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914World.com _ 914World Garage _ Need T-4 advice

Posted by: Lawrence Dec 4 2004, 05:03 PM

I purchased a set of 914-4 pistons and cylinders second hand from someone I believe to be reputable.

These are Mahle 94mm euro jobbers. New in the Mahle box.

As advertised, one cylinder had three broken fins. No big deal, according to stuff Jake has written. Well, when I get the package, one of the cylinders does indeed have three broken fins (all three together).

The three broken fins are at the widest part of the cylinder, and the fourth one (above the three widest) is cracked, right at the bolt hole. On the opposite side of the cylinder, another fin is cracked (second from the wide end). It looks like this cylinder might have taken a tumble from a kitchen table or something.

Is this cylinder usable... or do I need to seek redress with the seller?

Don't ask for pictures. I no longer have a digital camera. Don't ask.

-Lawrence

Posted by: cnavarro Dec 4 2004, 07:34 PM

The cylinder is unusable, unfortunately. Either get a single cylinder and bore it out and hone for the new piston, or try to find another loose NOS cylinder. Personally, I think it's the pistons that are most valuable and rare of the set. Cylinders are always replacable.

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Posted by: Lawrence Dec 5 2004, 08:32 AM

Thank you for the advice, Charles,

There is no way to repair this cylinder?

-Lawrence

Posted by: Jake Raby Dec 5 2004, 08:48 AM

Nope...

I may have one spare..

Measure the overall length from the cylinder seating surface on the case to the head sealing surface and I'll see if I can find one that measures up in my stash..

Posted by: Lawrence Dec 5 2004, 10:17 AM

I measured the depth of the inside of the cylinder... using a crude instrument.

5 1/32 inches... or 127.7938 mm. I don't know how exact you need these to be. Is there some variance among cylinders?

Posted by: Jake Raby Dec 5 2004, 02:36 PM

Yes, alot of variance, up to .015 for OEM and up to .040 for aftermarket or replacement Mahle's...

I need it down to .001 if you can, anything more than .002 and you'll have a head leak waiting to happen.

Posted by: Lawrence Dec 6 2004, 09:31 AM

That far out of tolerance? How can they sell crap like that?

Would it be better to send them all to you, and have you true them up?

-Lawrence

Posted by: Jake Raby Dec 6 2004, 09:35 AM

They sell crap like that all the time....

Take it to a machine shop and have it measured.. Right now I have time to find you a matching cylinder and thats just about it!

I have averaged 3 hrs of sleep for the last month- 7 days a week trying to get the new venture up and going!