valve covers to see whats really going on.

 

[RandomNerd2000]

Not likely. you pretty much have to remove the balance shaft to get the chain to move. The tensioner sucks down there, but even if it isn on the gear there still isnt enough room for it to jump a tooth. Pulling the tensioners will tell you nothing about cassette wear either, the chain runs on the cassettes, all the tensioners do is hold the cassette tight. You need to pull the valve covers to see whats really going on.

Well mine started a vibration when the rattle began, it's downstairs on the front of the engine, compression shows equal on all 6 cylinders, and the coil pack, wires and plugs are all relevant, as well as I had no rich looking plugs, all were perfect. I have a drop in engine and to be really honest, I am intent on pulling the covers, but just not at the moment, lower oil pan is coming next oil change though since it leaks anyhow.