Synyster

So a while back I had swapped a PI engine into my 98 and everything was all good till recently.
My best friend who swapped the engine with me told me it can happen, but after an oil change can a lash adjuster collapse at random?
It happened right after the oil change but it almost resembles a spun bearing knocking at the same time.
It's not constant like that though, just bad at a cold start and could only be heard up to 2.5RPM. If you hold the revs past that, the noise disappears. Disappears for the most part when warm also. So could that be the verdict?

Thanks.

reldla1996

Sounds like something in the valve train. Certainly bearing issues do not go quiet above a certain rpm...and they are much louder.

Synyster

Definitely know that for sure.
Since the last motor was taken out cause of a bearing.
I really don't wanna put my hands on the motor again, especially cause it hasn't even been a year after the swap and there's already some problem but it seems I'll have to.

Stevo86

The camshafts spin half as fast as the crankshaft so if the engine is at 3k and the noise is about 1.5k it's in the top end. Obviously there are limitations to this since you can't exactly count that fast but use your best judgement.

I would also try the old extension method. Get the longest extension or solid piece of metal you have. Preferably pretty long, and use it to listen to the valve covers individually. If it is a collapsed follower you can usually track down which one it is just by listening. Then pop off the valve cover and replace it. You most certainly can change them without taking the cams out.

petrock

When you changed the oil, did you use the recommended oil weight/viscosity for your motor? Its fairly common for motors to develop a tick/knock if you put in too heavy an oil. It takes longer for the oil pump to push the oil through the various passages till it gets to the lifters to pump them up. Its also not good for your motor because during the initial startup time period the moving parts inside the motor don’t have enough oil which can quickly wear your motor out.

With that said, a lifter can definitely go bad that quickly if it was starved of oil for a little bit. Lifters have some fairly tight clearances internally. It could also be a loose rocker and its taking a little while for the lifter to close the gap, so you hear a ticking/knocking until it has. If it is something in the valve train, your in luck with your motor because you can gain access to them “simply” by popping off the valve cover.

Stevo86’s idea of the long metal rod is a good one. You can also pick up a mechanics stethoscope from your local auto parts store for around $10. Its a pretty handy tool to have in your toolbox, especially as your ride gets older and unexpected noises start appearing.

Stevo86

4.6 rockers arms don't come loose unless the follower is collapsed. They aren't bolted down to anything like in an OHV motor.

Just an FYI

petrock

Yes, your correct. I’ve worked on too many push-rod motors over the years.

dawson1112

Im with petrock on the correct viscosity oil being used. Some times guys think thicker is better. I have seen engines that develop a tick or knock after the use of
10w30 and a quart of lucas oil.. IIRC the 4.6l engines call for 5w30 .

Synyster

Thanks for the replies you guys.
Dawson was right though, I had decided to throw in Lucas when I changed the oil.
Big mistake. Since I had drained the oil all out earlier today and added 6 quarts of mobile 1 Synthetic 10-30 there was not a single noise anymore. Should of probably went with the regular 5-30 but since there's no noise anymore.
I'm happy