Strange problem, need some common sense

[T6andT]

71' T with some improvements. I rebuilt the engine about 3 years ago, no issues and runs strong. It has been through several oil changes with no issues. Today I did another change, all looked fine, about 6qts from tank, normal used looking, about 3 qts from sump. Now it gets strange. Removed oil filter and it appeared dry. I know this is not normal. Is it possible pick up tube in tank is clogged or dislodged? Fact that oil in tank looked dirty makes me think it is circulating in engine. Pressure and temp are fine when running, just took it on a 300 mile drive in relatively hot temperatures. Again no issue but of course a concern if filter is not seeing any oil.

Help.

[Locker537]

Dry...as in the pleats in the filter aren't oily?

Or dry as in you didn't make a mess when you removed it.

[T6andT]

Dry as in no oil in pleats. A bit of oil on manifold, but nothing in filter.

Added info, had engine out about 8 months ago for some tranny work. New oil at that time. Plugged oil lines while engine was out. 98% sure removed all plugs but I have done stupid things in the past.

[icarp]

check for removal of all plugs

[smadsen]

Run it up to normal operating temp and see if the filter is really hot.

[GaryR]

If the oil tank had oil, one would surmise that oil is being returned to it. The path is shown in this picture. I really don't see a way you can "bypass" the filter other than having a filter that blocke oil entry due to a stuck (or too strong) of a spring..

[T6andT]

Thank you for the replies, pulled the hoses at tank and verified that yes all plugs were removed. Then checked that the tube in the tank leading to the filter was not disconnected, air pressure verified tube was good. The low pressure from the scavenge pump could fill the tank if tube was disconnected internally, shown above (non colored line that goes to the filter), but this was not the problem. It is a 71' so no external cooler or thermostat. But Gary is correct otherwise it does not make sense. So, new oil and new filter and start car. All behaves as normal, tank level gauge moves as expected, high at idle and lower when revved. Yes, filter got warm/hot. Removed filter to verify, yep oil in filter. Had used a filter that was recommended to me that showed no oil when removed. So either spring tension was too high or filter had the ability to drain itself completely and appear dry, Did not remove filter for about 2 hours as I let the other two areas drain completely. Moral, stay with brands that I have used for many years and trusted. Again, thank you for replies.

[john walker's workshop]

Mahle is chinese made now, ya know. Been using Mann now. Says made in germany, hopefully it is.

[GaryR]

Originally Posted by T6andT

Thank you for the replies, pulled the hoses at tank and verified that yes all plugs were removed. Then checked that the tube in the tank leading to the filter was not disconnected, air pressure verified tube was good. The low pressure from the scavenge pump could fill the tank if tube was disconnected internally, shown above (non colored line that goes to the filter), but this was not the problem. It is a 71' so no external cooler or thermostat. But Gary is correct otherwise it does not make sense. So, new oil and new filter and start car. All behaves as normal, tank level gauge moves as expected, high at idle and lower when revved. Yes, filter got warm/hot. Removed filter to verify, yep oil in filter. Had used a filter that was recommended to me that showed no oil when removed. So either spring tension was too high or filter had the ability to drain itself completely and appear dry, Did not remove filter for about 2 hours as I let the other two areas drain completely. Moral, stay with brands that I have used for many years and trusted. Again, thank you for replies.

Glad you got it sorted! Two things, first is if John Walker speaks, just say thank you and write down what he tells you, it's gospel. Second, and possibly more important, I have to show my wife this so I can say I was correct once in 2024...

[930cabman]

Originally Posted by GaryR

Glad you got it sorted! Two things, first is if John Walker speaks, just say thank you and write down what he tells you, it's gospel. Second, and possibly more important, I have to show my wife this so I can say I was correct once in 2024...

All you get is one for the year, use it wisely

[eastbay]

My first guess would have been a leaky drain back on the filter. I don't know if you ever owned a 944 with the upside down oil filter, but would occasionally see apparently dry filters in those once in a while because of that.

[Mr. Merk]

Originally Posted by T6andT

Had used a filter that was recommended to me that showed no oil when removed.

What was the oil filter in question?

I've switched to Genuine Porsche filters.

Originally Posted by eastbay

My first guess would have been a leaky drain back on the filter. I don't know if you ever owned a 944 with the upside down oil filter, but would occasionally see apparently dry filters in those once in a while because of that.

I've seen another local shop using the tall 928 or 993 oil filters on 944 engine rebuilds. Apparently they've never looked inside the 944 filters.

[T6andT]

Gary enjoy your time of being correct, and yes whenever I see one of John's suggestions I know it is correct. Filter was a K&N, first time trying this filter on the 911. Maybe it did a great job filtering the oil, hopefully yes. But it sure looked dry upon removal. Back to the basics on oil filter.