Greetings!

I am working my way (slowly) through my XKR engine rebuild and am ready to assemble the rods and pistons. I have reviewed the assembly training manual 168 and the other sources available, and all indicate there should be an arrow to be used to face the pistons correctly as they are put together with the rods. Looking at my pistons, there is nothing of the sort in the crown of the piston. Mahle even refers to such a mark. All that I can see on mine are the letters CE stamped in the bowl, and another faint marking showing another symbol from Mahle, but no arrow.

Looking at the skirts, there is what I will call a pimple in the casting to the left of the pin hole on only one side of the piston. Perhaps indicating the front facing side?

I know the pins are offset, so I want to use the correct orientation of course.

If anyone can assist, it would be greatly appreciated. My next call will be to Mahle, if nothing comes of this inquiry.

Also posted in the Engines forum with many views, but no responses.

Thanks in advance for your help!

TC

 

why even take the chance (all the time & money & love) you're putting into your car/rebuild?!


MAKE THAT CALL!

 

If all else fails, you could measure the offset to determine the direction of
offset and then lookup the theory on offset to decide which way to install.

You don't need to know how much offset, just the direction.

It could probably be worked out by laying two assemblies on a flat surface
if really desparate.

 

Hi!
I had the same problem to my aftermarket Wiseco forged piston.
The old piston have a direction mark that i use. It is offset. If you mounted them opposit, then you got a piston knocking noise....
Good luck.

 

Called Mahle today, and ended up talking to three different people, including the importer of OEM Mahle stuff (not Mahle USA). No one had a definitive answer as yet.

One search I did had a suggestion that the CE marking I see on the piston crown could be an indicator (not Jag related, but Porsche with Mahle slugs). That comment was that the E in the CE should be pointing at the Exhaust side of the engine. If that is the case, I can use it to assure the offset in the piston pin all face in the same direction. If I use the pimple to face the front, one bank will have the offset on the opposite side of the other.

Perhaps one of you with heads off your engine, but pistons in place, could take a look and see if any markings are visible on the crowns.

Still looking for the final answer, but willing to wait to do it right.

Thanks

TC

 

As a followup to post #3, install them offset the same as factory.

By that, I mean that you would determine the offset direction for each
bank on the factory pistons, then install the Mahle the same way.

Since the exhaust is on different sides of each bank, the CE may not
be the way to go since the offset is according to the direction of
rotation of the crank. Unless you have different part numbers for
each bank.

 

"CE" appears to be a marking for machinery made in
the EU for VAT processing purposes.

communite europeen.

 

The markings:

MAHLE Aftermarket North America | Pistons

if they are missing:

I have a question about piston offset. - F150online Forums

 

Plums,

You're thinking may be the right approach. I have been to that Mahle site and also spoke to their techs. However, your offset link may be the right way to go to figure things out. I will take a look at which direction the offset is on the pistons.

Just to be sure, when facing the front of the engine, which direction is the crank turning: Clockwise or counter clockwise?

Thanks

TC

 

Standing FACING the front (damper), MOST engines turn clock-wise. The engines I know that turn the other way are (older?) HONDA engines. I found that out 30 years ago trying to put a timing belt on a Honda car engine. (they are weird!!!!!!)

Sitting in the car looking forward, the engine rotates ANTI-CLOCKWISE. (looking at the flywheel or torque converter drive plate)

bob gauff

 

As Bob said, clockwise viewing from front of car.

I still say the best way is to match offset to original on each bank
by looking at one of each. No room for error that way.

Be aware that the procedure from the Mahle tech in the F150
forum results in an arrow that is backwards from what is shown
at the Mahle site. Therefore, you have to carefully interpret the
instructions. The alternative is to reverse the instructions to
have a more sensible arrow direction. Arrow in direction of
rotation.

++

 

TC
I have a 4.0 XKR with the heads off at this minute.
Checked the pistons and the CE mark is facing down.
I will try to post a picture.