SonexBuilders.net

Hello All
I tightened the 8 cylinder head nuts to 18 ft lbs, came back the next day, noticed that they had loosened, so I retightened them. Left it alone over the weekend to find that the nuts had loosened again. I've done this 3 times already. Trying to figure out what's going on. I expected to retighten aafter a run, but not after just sitting for a few days. Any thoughts?

Thanks

Sounds odd. I didn't check after retourquing though. I have had movement every time I've gone to retourque though.

SP1 wrote:Hello All
I tightened the 8 cylinder head nuts to 18 ft lbs, came back the next day, noticed that they had loosened, so I retightened them. Left it alone over the weekend to find that the nuts had loosened again. I've done this 3 times already. Trying to figure out what's going on. I expected to retighten aafter a run, but not after just sitting for a few days. Any thoughts?

Thanks

Has the engine ever been run?

Hey Graeme,
I bought the engine used. From the seller, it was run very briefly, like less than 15 minutes. I tore it down all the way down to the crank, and the insides looked new, including the cylinders and pistons.

Today the torque reduction is associated with the bolts numbered 2 & 4 in the final torque diagram in the manual, dropping to ~14 lbs.

I just made some marks to see if the steel inserts are turning. Didn't think about that until after i posted.

I'd probably leave it be and torque after the 10 hours. I found it was possible to chase my tail round and round on those torques. Maybe some more experienced VW guys have some advise. Definitely make the tools etc to make periodic retourquing easy.
viewtopic.php?f=7&t=4910

Are they cast iron cylinders, or Nickasil?

mike.smith wrote:Are they cast iron cylinders, or Nickasil?

There was no mention of Nikasil on the invoice from Sonex / Aeroconversion, so thinking they are not.

If for some reason they are Nickasil, this is what I experienced:
http://www.mykitlog.com/users/display_l ... 380&row=58

I have built the VW 4 times. What you describe does not sound normal. I can't think of any reason why the torque would change that much just sitting there. I had to retorque per the construction and break-in recommendations, but there was not a lot of movement in the nuts. When I check torque each year, nothing moves, so after a time, the torque gets pretty well locked in until you change something. The only 2 things I can think of:
1. If the base of the cylinders were set against the case with RTV (not recommended), then the RTV could be getting squeezed out with each torque.
2. If the pushrod tubes were extended (the accordion ends) a lot, then I supposed it's possible the first torque compressed the pushrods only part way, and the next time they compressed a bit further.

Anyone else have any ideas?

I wish I had used loctite on the inserts. I think some of my motion was the inserts moving in the case. The manual doesn't call for it though.

I do feel like torquing one nut affects the others. That is what I mean by chasing my tail.

Any chance the push rod tubes bellow are not even seated correctly? It is kinda easy to have one twist off at an angle - especially at the head end.