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Discussion Starter · #1 ·
I know I don't have the most miles, but I've got a bunch of them on my '98 200SX-SE...Rust is kicking in on the lower panels fairly fast these days though...

Also have a '98 Sentra XE with 197K+, and a wrecked '97 Sentra GXE back in 2012 that had 192K miles. Still got the 1.6L from the '97 Sentra sitting in the back of the garage. The transmission from the '97 Sentra got transplanted into the '98 Sentra.

6450
 

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Discussion Starter · #2 ·
Well, time ticks on...

Got 290K+ on it now. Have always ran 5K miles on oil changes,Mobil1 5W-30, no problems. Oil usually brown at oil change time, but not black.

Fast forward. Thermostat stuck open this winter. Barely made it off the cold peg. Oil has 2,500 miles on it. Just changed the thermostat today. Oil is already black and been burning about a quart every 1000 miles or so. Not horrible, but wayyy above normal. Thinking the oil consumption and stuck open thermostat are related.

But the real question... Did a compression check for grins today while I was playing with the thermostat.
1-150
2-145
3-143
4-147

Book says 171 PSI minimum. I'm at about 1,600 FT MSL. Today was a low baro pressure day. Factor some of that in, and maybe that 171 PSI at sea level should be around 160 or so where I'm at.
AND the engine has 290K+ miles on it.

I think I'm just fine at this 143-150 PSI compression, bone overnight old, throttle wide open, charger on the battery, all 4 plugs out.

Opposing thoughts?
 

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Cold engines run rich, and excess fuel ends up diluting and polluting the oil by migrating past the piston rings. That's the source of your black oil (which will also be abnormally thin). In addition, engine wear at 90F can be as much as 8 times greater than at 180F due to clearances. Sadly, you didn't do the old girl any favors running her with that stuck 'stat. The compression is still fairly even so you probably won't see obvious issues like rough running, but I'm sure it's down on power. You probably scrubbed quite a bit of useful life out of the piston rings.
 

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Discussion Starter · #4 ·
Except that, maybe 98%(maybe 99.99%) of the mileage is highway, above 50MPH, and I've got Torque running on a tablet. Closed loop, fuel trims, O2 sensor readings, all normal, and/or oscillating, etc.
I put the borescope down the holes while I was in there.
STILL have visible crosshatch on all 4 holes. Freekin amazing.
But I'll agree I probably put 100,000 miles worth of wear on the rings inside of a 1,000 miles worth of driving.
Not really down on power. Never been a power house ya know. Still getting 30-40 MPG though depending on weather, winds, hurry, etc.

Finished the thermostat yesterday (after breaking the bottom mount bolt on the housing, easy swap thanks to the spare motor in the garage).
Oil change here in a couple hours. We'll see what happens.
 

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I put the borescope down the holes while I was in there.
STILL have visible crosshatch on all 4 holes. Freekin amazing.
Nissan makes great 4-bangers, what can you say? Over the years I've seen 4 of them (3 Altimas, one turbo Sentra) towed into the shop hydrolocked and drive out happy. The bottom ends are as close to indestructible as you'll ever see. :)
 

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Discussion Starter · #6 ·
Spare motor is out of a '97 Sentra, with 192K miles on it. Just getting broke in.

And after some driving today, kicked up a P0400. Thinking maybe those 5K miles over the winter with thermostat open might've clogged up the EGR path.
Clear codes today. Check it out tomorrow if I'm feeling froggy.
 

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Discussion Starter · #8 ·
AND I just got done reading the FSM for this particular issue. Mind you I haven't check any hoses, solenoid, EGR valve, or anything yet, just reading...

Apparently the ECM doesn't check the viability of the EGR functionality until the coolant temp is above 160F, and another dozen conditions are met as well.

Kinda makes me want to put that half-ass cold, stuck open, thermostat back in there for the summer just to eliminate a CEL :D
 

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Discussion Starter · #9 ·
So...about that saga...it kinda continues a bit...

Manually actuated the EGR about a dozen times a few days ago. Been driving it a fair amount, a few complete drive cycles. No P0400 EGR code any more.

NOW...go figure. Took a 300 mile trip today, ~600 round trip. Had to make a few stops along the way. After every 3rd stop, about 20 miles down the road, CEL for P1447. Clear the code. 3 cycles later...Pop goes the CEL for the same P1447.

Thinking maybe I beat on the area around the canister too hard when I was changing oil rotating tires last week.
:p

Only 291K on it now. Just getting broke in.
1st ~300 miles (going to the site) got me 37.5 MPG (with the wind, what little there was).
2nd ~300 miles (coming back home) got me 32.8 MPG (bucking the head wind, hauling a bit of ass to get home a tad bit sooner)
 
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