Early SC Oil Sump Mod

[echrisconnor]

Does anyone have information on, and specifically pictures of the early SC oil sump modification. I've heard this is necessary to prevent oil cavitation on the early SC motors, and am curious if the same applies to the early Carrera 3.0 motors as well.

A couple weeks ago at DE, I was experiencing some very high oil temperatures. The car runs reasonalby cool when being driven normally, but at sustained high revs, it gets damn hot. All other cooling system components are in good working order and have been tested, so I'm curious if this might be my problem.

[Kroggers]

Hay echrisconnor, do you have any more info on this? I have a very early SC (78), and have never been told anything like this before! Is there something I should be worried about here?

[Bill Verburg]

'76 & '77 C3s wouldd not have had that problem.

The issue first arose on "78 SCs

The problem 3was caused by a redesign of the pressure relief valve that year.

Symptoms are low oil pressure, loss of power and elevated oil temps under track conditions

The fix
here

and

here

another contributing factor can be the smp screen
updated part # 930.107.314.00

It looks like this



and also helps prevent cavitation.

see
PCNA Tech. Bulliten 78-03
PCNA Pub. PNA 000 056 9/87

[Kroggers]

So, if I do not track my car I am OK?? How do I know if the modifications have been done on my car??

[Bill Verburg]

An easily observed clue is the pressure relief valve screw cap,
original cap 999.064.010.02 was 25mm diameter plain sides, 12mm thread depth

interim update cap 999.064.016.02 23mm groove around the outside edge,14mm thread depth

final update cap 999.064.026.02 has a raised 17mm hex head

you can also pull the sping out the original had a free length of 71mm, the update is 88mm

[Kroggers]

Thank you Bill, but can I have that in English

[Bill Verburg]

[Kroggers]

Sorry Bill - I know very little about cars, and just pretend to know I try my best to work on my car, and get a little more knowledge every day. Is there an easy way for me to see if there is a danger for my engine or not??

[Bill Verburg]

Oil pressure relief valves

The crankcase incorporates two different oil pressure relief valves. The main oil pressure relief valve (A) is mounted at the bottom of the crankcase. The safety relief valve (B) is mounted in the left side of the crankcase.

The oil pressure relief valve opens and allows oil to pass directly into the crankcase when oil pressure exceeds 6.2 :t 0.8 bar. (88.2:t 11.3 psi). The oil pressure relief valve spring is 87 mm (3.43 in.) long.

In the event that the oil pressure relief valve doesn't open when oil pressure is excessive, the safety relief valve will open to prevent damage to the oil cooler, oil filter and oil lines. The oil pressure safety valve spring is 69 mm (2.71 in.) long. The safety valve is regulated to open at approximately 8.0 bar (113.7 psi).

[Kroggers]

Thank you Bill - I think I will get someone with brains to look at this for me - I am still at the replacing spark plugs and air filter stage of my "getting to know my 911" experience

[rlane]

Bill is correct, you or your chosen wrench can easily measure the lenghth of the oil pressure relief springs and see if they have been upgraded. You often need to grind a tool (a chisel works well) to fit the large slotted head..or else find a good quality drop link socket for a 3/8" drive ratchet .
Now the "improved venturi effect" oil sump screen is NLA....and really hard to find. It was the key to my overheating on the track. I had updated oil pressure relief system, AND invested in a Carrera type front fender cooler to replace my "trombone". It took the screen to quit hitting 250 degrees on the track.

[echrisconnor]

rlane,

Sounds like you were in the same situation I am in now. I've got a carrera cooler, I've checked all my thermostats, mixture & timing, de-gunked everything. I've got the 11 blade fan, tight pullies etc. On the track, or even with a lot of high-rev driving I'll hit 250 pretty quickly.

I've never seen my oil pressure warble, and consistently have good strong oil pressure. In my sump I have just the plain screen with no venturis or blockoff plates above.

I'm fairly certain my block has the oil bypass modification. It has the slotted pistons in it (not the ones with holes). I've never checked the spring length though. Could that really effect cooling? If I don't notice low oil pressure, should I even bother checking this?

Thanks all!

Chris

[wfbal]

Chris,

I don't know if the early 3.0l engine are affected by sump screen problem of 78-79 SC.

Fot my part, I had exactly the same problem than you and also updated to the carrera cooler.
My pressure relief valve is the latest type but my sump screen is the early design.

I finally got an updated sump screen, but I haven't install it yet.


This very well might also be your problem.

[rlane]

I think it would pay to check the releif system...seems I recall that the updated psitons and springs HAVE to go together or the system doesn't work (I think that you basically can not mix and match original releif piston with later spring and vice-versa. Try and find a new sump screen though..It should make a big difference

[Carl Bauer]

Originally posted by Bill Verburg
Oil pressure relief valves

The crankcase incorporates two different oil pressure relief valves. The main oil pressure relief valve (A) is mounted at the bottom of the crankcase. The safety relief valve (B) is mounted in the left side of the crankcase.

The oil pressure relief valve opens and allows oil to pass directly into the crankcase when oil pressure exceeds 6.2 :t 0.8 bar. (88.2:t 11.3 psi). The oil pressure relief valve spring is 87 mm (3.43 in.) long.

In the event that the oil pressure relief valve doesn't open when oil pressure is excessive, the safety relief valve will open to prevent damage to the oil cooler, oil filter and oil lines. The oil pressure safety valve spring is 69 mm (2.71 in.) long. The safety valve is regulated to open at approximately 8.0 bar (113.7 psi).

Bill I'll ask here as well...

Why only replace the pressure relief parts on the bottom of the case (A)? Why not on the side as well(B)? How come you don't replace the pressure piston with the updated version when you replace the spring, sleeve, washer, and screw plug?

[Bill Verburg]

You'll have to ask the factory engineers, I just repeated the TSB info