7MGE oil pressure

[Arne (Denmark)]

Hi there. My first time here.

I have a 1987 MKiii Supra (7MGE) which I bought three months ago.
I topped up the oil with some Mobil 10W40 oil even though the guy I bought it from said I should use 15W-40, because the mileage is about 250.000 km
.
The problem is that after that the oil pressure has tuned down quite a bit. Normally the pressure idling was 1.7 kg/cm3.
Now I can hardly get the pressure to rise to more than 2.0 and it's generally too low. -Only about 1.0 idling.
AND there is a rattling, knocking from the engine!? Nothing when it's idling but gets bad about 2000-3000 rpm. Hmmmm.

Have you guys ever had or heard an oil pump go bad?
What is your normal oil pressure reading on the cars?
Can a faulty bearing cause the oil pressure to fall?

After all I hope it is only my oil pump otherwise I got to look around for another engine.

I will be happy for your comments.

[Bill UK]

Sorry but that sounds like big ends to me, mine started knocking at start up from cold and then disappeared until about 2K to 2.5 K revs. Driving back from work one night the engine just seized, being an auto the supra just skidded to an immediate holt. Just avoided a ten-car pile up behind me. I drained the oil but found no evidence of bearings wear, but after opening up the oil filter I found bits of bearing shell. Striped the engine down to find the crank was beyond a regrind due to hairline cracks. My advice would be don’t drive it and don’t make any plans to buy parts until you have checked out the crank..

[Bill UK]

Bearing Shells.

[Arne (Denmark)]

Damn it.
I hope that it's a rod bearing or more.
I will have to split it apart and will take photos to show others what has or is going wrong in my engine.

Bill, thanks. Did you notice that your pil pressure became lower and lower?

It's summertime and now this has to go wrong now the car being a Targa..
that's life.

[Bill UK]

That’s how it first started; the oil pressure would normally be just below 60 psi at 3,000 revs continuous driving. The first indication of any problem was when it dropped to 40 psi at 3,000 revs. 40 psi is probably within the supras specification, but as I normally would run at 60 psi I started to get concerned. The obvious thing to do was to change the oil and oil filter; this improved the oil pressure but only for a short time.Then the slight knocking started, the rest is history. I think the first thing to do is to open up the oil filter and to see what's inside; this should give you some idea of any internal engine wear. Apparently its common practice to open up the oil filter for inspection on aircraft engines. I suppose when you think about it, it makes sense.

[Bill UK]

Arne I've just had an idea, your 1 hour ahead of me and I'm 5 to 7 hours ahead of the US. If you shipped your supra to the US you could go back in time when it was ok.. Must remember to stop watching those time travel movies!

[Arne (Denmark)]

BTW.

When the car idles it sounds like a new engine. No knocking at all. Only when you accelerate the engine makes a rattle and I suspect that one ore more valvelifters might not be opening. I've heard this before on other cars and they can make a terrible noise.
I topped up the oil with some thinner oil and now the problem arose. I will change the oil to see whether this helps and check the cylinder head/valve lifters to see for damage.
I have found that the pressure is actually "ok" for the oil. It is supposed to be 0.3kg/cm2 or more once idling. 2.5-5 kg/cm2 at about 3000rpm.

Am I right. If it was one or more bearings the car would knock once idling as well?
All just assumptions but you guys must know how nervous a person gets once your baby is sick :-)
I hope for the best. The engine is otherwise so smooth and cultivated...