Variocam solenoid bench test

[redpepperracing]

I've done a bunch of searching but haven't found a definitive answer. I was at the track last Thursday and after my very first session (of course) it was running really rough. I checked the codes and I had one for bank 1 intake deviation or something like that (I was a bit flustered and didn't make note of it before I cleared it). It was cleared but still running really poorly at idle, but just driving it normally was ok. I checked the codes again and had a bunch of misfires, but not the bank 1 error. When I checked cam deviation bank 1 was at 17 and bank 2 was -0.2. I checked the wiring to the solenoid and unplugged and replugged it and made it back home. Last night I checked the Ohms and it checked out ok, and I also put 12V to the plug and it would click, but just a 'light' click. I did the same on bank 2 and the sound was distinctly different, it sounded like it went in and came back out, as I would expect. I took the solenoid out and when I apply 12V I get this Does that look like correct operation? And if so, I guess I'm pulling the actuator to see if the plunger is stuck?

[redpepperracing]

Another question, does this look like an actuator that is working?

actuator

From disassembly videos I have watched, the piston should just slide out, but mine doesn't, it does move in about 2 mm though, which seems to match the solenoid movement.

[Homeoboxter]

Operation on both videos looks fine to me. What did you find out?

[redpepperracing]

Originally Posted by Homeoboxter

Operation on both videos looks fine to me. What did you find out?

It's been a saga, to say the least. 3 weeks of pain, but I finally got it back together and working properly over the weekend. I'll spare the details other than to say that the rebuild of the actuator is not all that hard, once you know how to do it.

In my initial research I found zero information, and put out threads here, on rennlist and facebook, and got zero response on the rebuild process and especially bench testing. I ended up just reassembling everything after cleaning out the rubber bits from the side that I could disassemble. I put it all back together, and surprise surprise, it still didn't work. I started looking again, more so for a used actuator to replace mine, and somehow I found all of the information I needed. I found an ebay listing with a rebuild video (it wasn't great, it was just still photos with annotations, but it helped), and then I found someone had posted the mythical Hartech rebuild instructions, and more importantly, a link to a disassembly video with a bench test. While not as detailed as I would have liked, it got me in the right direction.

The main tips I would say are to remove the circlip use the method in the Hartech video with a small screw driver. I struggled with it until I did that and it was so much easier that way. Also after reinstalling the circlip you need to bend the tabs over, for this the method in the ebay video was the key by using needle nose pliers. I didn't do a great job here, but I think it will suffice.

For the bank 1 actuator there are 5 total o-rings/seals. I had 2 of the correct size already in an o-ring kit, I got a pack of 10 for $10 on Amazon that covered 2 of the remaining 3. The last one is a combination o-ring and metal sleeve like assembly that I couldn't source so I just left the one I had alone as it looked fine. I reassembled it and bench tested it as in the video and it appeared to work the same way, so I was pretty happy with that. To bench test you lock the pads with the special tool, then apply air to the lower oil inlet on the solenoid side and it should move it up. I also went so far as to actuate the solenoid to make sure that did what I think it was supposed to and that worked as well.

I put it all back together, again (it's amazing how much easier it is to do the second time, knowing all the mistakes you made the first time!) fired it up and it was perfect (within the margin of error for perfect), and I've driven it fairly hard over the weekend with no issues. My main concern was oil leaks on the valve cover, but so far so good. I have a track day on Thursday so that will be the real test.

These are the links I have that helped. I also downloaded both of the videos locally just in case. I have the PDF from Hartech which is linked in the Rennlist thread as well.

Rennlist link: https://rennlist.com/forums/996-forum/1403677-variocam-rebuild-part-numbers-3.html
Hartech video: https://youtu.be/LoH_pgOiuoI?si=GfsWMnYBnlSru1K-
ebay listing video: https://www.youtube.com/watch?v=8YglhYfqduY
rebuild kit: https://ebay.io/m/Shbddo

Hopefully this helps someone else.

[elgyqc]

I just read through this thread and have started to think about rebuilding the spare solenoids that I have. A couple of questions... how many kilometers on your engine, to have an idea of how long these parts last? My buddy's 986 has a big difference in deviation between bank 1 and bank 2 (Bank 1 -10.06 Bank 2 -6.19 at just under 190,000KM), could this be the explanation? It is not clear to me if you bought the o-ring kit in the link or if you sourced the o-rings on Amazon.
Thanks for your contribution to the community.

[redpepperracing]

Originally Posted by elgyqc

I just read through this thread and have started to think about rebuilding the spare solenoids that I have. A couple of questions... how many kilometers on your engine, to have an idea of how long these parts last? My buddy's 986 has a big difference in deviation between bank 1 and bank 2 (Bank 1 -10.06 Bank 2 -6.19 at just under 190,000KM), could this be the explanation? It is not clear to me if you bought the o-ring kit in the link or if you sourced the o-rings on Amazon.
Thanks for your contribution to the community.

Hi Grant,

My car had about 117,000km on it when I did the variocam pads, they were quite worn. I also did new chains, chain tensioners, and a bunch of other stuff. The actuator I just did is around 121,000km. To be clear, in my case it wasn't the solenoid but the piston that needed rebuilding. The solenoid was actuating, but the piston wasn't moving.

In your buddy's case, it is most likely the pads are worn to cause that deviation. Mine was similar at 117,000. When the actuator wasn't working the deviation was -2 on bank 2 and 17 on bank 1. For completeness I would do new pads and replace the o-rings I show below, and you should have 2 practically brand new actuators ready to go for not a lot of money.

This diagram is from a rebuild video I found and shows it all nicely:


The first time I opened it up, the solenoid plunger was actually stuck with green o-ring material. I cleaned that out and then it moved freely, and the piston moved as well. At the time I didn't have the knowledge to test it properly, so I put it all back in the car and it was still not working properly. I took it all back out and then found the actual instructions. In the diagram I replaced the two o-rings labeled 'Two o-rings on Piston cap' with the ones from Amazon that were a perfect match. The existing ones were pretty hard/stiff, so it made sense. The one labeled 'Piston seal o-ring (under piston seal)' I did not replace as the seal looked fine and I didn't want to risk damaging it by taking it off. The large green one (on mine it was completely gone, whcih i what I found in the plunger) that is not labeled I had in an o-ring kit I bought from Amazon years ago, and there is another one that isn't in the picture on the shaft between the two o-rings and the piston seal that I also had in the kit.

This is the link to the larger o-rings: https://a.co/d/0eeD79t2 they are 40mm OD and 37mm ID which exactly matched the ones I took off.

This is the other kit I had bought almost exactly 2 years ago that had the two smaller diameter o-rings: https://a.co/d/0gs3sPrj

All in I am about $35 and change, plus countless hours of my time.

The bench test is at the end of the Hartech video I linked, basically you install the tool to compress the piston, then apply air to the opening opposite to the solenoid. I went one step further and applied voltage to solenoid to ensure that worked as well, and it did. It all went back in, and it ran perfectly. I am one track day and about 1,000km on it so far with no issues.

The hardest part (for me) was removing and installing the circlip. I spent a bunch of time trying to remove it with a pick, turns out it takes about 5 seconds if you actually do it the way he shows in the video. Crimping the tabs once it is back in was also difficult, until I watched the other video again, and they show using a pair of needle nose pliers, whiched worked fairly well. Fingers crossed!

[redpepperracing]

I forgot about this link, it's very good and has some good images as well: https://rennlist.com/forums/996-forum/1403677-variocam-rebuild-part-numbers-4.html#post20580112