Oil leaks, also oil pressure - some questions

[Otter74]

I’m replacing a starter and doing some other maintenance on my SC prior to taking it on a trip in June. Lying under the car made me very aware of the collected fluid evidence of oil leaks. I generally accept a certain amount of this as normal for old cars but decided I wanted to address this.

Transmission: the shift rod seal is leaking, and the RHS axle seal. I’ve ordered both.

Can I unbolt the inner CV from the stub axle and swing it out of the way without removing the outer end at the hub? It looks like I can, but I haven’t done it.

Is replacing the shift rod seal easier from the tunnel inside the car, or from underneath? I can see it underneath when I pull the boot back but it sure doesn’t look like there’s any room to get a seal puller in there.

Engine case:

I’ve got oil on the right side of the case only. Exception is some from a small leak from the left side timing chain cover gasket, which I knew about and is minor (I ordered a new gasket for that too.) So jugs and oil tubes and etc are bone dry on the left side and wet on the right side, pretty evenly across cylinders 4-6.

I know that I have leaks from the triangle of death, so I’m replacing the low oil pressure light sender and the O-ring for the thermostat. I just remembered I forgot to order a gasket for the little rectangular lid in that area too, so I’ll get that.

What I’m not clear on is whether all of the oil on the bottom of my engine case - again, right side only - is from the ToD, or potentially from somewhere else. Can years’ worth of slow leaking from the ToD coat the whole length of the right side of the bottom of the case as it works its way down? Or is it only going to be around, say, cylinder 6? If it’s not coming from the ToD then I have some other leak that I don’t know yet.

I am running a Megasquirt without the CIS air box, etc. So access to the ToD is pretty easy - I can see it just by sticking my head in and looking - and there’s a lot less stuff to take off first. I may end up removing the remaining bottom portion of the OE air box - is it worth replacing the rubber connectors at each intake runner?

Final question - I have chronically high indicated oil pressure on the gauge, usually camped out around 5 bar. I’m aware that this can be caused by a fault in the sender at the back of the engine. I wrote down how to test it but can’t find it. I’ll look it up again. This will tell me whether I actually have abnormally high oil pressure or not.

What could most likely be causing high oil pressure if this exists, and if so could this plausibly (over years) be causing my leaks? If I do have high oil pressure, I’m not quite sure where to look. I’m not sure if high crankcase pressure would promote leaks either.

[Otter74]

The lined rubber oil breather hose was replaced last year.

[ahh911]

"Final question - I have chronically high indicated oil pressure on the gauge, usually camped out around 5 bar. I’m aware that this can be caused by a fault in the sender at the back of the engine. I wrote down how to test it but can’t find it. I’ll look it up again. This will tell me whether I actually have abnormally high oil pressure or not.

What could most likely be causing high oil pressure if this exists, and if so could this plausibly (over years) be causing my leaks? If I do have high oil pressure, I’m not quite sure where to look. I’m not sure if high crankcase pressure would promote leaks either."


With the ignition on, (car not running), the oil pressure should read zero. If it reads 5, the connection to the oil pressure sender most likely has failed. Locate the oil pressure sender on the right of the fan in the engine bay. Disconnect and ground the wire. The pressure indicator should drop to zero, (if not the issue is not the pressure sender but from the wire forward). Clean connectors, crimp gently and re-connect. A pressure of 5bar hot idle is not possible.

[Otter74]

Thanks for saving me having to look for that again (I’m more organized than I used to be, but still not exactly tremendously organized.) I honestly can’t remember what the gauge reads at idle, but I do recall that it is usually sitting around 5 when I’m driving. I’ll find out once the starter is in.

[wazzz]

Gauge should read a little below zero when ignition is off. Then it should climb up to zero mark when you switch ignition on but don't start the engine. That's a baseline.

If your gauge is reading 1 bar when you switch ignition on but engine is off, like mine is doing sometime on my 3.2, then your sender or its wiring are suspicious.
Could be a bad ground to the sender.

[Otter74]

Thanks again for that. Will be easy to check once the starter is in.

This is the bottom of the case. Oil is all on the side seen - other side is dry.

[yelcab1]

I have never seen that sump cover on an SC ...

[Otter74]

I don’t think it ever occurred to me that there was anything unusual about it, and it’s been on the car for probably close to 20 years.

It appears that it may be this:
https://www.pelicanparts.com/More_Info/PELRWSP.htm?pn=PEL-RW-SP

[Otter74]

The biggest question still extant in my mind now is whether all of that can likely be explained by the various ToD leaks, or whether it may be something else.

[stownsen914]

Do check your idle oil pressure. 5 bar is within normal range at higher RPM.

ne way to validate what your gauge is telling you is to substitute a mechanical gauge for your oil pressure sender or idiot light sender.

[Otter74]

Yeah, I’ll be doing that today once the starter is done. (I couldn’t work yesterday evening because of, of all things, a…dust storm??) I got some dye and a black light so I will put some dye in the oil before I change it and run the engine some to get a better idea of where it is and isn’t leaking from.

BTW, about how long does it take to replace the LHS timing chain cover gasket? I’m on the fence about this since it’s a minor leak while the oil is out I’ll only do it if it’s not too much time. I’ve got to take the rear tin off but not sure if muffler has to come off. Also don’t know if there’s enough oil that typically collects there that it really matters whether I do it with the oil drained or not. I may just give the lower nuts a quarter or eighth of a turn, clean, and check again in a couple thousand miles.

Also, I have some Curil T2. Any seals where this is recommended/useful?

[911obgyn]

Dont forget to check oil cooler seals they are on that side too. There is a spot behind cooler on the case that may weep and needs to be JB welded. There is a bulliten on it.

[Otter74]

I thought of the cooler but didn’t think it likely as a leak source. Where does it tend to show? My leak down the right case half is visible at least as high as the bottom of the jugs, though the oil tubes are clean.

I somehow didn’t notice that my right exhaust valve cover gasket is leaking so if I need to replace oil cooler seals I can do those together later. Starting on the leaks this afternoon.

Still a little unclear on shift rod seal - do I need to undo the trans mount and lower the nose of the trans? Seems like that would make access a lot easier, but I don’t see it mentioned.

[ahh911]

Turbo is 5 bar at 5000 rpm hot.

SC Porsche tech spec indicates: approx 4 bar at 90 deg C, 5000rpm. Once you've got it all sorted, you should see the oil squirters start to open at roughly 3.5 bar as the gauge hangs there slightly, at higher rpms mine will max out at 4 bar as the oil pressure bypass limiter kicks in. On the highway, warm days in the high 80s, low 90s, at my cruise speed, the rpms are such that the oil squirters are coming on and off, I'd like to see the oil pressure hit 4 bar at lower rpm (again, the car is fully in spec, just a personal driving experience/preference), cam restrictors I'm thinking, that's another subject.

Phil

[Otter74]

My indicated oil pressure is I think generally around 1 bar higher than each 1000 rpm. I’m running the engine today to get the oil dye circulating before draining the oil, but it’s not getting warmed up. Won’t get warmed up until I take care of all the leaks I have time for and refill. When I started it yesterday I think it was at least 2 bar indicated at cold idle. I trust the gauge more but I’d like to find my dielectric grease to put in the connector, then I’ll know it’s as good as it can be.

My low sort of wub-wub undertone to the engine noise (from the left bank) is still there and I’m still puzzled by that one (I created a thread about it a couple of years ago) but I’ll thing about that after I finish other things.