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| 3800SC sudden loss of oil pressure? (Page 1/2) |
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Additivewalnut
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JUL 15, 10:16 AM
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I went to my biweekly autocross event, car was running great with about 60psi of pressure. I was running the thing pretty hard and at the end of my last run I noticed I have ZERO oil pressure. It was very hot yesterday (approx 96 degrees F), engine didn't overheat but the engine bay was very hot, and I did spin out at one point and stalled the engine. It's not knocking while running with "zero" oil pressure, I didn't run it much but I drove it onto the trailer to go home. I did notice some ticking, but I can't remember if it's always done that or not. I have oil in it, maybe a bit low as it's showing on the first dot of the dipstick. I looked in the valve cover while it was running and it looked like there was oil on the rockers. Maybe my pressure sender overheated and died? Can a 3800 just go from 60 to 0 like that?
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Frenchrafe
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JUL 15, 11:41 AM
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I hope it's your oil pressure sender.
Since you say no knock, then probably not the crank or rod bearings that suffered.
I made a baffled sump after blowing up my engine with oil starvation one trackday:
(Sorry, long video. One of my earlier ones.)
------------------
"Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero
https://youtu.be/hUzOAeyWLfM
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theogre
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JUL 15, 12:35 PM
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Additivewalnut
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JUL 15, 12:37 PM
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| quote | Originally posted by Frenchrafe:
I hope it's your oil pressure sender.
Since you say no knock, then probably not the crank or rod bearings that suffered.
I made a baffled sump after blowing up my engine with oil starvation one trackday:
(Sorry, long video. One of my earlier ones.)
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you know, if I keep spinning out like I did yesterday, I might really need to baffle the pan.
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Additivewalnut
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JUL 15, 12:39 PM
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I'll throw a mech gauge on per Ogre. God I hope that's just the issue. If I have to pull this engine out I might cry 
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Additivewalnut
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JUL 17, 08:38 AM
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Alright good news, I got underneath the car and noticed my pressure sender snapped in half! So that's been replaced on, I have oil pressure again, yippee! However the new sender I put on seems to read significantly higher than the last one and when you turn the key to ACC it shoots past zero then slowly goes back down. It doesn't fly past 80 like it would if it were an open circuit or anything. Maybe a cheap autozone sender being janky?
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theogre
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JUL 17, 09:44 AM
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I think I-key in ACC should Not turn on most or all the dash.
Problem is I having seen ACC in years because hard to adjust the I-switch to hit Start & ACC on many Tilt column even when have new parts.
FSM etc say only the radio & wipers are On in ACC.
So Maybe more then just a broken sender like wiring problems.
Example: if the dash plugs has ever been pulled for any reason... maybe bad sockets shorting the gauge. See https://www.fiero.nl/forum/...HTML/138175.html#p18
or Sender is defective out of box & short there to fuel pump wire.
which sender broke like that?
Pic's are wanted for this.[This message has been edited by theogre (edited 07-17-2024).]
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Additivewalnut
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JUL 17, 11:36 AM
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| quote | Originally posted by theogre:
I think I-key in ACC should Not turn on most or all the dash.
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okay sorry I misspoke, with the key on engine off, all the gauges come to life as expected. Just the oil pressure goes to about 5 or 10 PSI and then slowly drops to zero. When the engine is running it reads 80+ which is about 20psi higher than it used to. I think it's just a shitty chinese sender... hopefully.
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theogre
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JUL 17, 01:37 PM
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All gauges "float" & read random values w/ I-key off or in ACC.
I-key On, engine Not then OP gauge should drop to 0 near instantly. Gauge Coils slow down the 0 out a very little bit so doesn't "slam" to 0. Fuel & temp goes to value for each sender or temp stay @ 100°F until engine start to warm up went sender is hot enough to work.
Check Ω @ sender gauge pin & block should be 0 any time the engine is Off.
Then if can get a reading safe, run the engine & read Ω Same way. Should be ≤ 90Ω. ~ 40 - 45Ω w/ stock engines but don't have OP spec for this swap.
see https://web.archive.org/web...rocave/oilsender.htm for pin layout.
If sender is installed w/ Teflon tape... sometimes that causes ground problems.
Often people claim won't matter but many times it is a problem w/ any sender ground to the block/head. More so because OP & some others work under < 100Ω & just adding 2-5Ω for iffy ground(s) hurts.
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Additivewalnut
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JUL 17, 01:47 PM
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| quote | Originally posted by theogre:
If sender is installed w/ Teflon tape... sometimes that causes ground problems.
Often people claim won't matter but many times it is a problem w/ any sender ground to the block/head. More so because OP & some others work under < 100Ω & just adding 2-5Ω for iffy ground(s) hurts. |
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The new sender had tape preinstalled. Bet that's the issue. I'll take that off and see what happens
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