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MikeJinCO · Posted: Tue Jun 09, 2015 10:35 pm Post subject: Oil Pressure Light

At what pressure should the oil pressure light come on?

I'm finally getting to drive the car around some and found a n oil leak that appears to be the rear main seal. I dumped in some stop leak in the faint hope it might help and it appears to have thinned the oil enough that the oil pressure light is coming on at about 2 bar. The 2 bar pressure shows up at 2k rpm, it had been running about 3.5-4 bar at 2,5-3k but is down to about 2.5 bar with the sealer. I've been using some straight 30 wt oil to help re-seat the rings after my problems with corrosion in the cylinders due to a leaking head gasket and will change to some 20-w50 Valvoline.

I would rather spend my time working on a new motor than half dismantling the car to change a main seal, but my cylinder head work is going very slowly.
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Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

924RACR · Posted: Tue Jun 09, 2015 10:47 pm Post subject:

The oil pressure light should come on around 0.5 bar.

So your light doesn't match your gauge; you may have some wiring issues to sort. Maybe the light wiring is grounding somewhere?

Lower resistance than expected in the pressure gauge wire would lead to higher pressure reading than expected - but normally you just have a short to ground. Otherwise I'd expect a resistance to be unexpectedly high, not low.

And no light near 2bar.

So maybe a wiring problem on the warning light.

Those pressures, if accurate, are reasonable.

Note that the rear main doesn't hold pressure, except for crank pressure. If it's leaking on a relatively fresh engine (so fresh seal), you either have a groove worn in the crank from mileage, or too much blowby. Because the rings aren't seated.

So maybe you should change the oil out, get the stopleak out of there, and just drive it to seat those rings. Valvoline non-synth is just fine for seating the rings; we use the VR1 race dino oil. I also am quite fond of Castrol, it holds up very well.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikeJinCO · Posted: Wed Jun 10, 2015 6:40 am Post subject:

Thanks, I'll check it out. It starts flickeringg at 2 bar and then stays on just below it. It noticeably leaks just after being shut off when sitting and shut off.

As far as I can tell this is the original '77 motor. The head had been off before my time as when I had it off the locating collars were no where to be found, so I had to make new ones.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

MikeJinCO · Posted: Wed Jun 10, 2015 10:17 pm Post subject:

Started up again and 0 oil pressure, light on. So I took off the oil cap and saw no oil flowing. I either lost the pump prime, lost the pump(clogged?), or broke the intake tube. I'll change the oil and see again. I can't quite believe that some CD2 seal sealer would ruin the pump.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

924RACR · Posted: Thu Jun 11, 2015 3:06 am Post subject:

Agreed - that should not be able to ruin things...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikeJinCO · Posted: Sat Jun 13, 2015 8:34 am Post subject:

Update Thought a clogged oil intake screen might be the problem so I drained the oil and poured 2 quarts of paint thinner into the sump thru the dipstick hole. It set for two days then I pulled the pressure relief valve on the oil pump and inserted a hose and air compressor nozzle and blew back thru the intake. Drained again and filtered out the junk with a coffee filter. The filter was pretty well plugged by the time I got the 2 quarts thu it. There was quite a bit including some silicone gasket material and fairy large chunks of probably carbon deposit up to 3/16" dia. My next step is to fill again this time with kerosene and repeat the process. Final step will be to fill with cheap oil, a quart of diesel and a new filter, get a prime on the pump and run it for about 15 minutes with no load. This is the local country boy recommended method. Then drain again and refill with good oil and a fresh filter -and hope it works.

From the information I can find, Ford/Bilstein has come up with some kind of adapter to pump solvent from the oil filter back thru the pickup to clean the system filtering and recycling the solvent.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

924RACR · Posted: Sat Jun 13, 2015 10:15 pm Post subject:

Wow, that's nasty!!!

I like the cleaning technique, though. Best of luck...
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

You may find that washing the pump with thinners will not allow it to self prime, pull the relief valve out and force oil into the pump. This worked for me when I forgot to pack the pump with grease with a new engine.
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

MikeJinCO · Posted: Mon Jun 15, 2015 10:54 pm Post subject:

I agree completely with that. I have the relief valve pulled and have blown air back thru it multiple times in an effort to wash the pickup out. I'll use my small shop vac to get the pump re-primed.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

MikeJinCO · Posted: Fri Jun 19, 2015 1:34 pm Post subject:

Need to finish this off. Got the multiple step clean out done-what a mess. The small vacuum pulled oil into the system, but didn't get it primed. So I pulled the PRV and stuffed it full of vaseline, pulled the plugs and it primed quickly. After a fresh fill of Valvoline VR1 I have 5 bar at 3k rpm when warm. So it was successful. The amount of dirt and old gasket material I got out was amazing.

To change the subject, my oil pressure switch is the source of one of my oil leaks. What kind of sealant can I put on the 10mm straight threads? If it was a tapered pipe thread I would use teflon tape, but I'm not sure what to use on a straight thread.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

Fiber washer should seal it up, remember if you put something on the threads you have to be sparse enough to allow the thread on the sender to cut through to make an earth contact - which is usually why they leak...
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

MikeJinCO · Posted: Fri Jun 19, 2015 2:18 pm Post subject:

Thank You
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Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Don't use any sealant. Sender is straight thread, seals with Al or Cu crush washer.
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WeiBe (1987 924S 2.5t) - 931 S3