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Engine starved of oil briefly at startup

95 993 has started sounding as it would if it had a oil change and the DME not pulled when started? Itís only started doing this recently after not starting for a month. The oil pressure has also dropped a bit to about 1.5 at idle. I run 15-50w Mobil and wouldnít think the pressure should be that low ? The car just turned 140k. Besides that the car runs fine. Should I be worried or just remove the DME every time it sits for a couple of weeks before starting ? Thanks

Old 06-02-2019, 10:44 AM
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If you are concerned test it/ have it tested with an external oil pressure gauge. If all well with that, poss prob with oil pressure gauge and/or sender. 1,5 bar att Idle with a warm engines at your mileage isn't bad. If you crank it w the starter do you get any pressure reading?
Old 06-03-2019, 05:04 AM
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Originally Posted by Paperboy View Post
If you are concerned test it/ have it tested with an external oil pressure gauge. If all well with that, poss prob with oil pressure gauge and/or sender. 1,5 bar att Idle with a warm engines at your mileage isn't bad. If you crank it w the starter do you get any pressure reading?
Thank you for responding. I replaced the oil pressure sending unit last year. I pulled the DME then cranked it and it showed 1.5 on the pressure gauge.

Last edited by wesleyc; 06-03-2019 at 09:34 AM.. Reason: Information
Old 06-03-2019, 09:28 AM
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How long does the low/no pressure situation last when you start it. A few seconds, ten? Have had something similar happen when I had the car standing for a while and at a slight angle/canter. Could something cause your oil galleries to drain abnormally when standing w/o showing a pressure drop when running. Oil release/ safety valves ?
Old 06-04-2019, 06:49 AM
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Does your car have one of those aftermarket check valves that keeps the oil tank from draining into the engine when it sits for a spell? Otherwise, gravity should keep the oil pump primed. I know the 993 has an extra oil filter on the pressure side of the pump that the earlier cars don't have, but I believe that the filter is mounted vertically so it shouldn't drain out. It seems like oil pressure should build very quickly.
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Old 06-04-2019, 07:16 AM
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Originally Posted by Paperboy View Post
How long does the low/no pressure situation last when you start it. A few seconds, ten? Have had something similar happen when I had the car standing for a while and at a slight angle/canter. Could something cause your oil galleries to drain abnormally when standing w/o showing a pressure drop when running. Oil release/ safety valves ?
It shows 1.5 at idle even after driving for a while. It goes up to 4 with rpm is raised. I park on level ground when it sets. I donít know what would drain the oil galleries?
Old 06-04-2019, 08:44 AM
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Originally Posted by RedCoupe View Post
Does your car have one of those aftermarket check valves that keeps the oil tank from draining into the engine when it sits for a spell? Otherwise, gravity should keep the oil pump primed. I know the 993 has an extra oil filter on the pressure side of the pump that the earlier cars don't have, but I believe that the filter is mounted vertically so it shouldn't drain out. It seems like oil pressure should build very quickly.
Iíve seen a aftermarket oil check valve that they sell but I donít have one. Iím Thinking I should have one now ? Btw. I only use Porsche oil filters
Old 06-04-2019, 08:51 AM
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Originally Posted by wesleyc View Post
Iíve seen a aftermarket oil check valve that they sell but I donít have one. Iím Thinking I should have one now ? Btw. I only use Porsche oil filters
I'm not a fan of those valves. The idea is to prevent too much oil from migrating into the engine from the oil tank when the car is stored. This is to prevent smoke upon start up. But, without the valve, you know that the oil pump is full of oil and is ready to start pumping as soon as the engine is cranked. I believe that your problem is somehow related to the oil filter on the pressure side of the oil pump. This is the extra oil filter that was added for the 993 series. If something is wrong with filter, or its plugged, it may be taking the extra time to bypass the filter and get oil pumping to the rest of the engine. On the 993 I don't know if the bypass is built into the filter or in the engine, but I think something is amiss with the filter on the pressure side of the system,. The other, big filter is on the scavenge side of the system and it only filters the oil as it is returned to the tank.
Old 06-04-2019, 10:14 AM
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Originally Posted by RedCoupe View Post
I'm not a fan of those valves. The idea is to prevent too much oil from migrating into the engine from the oil tank when the car is stored. This is to prevent smoke upon start up. But, without the valve, you know that the oil pump is full of oil and is ready to start pumping as soon as the engine is cranked. I believe that your problem is somehow related to the oil filter on the pressure side of the oil pump. This is the extra oil filter that was added for the 993 series. If something is wrong with filter, or its plugged, it may be taking the extra time to bypass the filter and get oil pumping to the rest of the engine. On the 993 I don't know if the bypass is built into the filter or in the engine, but I think something is amiss with the filter on the pressure side of the system,. The other, big filter is on the scavenge side of the system and it only filters the oil as it is returned to the tank.
Thanks for your information! Iíll change the pressure side filter ASAP.
Old 06-04-2019, 12:41 PM
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Thanks for your information! Iíll change the pressure side filter ASAP.
When you change the filter, I'd cut the old filter open and see if anything is amiss or it's plugged. It also gives you an opportunity to see if there is a bypass valve built into the filter and check that it was working properly.
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Old 06-04-2019, 07:12 PM
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When you change the filter, I'd cut the old filter open and see if anything is amiss or it's plugged. It also gives you an opportunity to see if there is a bypass valve built into the filter and check that it was working properly.
This car is making a fool out of me. I started it last night and immediately read 4.0 on the pressure gauge ? Starting it this morning and 4.0 again.
Old 06-05-2019, 06:03 AM
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Originally Posted by wesleyc View Post
This car is making a fool out of me. I started it last night and immediately read 4.0 on the pressure gauge ? Starting it this morning and 4.0 again.
Still think something is going on with that pressure-side filter. Maybe a bypass valve that wasn't seating properly or something like that. Can't imagine that the engine's relief valve and safety valve have a problem, though.
Old 06-05-2019, 09:41 AM
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Originally Posted by RedCoupe View Post
Still think something is going on with that pressure-side filter. Maybe a bypass valve that wasn't seating properly or something like that. Can't imagine that the engine's relief valve and safety valve have a problem, though.
Youíre probably correct. Iím going to change it just to rule it out. Thanks
Old 06-05-2019, 02:53 PM
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Youíre probably correct. Iím going to change it just to rule it out. Thanks
Good idea, but drive it some and report back.
Old 06-05-2019, 08:10 PM
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Originally Posted by RedCoupe View Post
Good idea, but drive it some and report back.
New small filter and oil topped off. Shows good pressure hopefully it was just a sticky check valve.

Old 06-09-2019, 11:33 AM
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