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1988 944 S Oil pressure issues
I have owned this car for 6 months, driving it regularly. Several days ago I noticed that the oil pressure gauge was quite low. The in-dash OE gauge is defective since before I bought the car but previous owner installed a aftermarket unit that has a plastic tube running from the sending unit to the consoul. In the past it would show about 60lb of pressure at start up and as the oil would warm the pressure would drop to 15-30 at idle and around 40lb at rpm's over 2k. It has been very consistant in the readings. Now there is 0lb at start up but climbs a bit as it warms if the rpms are up. At idle it reads 0, warm or cold.
I've looked at the forums and don't see anything that quite matches my symptoms. Any idea's. The previous owner did a lot of engine work previous to selling including installing solid lifters so it always has been a bit noisy when running. I don't sense any increase in noise and engine is idling smooth. I have put 4,000 miles on it and it has been trouble free till now. Any thoughts? |
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10-14-2021, 08:56 AM
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Definitely not normal, but if I were you I would first verify the gauge reading is correct. The best way to do that would be to buy a mechanical gauge and screw it into the port of the existing oil sending unit (just above and behind the power steering pump).
If you can verify the pressure and report back, we can guide you on next steps. No oil pressure can cause severe engine damage so its critical to verify the actual pressure. 60lbs is about 4.1 bar, which seems ok (mine is 5 bars at idle cold), 15-30 lbs is about 1-2 bars, which is a bit low compared to where mine sits fully warm at idle (mine is about 2 bars). The viscosity of oil also can make a difference so be sure you are running at least 10W or preferably 20W-50 in warmer months/climates. Given that the current gauge you are using is unknown quality, unknown installation quality and suddenly started giving different readings, I wouldn't trust it until I could verify with a mechanical gauge. As a side note: you could also look at fixing/replacing the existing oil pressure sending unit. First you will want to verify the voltage at the unit itself, if thats within spec, then your sending unit is still good. Next move on to the connections themselves, making sure the terminals are clean and the wires are hooked up correctly (if they are backwards pressure will read high all the time). Once that is done, pull off your gauge cluster and clean all the contacts on the back (on late models there are 4 black ovals which correspond to the 4 secondary gauges - fuel, oil, temp and voltage).
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Tyler from Wisconsin, 1989 944 S2 on Megasquirt PNP Last edited by walfreyydo; 10-14-2021 at 09:29 AM.. |
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10-14-2021, 09:21 AM
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So the oil pressure is 0-10 pounds. It barely dribbles out when I take the gauge off the line. I plan on pulling the OPRV and seeing if it is stuck/damaged. The weather here in the NW has been quite poor and I have had some boat repairs that have competed for my time. Thank you so much for your help. Given that there is some small amount of oil coming out would that make you lean towards the OPRV vs the oil pickup tube in the oil pan? What would be an indication of a spun bearing?
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10-28-2021, 05:58 PM
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Im going to assume you have the correct amount of oil and the dipstick reading is within normal range.
Before doing anything, drain the oil into a clean container (ice cream buckets work well) and run a magnet through it. Look for metal sludge or shavings in the oil or on the magnet. If you find anything, I would stop there and re-assess my options as there is likely damage to the crank or rod journals. From there the things to check are (in order of easiest to hardest): Crank bolt - it it torqued to 155 ft lbs? (youll need a flywheel lock). Crank bolt holds the oil pump drive gear in place and if its loose the gear will just slip and not drive the pump resulting in low oil pressure. OPRV - inspect and upgrade if its the old style, reinstall with the alignment tool and while you are at it maybe replace the air/oil separator housing gasket. From clarks: "Although I've never tried it myself, I've read reports from others who have removed the relief valve and turned the engine over to verify that oil comes out the hole for the relief. If oil comes out of the relief hole, this indicates a problem with the relief. If no oil or very little oil comes out, this normally indicates a problem with the pump itself."http://www.clarks-garage.com/shop-manual/lube-03.htm Oil pump/oil pump drive gear - I havent heard of these failing since they are mechanical, but the seal to the engine block could be bad enough to create cavitation/air pockets. Take off the timing belt covers and look for major leaks coming from the front main seal or around the oil pump housing. If large oil leak present I would suspect this as a potential cause. Replace oil pump to block seal (Loctite 574), drive gear, front main seal. This will also be a pain as you will have to remove timing and balance belt, and the crank pulley and gears to access. This would be a good time to do a timing/balance belt service and front engine reseal if needed. http://www.clarks-garage.com/shop-manual/lube-07.htm Oil pickup tube - is it cracked? - like a straw with a hole in it, it wont suck up oil. This will be a pain because it will require removal of the oil pan, and to remove the oil pan it means youll have to remove the front crossmember/steering rack/LCA's. The benefit of doing this is that you can then inspect your rod bearings to see if theres any damage. This will allow you to be 100% sure your bearings are ok. Recommend to replace oil pan gasket/rod bearings while you are there, but only if needed. Lastly, low oil pressure can be due to excessive engine bearing clearance. This is usually because they are worn (engine will need a rebuild). You can verify this when checking the rod bearings/oil pickup tube. You mentioned the engine was recently rebuilt so hopefully it was done properly. There is always the chance the builder did something wrong (didnt use assembly lube for instance) and the bearings are toast. I would expect to find metal in the oil under this scenario Sounds like a great set of winter projects while you wait out the cold season, and hopefully some of these worst-case scenarios are not the problem.
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Tyler from Wisconsin, 1989 944 S2 on Megasquirt PNP Last edited by walfreyydo; 11-01-2021 at 10:20 AM.. |
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11-01-2021, 09:48 AM
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Thank you for the suggestions. I tested the crankshaft torque and it was fine. I pulled the OPRV and found the o-ring to be distorted, very thin for about a 1/4 of the circumference and quite hard. I have ordered a new one with crush washer to be here by this weekend. Before I pulled it I took the oil line on the aftermarket gauge off at the sending unit and it pumped much stronger than at the gauge so I have ordered up a new gauge and line as well.
In talking with another fellow, he had the same suggestions as you. The dropping of the oil pan does not seem to be as easy as my 1966 Impala (the only other pan I have taken off) so I hope these two efforts pay off. The engine was supposedly rebuilt very recently (and shows many evidences of this being true). I have driven it quite a bit in the 6 months I have owned the car and it has ran flawlessly. I am a bit of a sick son of a gun and am enjoying working through this. Thanks again for your help and I will check for shavings in the oil. |
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11-02-2021, 03:32 PM
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oil pressure loss
Well, I have tried all the easy checks. Now I am going to drop the oil pan and look at the oil pickup tube. There were no metal pieces in the oil I drained out. It looked clean and was very smooth. plug has a magnet and there were no metal particulates on it either.
When I look at the oil pickup tubes online I see the new ones are the tube with the screen only. The used ones have what I assume is a return tube also. Any thoughts on this? Thanks, Bill |
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11-10-2021, 05:00 PM
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I guess it's too late for this since you drained the oil but you could have considered sending a sample of oil for analysis. The lab can tell you if there are elevated metal levels indicative of worn bearings.
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1984 944 Zermatt Silver 1987 951 Flamingo Metallic |
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11-11-2021, 04:21 AM
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I think what you're seeing about the pickup and return lines is that the used market is offering you both of them - together, even thought they are separate parts. In the new market they are sold separately.
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1984 944 Zermatt Silver 1987 951 Flamingo Metallic |
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11-11-2021, 11:34 AM
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The good news is that it was the oil pickup tube. The bad news is that this is a huge job! I had a problem getting the sub-frame to drop. The driver's side engine mount released just as it should but the passenger side did not release after I took off the two bolts on the top and the nut on the bottom. It did allow me to push the frame down and forward enough to get the pan out. I have been struggling to get the pan back in. Any words of wisdom? I have used dental floss and that didn't work (knots slipped) I am trying small amount of gasket sealer at the corners but that did not hold. I got close so I am going to draft some help in getting it in place tomorrow but not holding my breath. I am concerned about getting the engine mount back in as access is so tight. Also, good news is the bearings look great as well as all the lower half of the engine.
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11-23-2021, 08:00 PM
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Hello There:
I am coming late to this party, but I think the "real" issue is the OPRV. You mentioned that the O-ring was messed up. I believe the problem may be that the Oil Cooler housing is not aligned properly, which would explain why the O-ring on the OPRV was damaged. One way to test this is 1) remove the OPRV from the housing 2) trying putting it back on. IF there is any resistance with removing or replacing the OPRV this proves the Oil Cooler housing is not aligned properly. ( Ask me how I know ). As far as the engine mounts, if you are going this route then tighten up the side that is now loose/off and then try to see if you can remove the other engine mount first. Hope this helps. Good luck 
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Ed Paquette 1983 911SC 1987 944S 1987 944 Manual (Donated to the Nat. Kidney Foundation) 1987 944 Automatic (Recently sold to another Pelican) |
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11-24-2021, 02:34 PM
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In the Fires of Hell.....
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If your oil pickup tube was cracked, then you need to carefully go through your balance shaft/gears for alignments.
Make sure that both of the gears are on the correct shaft in the correct orientation (they can go on in 2 different ways). Then make sure that you get the correct marks aligned with the marks on the belt cover. My guess is that whoever did the rebuild did something wrong on one of the these. Dental floss worked for me when I had to put the oil pan back in while the engine was still in the car. Good luck!
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PCA Instructor: '88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG, 3120 lbs, 256 RWHP, 15 psig boost |
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11-25-2021, 07:19 PM
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I got the pan off and it was the oil pickup tube. It was broken off about 2" from the mounting foot. The bracket that bolts the oil return tube was also broken off. I had a friend weld the bracket back on and strengthened it. I bought a new OEM pickup tube and got them installed. I have got the pan back in place and am in the process of torquing the bolts to 6 FT/LB's. This is a PITA as I have the car on stands in my driveway and we have had record rains this last week. The engine mounts will be a pain getting back in place but the rest seems straight forward. Thank you for all the advice. I will let you know how it turns out. On the alignment of the gears and directions...not sure but wouldn't this make the car run or perform poorly? The car was running flawlessly for 7 months and ran smooth and strong and was running fine but lost oil pressure.
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11-28-2021, 03:04 PM
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In the Fires of Hell.....
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You may not have noticed the vibrations, but they are a VERY likely reason your PU Tube cracked and failed.
Get or download the shop manual for the engine and look very carefully at how the gears are mounted on the upper and lower balance shafts, and then make sure that you are not a tooth or more off on the belt when installing it.
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PCA Instructor: '88 951S - with LBE, Guru chips, 3Bar FPR, 1.3mm shimmed WG, 3120 lbs, 256 RWHP, 15 psig boost |
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12-01-2021, 08:48 AM
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Quote:
Very glad that you took the extra time to inspect the oil pickup tube and found it before any damage could occur!
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Tyler from Wisconsin, 1989 944 S2 on Megasquirt PNP |
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12-03-2021, 05:39 AM
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Quote:
If they are out of alignment the car would exhibit noticeable vibrations especially above 2000 rpms. Some people report that they didnt realize the vibration was gone until after the mounts/shaft alignment was fixed. Clarks has a good writeup on checking mounts (measuring how much they are compressed) and aligning balance shafts, so I would refer you there.
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Tyler from Wisconsin, 1989 944 S2 on Megasquirt PNP Last edited by walfreyydo; 12-03-2021 at 06:04 AM.. |
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12-03-2021, 05:44 AM
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Thank you for the clarification. In doing the work I was able to observe many new parts including the engine mounts installed. I bought the car through a third party and was not able to talk to the PO unfortunately. The details that were shared so far have proven to be true. It is a high milage car though and I will expect some issues in ownership as I would with any 33 year old car. The car starts easy and idles smooth and continues to be smooth thru the rpm range. While I admit to very limited experience with 944's I have owned a fairly wide variety of other cars of this vintage and feel this one is performing well. It seems to have had the radiator, all belts and hoses replaced (visually confirmed) and reportedly the water pump and tensioner as well as a new cam and solid lifters. The engine bay is clean and orderly with high end or OEM parts used. The front end seems also to have been addressed with many new parts installed (tags still fresh or rubber parts like new). The oil is staying clean after the oil change and there was no build up in the oil pan. I appreciate the suggestions and will follow up on them as I find time.
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12-06-2021, 02:33 PM
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1989 Porsche 944 S2
1983 Porsche 911SC Targa
Eggplant
944 Turbo
