Jfrahm

1992 968 Cabrio, 155k miles.

I have a rattle I thought was cat converter heat shield. Today I decided to try to sort it out. It makes a quick 'braaap' at about 1700 RPMs, in or out of gear, clutch in or out. Revving the car from the throttle body with the hood up, I was surprised to find the noise coming from the head, and disconnecting the variocam harness seemed to make it go away.

I think the variocam system was working, and I will pull the cam cover and take a look under there, but I thought I would post and see if anyone has heard this before.

The head, cams and variocam system was supposedly redone at 138K miles by the PO. It does look as if the head has been off.

Any thoughts?

Thanks,
-Joel.

Jfrahm

Doing some searching, it might be a failing Variocam solenoid valve.
Part number:
94460512300 or 944 605 123 00

About $300.

-Joel.

Jfrahm

Update:

I whipped off the cam cover, about 20 bolts and the fuel lines need to come off. No big deal. Everything under there looks fine, the variocam chain pads are in fine shape. Very dark brown but less than 1mm grooves in them.

I took the solenoid off and operated it with the battery, it seems OK but it might be hard to tell without a jig to make it lift against something simulating the oil pressure. I decided to try to clean it so I sprayed it with deep creep a few times and gave it the juice again a few times. Now I have it soaking with Deep Creep sprayed into the bore. It could be sort of a backwater for varnish and vapor and smoke, so it might be sleazy inside. If this does not work I'll source another one. Either way it's nice to know it's probably not a major deal.
I was imagining chain slap against the cam cover.

*Notes* Don't drop any bolts or washers, particularly the small ones on the solenoid, those could disappear into the head pretty easily. I might put some blobs of grease on them to hold them in place for reinstallation. also the gas-soaked rags used to soak up the fuel from the fuel lines, make sure not to leave those lying around, they can spontaneously combust. They either need to be left outside to dry or stored in a sealed container where the oxidation that causes them to burst into flame is kept out.

-Joel.

RajDatta

Joel, make sure you are careful when installing the j-pipe. The checkvalve for the oil feed has a tendency to pop out so make sure you either install it after the tensioner has been installed or keep it under check. Its very small and can easily drop in one of the galleys.
Raj

notthd

Joel

I haven't done it personally but many here have had similar experiences. I would of first thought that the chain pads were worn but that is not the case. You may have a weak solenoid but I'll let the guys who have delt with these before chime in - good luck...

Cheers, Mike

968workaholic

The three things to check are if the J tube is cracked, that the check valve is actually in there, and lastly if it is still making noise the pressure valve at the back of the head could be causing lower than normal pressure in the head which would cause the vario-cam unit to make noise. I had this happen on one other car, same kind of noise and it turned out to be the pressure valve in the back of the head. If your solenoid is working it is probably fine. The fact that it is making the noise when the car is running tells you that the solenoid is trying to operate but there may not be enough oil pressure for it to operate properly. Just some things to look for.

Luis de Prat

Does the J tube crack even though it's made of brass?

968workaholic

Well the joints that are brazed together could seperate, causing a crack between the two.

Jfrahm

Thanks for the input. Cleaning the solenoid did not help. I will read up on how to check the check valves. It is possible something was not done correctly when the head work was performed.

Is the oil check valve parts 39-44 in this diagram?

http://www.autoatlanta.com/model/968-92-95/103-00.htm

Thanks,
-Joel.

Jfrahm

I'm going to try replacing the solenoid, but the part is on backorder. It's only $143 from Sunset, but no ETA so I figure I'll try to find a used one for now.

Does anyone have this part from a scrap head or variocam unit? It's the silver gray solenoid mounted on the variocam assembly with the electrical connection on it. Part number 944 605 123 00

*update* I could not find a used one for a good price so I ordered one from Sunset. Hopefully it won't take too long.
TIA,
-Joel.

968rz

Not to point you in a different direction but have you checked the heat shield around the header? I had a similar noise and it was a crack in the shield that would vibrate a certain RPMs.

Jfrahm

Yes, I have traced the noise to the variocam system. If I pull the plug off the solenoid it goes away.

Thanks though,
-Joel.

968workaholic

That is the part. Sometimes the check vavle gets gummed up and the pressure in the head is changed. I have only seen this happen on one other car, so I doubt that there was anything done wrong when the head work was performed. You could try taking the valve out and cleaning it while you are waiting for the solenoid to come in just to see what it looks like or if that fixes your problem.

kwikt

I have a spare used variocam solenoid. I'll check it to see if it works if interested.

Kevin

968turbos2

If you had head work done then I would as, 968workaholic suggests, to check the pressure valve.

The channels may need to be cleared from debris or cleaning agents. That clicking noise you hear is the force of the camshafts pushing against the chain tensioner when it engages.

Solenoid, if operational is not the source of your problem I would think, saving you money there.

The procedure to check/clean that spring ball and plunger is in the manual.

It basically has to be able to adjust the intake camshaft while two or more lobes are depressing valve springs. That click is the lack of enough force to keep the camshaft adjusted against the valve springs so the piston gets pushed back down and the pad holders hit the varicam housing. You can see this same thing in slow motion when adjusting the lift and not keping enough pressure to the variocam for it to keep its adjusted position.

Can break a tab so I would not really drive it with that noise.