Question : 3.4 Rattle wont go away

[wkz231]

My wife's van engine has a rattle in the top end. 3.4L V6 SFI sounded like lifters so I tore it down and and found 3 stuck lifters on right hand bank. Replaced lifters, pushrods, and gaskets. Sounded great for about 20 minutes then began to rattle again. Took it down again and the new lifters show scuff marks on the sides. They do not seem to be stuck but I can not find why there is a rattle. Any ideas?

[pocket-rocket]

My wife's van engine has a rattle in the top end. 3.4L V6 SFI sounded like lifters so I tore it down and and found 3 stuck lifters on right hand bank. Replaced lifters, pushrods, and gaskets. Sounded great for about 20 minutes then began to rattle again. Took it down again and the new lifters show scuff marks on the sides. They do not seem to be stuck but I can not find why there is a rattle. Any ideas?

If the new ones are scuffed, it sounds like they aren't getting oil for some reason. How is your oil pressure?

[geoffinbc]

Does it always rattle or only when cold?

[wkz231]

Rattles hot or cold. Just replaced the oil pump before doing the lifters.

[60dgrzbelow0]

This definitely sounds like symptoms of low/lost oil pressure. When you replaced the Oil Pump...did you secure the Oil Pick-Up Screen Tube with either Brazing or Mig/Tig welding? If not, you'd be surprised how easy they can be turned inside the insert point on the cast iron body of the pump and simply fall off from engine vibration. Oil starvation and cavitation (...and engine death) will follow as soon as the residual oil passes the Oil Pump Gears... with nothing following on since the liquid pump is incapable of compressing and pumping air.

The best way of making a definite determination of this as the problem (without unbolting the oil pan and looking inside) is to hopefully find the extra plug on the aluminum Oil Filter Manifold take off and install a proper fitting with a plastic oil line long enough to reach from the bottom of the engine up to the fender area where you can attach an analog oil pressure gauge and have your spotter read first hand whether the OP is coming up to the proper level (something above 50 PSI to a max of 65 PSI) when you start the motor briefly and shut it down quickly if the oil pressure fails to rise. If not this method... it is also possible to find out if the pick up screen/tube has fallen off by draining the engine oil and then taking a small dead-blow hammer and tapping the bottom of the oil pan. If you do this and hear a metal-against-metal clanging noise or a rattling sound inside the pan from the transfer of the hammer's energy (like a drumstick on a snare head)...then your pick up tube came off the pump and sank like a torpedoed battleship to the bottom of the oil pan.

It is also possible that if the screen did fall off and something got pumped up into the oil channels/galleries feeding the oil to the lifters, it may be obstructing it enough to prevent the oil from pressurizing the hydraulic innards of the lifters. Not sure about whether or not the Oil Filter Bypass Valve would come into play in this condition and possibly allow the oil to skip filtration and let some junk get up inside and trapped in the galleries that would prevent sufficient oil pressure. Did you do any bottom end engine cleaning- oil pan scrubbing to remove old carbon-oil deposits at the time you replaced the Oil Pump?

[Firehawk94]

Doesnt it suck when you use about 15min. of your time to fully explain something to somebody and the thread just dies? 60dgrzbelow0 you have some very good explanations and most of the time they are correct, but I just hate to see good info like this go to waste. I mean where is the op? he hasnt even posted since? Oh i see.....he's new to the site

[60dgrzbelow0]

Doesn't it suck when you use about 15min. of your time to fully explain something to somebody and the thread just dies? 60dgrzbelow0 you have some very good explanations and most of the time they are correct, but I just hate to see good info like this go to waste. I mean where is the op? he hasn't even posted since? Oh i see.....he's new to the site

Well... Thanks for the Props... but you know what they say about "The Road to Hell is Paved with Good Intentions...". Even if I always mean well, sometimes...being TOO wordy is just no help when someone is sweating blood and needs a target specific answer for a fix...right now. Perhaps the OP found out what was wrong on his own and did not want to waste anyone's time beyond getting that damned "Rattle" to go away.

But now you have me curious... He did say the Rattle was situated in the Top End... I wonder if he either bent a push rod... or cracked one of the rocker arms and a piece broke off? Hmmmm....