quik95lt1

iTrader: (7)

ok after actually reading all this now lol..........thinking maybe it could be a drainback issue if you have some sludge clogged oil return galley holes.......again just a guess......i had that issue with my motor the oil couldn't return fast enough from the top end and every time i got on the brakes at the end of the track the pressure would dip a bit......i solved it by overfilling a quart temporarily.....real solution was modifying my oiling system a bit..this isn't your answer my application is higly modified im just giving you an example....long story short if you are loosing pressure on braking there is a lack of oil in the pan and the little bit that is in there is surging forward upon braking......quesiton is why is there such a small amount? if there is 5 quarts in the motor then its not draining back for some reason......or as stated above the pickup has become dissconnected.....i WOULD NOT try your "rev it up while braking" idea.......your taking a cheap fix and possibly making it a very expensive one......

FAD2BLK93

Is the dipstick in this car correct? U could have one that is incorrect just throwing that out there. But if u have drained it and refilled with 5 quarts then that would not be an issue. The only time i have seen this problem was in a v8 s10 i had, the oil light did not work and under braking the oil pressue would drop and i knew it was low.

stuart4185

just drop the whole engine and rebuild it, no point in chancing it and grenading the whole **** and caboodle. minimum new bearings and ARP bolts, maybe even new pistons of your feeling squirrelly. build it on your terms, not when it ***** the bed like the rest of us

Syvman

iTrader: (1)

SS RRR - To be honest, it may have been a problem ever since the "new" motor went into the car - just didn't notice it until the first hard brake incident (approached a stale yellow that turned red on me - can't take chances here in Mesa - lots of red light cameras)...

quik95lt1 - I'm not sure if there is a drainback issue or not now - one time I checked the oil while the engine was running, and it looked like it was really low. Later the same day, I checked it immediately after the engine had been shut off and it looked fine. I'm absolutely baffled. Don't worry, after I re-read my post about revving the engine and attempting another hard brake, I decided it would be a bad idea (probably should make better use of that "Preview Post" button at the bottom of the page, huh?) . I have a running motor right now - I'd like to keep it that way. The only reason I let my old man take the car for a drive is because I know he's good for the money to buy another motor if it "grenaded" on him.

I won't claim to be an automotive expert - I 'm just sorta thinking out loud here... Is it possible that because the oil pressure switch/sensor is located on the very top rear of the motor, hard braking could pull oil away from it during a hard brake if there is something clogging the passage to the switch itself? Doesn't seem like it to me - pressure is pressure - you'd think if there were an issue with the oil passage to the switch, it would cause faulty readings all the time.
What I'd REALLY like to do is hook my gauge up to the "alternate" oil pressure plug (just above the oil filter) and then see if the same thing happens. Problem is, my gauge only has about a 5 ft. hose or so... Definitely not long enough to bring the gauge close enough to read while driving the car.
Bottom line - this REALLY is identical to the stereotypical "pickup fell off" issue - so I think I'm going to get to the bottom of the issue by inspecting the oil pump and pickup. Sure would be nice if removing the pan wasn't such a PITA, but it's par for the course with my luck.
One more thing - I noticed on my old oil pump that there is a spring-loaded valve or plug on the bottom plate that connects to the pickup. It looks like when this plug is "open" it allows oil in through a hole in the side of the pump housing itself as well as through the pickup. If that were stuck open for some reason, that would cause this also. But I am not 100% sure that's how it works. Maybe someone can tell me what this little valve does - I've attached a photo...

Please keep in mind, that this is off the oil pump from the old motor - please disregard how f'd up it looks (it's been sitting outside in the elements for a few months now), I just am using this as an example.
You can kinda see the valve I'm talking about in the middle hole on the left... There's a metal spring-loaded plug in there - is it possible for this to get stuck, and if so, what would be the result?
Thanks everyone!

Syvman

iTrader: (1)

Hehe - that was actually the original plan. But after my daughter was born I noticed just how little time I had to even get the car running again - let alone rebuild a motor. However, I really think I'm going to end up having learned a hard lesson here - I probably should have inspected more of the motor while it was outside the car before installing it. The thing that is really frustrating is that the motor runs well - it's got a lot of pull, doesn't smoke, and fired right up on the first try. Even passed smog with flying colors - all emissions levels were fantastic. Up until this issue was found, I really thought I had lucked out and got a good motor.
The upside is - I know how to remove/reinstall the engine now, and I'll probably be able to do it in half the time it took before, now that I know what I'm doing. I just really don't want it to come to that. I'm really hoping I'll see something when I pull the pan. But if push comes to shove, I guess I'll have to explore a rebuild - with my luck, I'd get it all put back together and end up with the same problem, haha.

Syvman

iTrader: (1)

I actually thought about that - but I compared the length of the dipstick/tube from my old engine to the one that's in the car now and they're identical. And you're right - I measured over 5 qts. when I drained it, so I know I'm not low.

trilkb

iTrader: (4)

Not sure if your test would help or not. I had a Lincoln LS v8 that when i ran a fram filter It would do this. I never really "brake hard" so i dont know what the difference would be. My issues happened when the car was warmed up, but not really "hot". But it would do it hot as well, it just came on that quick into running. At stop lights the oil light would come on, oil level was full. If i put it in nuetral and gave it a little bit of gas it would go away. No pressure gauge in the car, just the low oil psi light. I switched and problem went away. A friend with a honda civic who ran frams also switched and he said he also noticed better oil pressure. Ive heard the highest top shelf frams arnt as bad, but ill never run one again. My lexus doesnt have any issues at 175k miles and all ive ran is wix...love jap engineering!

Im not sure if its been suggested, But the oil pressure gauges in these cars are crap. People have all kinds of issues with them.

Have you hooked up a mechanical gauge? Do you plan to? Befor tearing it apart i would do that first just to make sure.

Syvman

iTrader: (1)

Yes - mechanical gauge has already confirmed that the pressure is indeed being lost - at least at the spot where the sensor/switch screws into the block. That's why I'd like to hook it up to the alternate spot above the oil filter and see if the pressure drop is the same there...

mab6680

iTrader: (1)

i had this same problem for me my pick up fell off i was able to hear it rattle around but i also took a look in there with a inspection camara. i have seen cheaper ones at harbor frieght for around 100 bucks might be worth the money to take a look in there with out froping the pan is it possible your windage tray is missing or fell off

Syvman

iTrader: (1)

I can see the windage tray also - not through the drain plug, but through the hole where the oil level sensor goes (I removed that also to try to inspect the inside of the pan). The tray is there, although I don't know if it's properly attached or not at all four points. Honestly, I didn't even think to try an inspection camera - I've been wanting to get one of those for a long time, but didn't think I'd really have a practical use for one. Maybe I'll have to take a look now. Always looking for a good excuse to buy a new toy.

mab6680

iTrader: (1)

there awsome i use mine for more then just my car. i use it in my house all the time i just closed on my first house and had a leaking pipe i was about to tear the wall apart when i thought about my camara turns out it was coming from the second floor hell of a lot better patching a hole the size of a quarter then a big gapping hole

SS RRR

iTrader: (2)

I am also wondering, if this indeed has been a problem since the engine was built, if there may be a clearance issue between the bottom of the pan and the pickup. Maybe it's too far away from the bottom of the pan? Once you brake hard the level may go under the pickup causing cavitation? Who knows.

quik95lt1

iTrader: (7)

thats what im thinking now that the motor has been completely rebuilt before...........if the pickup is too far up that will def do it........it HAS to be something to do with the pickup its not cavitation and its not a mechanical issue with the motor....its starving of oil on braking it HAS to do with either the amount of oil in the pan or the pickup is misaligned.......rebuilding the motor as stated above is completely unnecessary espically if this was only a couple of isolated incidents while off the throttle and the pressuer came right back........pull the pan off and figure out the issue........do the play dough test with a piece of celophane and see what it says......should be between .250-.375 off the bottom of the pan if its a high volume pump i tend to ear closer to the .375.....

Syvman

iTrader: (1)

First - let me clarify - the motor wasn't rebuilt in the past to my knowledge - I just bought it off a guy in Phoenix who posted it on Craigslist. He told me it had about 76k miles on it when the car was wrecked. I discovered the motor came out of a 1994 because of the style of Opti it had, but it still seems to jive fine with my PCM. So I'll take the gentleman at his word, and we can go on the assumption that I have an LT1 from a 1994 with approx 76k miles on it. The valve covers and oil pan were taken from my old motor and installed on this current motor because they were in much better shape (not banged up/dented).

Now on to your recent comments - you guys are talking about the clearance of the pickup from the bottom of the oil pan - it's an amazing coincidence that you mention this, because I drained the oil again, and I actually moved the pickup up and down a couple of times to see if that would help the issue. I decided to try this because when I pulled that part off the old oil pump (see photo above), I noticed that I was able to move the pickup up and down on it. SO, I took my handy screwdriver, and pried the pickup all the way down as low as I could (basically to where it was touching the bottom of the pan) and then back up about 3/16 of an inch or so. This didn't help the problem. So then I pried it up a little higher than parallel to the bottom of the pan. This also didn't seem to help. But I was able to move it around. It's back down to the parallel position (not entirely sure what the distance is - I'll confirm it's correct when the pan comes off with the playdough/cellophane trick - I never would have thought to try that).

I can't tell all of you how appreciative I am for your advice - head-scratchers like these get really frustrating, so it's nice to be able to share my frustration with someone else.

Bottom line - oil pan and valve covers are coming off tomorrow morning. I figure IF everything looks in order with the oil pickup and pump, how would I go about cleaning/inspecting the oil passages? Can I run compressed air up through the main passage where the oil pump sends oil into the motor? If there is a clog, I read on another post that really the only effective way to ensure all the passages are clean is to remove the block and have it hot-tanked... If I'm gun-shy about removing the oil pan, I'd be REALLY bummed if I had to remove the whole motor again. BUT, if it must be done, it must be done. Let's see what we can see tomorrow - I've got the day off, and I am allowed to drink beer again, so now nothing is stopping me from working on it.

Oh, and in case anyone is wondering - YES, I HAVE drained the oil and refilled it that many times... And YES, it's getting old. I have been re-using the 10W-40 oil - it seems REALLY weird pouring oil from my drain pan back into the motor - just doesn't seem right.

quik95lt1

iTrader: (7)

good info......as for being able to move the pickup around it should be set to the correct height then welded on to the pump........as for a clogged oil passage i can tell you thats not the issue...youd have issues under accleeration and also crusing.....this is a pickup issue......do what i said with the playdough and celophane then weld it on and you can rule out that issue.....just remember the first rule to taking apart motors........BE CLEAN!!!

heres mine with the plastic and pladough mocked up.......i went .375 with mine its a high volume circle track pump thats made to move alot of oil....

Intimidator02SS

The pressure side ports don't seem to be your problem. The oil return holes would be your culprit. These are in each cylinder head at the front and rear of each and also under the intake manifold where the lifters sit. There are bigger holes there that can be gunked up restricting flow back down. I hope this makes sense.

Syvman

iTrader: (1)

Looks like I'll be adding pladough to the shopping list. And thanks for easing my mind about having a clogged oil passage. I'm more than willing to pull the pan, valve covers, even the intake. I just REALLY don't want to pull the whole motor (again). I did it once, I've got the t-shirt.

I don't have a welder, but I know a couple of guys who do - I'll be hitting them up for a "favor".


Yes - makes perfect sense. I actually took a look at the old motor (intake and heads are removed) to see where the oil flows back down - those holes are pretty big - I think it would have to be gunked up pretty bad in order to clog them up (like the old Castrol commercials). Judging by how clean the valvetrain and bottom end looked when I swapped the valve covers and oil pan, I am reluctant to think that those might be clogged. BUT - I've discovered that with my luck, anything is possible.

At this point, I'm fairly certain the problem will present itself to me when the pan comes off. If nothing looks obvious when I remove the pan, then I guess that's when I'll be back here (with photos) begging for more help, haha.
Down to 20 hours until that effort starts - I'll have the camera by my side to post pics tomorrow!

leadfoot4

iTrader: (1)

I know that this is really an "off the wall" thought, but after reading all the way through this topic, it seems that "Syvman" has a really unique set of circumstances. Please don't laugh, as I present a wild thought ....

There have been a few discussions on this forum about worn cam thrust plates, as well as oil pump drive "stubs" that have been broken/damaged over time. One of the "theories" about the car that's on 4 Optis in 3 months, is that the cam retainer is allowing the cam to walk forward, jamming the rotor in the Opti. In that discussion I seem to recall that it was mentioned the oil pump drive gears "might" hold the cam in place.

What if the oil pump drive stub is well-worn, and also doesn't have the ability to keep the cam in place. Under hard braking, inertia shifts the cam forward, the oil pump is momentarily dis-engaged, hence the oil pressure drop.


It's just a thought......

quik95lt1

iTrader: (7)

i see where you are comming from but i see this HIGHLY unlikely.....for two reasons.......
1. the amount the cam would have to shift forward to disengage the teeth would be more than the thickness of the retaining plate which would mean the plate is completely gone which would mean the opti would be dead meat immedieatly......no to mention the rest of the motor

2. teeth would have been broken off of the dummy drive gear causing more issues

those are my two main reasons saying this isn't it........not trying to shut you down at all that was a very valid thought

leadfoot4

iTrader: (1)

No offense taken! As I said, this problem seems SO weird, that almost anything seems possible....