I have a 1984 suburban with a mystery oil leak. I can drive it around all day until I get into some stop and go traffic and the engine temperature gets close to 190 (still safe but higher operating temperature). At this point it starts dumping oil at an alarming rate and the oil pressure goes down at idle to near 0. My oil presure sender is a little gummed up, so I'm sure there's still oil pressure but obviously a drop.

Any ideas? I can't seem to get it to replicate unless the engine is under load. Its obviously got alot of pressure behind it because it sprays everywhere and has a splatter pattern on the ground, not a drip. I don't see any oil coolers/lines, and the housing for the oil pressure sending unit looks bone dry. The oil filter is spotless as well.

What would be a normally small almost nonexistent leak until it hits the upper range of safe operating temperatures and under load?

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Maybe the oil is spraying out 'perfectly' from under the oil filter gasket, not leaving any drips or stains.

Does the oil pressure gauge usually drop to 0 at idle, or only in this situation?

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

It's not at 0 though close to it. (between quarter mark and 0). Every one of these old ones I've ha has a gummed up sender. Never shows more than 1/3 evern at cold start or on the highway. Obviously if it were starved for oil something would have gave in 100 miles I drove it.

Oil filter is facing downward so any spray would show on it; it's totally one dry. Oil pressure sender is a few inches away and it's bike dry as well.

Maybe it's the housing gasket?

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Only place I can envision a leak that would spray all over the place like you describe is the timing chain cover.
My experience building small block Chevys is limited to vinatages from the mid 60's, but I believe the T.C. cover has remained the same into the 80's.
As i recall, there is a rubber wick of sorts at the very bottom of the cover that sits in a groove which kind of hooks onto the oil pan.
If this rubber is deteriorated, logic tell me it would leak (more) when very hot. A relatively small leak in this location combined with the air flow of the fan could certain blow a lot of oil onto the ground, and you would have a tough time actually seeing where the leak is with engine off & cool.

David

check the pcv valve.if it's plugged oil will come out at the weakest link so to speak.fords are good for this in the winter.as ford motors in general seem to have more crankcase moisture then others.when it gets below freezing that moisture freezes in the pcv valve so they blow oil from the weakest link,usually the rear main seal

Turned out to be dirty transmission fluid that resembled oil on the ground from the pump seal. It does not explain the change in oil pressure gauge right after the oil change. I'm hoping its just the sender getting wonky.

Failures for the week

'84 Suburban with 112k miles: Transmission pump seal (required removing the trans)
'00 Tahoe with 95k miles: Radiator and AC compressor. Once I had finally sold it the new owner didn't make it out of the parking lot before the alternator failed.
95 E320 with 98k miles: Transmission failure. This is not a month after doing the head gasket and wiring harness.
94 Buick Roadmaster with 100k miles: AC leak that's most likely the evaporator. I'm slowly losing performance and smelling gas through the vents.
95 Buick Park Avenue with 190k miles: Brake master cylinder crapped out and almost caused an accident.
00 BMW X5: Water pump started leaking badly. Dumped it at the dealer auction today because I had way too much else to deal with and got my money back.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

eesh. thats a lot of cars to crap out on you... atleast you got your money back on the X5

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

What did you do with the forties buick?

I'm at the "I'm not sure whether to laugh or cry part right now". Selling the X5 was a huge load off since money is flying out obviously. All the money going out is the cry part. The laugh part is the only cars fully functional right now are the 500SL and the Jaguar XJR. One has cost tens of thousands to keep going during my ownership; the other everybody told me it would cost tens of thousands to keep going but has been flawless. (knock on wood)

I suppose the 300SD is good too, and the Miata as well if it weren't in pieces for an interior swap and repaint.

This last month has been a breakdown parade, my own Carmageddon if you will. I'm getting very tempted once the storm passes to pick up a 2010 GTI (slightly used with 10k or under on my dealer wholesale for 18-19k), and enjoy VW's free maintenance program for a few years. Also get a really fun car that gets 31MPG.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Laugh maniacally and cry. s'what I'd do.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Sold it to a collector in California. That was my last big hurrah towards then end of May, and I was ecstatic to sell it to someone who appreciated it for what it was. No plans to restore or rod. June and July have been awful. Couldn't get any cars in June, and July every one has grenaded.

Once I have good cars, selling them is not a huge problem. Plenty of bottom feeders and low ballers, but plenty of good cash buyers too.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Theres an old junkyard in Aline Ok northwest of Enid --just north of the original Sod House historical site. Bud has two cool pickups besides the rest of the cool old heaps there. The rarer of the two is a 36 Plymouth--the first yr Plymouth offically made a pickup, its a long bed.
Sitting right next to it is a 37 Dodge short bed-complete with the ram hood mascot.
Either could be had for $1500.00 and both got good fenders/runningboards and grills.
I really wish someone would save these two, and have told many people about them.

Any chance you have a contact number?

Yea I got cards at home but
Buds auto salvage
Not Cycle
Aline, OK 73716
(580) 463-2204

I was going to guess oil cooler. GM used cheap-@$$ quick connect couplings and fittings in 90s trucks. Maybe they honed their cheapness skills on 80s trucks.

Sixto
87 300D