Low Oil Pressure

[Azar]

Hello, sorry for the long read but I am seeking advice on the low oil pressure problem - already started discussion in the “tap tap tap” thread but would like to move here since it is off-topic there. http://dmctalk.org/showthread.php?43...-tap-tap/page2. The new addition are the manual gauge oil pressure readings and I am hoping they would bring more insights and the motor is not yet due for the complete overhaul….

Brought the car (VIN 05257, 1981, 42k miles, manual) early last year in US and shipped it to Germany. Before shipping, DMC Houston dome some work on the car to remedy immediate issues. The car was not driven for some time and was a non-runner so the fuel system required overhauling (new fuel pump unit, rebuild fuel distributer and warm-up regulator, new fuel lines, 4 year/30k major service performed as well as some other work). It took some time before the car arrived in Germany and I had to sort the documents (import, technical inspection and registration).

Drove just a couple hundred miles end of summer and noticed that after drive (minimum 30 minutes) the oil light was coming up for a short time during the idle. Only at the end of the drive the temperature would go up to 200F when fans kick in and drop it to 170F. Also noticed that the engine takes much longer to reach operating temp – at least 20 minutes (its relatively cool here in the summer, at that day it was +19C) – I am pretty sure the thermostat is stuck open and already got spare (The temp gauge was also once showing 120F driving downhill).

I also noticed the loud tap-tap-tap noise but it turned out to be the valve clearance in the right bank (almost all valves had higher clearance). After adjustment the tap-tap-tap sound gone. Here are the videos before and after the adjustment as well as the photos of the cam lobes. https://photos.google.com/share/AF1Q...pDSjZrZmNBRlZn

Judging from the instrument cluster gauge, when starting cold, the oil pressure is around 15-30 psi at idle and 45 psi at 3000 RPM. These numbers slightly improved after swapping the oil to 10W-40. Still, when warm, idle pressure drops to zero and the oil pressure light occasionally would come on. Only 20 psi at 3000 RPM. I am posting the manual gauge readings below.

Sometimes I find a couple of fresh drops of oil under the car after driving. I decided to check the oil and change it from Castrol GTX Conventional 20W-50 to Castrol GTX Ultraclean 10W-40.


The oil film is on the passenger side motor mount and the lower part of generator.


The magnet on the oil drain plug had some metal particles collected. All photos and Videos are here: https://photos.app.goo.gl/JrHE4iFQBXt7cx6WA


I have cut the filter open but did not find much metal particles there. Most are probably from me cutting the filter with the saw in order to open in.



I have sent the oil sample in to the lab to investigate. Dropped in a few metal particles from the magnet in to the sample so it would represent what was in the oil in the engine. Here is the translation from German:
Impurities (particles> 40µ) in the sample are visible to the naked eye. A slightly increased proportion of magnetizable iron particles (mostly> 5µ) can be determined on the basis of the increased PQ index. All other wear values determined are within the permissible or expected values. The fuel content has increased. The cause is unburned fuel in the engine oil, a cold start, short journeys or incorrect fuel entry. The viscosity has decreased due to the entry of fuel.
Here is the report with numbers, spectrum and photos. The oil was fresh from DMC changed in April 2020 (Castrol GTX Conventional 20W-50). https://photos.app.goo.gl/k3rZJHYMhH9zwjdG7

Recently in December I have connected the manual gauge instead of the pressure sensor and here are the readings with links to the videos:
- Cold start in the garage and rolled out of the garage (it is almost freezing outside)
o Idle with 40-55 psi (the idle is @hunting” when cold)
o https://photos.app.goo.gl/95ZJPmotnkDaSVbu8
- 100F engine Temp - Idle at 20-30 psi, still hunting
o https://photos.app.goo.gl/u8x6p9DvRkT96rqD7
- 110-120 F, Idle is stable and oil pressure is 16-18psi pressure
o https://photos.app.goo.gl/bgFc86VTvYJx1VZs9
- 160-170F, idling with 10 psi, about 40-50psi when giving revs (approx. 3000 RPM)
o https://photos.app.goo.gl/wpDsAswohFoG5Qrq5
- 200F, fans turn on, idling with 7-8psi, about 40-50 psi when giving revs
o https://photos.app.goo.gl/iKj2By9Absup6hq77
- fans turn off at 160 F but its same reading as with 200F above
o https://photos.app.goo.gl/qxPafiym2o8SjmkQ9


This gives an idea of the gauge in the car showing 10-20 psi less than it in reality is, assuming my manual gauge is correct (discrepancy in larger at higher pressure and smaller at lower pressure, for example idling only 10 psi difference).

Drove it back in to the garage and noticed clunking noise coming from below the engine (driver’s side) like every couple of seconds: https://photos.app.goo.gl/Xm8JnJPo6e76QmFf9 wondering what this could be, probably it was there before but I did no notice it.
I drove the car only 200 miles in summer and the engine runs great, has power and no issues apart from idle hunting. We have tried to adjust the CO to get it pass through the smog check in Germany and we were able to do so (I think it is 3% CO limit for this injection system). But I noticed that there is sometimes black smoke coming from the exhaust when aggressively rising revs from idling.

Many thanks to Ron, David T and Mark W., they have pointed me at the possible reasons for low oil pressure and valves needed being adjusted:
- The wire going to the oil light is known to get burnt up and short to ground where it passes alongside the motor. Can make the light flicker and light up. - Wire is fine, the oil light comes on only when oil pressure is below 8 psi according to the manual gauge
- The wrong oil or not enough - correct oil was used changed it. Using 10W-40 since it is much cooler here. 7 quarts as prescribed.
- A very dirty filter can cause low oil pressure – changed the filter
- internal leak – probably not the case
- Rings - I hope it is not…the engine would burn oil and I would see the white smoke, but it is not the case.
- Oil Pump worn – well might be?
- restricted pickup screen – Hoping for this one!
- components in the lower half are worn (crank/bearings) – I hope it is not…
- Mark w. wrote: that kind of dark gray sludge like grease is ground up metal. time to rebuild. my fear with low oil pressure is that you have an excessively scored/worn oil pump bore.

…and given me some advises in the other thread, some I followed, some are still outstanding:
- Verify oil pressure with an accurate mechanical gauge. – done
- Accurately measure the coolant temp – my bad, did not bring the infrared thermometer. will do next time
- Check the oil pickup screen with the bores-cope – I tried but couldn’t see much or was not sure what to look for… I have the video and can upload if it helps.
- Drop the pan to check the oil pickup screen – in the planning!
- compression test – haven’t done it yet
- leak-down test – of the cylinders? haven’t done yet.
- pull the spark plugs, see if they are oily – not done yet - I have o problems with cold or warm starts, the car starts almost instantly.
- measure valve lift to see if the cams are damaged too – not done yet
- pull the timing cover and the oil pump and inspect that – pump inspection is the must. Can I do that by dropping the pan? Why timing cover?

To sum up, the new manual gauge oil pressure reading are in. The cold start Idle pressure reading 40-55psi is probably not that bad but what about the 7-8 psi idle at operating temperatures and 40-50 psi at higher revs (3000-4000 psi)?
I am really hoping it is a pickup pan. May be oil pump (is it easy to get to dropping the pan?).
If all is good with the pump and you think the oil pressure at these levels is unacceptable I will have to get someone to take the motor out and do a rebuilt ☹

Sorry for the long post and thank you for your suggestions!
Azar from snowy Germany.

[mark w]

To sum up, the new manual gauge oil pressure reading are in. The cold start Idle pressure reading 40-55psi is probably not that bad but what about the 7-8 psi idle at operating temperatures and 40-50 psi at higher revs (3000-4000 psi)?
I am really hoping it is a pickup pan. May be oil pump (is it easy to get to dropping the pan?).
If all is good with the pump and you think the oil pressure at these levels is unacceptable I will have to get someone to take the motor out and do a rebuilt ☹

Sorry for the long post and thank you for your suggestions!
Azar from snowy Germany.

the oil pump is not in the pan, its in the block, behind the timing cover, lower right corner. driven by timing chain from crank.
only the oil pickup tube is in the pan.

i would for inspection, drop the pan, and you will probably find more of the dark grey greasy stuff- finely ground up metallic metal. thats wear of your cams, chains, rings, bearing surfaces- anything steel. check that the pickup tube is not obstructed by some foreign matter.

Now back to your oil report- the clue is fuel in the oil. you have too much fuel. if the car is smoking black- too much fuel. this is washing the oil off the cylinder walls and rings and getting in the oil, thinning it out and causing it to lose its ability to protect parts in contact that require that oil film. as the car heats up, the oil thins out (lower viscosity) and metals expand, increasing tolerances between parts- and thus lower oil pressure.

check your fuel injection system is working and that your mixture is correct and check your injectors are spraying correctly and not leaking.

but if there is that dark gray matter in the pan, the damage may of been done.

[Azar]

the oil pump is not in the pan, its in the block, behind the timing cover, lower right corner. driven by timing chain from crank.
only the oil pickup tube is in the pan.

i would for inspection, drop the pan, and you will probably find more of the dark grey greasy stuff- finely ground up metallic metal. thats wear of your cams, chains, rings, bearing surfaces- anything steel. check that the pickup tube is not obstructed by some foreign matter.

Now back to your oil report- the clue is fuel in the oil. you have too much fuel. if the car is smoking black- too much fuel. this is washing the oil off the cylinder walls and rings and getting in the oil, thinning it out and causing it to lose its ability to protect parts in contact that require that oil film. as the car heats up, the oil thins out (lower viscosity) and metals expand, increasing tolerances between parts- and thus lower oil pressure.

check your fuel injection system is working and that your mixture is correct and check your injectors are spraying correctly and not leaking.

but if there is that dark gray matter in the pan, the damage may of been done.

Mark, thank you for your advise! As mentioned, DMC Houston have rebuilt the fuel distributor and the warm-up regulator, as well changed the spark plugs, cables, fuel lines. DMCH have fuel injectors cleaned and "they are spraying nicely". Since it was hunting for idle from the time I received the car, I have asked them what for the advise so they advised to burn through the old fuel and be refilled with local fuel and the car needs to really be driven around and get the soot and other settled-in carbon blasted out of it.

As I mentioned, we have tried to set he mixture adjusting the CO but it was not easy - when CO was low, the Lambda was high and HC (unburned fuel) very high. so we settled at 2% CO, 269 ppm HC and 1.020 Lambda. Also, the left bank exhaust manifold measured with the infrared thermometer was cooler than the right one. After adjusting the CO the temperature left and right stabilised.

Is there a nice write-up how to set up the mixture?
I will drop the oil pan within Jan/feb but I can drive the car from 1st of March (we do this in europe for the winter to save registration fees and insurance).

[Azar]

Here are the before and after results of the adjustments.

Gesendet von meinem Mi 9T mit Tapatalk

[dn010]

If it was me, I'd stop running this engine and start pulling it to open it up. I'd want to check bearing surfaces, the oil pump and figure out where all this debris is coming from before it does more damage if it isn't too late already. You can't really just "drop the pan" anyway.

[Jonty]

If it was me, I'd stop running this engine and start pulling it to open it up. I'd want to check bearing surfaces, the oil pump and figure out where all this debris is coming from before it does more damage if it isn't too late already. You can't really just "drop the pan" anyway.

I agree. I know you really want to avoid this but it’s not a huge job to pull the engine. Get it out of the car and get it checked out. Pulling it out makes it easy to take the pan off and the timing covers to check for damage. It might all become obvious at that point and you either need to rebuild or you’ve found the issue.

[Azar]

Thank you for your suggestions! Currently the car is in the "wintersleep" till 1st of March so I am planning to do some work during this time. Unfortunately, I don't have space in the garage to do the engine-out and disassemble the engine. I have to ask one of my friends. The motor specialist, who could do this can only start in April. Let me see what I can do in between.

[Azar]

Hello, we have pulled the engine and started disassembling it. Looks like the coolant has found its way in to the oil probably resulted in low oil pressure (although it was also low after oil change and I drove about hundred miles after both changes last year, oil was constantly low). The bearings, camshafts and crankshaft look good. But the cylinder liners are not good! Already have marks on the walls (42k miles)...

Here are the photos: https://photos.app.goo.gl/rbw8B99AnvvkKDBQA

I will be ordering the Volvo style pistons and liners kit from DeloreanGo https://www.deloreango.com/eu/piston-kit-volvo.html

We did not disassemble the oil pump but I will order the new one from Delorean.eu https://www.delorean.eu/catalog/prod...ducts_id=39005

The catalysator inside is crushed and blocked - might explain troubles getting the CO mixture right. Will just clean the cat and try without it.

I will also replace all seals and gaskets, Cylinder Liner spacer shims, Rod bearings, main bearings, timing chain guides and tensioners, Clutch with bearings and slave cylinder, thermostat (takes ages to warm the engine) and the fuel lines to the frequency valve (were not part of the DMC kit).

Water pump looks like new so will keep it.

What else should I check / change while there? Thanks!
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[Michael]

As long as the engine is apart, I would replace the waterpump no matter how good the old one looks.

[Azar]

As long as the engine is apart, I would replace the waterpump no matter how good the old one looks.

Thanks Michael! Which pump would you suggest? there are different ones - DMCH, Delorean EU (Ed) and DeLoreanGo.