Cylinder head retorquing
Posted: Tue Jan 24, 2023 3:24 pm
by SP1
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
Re: Cylinder head retorquing
Posted: Tue Jan 24, 2023 4:41 pm
by Bryan Cotton
Sounds odd. I didn’t check after retourquing though. I have had movement every time I’ve gone to retourque though.
Re: Cylinder head retorquing
Posted: Tue Jan 24, 2023 6:43 pm
by GraemeSmith
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?
Re: Cylinder head retorquing
Posted: Tue Jan 24, 2023 8:49 pm
by SP1
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.
Re: Cylinder head retorquing
Posted: Tue Jan 24, 2023 9:29 pm
by Bryan Cotton
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
Re: Cylinder head retorquing
Posted: Tue Jan 24, 2023 11:07 pm
by mike.smith
Are they cast iron cylinders, or Nickasil?
Re: Cylinder head retorquing
Posted: Wed Jan 25, 2023 3:52 pm
by SP1
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.
Re: Cylinder head retorquing
Posted: Wed Jan 25, 2023 6:16 pm
by mike.smith
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:
- 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.
- 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?
Re: Cylinder head retorquing
Posted: Wed Jan 25, 2023 7:10 pm
by Bryan Cotton
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.
Re: Cylinder head retorquing
Posted: Thu Jan 26, 2023 8:58 am
by GraemeSmith
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.
Re: Cylinder head retorquing
Posted: Mon Jan 30, 2023 7:09 pm
by karmarepair
A tool I didn’t even imagine, and now I need http://www.motionpro.com/a/adjustable-t … r-08-0380/
I started to make the Torque Adapters Bryan highlights in an earlier thread but I am ot set up to weld to do If have to pay someone for it. This adapter maybe the cheaper way, and it is certainly more versatile.
Re: Cylinder head retorquing
Posted: Sun Jan 21, 2024 8:38 pm
by Bryan Cotton
I’m doing my annual because the weather sucks. It’s not actually due until June but June weather is generally nice compared to January and February in northern Illinois. I had a fair amount of motion when I torqued my heads, especially nut 1 and 3 in the manual. I’ve never had no motion. I’m trying to decide if this is an issue or not. Also considering torquing every other valve adjustment, or 100 hours. We have been flying at a rate of about 200 hours per year. Any Aerovee guys who have thoughts would be great if you shared them.
Re: Cylinder head retorquing
Posted: Mon Jan 22, 2024 2:38 am
by Murray Parr
Proper method of torquing almost anything is to follow the recommended torque sequence (usually starting in the center and working outwards in a circular pattern) starting at a fairly low torque setting and complete the sequence a few times increasing torque each time you go around, working up to the proper torque in stages.
I would imagine the manual shows this somewhere. What it might not show is final torque should be held for a few seconds on each nut during this sequence (the click off type of torque wrench isn’t good for this) and once done go around again and keep going around until no nuts turn any further holding the torque value for a few seconds. Each time one nut torques down a bit further it effects the other nuts a bit (especially those nearest to it) and that is why you usually find yourself going around the sequence and seemingly getting nowhere. I am not a VW expert but most likely these best practices would still apply. If the nuts keep needing torquing after a few runs around the sequence and don’t seem to be improving then something could be amiss, most likely the stud pulling through the casing or stripping out somewhere, but this shouldn’t be a problem if everything is designed and installed correctly.
If the studs are installed so that they are unable to move, you will find that after a few heat cycles and torquing a couple of times the torquing should become only minor or no changes once everything has settled in.
Re: Cylinder head retorquing
Posted: Mon Jan 22, 2024 9:14 am
by Bryan Cotton
Thanks Murray. What you described is what is in the Aerovee manual, and what I have been doing. My one thought is I wish I had loctited in the studs, but that was not in the manual. I do use a click type wrench though.
Re: Cylinder head retorquing
Posted: Mon Jan 22, 2024 10:10 am
by Area 51%
You might try a dab of torque seal at the junction of the case and stud before torquing to make sure the stud isn’t turning or pulling.
Re: Cylinder head retorquing
Posted: Mon Jan 22, 2024 4:12 pm
by Murray Parr
Bryan Cotton wrote:Thanks Murray. What you described is what is in the Aerovee manual, and what I have been doing. My one thought is I wish I had loctited in the studs, but that was not in the manual. I do use a click type wrench though.
If you use a click type, just add the pressure real slow and smooth. You will likely have to go around the sequence an extra lap or 2.
Area 51"s advice is good with the torque seal paint. Hopefully the studs aren’t pulling through.