Need help installing mechanical oil pressure gauge

When warm, my car sits idle at 0.5 bar. I have never had a warning light. 100,000 miles. I just spent $4k on a clutch and LNE IMS bearing. I would like a little peace of mind by hooking up a mechanical gauge to see if the oil pressure is really at 1.5 bar. I know many people have done this, but where do I hook up the mechanical gauge? Any particular gauge I should use? Any particular fitting need purchased or created to properly measure the REAL oil pressure. Thank you for your help!

I don't know the exact size, but you should remove your oil pressure sending unit, passender side near fire wall, and installed the mechanical gauge there. The fitting may come with the mechanical gauge kit.

Harbor Freight: http://www.harborfreight.com/engine-...kit-98949.html

If your sending unit is OK, that does seem less than most but you also have a 100K miles. Im curious what the mech gauge is going to read.

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I'm confused! 0.5 or 1.5 which is it? When was your OP sensor changed? You know they go bad all the time right? I just changed mine and it works fine.

You would think that if its really around 7psi at idle the engine would be noisy.

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Thread size is M14 x 1.5mm thread pitch.

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Yup BUT, mine when I came off the drag strip, the low pressure light came on and the engine was quiet. After that, it was around .5-.75 bar at idle when hot and no noise either. An engine needs very little pressure at idle before the con rods start knocking. My engine is apart now because the oil filter had more glitter than a cheap stripper so the main and/or con rod bearings are done but that's in another thread.

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"the oil filter had more glitter than a cheap stripper" Now thats a great post!

Arguably, oil Temperature is as important as pressure in the M96. It would be interesting to combine both oil temperature and pressure in a single gauge.Most such gauges need cosmetic surgery to obliterate the brand name. Maybe someone could find a VDO dual gauge for the OP ?Like the 911 turbo had . http://www.rallysportdirect.com/Inno...ure-Gauge-52mm http://www.mcnallyelectronics.com/psi_oil_pres_temp.htm

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Yeah, general rule is 10psi for every 1000rpm, to be able to overcome centrifical force in the crankshaft.

Thank you for the great feedback. I have not replaced the oil pressure sender. It does not seem erratic in any way, and it is generally closer to 1 bar. I have ruled out the VDO dash gauge being off. But when the temp is warm in the summer, it has dropped to 1/2 a bar. I have never had the warning light, though. I took it to an indy to have the oil pressure checked. They ended up giving me a list of other things to check (coolant, slow starter, ignition switch and headlight switch) and said that 0.5 bar was to be expected with 100,000 miles. Then I asked if they actually checked the oil pressure and they said, "No." "Ugh...just do what I ask", I thought. Anyway, no oil shavings in the last filter change. No knocking or ticking (knock on wood), and it burns the expected amount of oil for a 996. I'm really very pleased with the car in every aspect, and I was SO happy to have the the IMS replaced with the LNE bearing. Now, I just want this peace of mind. Thank you for all your help!

I will let everyone know my findings.

Thank you for the thread size. That was a big help.

Schnell Gelb: When you say temp is just as important, do you think I should install a cooler thermostat. I'm going to do the water pump as preventative maintenance so I can drive long distances without worry. I may as well get a cooler thermostat or an additional radiator/fan. Any recommendation?

We have lots of cars here on RL that have past 100k and I don't think they have 0.5bar oil pressure. I strongly suggest yoi get to the bottom of this before you try to address other PM. Was the pressure that low even before the IMSB upgrade? Not that I think they are related. More out of curiousity.

I mentioned combining an Oil Temperature gauge+Oil Pressure gauge because both are important. High Oil temperature will negatively affect oil film strength, oil shear performance. Low oil pressure may be just a (temporary?) consequence of high oil temperature. I labor this point because the M96 seems to have an issue with marginal oil cooling in severe conditions. Hence the interest in fitting the "S" oil heat exchanger. Both gauges could be fed from a T connector into the best tapping point. If you use the blanking plug in the cam cover, that may somewhat under-read actual max oil temps in the engine ?

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That's my understanding as well and that's why I tap the signal from the built-in oil temp sensor and use that (with some electronics) to drive a regular 300F VDO oil temp gauge. https://rennlist.com/forums/996-foru...mp-sensor.html

BTW, in steady state, the oil temp is on average ~10F higher than the coolant temp. However, at burst of acceleration (e.g., 0-60 runs or mountain climbing), the oil temp can spike up very fast and you won't see ANY change in the coolant temp.

"the oil temp can spike up very fast and you won't see ANY change in the coolant temp" Useful data - thanks. The oil temp sender may not be reading from the hottest part of the oil circulation system ,so the spike in actual oil & bearing temps is much greater. You make a great case for a combo pressure /temp gauge. http://www.mcnallyelectronics.com/psi_oil_pres_temp.htm also add an adjustable warning buzzer for low pressure/high temp?

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My understanding is the oil flow at where the stock sender plugs into may not be high enough to make the oil temp reading responsive. Yes you will see oil temp changing but it maybe "dampened" as compared to what the stock oil temp sensor picks up (which measures the oil at the sump).

Agreed. Hence my suggestion of using the blank plug in the camshaft cover - at least it is close to some hard working bearings.

Gotcha, I missed that suggestion.

An interesting combo+compromise may be to dump the OEM oil filter assy., fit a 'sandwich' adpater with many NPT ports and then use a spin-on filter. http://www.rallysportdirect.com/Gred...FciEfgodeCEAnA

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You are relying upon a less than ideal oil pressure reporting system for your oil pressure. If you are really concerned about oil pressure you need to make an accurate measurement of this and verify the oil pressure is within spec. AFAIK, the factory only calls out a hot oil pressure at some RPM. Something like -- but don't quote me -- 5 bar at 6K RPM at 90C. There is no hot idle oil pressure callout. For hot idle oil pressure, what I was told was that as long as the low oil pressure light wasn't coming on or the engine wasn't generating any untoward behavior which could be attributed to too low of hot idle oil pressure the hot idle oil pressure was ok. While I have installed an oil pressure gage in other cars I do not like them. They are a source of a potential oil leak should the oil line from the engine to the gage break and there is always this possibility. If by accurately measuring the oil pressure you find it ok and contrary to what the car's oil pressure reporting system provides consider replacing the oil pressure sending unit with a new one, hopefully one that agrees with what you actually measured.