Tonight, I decided to pull the oil pressure relief valves and take a look at them.
First, I pulled the one the runs horizontally (letter B in the diagram above).
There appeared to be a fair amount of tension on the spring and I was able to easily pull out the piston with a magnet.
The piston looked like the one on the right in the picture below. (it has holes in it)
I wiped it off and put it back in.
Next, I pulled the valve that runs vertically (letter A in the diagram above). The spring on this one also felt like it had good tension and although it was quite a bit more difficult I was able to pull the piston out with a magnet. This piston however was the same as the one on the left in in the picture below (no holes in it)
Now I am not sure which is the correct piston.
Recall, that this is a 1974 2.7 engine and I do not know for sure, but I believe it has never been opened up and would therefore not have the oil bypass modification.
So the question is...which is the correct piston for a 1974 engine without a bypass mod. PP has the piston listed in the catalog as 911-107-512-00 for 911's (1974-89) which appears to be the one pictured on the left in the picture below.
Frankly, there is no telling why these valves would have been changed in the first place but maybe it was someones attempt at correcting the overheating issue.
Should I replace the piston with holes in it with one that does not have holes?
Thanks again for all of the help.
