Help-No oil pressure again @ start-up-86 Turbo
12-17-2004, 03:02 PM
#16
Hey Man
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Originally Posted by gmsracing
I've been chasing the same problem for 6 months now. It always has no oil pressure for a second or two when starting cold. On hot start ups it's fine. To date I've done:
1. Checked crank pulley torque.
2. Replaced oil filters several times. The check vavles were working properly.
3. Tried different oils.
4. Changed scored 3-piece oprv to NEW updated 1 piece oprv.
5. Pulled the pan to inspect oil pick up tube. It was fine.
6. Replaced the oil pick up tube sealing gasket while I was in there.
7. I actually got fed up and it is in the shop as we speak. I was loosing too much sleep!
I think the problem is that the oil pump is loosing it's prime. I've tried tracing the oil line system and now I'm starting to think about anywhere where the oil
lines could break it's vacuum. Pressure sensor sending unit, fittings, oil cooler seals, etc. I know this doesn't exactly help your diagnostic, but I understand your pain. If the mechanics can diagnose my problem I will post what their findings were.
Rob
1. Checked crank pulley torque.
2. Replaced oil filters several times. The check vavles were working properly.
3. Tried different oils.
4. Changed scored 3-piece oprv to NEW updated 1 piece oprv.
5. Pulled the pan to inspect oil pick up tube. It was fine.
6. Replaced the oil pick up tube sealing gasket while I was in there.
7. I actually got fed up and it is in the shop as we speak. I was loosing too much sleep!
I think the problem is that the oil pump is loosing it's prime. I've tried tracing the oil line system and now I'm starting to think about anywhere where the oil
lines could break it's vacuum. Pressure sensor sending unit, fittings, oil cooler seals, etc. I know this doesn't exactly help your diagnostic, but I understand your pain. If the mechanics can diagnose my problem I will post what their findings were.
Rob
Thanks for the great info. I feel your pain but mine has lasted as long as 30 seconds once so I feel it might be primarily a priming problem. I was wondering also if a bad sealing ring on the sending unit, pick-up tube, etc could break vacuum but then there would be a serious leak under pressure if it was an outer seal. Wouldn't a vacuum break be permanent and never build pressure? I'm still going to try the OPRV inspection/swap first. Seeing how the car maintains good normal OP after priming I doubt if the oil pump is wearing; those things are hell bent for stout.
So does anyone know for sure where standing oil is supposed to remain in the lines and system after shutdown? I assume there is a full oil filter and oil gets pulled up a dry pick-up tube at start-up. Does this sound right?
I hope your mechanic finds something, you've done everything else imaginable.
Steve
12-17-2004, 03:49 PM
#17
Race Car
The whole conventional to synthetic thing is a myth. Whenever it happens, it's just bad luck.
I think it's a worn oil pump that causes these problems. I would really like to investigate more, and perhaps try replacing mine, however I am just about to put it up for sale. I just closed the deal on an 87 turbo to replace my 86 N/A.
I think it's a worn oil pump that causes these problems. I would really like to investigate more, and perhaps try replacing mine, however I am just about to put it up for sale. I just closed the deal on an 87 turbo to replace my 86 N/A.
12-17-2004, 04:04 PM
#18
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I do have a spare oil pump, but I have no clue how pitted the gear inside is... It is the one that was on my car when I spun a bearing.
$100.00+shipping and it's someone's. They go for $625.00 new at Pelican...
$100.00+shipping and it's someone's. They go for $625.00 new at Pelican...
12-17-2004, 05:36 PM
#19
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Guess I won't be trying an OPRV swap with my spare motor. Turns out the spare N/A motor I got with the 83 is an 87+ with the 1-piece valve. I also assume the special 1-piece valve conversion for the pre-87 cars is different than the 87+ OEM OPRV. I didn't want to remove the one off the Turbo until I had a replacement to try. It doesn't sound like cleaning/smoothing the 3-piece unit has been very successful for most people. Oh well back to square one.
12-17-2004, 05:41 PM
#20
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I wetsanded the piston of my 3 piece valve with 2000 grit wet/sand paper, using soapy water as a lubricant. That helped to cut my cold oil pressure build time down from around 30 seconds to around 5 seconds. 5 seconds was still too long though, and I could see that the 3 piece valve had some scoring due to a previously misaligned oil cooler housing. The new 1 piece valve now builds the pressure instantly.
12-17-2004, 07:47 PM
#21
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Originally Posted by 2Tight
Andy-Was your problem after a rebuild or on a previously running motor? I've heard that the initial start-up can be a problem sometimes after a teardown. I'm doing a oil/filter change first, it's due anyway. I would think my problem is definitely a priming problem otherwise it wouldn't maintain OP after warm-up. If the oil filter check valve had failed could it take up to 30 seconds to build pressure, sounds a bit too long to me but I'll find out tomorrow.
I drove the car to work, went to leave and the oil guage never moved. No noise, oil level ok, all looking good I decided it was the sender and drove it home, 20 miles on the highway and at the end of the ramp it started ticking bad. I limped it the remainder. No problem found, did rod and main bearings still fine 12K later
12-17-2004, 09:43 PM
#22
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Originally Posted by nine-44
Sorry to get back late, but...
I drove the car to work, went to leave and the oil guage never moved. No noise, oil level ok, all looking good I decided it was the sender and drove it home, 20 miles on the highway and at the end of the ramp it started ticking bad. I limped it the remainder. No problem found, did rod and main bearings still fine 12K later
I drove the car to work, went to leave and the oil guage never moved. No noise, oil level ok, all looking good I decided it was the sender and drove it home, 20 miles on the highway and at the end of the ramp it started ticking bad. I limped it the remainder. No problem found, did rod and main bearings still fine 12K later
12-17-2004, 10:41 PM
#23
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steve,
try the crank bolt first,the 83 i have had that oil pressure
drop and i could tighten the bolt with my hand,it was that loose.
once i was able to tighten it properly it was fine.
rolf morrow
83 944
86 951
98 z3 (still a chick car)
try the crank bolt first,the 83 i have had that oil pressure
drop and i could tighten the bolt with my hand,it was that loose.
once i was able to tighten it properly it was fine.
rolf morrow
83 944
86 951
98 z3 (still a chick car)
Originally Posted by 2Tight
I posted on this problem last month but I could really use some feedback now. The early consensus was bad OP sending unit but now it has mild valve clatter right up to the point where the OP jumps to 5bar. The noise isn't really loud and absolutely no knocking at all.
At first I thought it was a bad OP sending unit but last night I actually heard it suddenly quiet down after 30 secs of no OP. Suddenly it shoots up to 5 bar and acts normal again. This one scares me because it's obviously not the sending unit as many suggested. It's done this about 3-4 times and only since cold weather has set in and never before in warm weather or after the car has warmed up. The car has 140K miles, Mobil 1 20-50wt after dino oil by PO, Mahle filter, runs strong, always good OP, 5bar at cruise, never less than 2.5-3 at hot idle.
Here's my thoughts in the order of suspicion. I wonder if you might comment:
1. Sticky OPRV (don't know if it's 1 or 2 piece) yet, replace o-rings;
2. Change oil/filter w/ 10-40wt for winter(will do this first)
3. Cracked oil PU tube or bad top seal (wouldn't this drop pressure all the time not just at start-up?)
4. Re-torque crank (belts and WP have 15K on them form last TB change).
I don't want to start throwing money at it or drop the pan until I know more. I'm suspecting that the higher detergent properties of Mobil 1 might have washed some crud loose and lodged on the OPRV. This problem started all at once about 3 weeks ago during cold weather. Any help or insight would be greatly appreciated.
Thanks,
Steve
At first I thought it was a bad OP sending unit but last night I actually heard it suddenly quiet down after 30 secs of no OP. Suddenly it shoots up to 5 bar and acts normal again. This one scares me because it's obviously not the sending unit as many suggested. It's done this about 3-4 times and only since cold weather has set in and never before in warm weather or after the car has warmed up. The car has 140K miles, Mobil 1 20-50wt after dino oil by PO, Mahle filter, runs strong, always good OP, 5bar at cruise, never less than 2.5-3 at hot idle.
Here's my thoughts in the order of suspicion. I wonder if you might comment:
1. Sticky OPRV (don't know if it's 1 or 2 piece) yet, replace o-rings;
2. Change oil/filter w/ 10-40wt for winter(will do this first)
3. Cracked oil PU tube or bad top seal (wouldn't this drop pressure all the time not just at start-up?)
4. Re-torque crank (belts and WP have 15K on them form last TB change).
I don't want to start throwing money at it or drop the pan until I know more. I'm suspecting that the higher detergent properties of Mobil 1 might have washed some crud loose and lodged on the OPRV. This problem started all at once about 3 weeks ago during cold weather. Any help or insight would be greatly appreciated.
Thanks,
Steve
