Blimey, that was close!

[Timm]

A couple of days ago (after pressure washing the drive) I found a bolt under the car - so I had a good look around the engine and couldn't find any missing ones - I even went through all the last jobs I had done on the car to see if I could find where it came from but no luck.


The car is my daily drive so I drove to work as usual with nothing unusual and just guessed that I had blasted the bolt across the drive when pressure washing. The next morning I fired it up and reversed out of the drive and I noticed another bolt sitting there - exactly the same as the last one.


From Realoem I found that an M8 x 16 bolt is only used in a couple of places - and one of them being the Harmonic Balancer (Vibration damper) so I guessed I best have a look at it - and this is what I found:





The four bolts that seemed to be OK were all very loose - that damper was ready to fly off any second - and at 5500 RPM it would have done a lot of damage!


So, how's that for luck, the car has covered over 100 miles this week and both bolts that came off ended up in the drive - what's the chances of that!


P.S. I've had the car for eight years or so and have never removed those bolts, my only guess is that the water pump was replaced before I bought it.....

[nrp22101]

Go buy yourself a lottery ticket!

Sent from my SM-G965U using Tapatalk

[Spandrel]

Very fortunate! I've had those bolts off a bazillion times in the last few years. As long as I've torqued them to spec, I've never seen any back out. Vibration issues?

[rogbmw]

Timm...you are one lucky guy!!

[bdiefAZ]

Timm, thanks for the heads up, how many miles on your 840?

While you are at it, check your oil pump bolts, they are also known to come loose on the M60/62, I have seen as many as 4 bolts and a nut in the lower sump. 3 from the pump body, the other 2 were attachment fasteners, only one was holding to the engine. Here is a photo from a car in Arizona that we inspected recently with 160k miles on it.

oil pan bolts.jpg

This is on another car with 120 on it:

IMG_4489.jpg

Both cars are M60 engines.

[Timm]

167,000 Miles or so on the E31, I wouldn't be surprised if half a dozen bits and bobs are about to fall off - but hopefully in a less spectacular way than the harmonic balancer would have departed the engine bay.

[ltbrett]

That's a good mystery. There's literally no reason to take off the harmonic balancer unless it is out of balance or if the lower timing cover has to come off for a timing chain replacement or something. Lady luck smiled on you.

Brett

[Belgiumbarry]

you are indeed lucky Timm, a few rallys ago i lost the entire piece ( balancer/pulleys/flange) on the E9 M30 engine which has a nut on the crankshaft ( not a bolt as the 850) . Lucky too it smashed against the road ( not the hood) in pieces ... to find later a pulley piece in a flat rear tire.

I check often many things , but so far never the "Jesus" bolt.... now i do

[TxGR8White]

That's a good mystery. There's literally no reason to take off the harmonic balancer unless it is out of balance or if the lower timing cover has to come off for a timing chain replacement or something. Lady luck smiled on you.

Brett

I guess you have never had to replace a water pump yet...

[toomanyparts]

I guess you have never had to replace a water pump yet...

From what I recall, I don't believe this needs removed for the waterpump - it is doable with it in place.

Bigger issue is the rubber separating on the balancer itself. Mine has quite a bit of cracking and was removed to send out for repair:

damperdoctor.com

[TxGR8White]

V8’s have to have the damper removed to change the water pump - just did it on an M60 a couple of weeks ago.

[toomanyparts]

I'm going off 7 years ago. You're right. Balancer comes off but the the J bolt stays.

[72tpik5]

Do you always drive at 5500 rpm? I would love to take a ride with you Timm. That sounds like a lot of fun.

[ltbrett]

Apparently there is some disagreement about pulling the balancer to replace the water pump. I've done it both ways on an M60. Better access with the balancer removed but it is not necessary.