Identifying a bolt/plug

copper · copper's Garage

I can attach a photo when I get it back in the air, but for now, if anyone can help me from my description, that would be appreciated.

In front of the sump plate, where the oil drain plug is, there is a larger round plug with a slot running across it's face. I am getting a fair bit of leakage around it. Is this a secondary drain for the sump?

Also, the PO ran grey/blue silicone along the case centerline and around the sump plate. I was going to replace the gasket shortly and was wondering if the silicone on the sump plate was done through laziness or another reason. Do the sump plates warp like Valve covers do? Could the PO have put in a sump gasket and still had leakage problems?

Jim

Yellowbird RS · 10-09-2004, 08:23 PM

which one?

copper · copper's Garage

Thanks Yellowbird

It's in the area of the yellow circle.
Looks like what I've drawn in the corner. Only mine is covered in oil...

If memory serves me correctly, it's on the passenger side of the centerline of the engine case. Still on the engine, not the tranny.

My engine is a little different. The sump plate is more towards the rear than centered. The bolt/plug is ahead of it and higher, like above the lower portion of the sump.

Jim

Yellowbird RS · 10-09-2004, 09:27 PM

I don't know for sure but probably seal stud

copper · copper's Garage

Looks more like #54, whatever that is on the list. It's on the engine underside and the bolt face is to the bottom.

Jim

smestas · smestas's Garage

Its the oil pressure relief plug. I think the newer ones have a 17mm hex head.

http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_oilsys_pg8.htm#item28

copper · copper's Garage

That's it.

Thank you. Now what exactly is it's purpose?

Jim

Joeaksa · 05:03 AM

Jim,

When its cold, like in Ontario in winter, the oil is very thick when starting the engine and until it gets warmed up. The oil pressure relief valve will open if the oil gets to a high pressure that is over "what is considered normal." What this value is depends on how the engine was set up and can be adjusted but is normally left alone.

This allows a bit of the high pressure oil to bypass the system until it gets a bit warmer and the pressure drops to a more normal value when the valve closes. It keeps from bursting seals, gaskets and so on. The thermostatic valve in the RR wheel well does the same thing for the front cooler. Oil to the front does not flow until its warm enough to need the front cooler, thus keeping it from bursting hoses and seals in this system.

Assume that you have tried to tighten the plug? If so and its still leaking its time to pull the plug and replace the gasket underneath. I would have a spare before you remove it unless you are putting the car down for the winter.

Also its under pressure from the spring and so when you remove it be ready to catch everything! Have forgotten but believe that it uses washers to adjust the pressure on the spring, thus the pressure it will open. Make sure that you put the same number and type of springs back in when replacing everything to keep the value the same.

JoeA

copper · copper's Garage

Thanks Joe

Very helpful. Did try to turn it. It's tight. New seal in order.

Jim

Randy Webb · 10-10-2004, 11:02 AM

When it's out, check and see if the new hex type will fit. That will make it easier next time.

TroyGT · TroyGT's Garage

FYI, when you remove that sucker, it's under tension from the spring inside and it will fly out of the hole and deposit parts within a 10 ft radius of your car. If you're careful, unlike me, you can easily hold the tension with your tool and your other hand just before it lets go.

dafischer · 08-11-2006, 01:10 PM

Jim,
The sump plate can get deformed around the stud holes from the nuts being over-tightened. It will definitely leak, even with new gaskets if this is the case. When you remove it, run your finger over the holes, on the engine side of the plate. If you feel bumps around any of them, you'll have a leak.

If you have a fairly thick piece of flat steel, you can place the plate on that and use a machinist's hammer to get it nice and flat again. If it's really buggered, repro sump plates can be had. Not sure if our host sells them or not.

When re-assembling, some spray tack will help prevent dribbles in the future.