Piston skirt slapping crankshaft making jackhammer sound

Steve99s70t5manual · Post by **Steve99s70t5manual** » 08 Dec 2017, 21:46

So my 99 s70 t5 has a ticking g sound that turns out to be one of the piston skirts hitting the crankshaft and the most cost effective way to fix it is shaving down the part of the piston that is making contact with the crank. Any feedback on this procedure and if it can make further problems.

WhatAmIDoing · Post by **WhatAmIDoing** » 08 Dec 2017, 22:42

How did you confirm this? Might want to find out what caused this to occur, since it obviously developed somehow. You might want to have the rest of the engine examined for damage before you start putting money into fixing it.

Post by **wizechatmgr** » 09 Dec 2017, 02:03

The two shouldn't be making contact. There is another issue present...

Post by **tryingbe** » 09 Dec 2017, 04:57

Probably rod knock.

Post by **scot850** » 09 Dec 2017, 11:18

I have unfortunately heard of rod knock several times on these engines. Can't say the cause as I don't know the cars personally or the owners, but I have suspicions it may have to with either poor maintenance or driving style in most cases.

Neil.

Post by **precopster** » 09 Dec 2017, 11:55

Wouldn't that be a twisted conrod or is that not even possible? Conrod bearings are pretty easy to remove and check while the sump is off in any case. You may be able to do this without head removal.

Post by **JimBee** » 09 Dec 2017, 13:30

I bought a good-looking 850 turbo wagon that had a "tinking" sound in the engine. After confirming that it wasn't a lifter and having a couple of rebuilding techs listen to it, we concluded it was likely a bent rod. It was. I pulled the head, sump and pistons, cleaned things up, replaced the bent rod and other things while I had it apart. Check out the link below that documents the process.

Engine rebuild tutorial pdf

If it's a bent rod, the skirt is "tinking" on the counterbalance as the piston is BDC when the counterbalance is at its highest point. Normally, those 2 parts run very close together so it doesn't take much of a bend to bring them in contact.

The problem with running it like that is the rod has lost its longitudinal strength and if you load it too hard it could break and you lose what might otherwise be a decent engine that could run another 100k miles. Also, it seems likely that the metal to metal contact would eventually damage the bearing on that journal.

My bearings were in excellent condition, even at 200k miles, so I reused them on the advice of 2 rebuilders. The rod bolts are reusable as long as they're still 50 mm.

If you need parts for your engine, you could try Crankshaft supply in Minneapolis. They had a large inventory of used parts, including the connecting rod that I needed. Part prices were reasonable. I also had them boil-bathe the pistons and put on new rings, they looked like new.
https://www.manta.com/c/mmc15zz/cranksh ... ompany-inc

The engine runs beautifully.

Good luck getting it solved.

Post by **jimmy57** » 09 Dec 2017, 13:43

If the hose from turbo control valve to wastegate or the hose from turbo outlet to TCV cracks the boost will go HIGH. Rods will bend and then the piston tavels is offset downward where skirt and crank counterweight touch. Also aggressive wastegate adjustment can do this too. I did it to a 98 V70 of my own by forgetting to hook up the hose to turbo outlet one time. The car ran R E A L L Y good too. The check engine light came on and when I stopped and rolled down window I heard the tapping noise. It was too fast as tappet rattle is once every two revs where skirt tap is once every rev.