oil pressure problem, oil light keeps coming on Options

[Dave_Darling]

at 3200 rpm

oil pressure 39 lbs
cylinder head temp 318
oil temp 212

at 900 rpm (idle)

oil pressure 13 lbs
cylinder head temp 308
oil temp 212

The oil temps and pressures sound just fine to me. Not sure about the head temps; there seem to be a lot more variables in CHT readings than oil temp readings.

--DD

[ME733]

I have often wondered why no one (among the engine builders here) never suggest a simple fix to the low oil pressure problem......just place a shim (washers) inside the oil plunger pressure covers. this will give a higher tensinon to the oil pressure springs, and results in higher engine oil pressure. I think SCATT even sells an adjustable (turn a screw) spring cover cap allowing really easy adjustment....The oil passages, gallies, in the 914 are very large relative to the oil pump size. thus typical low oil pressure at low RPM,s...Rule of thumb is 10 psi for every 1000 rpm,s.

[SCV]

I went through a problem with low oil pressure at hot idle when I first brought my '75 home. The oil light would flicker a bit at idle, and in the interest of taking the easy, relatively inexpensive route, I replaced the sending unit. As pointed out by Cap'n Krusty and others, there are multiple senders that fit, and they trigger at different pressures. It took a bit of digging to locate the correct sender, but that wasn't the problem. A highly-recommended, independent Porsche shop (who shall remain nameless for the moment) told the Previous Owner that it is "normal" for the oil light in a 914/4 to flicker at idle once the engine is hot. Riiight. (IMG:style_emoticons/default/screwy.gif)

A closer inspection of the engine revealed the issue. The oil cooler seals had hardened and cracked slightly, causing the seals to hold when cold, but not when at operating temperature. After following the procedure on the Pelican Parts website for changing the oil cooler seals without removing the engine, the problem was fixed and remains fixed to this day. (Insert superstitious gesture here)

My oil pressure, with oil cooler seals fixed, as verified by two mechanical gauges, is 12 PSI at hot idle. (98* day, after 45 minutes on the freeway at ~75MPH). At speed, I have at least 10 PSI per 1000 RPM. Problem solved. I don't have oil temperature or CHT gauges, but will add these when budget allows.

Mrbubblehead, I'm glad you were able to sort out your oil pressure issue without major engine work.

-S

[detoxcowboy]

The flickering oil temp light occasionally at idle say after a freeway run or low idle issue is not crazy, the sender for the oil temp light operates at some low calibration 11 psi? or 7psi? I forget which.. but I have went through it previously and read it in a porsche book, so not an oil issue but an idle issue.. or otherwise cause the circumstance,,.

my 2 cents, flickering light not crazy..

i remember now, it was noted again about the dummy light sender when i purchased a porche dual sender..

anyways for the books..

[mrbubblehead]

A closer inspection of the engine revealed the issue. The oil cooler seals had hardened and cracked slightly, causing the seals to hold when cold, but not when at operating temperature. After following the procedure on the Pelican Parts website for changing the oil cooler seals without removing the engine, the problem was fixed and remains fixed to this day. (Insert superstitious gesture here)

My oil pressure, with oil cooler seals fixed, as verified by two mechanical gauges, is 12 PSI at hot idle. (98* day, after 45 minutes on the freeway at ~75MPH). At speed, I have at least 10 PSI per 1000 RPM. Problem solved. I don't have oil temperature or CHT gauges, but will add these when budget allows.

Mrbubblehead, I'm glad you were able to sort out your oil pressure issue without major engine work.

-S

thanks, but its too early to tell if its fixed or not. i didnt think of the oil cooler seals. they are not leaking. were yours leaking? or were they allowing air IN?

im guessing the seals are the same as a type 1 dog house oil cooler seals. because if so im sure i have a few left over sets....

out of curiosity, how did you pinpoint it to your seals?

i really hate to split the case to check the bearings. seems like main bearings are not easy find for type 4's. i need to find a core to build on my time. and not while being held under the gun. my teener is now my daily driver.

[SCV]

Thanks for the info, Detoxcowboy. I've always associated a flickering oil light with very bad things in every other make of car or truck I've encountered. I'd never heard it described as normal, and it didn't sit well. (IMG:style_emoticons/default/blink.gif) Still relatively new to 914s here.

Mrbubblehead, sorry man, must have misread that you had fixed the problem. Maybe I need to get more (IMG:style_emoticons/default/yellowsleep[1].gif). My seals were leaking slightly. I just followed the stain to the source. I wanted to try everything short of a complete rebuild to fix the problem as I saw it, since I could not and cannot afford a complete rebuild done right this month. When I observed that the oil pressure switch is near the oil cooler and leaking seals, it seemed plausible that this might be the source of the pressure drop that was causing my flickering oil light. I hope your engine problem is fixed as easily.

[mrbubblehead]

Thanks for the info, Detoxcowboy. I've always associated a flickering oil light with very bad things in every other make of car or truck I've encountered. I'd never heard it described as normal, and it didn't sit well. (IMG:style_emoticons/default/blink.gif) Still relatively new to 914s here.

Mrbubblehead, sorry man, must have misread that you had fixed the problem. Maybe I need to get more (IMG:style_emoticons/default/yellowsleep[1].gif). My seals were leaking slightly. I just followed the stain to the source. I wanted to try everything short of a complete rebuild to fix the problem as I saw it, since I could not and cannot afford a complete rebuild done right this month. When I observed that the oil pressure switch is near the oil cooler and leaking seals, it seemed plausible that this might be the source of the pressure drop that was causing my flickering oil light. I hope your engine problem is fixed as easily.

no problem scv. i dont have any history on this particular engine, so i still dont trust it yet. i would feel alot better if i had one in the process of being overhauled just in case. this car is my daily driver, so i have to be careful. so far this flickering light has been its only quirck. we will see if raising the idle will buy me some time. fingers crossed. sounds like you had an easy fix. and cheap too. good for you. you saved yourself alot of dough. i love the simple fixes.

this is a bitchen little car. and i plan on keeping it. gotta keep it in top shape.

[Dave_Darling]

IIRC, the owner's manual states that some flickering of the light is normal when the engine is at idle and is fully warmed up. I myself think it's a sign of a worn motor, but not necessarily a sign of a motor that must be taking off the road NOW.

High oil temps, low idle RPMs, and worn main bearings all will contribute to a lower idle oil pressure. None of them is necessarily fatal, but the light is something to pay attention to.

--DD

[-JR-]

I know this thread is old, but thought I would add my 2c as I have a similar situation.

I'm running Mobile 1 synth 20-50 and have found the exact symptoms as described in this thread on my motor since it was new and rebuild new again.

I've found that the Mobile 1, while I don't have any charts on it's response, seems to thin out very quick after my oil temp clears 190F. At least that's what my oil pressure is telling me.

After oil temps pass 200F I get idiot light under 800RPM and oil pressure is reporting just under 1/2 BAR, which is the idiot light trip I believe. My engine is fairly well balanced and tuned, so it will like to idle as low as 600 RPM.

Once my oil temps pass 210F I find I can not maintain 1 bar per 1000RPM, which makes me nervous. I've added additional oil cooling with a forced air fan to try and regulate my oil temps below 210F. Works well unless I hit really hot days over 80F and traffic.

I'm running 2.2L on my engine, so I don't have a good "bead"on the concept of stock cooling managing the extra power. Personally, I want to see my oil temps under 200F.

When I said earlier that I've seen this on my new and rebuilt new again motor... I had some unrelated mechanical failures, in my top end, so it gave me a chance to look at the internals a couple times. After measuring bearing clearances I found no issues that would account for the low pressures, so don't write off your motor prematurely.

The first reply to the thread really nails it though. The oil is probably the biggest factor as long as the motor is in good shape. Running an oil that doesn't drop below 30W maybe 40W probably would help the low pressure issues at high temp. I've always run Mobile 1 synth 20-50, but after the last couple hot summers I have with the car on the road I think I'll look for something a little heavier. But I will add that the Mobile 1 Synth still has some of the highest zinc levels for our solid lifter cars on the market for an "off the shelf" oil. Most of the places around here don't carry Brad P.'s oil so the M1 is a good choice for me.

Happy motoring.

[Junebug]

Brad Penn Amazon 6.99 qt buy the case and free shipping if prime. comes in 3 days. You'll notice the difference immediately.I know I did.

[930cabman]

Fired up a partially repaired /4 today with an oil pressure gauge. It's running a steady 60psi cold at 1500 - 2000 rpms. Castrol 20w50. Should I be concerned?

[emerygt350]

Nope. Perfectly normal.