So a couple days ago I'm running low on gas and pull into the nearest gas station to fill up. As luck would have it, the premium pump was out of order, so I had to choose between a)pumping a couple gallons of 89 octane to get me to the next station and b)running out of gas.

I chose option 'a'.

Fast forward to yesterday, when I start hearing a knock from my engine. Not always there, but as I accelerate it goes faster yada yada yada.

My question - Could it just be a function of the bad gas and will go away, or is it more likely a serious problem such as rod bearings or?

Excellent timing too 2 days before I go into ACL surgery and drop a few grand on that.

Ryan

 

Are you running the car on boost with the lower octane gas? Did you fill the remainder of the gas tank up with 93 octane?

To be fair, draining the 951 gas tank is actually quite easy.

 

No boost. Well maybe a tiny bit, but not anything to note - just driving to/from the office.

And yes, I did fill the remainder with 93, but I'm still getting LOUD knock.

 

I would just drain what is in there to be safe because you don't want it to detonate badly and blow out a gasket. Use the drained gas for a lawnmower. If the knocking still continues it may be mechnical, e.g. rod knock.

 

The fuel pump is very easy to get to from my recollection. The car wouldn't even need to be that high on jackstands.

 

How loud are pings?

 

pretty damn loud, more so if I'm parked next to someone and it reflects the sounds back.

 

Does it make the noise at idle? If so, its mechanical. Bad gas pings under load like going up a hill. If youre sitting there idling and its making noise, its not the gas itself.

 

Yea, it's happening at idle too.

****.

 

dont tear the engine apart yet. isolate the sound. you have good oil pressure. could be a bad lifter

 

Yea, the oil pressure is fine. 4-5 bar on the stock gauge or a little less after it gets warm.

Now that you mention it, the sound does seem to be coming from the valve cover, right where the lifters are. What's the best/easiest way to test lifters?

 

it might just be stuck. is it close to time to change the oil? you could run a cleaning agent in the oil like seafoam then change the oil to clean some gunk out and unstick the lifter

 

FWIW, some people have had luck cleaning loud lifters with replacing the oil with ATF, warming it up (NO rev'ing or driving) and changing oil/filter. Some add a quart of ATF and drive around for a hundred miles.

 

SeaFoam makes me nervous...

 

Ryan, don't worry I have a great set of lifters for $ 29.99 shipped, I sure hope is nothing more serious.