Posted Sunday, March 23, 2008 @ 06:50 PM  

Here is some info from Limbach.

Posted Saturday, March 29, 2008 @ 06:08 PM  

It turns out that the Limbach 2000 E01 on SE-UDI is from 1982, thus too old to be possible to upgrade to 10 mm studs described in the Limbach info that Collin provided, reportedly because removing threaded inserts can damage the crankcase. Also, you would have to enlarge the studholes in the cylinders and cylinder heads(we checked today) leaving precious little margins.

It might be that these inserts on SE-UDI are rests after previous repairs were they had to drill stumps out or maybe original inserts with loctite around the stud, which would explain why the insert and not the stud came out. My plan is to change all the studs to stock 8 mm studs and if threaded inserts are unscrewed when dismantling just get new inserts to fit. I´d rather change the studs a little more often than do a more complicated repair/upgrade, a studkit is just 50 EUR!

Take 5(b) just 4 fun/ Jörgen, SE-UDI, SE-XST

Posted Saturday, April 5, 2008 @ 06:08 PM  

However, two insert came out with the studs, one of them was of course the broken stud but one more insert also came out when unscrewing the stud. These inserts are M 12 with 1,5 thread (usually M12 has 1,75 thread) on the outside and M8 inner thread, one is slightly less than 29 mm long, the other 34 mm. We removed the intact stud which required heating the insert red hot.

Forensic examination of the stud and the insert revealed that the end thread of the stud (at the bottom of the insert) had been damaged, which was why it couldn´t be unscrewed in a normal fashion. The most likely reason for this is overtightening, which probably explains why one stud broke too. Limbach calls for 25 nm torque on L 2000 E0 with 8 mm studs, and according to general workshop reference litterature this is consistent for 8 mm bolts of 8.8 metal quality. Friction "consumes" a significant part of torque, and 25 nm is valid for a stud or bolt which is oiled before insertion. Some Limbach studs (thicker ones) require 32 nm torque, so there is a risk of confusion. Or maybe someone just got sloppy.

My decision to change all studs seems correct, after all who knows how many have the wrong torque? When I asked if inserts are for sale the Limbach dealer in Sweden just laughed and wanted to sell me a new engine. Since the threads and lengths of the inserts are non-standard I have to get them custom made. I have 8 more studs to remove, so I might need more than two new inserts. Fortunately, I think I have a connection to a guy with the right credentials (and a huge lathe).....

Posted Thursday, July 3, 2008 @ 04:56 PM  

I cleared the threads in all inserts with brakedisc cleaner spray and installed the 2 new inserts with "heavy" Loctite (628?), to make sure they stay in there, and had no problems with that. The cylinders are grinded down (or forged that way) were the inserts sit, so there is no risk that a protruding insert compromise the cylinder fit. I changed all the studs and I decided to oil the studs before insertion, but you can of course use "light" Loctite as well. I just think it's not a big problem if the studs do come out if you dismantle. As you suggested I carefully measured the studs different lengths, but it turned out that all studs went in the bottom of the inserts by handforce only and a gentle tightening. Installing the cylinders were a little tricky, but with a modified piston ring compressor, some oil and a well judged whack it went comparatively easy. An experienced car mechanic comes in handy to learn that trick of the trade. Don't forget to install the "forget plates" (baffles that sit low and between the cylinders clamped on the middle studs) as I saw them called on a Swedish VW site. The rocker arm protector tubes need to be dragged out to length before installation and it is a good idea to change the rubber gaskets at the ends.

The liquide silicone gasket-guff was rather easily applicable before pressing the cylinders all the way in and installing the heads and the nuts on the studs(try to make the "guff"-string thick and with no breaks). Be sure you have the correct torqueforce for your engine, on the Limbach EO 2000 on SE-UDI it's only 25 Nm and since there are no gaskets on the cylinder heads it's crucial that you tighten the stud nuts in the correct X-wise fashion, Limbach has the manual as PDF:s on their website. When installing the rocker arms I discovered that some studs were too long. Instead of dismantling again I stuffed the head with rags to prevent grinding dust to get in and used a powered file to grind the studs down to proper length.

I think I even cured the slight oildripping that previously gave a faint oilsmell on full cruise, probably because the siliconegaskets at the cylinder foot is tighter now. Test flights have been satisfactory- that is, until I broke an outrigger again...see "outrageous outrigger" topic.