How do I check the oil level?!

dannytattersall · 06-23-2023, 10:56 AM

Hi all, I have owned my 1974 RSR replica for a while now and have realised that I don't know how to check the oil level! Fortunately it doesn't do many miles but it is still an embarrassing admission!

I am aware that dry sump engines normally have the oil level measured when the oil is up to temperature and the engine is idling. However, my car has two front mounted oil tanks and one has a dip stick whereas the tank on the left hand side of it has a sight glass. Why does it have two ways of measuring and which one is used when?

I took the photographs when the engine was cold and notice that the oil level is a bit above a (homemade?) notch on the dipstick. The oil level on the sight glass was just above the bottom of the glass. I've not tried checking again with the oil up to temperature and idling, but if I was to hazard a guess I'd say that the notch on the dipstick is an approximate cold level and the sight glass is used to measure oil level when hot and idling.

Does anyone have any suggestions? If have to take an interest in this sooner or later but have started looking at it now because I have just received the car back from a specialist and it now has very high oil pressure.

dannytattersall · 06-23-2023, 11:08 AM

Quote:

Originally Posted by dannytattersall

Hi all, I have owned my 1974 RSR replica for a while now and have realised that I don't know how to check the oil level! Fortunately it doesn't do many miles but it is still an embarrassing admission!

I am aware that dry sump engines normally have the oil level measured when the oil is up to temperature and the engine is idling. However, my car has two front mounted oil tanks and one has a dip stick whereas the tank on the left hand side of it has a sight glass. Why does it have two ways of measuring and which one is used when?

I took the photographs when the engine was cold and notice that the oil level is a bit above a (homemade?) notch on the dipstick. The oil level on the sight glass was just above the bottom of the glass. I've not tried checking again with the oil up to temperature and idling, but if I was to hazard a guess I'd say that the notch on the dipstick is an approximate cold level and the sight glass is used to measure oil level when hot and idling.

Does anyone have any suggestions? If have to take an interest in this sooner or later but have started looking at it now because I have just received the car back from a specialist and it now has very high oil pressure.

stownsen914 · 06-23-2023, 11:47 AM

It's possible the second "tank" is actually a breather can, and sight glass lets you know when it's full so you can empty it. By the way, I see a hose connected to it. Where does that go?

As for measuring the level in the other tank, aftermarket racing tanks like those usually like to be 2/3 - 3/4 full when the engine is running and warm. The dipstick can be used to measure for that purpose. In mine I usually just open the cap and look in, to be honest. It is important to only check when the engine is running - the contents of the tank tend to seep into the engine when it's been sitting for some time, and can falsely appear to be a few quarts low.

dannytattersall · 06-23-2023, 12:21 PM

I think you may be correct that the second tank is a breather tank. I wasn't sure initially because it has an oil catch can in the engine bay too. I haven't yet checked to see where the hose that connects to the breather tank goes, but presume it vents to atmosphere.

Thank you for the information regarding the levels of aftermarket oil tanks. I think I need to get it up to temperature and check how much the oil level increases. However, I am reluctant to run the engine because it has come back from a Porsche specialist and now has very high oil pressure.

stownsen914 · 06-23-2023, 02:04 PM

Gotcha. It may be worth making sure that the vent hose doesn't dump under the car. You don't want any oil that comes out of there to end up on the track (especially in front of your own rear tires!), that can be dangerous.

Re: the separate catch can in the engine bay ... is the breather on top of the crankcase routed to a catch can? It's common to vent this to the tank. This would mean running a long hose to your front mounted tank.

Regarding the high oil pressure ... how high? There are different reasons that can happen, including a mismatched gauge/sender combo. I'd talk to the shop that worked on it as a first step. One option is to verify pressure by putting a mechanical pressure gauge on the engine.

dannytattersall · 06-24-2023, 06:12 AM

The overflow/ catch can vents to atmosphere asI suspected it would. I don't think that is such a big problem though because it would be unusual for it to get full enough to vent out.

The oil catch can in the engine bay is fed by a connection at the top of the crank case and goes into a catch can which has two K&N style oiled filters to allow pressure to vent off.

The oil pressure is between 9 and 10 bar at cold, slightly fast idle (@1200 rpm) and maintains that pressure at 2k rpm when cruising as the oil warms through. Strangely, the oil temperature appeared to increase far more quickly than usual when I drove it for 6 miles at a constant 2k revs. I am reluctant to start the engine and do much further fault diagnosis because it is a very expensive engine and I do not want to potentially cause any damage. The problem was not present before the car went to the specialist to have the oil leaks resolved. Ideally I need to connect a mechanical oil pressure gauge to confirm the high pressure readings are correct, but it sounds like a coincidence that the gauge and/or sender has suddenly started misreading. I plan on emailing the specialist and asking them to book it back in to be fault diagnosed.