Late-Style 911 Carrera Chain Tensioners
 

I have a 71 2.2 911T engine which I am currently rebuilding.

When I took the engine appart I noticed that some of the crank bearinga had become pretty hot and looked like they had melted.

The PO had "upgraded" with the Late-Style 911 Carrera Chain Tensioners which are oil fed.

My question:
Is the stock 3 rib oil pump able to pump enough oil to supply both the tensioners and lubricate the rest of the engine and could this have caused the oil not to reach the bearings on the crank?
The engine does not have the oil bypass modification.


http://forums.pelicanparts.com/uploa...1707693663.JPG

The oil fed tensioners use very little oil. They just need the static pressure. I doubt that would be the reason for bearing failure like that. Lots of people have installed the oil tensioners on older engines without those problems.

Almost certainly a loss of oil pressure, but why? How many miles on the engine, racing time, etc.? Why did you tear it down? Open the oil pump and see if it shows wear.

Seeing the wear in the bearing saddle, you will definitely need to have the case rebuilt with oversize bearings and line bore, etc.

check your oil pressure relief valves
 

If the engine sat for a long period of time probably had some of the oil passages clogged. In the rebuild blow out all passages and replace the pressure relief valves. Make sure the oil system components are hospital clean.

The crank probably looks a bit rough.

Thanks for the advice much appreciated.

The crank is ok, the pump is also good. the case halves have been machined and line bore carried out. The reason for the teardown was that none of the cylinders passed a leak down test. Here a picture of the thrust bearing that was falling apart.


http://forums.pelicanparts.com/uploa...1707763043.JPG

Wow, I’ve never seen something that nasty without being totally welded to the crankshaft. it’s still roundish. ;)

Better mic that crank in lots of places on each journal. Looks aren't everything.

Wonder what the runout of the crank looks like too?