996 IMS Upgrade
Starting tearing into the 996 project today to see what we were looking at. The first thing was to go after the intermediate shaft bearing which is the weak part of these motors. Then was the waterpump and a few other misc. items while the engine is out.
I had to get the exhaust out of the way, so I pulled the headers/mufflers/cats (pulling cam covers later). Someone had upgraded the headers at some point (and mufflers) and replaced the manifold bolts with studs and nuts. Not sure what the logic was behind that, it still pulls the studs out when you don’t secure them in the block with some time of loctite. Odd.
A few cans of cleaner and I could actually see the IMS flange. Nice to get the oil and clutch dust out of the way.
Locking out the crank at TDC on #1
You can do it without the big tool kit, but having it is invaluable, especially once we start going into the cams to do the chains and tensioner pads.
Bank 2 cam locked out.
Bank 1 cam locked out. With the cams and crank locked, we assure timing will not be affected when we pull the bearing.
The IMS-Crank tensioner out, and the bank 1 tensioner out. There is debate about whether or not to use the old style tensioners or the new when replacing them, but that is pretty much solved since the old style tensioner (at leats the IMS-crank) is no longer available. Notice the IMS tensioner has a really short plunger…….actually it doesn’t, this tensioner was stuck towards the ‘in’ position. It should actually be about as exposed as the bank 1 tensioner behind it.
When I pulled the IMS flange off, look at the odd pitting in the flange. Looks to me like condensation in the oil sat against the flange and started to eat away at it.
Shop supervisor is on full alert for the evil vacuum cleaner inside the house.
With the flange off the case, you can see the dual row IMS bearing.
Using the IMS puller, out comes the bearing.
The bearing didn’t look horrible once out of the engine.
But once I popped the GREASE seal out, it was obvious that oil had penetrated the inside. What happens, is the oil washes the grease out of the bearing (which it did nicely), then as the bearing rotates, the oil inside the bearing can not get in and out fast enough to effectively lubricate the bearing and it leads to failure. A common solution to this is to remove the grease seals from the bearing, allowing oil to full pass through the bearing, allowing the lubrication. Our replacement bearing will not be metal, but will be ceramic with no seals. This will be a much longer lasting bearing than the OEM design.
Since parts won’t be here until the morning, figured I would get some other areas ready. Off comes the old waterpump which is another common failure in these cars. If you haven’t replaced it by 60k miles, you probably should. The plastic impeller will fail and come apart inside the motor, which isn’t good.
Then I decided to pull the secondary air injection valve while access was easier.
And you can see it was clogged with plenty of junk. A lot of this stuff was not necessary to replace, but you hate not doing this work while the engine is out and everything comes off in minutes, versus in hours with the motor in the car. It really saves on the labor in the long run.