Timing Chain Tensioners Replacement

[Prochase981]

I am planning on replacing the 3 timing chain tensioners on my 5 chain boxer engine. After reseaching this site I intend to employ the following guidance:

1. Index the crankshaft to TDC and secure using a 8mm or 5/16 inch locking pin
2. Lock the exhaust cam on bank 1 using the recommended cam lock tool

This assures that the IMS and the cams in bank 1 do not move when removing and replacing the tensioners. The question I have is do I need to lock the exhaust cam on bank 2 (cylinders 4,5,6) using the cam lock tool in order to replace the tensioner that is located at the top front of the engine?

Thank you,
Eric
98 Boxster

[elgyqc]

The engine is symmetrical, so if you do one side, do the other.

[Hartman]

Bank 2 is behind the driver and bank 1 is on the passenger side. I think that if you lock in any TDC and lock one side and then change the tensioner on that side you will be fine. Then rotate the engine 360 and lock again and then change that side. If you do one at a time you should be fine.

Do you know how to look at the cam shafts to tell if TDC of that bank. On the intake cams is a notch that is only on one side. On bank one (pass) you lock the cam behind the pass seat. On the transmission end the intake cam notch should be pointing away from the center of the engine towards the valve covers, this is TDC. Replace the tensioner at the bottom rear of bank one. Don't forget to pre oil the tensioner and use a new crush washer. I believe the torque is like 75 foot pounds. You can then do the crank to IMS at the side rear of bank two before you unlock the the engine.

Once both are oiled and replaced unlock the engine and turn the engine over 360 three times. This will bring you to TDC for bank two. Lock the crank TDC and check the intake cam on bank two behind the driver seat and the notch should be facing inwards away from the valve cover. You will need to loosen the alternator to be able to get a socket on the tensioner which is facing up under it.

[Prochase981]

Thanks for the input guys. I appreciate it.

[Hartman]

I would think that you would if you want to be 100% safe. Once you complete the upgrade on bank1 you need to unlock and turn the engine 360 degrees clockwise and lock TDC on bank two. The idea of TDC is to take all the tension out of the bank in question.

I'm sure there are people who would say you don't and I would guess that it is totally possible to do it without locking. it is really based on your personal risk level. Looking at the cam shaft notches can tell you if you are out of time.

On the exhaust cams you will see the notch is not centered. One edge of the notch is on the center line and the other edge is offset. When the bank you are working on is in TDC that notch will create a small "C" and bigger "C". The bigger "C" needs to be on the side closest to the crank and the smaller "C" will be on the valve cover side. This lets you know which bank is TDC.

[Hartman]

Also don't forget to take the new tensioner and put it in a cup of fresh engine oil and compress it a few times to prime it. this is important to ensure when you start the car for the first time it is able to apply tension right away. If not it will need a bit to fill with oil allowing the chain to smack around.

You can confirm this by pulling an old one and try to compress it and compare to the new one before priming and then after.

Im sure you are aware but all three tensions are different and have rings on them so you can ID them. The engine will have matching ring marks on the engine.

[Prochase981]

Thank you very much for the input.


Does anyone know the spec of the bolt that threads into the head to secure the locking tool?

Eric

[elgyqc]

Originally Posted by Prochase981

Thank you very much for the input.


Does anyone know the spec of the bolt that threads into the head to secure the locking tool?

Eric

You can use the allan screws that hold the pressure plate in place, which many people have laying around because one is not supposed to reuse them... M8 X 16.