Small Oill Leak and Low Pressure

[DavidH]

Well I'm still breaking in after my rebuild, although it seems it's been about a year.
I am using 30W non detergent oil for the first 500 miles, I have noticed a small leak behind the pulley. I assume this to be the seal at the #8 bearing (not the o-ring).
But just today I noticed at idle the oil light is flickering occasionally, and the oil pressure gauge rarely gets above 1.5 bars even at 3000 to 4000 rpm.
I recently changed the oil pressure relief springs and pistons as well as changing out the cam tower fittings to the smaller orifice size with no percievable change afterwards. I also changed the sender with no improvement and have hooked a variable potentiometer to the sender connection and can move the gauge through the entire range.

What's up??? Please don't tell me I have a bad oil pump.. The engine had 189K at the rebuild. The other things changed at the rebuild were: Tensioner upgrade, 3.0 to 3.2 98MM P's & C's, and 964 cam grind.

Any thoughts???

Is there another place to hook up an external gauge to check pressure?

Thanks...

[Jim Sims]

Some possibilities: You may have the wrong springs/pistons in the oil relief system or the pistons could be jammed (cocked or hung up some way) in the bores. The oil pressure sender is bad or not properly matched to the gauge. Have you put a mechanical gage on to the measure the oil pressure? During the rebuild did you install the right size main and connecting rod bearings? Was the crank ground undersize or worn? Did you check the bearing/journal clearances with plastigage? Did an oil pump seal get left out when the case halves were assembled? I bet the springs are wrong or your pressure sender is bad. Hope, hope. Good luck, Jim

[DavidH]

Jim,
I kept the old pistons, bearings and all the old parts. I did use plastigage and measured everything very carefully going back together. The crank was near perfect. The oil pump seals are there, I know because two of them are one size and the third is a different size (I almost put the wrong one in the wrong spot). I can only hope that maybe one of the pistons is binding up, I'm going to change the oil tomorrow and I'll check it then. I have the oil sender as well and have swapped them. No difference.
If I could find a place to hook up an external oil pressure guage I would try that.
I'm going to put the 20W50 in as well. I don't know if that will make a difference or not.
In the mean time, I am going to order a new seal and see if I can fix the small leak.

[Jim Sims]

Make sure you really have the correct oil pressure sender; see:

Need help with oil temp and pressure...

Leak behind the pulley could be case seam instead of pulley seal.
Let's hope it's the seal. My Porsche mentor showed me the following method for removing this seal without damaging the case bore or crank: Get a drill motor (an air drill has more control but an electric drill will work) and a small drill bit that matches the minor diameter of appropriately sized sheet metal screws. Place a bit of masking tape around the drill bit about an 1/8 of an inch from the tip; this is the drill stop to keep you from drilling too deeply. Then carefully drill two holes through the seal halfway across the radial width of the seal (metal section under rubber) 180 degrees around from each other. Vacuum away chips and cuttings. Then screw the sheet metal screws into the holes just enough to obtain good engagement. Then we used a small pair of visegrips rigged to be pulled with a slide hammer: a chain link was welded to the adjusting screw head of the visegrip and this was engaged to the slide hammer with a hook attachment. Then clamping the visegrip on the head of one of the sheet metal screws use the slide hammer to give it a pulling blow. Then move to the other screw and give it a blow. Alternate between the screws and "walk" the seal out. Clean out any chips that made it behind the seal. Install new seal. Cheers, Jim