Engine problems continued
 

Well, my check engine light/#4 Cyl Misfire issue is past. Good. Had a burned valve. Shop replaced the valve and no more codes. NOW!


I had to make a 150 mile trip on Thursday night, right after picking up the car from the shop (see above). Half way to my destination I started hearing a tap, tap, taping noise from under the hood. Sounded like a stuck lifter. Got to my destination and the tapping just sounded a little louder. Called the shop in the morning and discussed. Decision was to check the oil and return in the afternoon. So far, so good.

Late afternoon I started heading for Ashland, KY from just north of Parkersberg, WV. Out on the freeway the noise starts getting louder and finally, after about 40 miles I can't stand to abuse anymore and pulled into a service station and called a tow truck.

$480 later we dropped it off at the service shop and I went home to bed. It was a really long, expensive day.

Got a call from the shop this morning. Spun bearing on #4 cylinder. Doesn't look like there is any damage to the crank, so we are going to replace the bearing and see if it works.

Question for the group...WHY? Plenty of oil and no indication of low oil pressure. 84,000 miles on the motor. Any suggestions?

Re: Engine problems continued
 

If spun bearing on number 4 rod crank has to be scored no way to spin Bering and not screw up crank

Re: Engine problems continued
 

I'm trying to grasp why spun bearing would produce a tapping and not a screeching noise.
Was bearing gone enough that there was piston slap (connecting rod had play on bearing end)?
Why it happened is also a mystery - it is not common.
Since cyl 4 had misfire, could enough gas have washed down cylinder to dilute oil? I don't think so, but I have no other theories.

Re: Engine problems continued
 

i agree a bering will nto sound liek a lifter and if it got to the screaching point then there is 100% forsure crank danamage

Re: Engine problems continued
 

I've had bad rod bearings in Chevy's tap like that. They are usually badly worn but not spun. Let them tap very long like that and the rod will usually come out through the side of the block.

What year model is your PT? There was a crankshaft/thrush washer issue with either 2006 or 2007 models that came with auto transmissions. It might be possible that your crank is moving forward or back far enough off the oil vein to quit oiling one or more rod bearings.

But a more likely scenario is that whatever caused the bad valve is also at fault here. Could the earlier owner have run the car out of oil sometime in the past and caused localized undue engine wear that's just starting to cause problems now?

Re: Engine problems continued
 

Handy - good question. The history of the previous owner is unknown. I purchased from a local Mazda dealer. The Carfax did not indicate any previous engine issues. Guess I'll have to wait and see what the shop says.

Re: Engine problems continued
 

A spun rod bearing will not make a squealing noise (usually), it will start out as a deep thucking noise or rattle when you rev the engine and hold at a steady RPM and get worse as it progresses. Its very easy to mistake for a lifter noise if you are not familiar with spun rod bearings. It is very unlikely that no crank damage is done, almost impossible. You need to have your shop check the run out on that journal and see if its still in spec for diameter to. It is possible that trash got in the oil when the head was removed and caused the bearing failure.

Re: Engine problems continued