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ddruker · 03-18-2021, 01:19 PM

One question for the brain trust today, and one more bit of learning to share.

First the learning -

My secondary air injection system had failed over the year, and I fixed it last year by putting in new valves, a new vacuum accumulator, and new fancy silicon vacuum tubing. I couldn't easily get to the tubing going to the tiptronic transmission cooler coolant cutoff valve, so I left that portion alone. With the transmission out, I just replaced the section of vacuum tubing going to the transmission today, and checked the valve for operation - and guess what - the valve was broken. It's a cheap plastic part. How it is supposed to work is that the valve is normally open, allowing coolant to flow to the transmission oil cooler. When the ECU decides to close the valve, it activates an electrical switch that applies vacuum to the transmission coolant cutoff valve, which will cause the valve to close. There is a cheap rubber diaphragm at the top of the valve that is leaking on mine - so it doesn't hold a vacuum and it will never close. Easy to diagnose by sucking on the vacuum line. Current Porsche Part number is 92857457304, about $90, the version made by OEM supplier Mechano Bundy is $30 under a slightly older part number 92857457303. So - when you have your transmission out for this procedure, check your coolant cutoff valve by sucking on the vacuum tube. If it leaks air, or if you can't get the actuator arm to move, replace the valve.

Now the question -

It's about where to apply the cam lock when I install the new LNE bearing. I have a 5 chain motor. Most of the directions I have read say to pull the lower green plugs on both cam covers.

As you are looking at the back of the motor, one of the ports to see the cam position is on your left, right in front of you, wide open and easy to access. The other port is in the front of the motor on the passenger side, tucked away behind the edge of the access panel - without a lot of access or room.

My question is - does it matter which of the two lower cams I lock? If it's ok to lock the cam on the back of the motor, that's just so much easier. Do I need to even bother removing the plug from the front cam cover? Or is it important to look at the front cam position to make sure it has not moved following the installation of the new IMS bearing? Or should I be locking the front one because Porsche engineers are just trying to mess with me?

03-18-2021, 01:19 PM	#17
ddruker Registered User Join Date: Jul 2018 Location: Palo Alto, California Posts: 59	One question for the brain trust today, and one more bit of learning to share. First the learning - My secondary air injection system had failed over the year, and I fixed it last year by putting in new valves, a new vacuum accumulator, and new fancy silicon vacuum tubing. I couldn't easily get to the tubing going to the tiptronic transmission cooler coolant cutoff valve, so I left that portion alone. With the transmission out, I just replaced the section of vacuum tubing going to the transmission today, and checked the valve for operation - and guess what - the valve was broken. It's a cheap plastic part. How it is supposed to work is that the valve is normally open, allowing coolant to flow to the transmission oil cooler. When the ECU decides to close the valve, it activates an electrical switch that applies vacuum to the transmission coolant cutoff valve, which will cause the valve to close. There is a cheap rubber diaphragm at the top of the valve that is leaking on mine - so it doesn't hold a vacuum and it will never close. Easy to diagnose by sucking on the vacuum line. Current Porsche Part number is 92857457304, about $90, the version made by OEM supplier Mechano Bundy is $30 under a slightly older part number 92857457303. So - when you have your transmission out for this procedure, check your coolant cutoff valve by sucking on the vacuum tube. If it leaks air, or if you can't get the actuator arm to move, replace the valve. Now the question - It's about where to apply the cam lock when I install the new LNE bearing. I have a 5 chain motor. Most of the directions I have read say to pull the lower green plugs on both cam covers. As you are looking at the back of the motor, one of the ports to see the cam position is on your left, right in front of you, wide open and easy to access. The other port is in the front of the motor on the passenger side, tucked away behind the edge of the access panel - without a lot of access or room. My question is - does it matter which of the two lower cams I lock? If it's ok to lock the cam on the back of the motor, that's just so much easier. Do I need to even bother removing the plug from the front cam cover? Or is it important to look at the front cam position to make sure it has not moved following the installation of the new IMS bearing? Or should I be locking the front one because Porsche engineers are just trying to mess with me?