Greimann

I have been watching this thread with interest because I have the same symptoms Mike. A lifter tick at idle after the engine has fully warmed, when the oil pressure is below 3 bar. The noise subsides at higher revs, when the oil pressure builds. Tried detergent additives and am currently running Castrol Syntec 20W-50. After reading about your trials, and other threads commenting on lifter tick, I have come to the conclusion that it is not a destructive situation and that I it something I am going to live with by turning up the volume on the Blaupunkt. I have no doubt that it is a lifter considering the sound and the conditions when it occurs.

JPBNY

Try doing a leakdown test a bent valve will give you the same "ticking "sound as a bad lifter. It will go up and down with the RPM and they only have to have a very small bend to them to not seat flat and you will get the "tick".If it's on the exhaust side you can hear it with a scope on the exhaust manifold were it meets the cylinder head,the intake side is hard to hear because of the fuel injectors.Even with the valves bent the car will run well. Good Luck John

mike_hammond

Guys for fear of drifting off topic go back and read my last couple of posts again, the noise is not a tick on mine its a loud rattle on the top end in the vicinity of the variocam chain tensioner. It gets worse as the Oil gets up to temp, its not going to be a bent valve as it would be there all the time and its not lifters as I've just fitted a complete new set to eliminate them from the problem.

Anyway, continuing today I ran the engine with the cam cover removed and the noise appears to be coming from within the Variocam tensioner itself, I used the old screwdriver to the ear technique. My hair is lovely and shiney now after the oil shower who needs Vidal Sasson

When driving the rattle is accompanied by fluctuations in oil pressure, noise starts then the pressure will drop down. I'm also seeing the rattle on startup from cold with the pressure taking probably 5 seconds to build to 3 around at cold idle with it showing zero for the first second or two.

When hot if put my foot down the pressure readings are at 4.5 to 5 but the rattle occasionally kicks in and the pressure will drop half a bar.
When cruising at say 40 Mph in traffic the pressure will run at around 3 with the rattle coming and going. Now if I come to a stop the pressure can drop to as low as 1 before settling back up to 2.5 at idle and also it will drop if I push hard in right hand turns.

Now back to the rattle, I replaced the cam cover and ran it up till warm an the rattle was there again at idle only going once I revved the engine to say 3K. I then removed the variocam connector and put a meter on it whilst idling and read 13.8 volts suggesting that the solenoid should be activated. At this stage the engine was still rattling, so next I got some wire and energised the solenoid directly from the battery and the noise all but dissappeared completely , although the engine did start to hunt a little as if it was about to stall ? upon reconnecting the original supply the noise came back even though I could read a voltage.

So now logic ditates this could be a simple bad connection, so I turned off the engine and then with the ignition on, removed the connector once again checked the voltage which was at battery level. When I reconnected it I could hear the solenoid activate every time, so I cleaned it with some contact cleaner and reconnected it, no difference at all.

So now I'm wondering

1) where does the feed come from for the solenoid is it low on current and therefore struggling to hold the Variocam solenoid active ?

2) Is it just the solenoid itself has gone weak and the direct connection from the battery gives it the extra umph it needs to activate the valve.

3) I'm completely loopy and have missed the point totally

My only fly in the ointment is why is it affecting the oil pressure so much, it was certainly stable before the rattle started, and the engine never rattled on start up or struggled to build initial pressure. So have I got two faults here or is it that the valve on the variocam is allowing too much oil through by not fully energising / sealing at startup and hence why my pressure is struggling to build, it certainly sprays loads out from under the soleniod towards the inlet cam sprocket when idleing.

Next step unless anyone can come up with a better plan is to get a replacement solenoid first, then if no improvement closely followed by a second hand tensioner to prove with.

If this doesn't do it the I may aswell

Mike


P.S. on the positive side, since re-aligning the lower balance shaft which was 180 out the engine is a smooth as silk with no vibration at all if it wasn't for the rattle you'd hardly notice it was running.

nick_968

I have heard of one other case where the variocam solenoid was causing problems, check the 968.net archives with the search feature, I will see what I can find there now.

RajDatta

Mike, I will be shipping some stuff to UK soon. Do you want me to send my spare tensioner? Test it with that. I know its good and working and this way you will save yourself expensive parts that you might not need.
Regards.
Raj

mike_hammond

Raj, I'll let you know I've just got to make a few calls this morning to find out more on pricing etc. Also I'm gonna have to get this sorted quick as its making the noise almost constantly if below 3 bar and the oil is hot.

Mike

ugo968cab

Mike,

porsch-apart.co.uk

has certainly some good dismantled Variocam units at good price, so this is an option for you. Probably they can also provide dismanted "solenoids", the is the electro-valve sending oil to Variocam.

The effect you describe on oil pressure is strange, at least if Variocam is working properly. At this point, i suggest you to read the Worshop Manual when describing the "air pressure" method to test the Variocam. This allows you to see, with valve cover opened, if variocam is working properly, if the piston keeps the pressure, if there are air leaks in other parts of the mechanism.

I would put special attention to the "J-tube" and associated seals and bolts: if the J-tube looses oil, this could explain the oil pressure variation. Sometime, at least in 944 S2, these J-tubes go bad.

Ciao

Ugo

mike_hammond

Thanks Ugo, I've tried them but no joy and a new one is around £130 or $250 to you guys, which is a lot just to prove a fault. So now I'm ringing around to see if I can beg, borrow or steal one from a friendly specialist.

Mike

koirra

Mike,

I haven't been reading this thread for a while. I've got a spare top end of an engine if you want to borrow something.

I am in Kent.

Erkki

ugo968cab

Mike,

in your Web site i noticed something suspect in the 3rd photo of the Variocam area.

Where the "J-tube" is soldered to the ending plate plate (the plate is attached with 2 bolts to engine head), there is a strange "black spot".

Probably nothing relevant, i only suggest a check to verify the absence of any "cracking" in this soldering area.

Ugo

mike_hammond

OK, Koirra thanks I'll keep it in mind.

Ugo, I did check the pipe over thoroughly and there we no leaks or fractures, I think the mark on the photo is just that an oily residue mark, but I will double check it again when I next take the top off.

Anyway the plot thickens and today instead of working for a living I've been ringing around the UK specialists trying to find answers. The last person I spoke to was Barry at Hartech, this guy has been around the block a bit and is well up on the 968's.

Anyway he straight away focused on the oil pressure and the fact that it is fluctuating, pointing out that the lifter tick and Variocam rattle is indicative of low oil pressure in the top end of the engine. Meaning that the Variocam is struggling to maintain a stable pressure, and is sure my Variocam tests are a red herring.

Having discussed the problem at length he asked if when I rebuilt the cams and belts, had I noticed any problems with the lower balance shaft timing. Which if you've read my earlier post I did find it was 180 degrees out.

He then went on to explain that the vibration caused by this imbalance can commenly cause the oil pickup pipe to fracture and this would explain the low pressure at startup and at idle when warm as the pump is struggling to draw up the oil and is pulling air in through the fracture. Also this is why
I see the pressure dip when I go around right hand turns.

So the first job is to stop using the car, as if this breaks of I'm in deep doo doo, and then to get the sump off ASAP to verify the condition of the pickup pipe.

So the next question is can I do this with the engine in situ or do I need to lift it out ?

Cheers for all the help guys

Mike

The Dave

I think the apparent difference in the lobes may be due to their position, as the photo shows the "toe" on one and the "heel" on the other (for lack of a better technical description). I would expect the wear on all the "toes" to be similar and all the "heels" to be similar, though.

I wouldn't worry about the pads, they appear to have plenty of life left in them.

RajDatta

As long as your engine is suspended by something, you should be able to drop the entire bottom end in one shot. To do this, you will need to remove your wheels, remove the steering rod from the steering rack, remove all 4 nuts holding the struts on each side.
This should free the top part. For the bottom part, remove the steering resevoir and let it hang with the rack and crossmember. Remove the bolts holding the caster blks to the blk and that should really be it. Undo the bolts holding the motor mounts as well. Your entire suspension should come down in 1 piece.
You will need alignment when done.
You can also perform the same task by just dropping the crossmember while the steering rack is still connected.
Regards.
Raj

mike_hammond

Job done, the pickup pipe was completely severed, how on earth I was getting any pressure at all I do not know as it was right at the top of the pipe just below the union to the block.

Anyway point it ITS FIXED !!!!!!!!!!!!!!!!!!!!!!!!!!


The motor now purrs like a kitten.


So I'm V.V.V.V.V.V.V Happy


Thanks for all the help guys

Mike

mike_hammond

Forgot to add do I really need an alignment ? I marked the castor blocks before I removed them to ensure they went back on in the same place and as I haven't removed any other critical parts it should be OK shouldn't it ?

Mike