Hmm, good ideas there. Was that the Wurtec S3 analyzer? I'm not fond of it, because it has high impedance inputs, that can't tell the difference between just noise, and a bonafide high state. Wurtec was designing a new analyzer, last I talked to them, and I asked them to include the option of drawing just a little test current on the inputs, so it won't be fooled by noise.

That's an interesting situation you had there, where the car is trying to level up, but hitting the top normal limit. I've seen 'em where they won't make the floor, if the limit is set too tight, but never seen it generate many relevels. Cool, thanks.

Here's another clue, that came to light during long marathon periods of observation.

On the rare occasion it was still hot when I got there, and I'd reset it, it would run on automagic just fine, but every couple of minutes, you would hear it relevel. Seemed to taper off after a couple of hours. (Yes, I sat there in front of the controller until my butt had a Home Depot bucket halo permanently imprinted on it. Too much info? Ok, right) Noticed tiny air bubbles seeping through the jack packing. Never releveled when reset after sitting for a while.

If I give too many clues, you won't have the fun of solving it, but it could get stale if I don't offer evidence that would be evident if you yourself were working on it.

This one threw me for a loop, because there was actually two separate problems, that both caused the same relevel/MLT symptom. Solved one first, then got a crushing dose of humility, when even after fixing one problem, the exact same fault did not go away. It was really strange, becuase I found a definite problem, that could absolutely cause that fault, and it had been identified and corrected. Yet it had the same exact fault again! Defied common logic!

You want more clues? Or is this pace about right?

Before I forget, there was another hydro issue where there were a plethora of door zone faults, always at the top floor. Oh, yeah, another one that ran with the doors open! Scary sh*t. And another one that blew the entire buildings' instantaneous circuit breaker, intermittantly. They're coming back to me now..like old friends, are the battles won.

A little more-

Opening the boiler room door cooled the machine room until I could stand the sweltering heat, but then that changes the ambient temperature, changes the exact operating conditions, and that's not good, because to find the problem, it has to be in its' failure mode, with the m/r door closed! Must observe, without affecting. It was some real "hot" troubleshooting!

Ok Vic, how about this, when the tank was hot, it expanded, and the oil level was lower then when the tank was cool. Not likely, but you said it was a dose of humility. Ok just give us the answer I can't wait any longer. Ha ha.

Whoa, I almost thought you were gonna guess the answer! It had to do with temperature, definitely. I'll let you off the hook in a second- But first, here are some things I did to ascertain the problem.
1. I sat there for hours, and recorded the time that relevels occured, put 'em on a time-based chart, and found that relevels generally subsided logarithmically, meaning the incidence of relevels was high after a reset, but dropped off quickly, continued to decline at a diminishing rate, like an olympic ski jump. That rate of decline reminded me of temperature based issues.
2. But I still had the bubbles escaping from the jack packing! That loss of volume would cause it to relevel. Bubbles never subsided, they just kept coming "forever".

So where was the air coming from? After all, the pump is submersed in the oil, and the only suction is at the end of the pump, everything after that is pressure only. I theorized about a multi-sectional piston, with loose joints, where the oil is entering the piston cavity through a lower joint, and pushing air out of the upper joint. Sounds good, except this was a one-piece piston. Hmm.. I even looked at the pit pump return line into the tank, but that was way across on the other side, away from the pump inlet. Yes, on the other side, until the pump started! The suction and/or turbulance pulled the long return line hose all the way over to the other side, where it got sucked up to the pump inlet. Since this was a new job, there was no oil in that line, just air, and it sucked that air into the pump, blew it into the jack, filled the jack with bubbles, and the car would sink as the air escaped through the packing. Then the whole process would start over again, and it basically would just keep releveling until it faulted out. Cut hose shorter, no more bubbles. Thought I fixed it, but the exact same fault came back. Still releveling, still faulting out. Weird.. Conclusion tomorrow. I really gotta go.

So, we got the bubbles problem out of the way, and still have relevel issues.

I was doubting the sealing of the Maxton check valve, and so took that all apart, cleaned it up, and replaced the valve stem seats, but it still releveled. Like always, it would initially level into any floor just fine, cycle the doors and park. Then after a couple of minutes, you would see the LU relay come in, and she'd relevel up. The packing was oil tight, no oil in the pit return sump, no oil going over the top of the jack. Everything was bone dry. Where was the volume of oil going?

I tried a pressure test, chained the push plank down to the pit channels, and put 400 psi on it. Watched the gauge, no bleedoff.

One day I put the car at the top floor, closed the gate valve in the machine room, yanked the power, then disconnected the feedline from the valve. Not a drop of oil came through that Apollo ball valve, all night long. Dems some great sealing ball valves, rite dere. Even with the ball valve closed, the elevator dropped 4" !!!

Where is the damn oil going, that is allowing the car to drift downward? It's not going back into the tank, it's not going back into the pit can, the jack's not leaking! Arrgh!

I consulted an engineer. Yeah, I'll admit this one had me baffled, and no, I didn't solve it without help. Wish I did. But the engineer measured the temperature of oil in the tank, and the temperature of oil at the jack, and we found that it had a difference of over 40 degrees! Sometimes much more, depending if the boiler room was hot where the tank was located, and if the elevator was being used a lot, etc. But generally, this point is that the hot oil would go through a long feedline, dissapating heat like a radiator, and then into a pit that was cold as a witches' tit. Must have been a high water table, bcause that pit was unusually cold.

Hydro oil, aka "32" oil, or ASO 150, has a coefficient of volume expansion of 0.027% per degree of Farenheit, (iirc, was over 10 years ago) and the contraction is the same when cooling. So for the given volume of jack oil, when the elevator is at the top floor, plus the feedline, equals "X", times 0.027%, times the degrees of temperature shift, equals "Y" volume lost, which came out to about 4" of piston length, when cooling over night, in worst case conditions.

It was just the conditions the job was installed under, and nothing at all was wrong with the equipment in any way. Chalk it up to the Fed's divine right to put the tank unit in a boiler room.

So I took the "FLO" fan/light output timer, which changes states after demand ceases according to the set time value, and drove a relay with it, which I used to inhibit the LU signal from getting to terminal 26, or up level input. When the car was running, FLO is dormant, car levels normally. After sitting for one minute, FLO changes state, the LU signal is inhibited, car drifts below floor level. It might drift even a few inches off floor level, but that's ok. There is no way to get into the car without having it relevel itself back flush with the floor, because any form of demand, whether Phase 1, hall call, car call, MLT, etc, would cause FLO to change states again, then it would level up flush. Even if the car had drifted out of the door zone, it wouldnt matter, because it won't open its' doors until it's in the door zone, after leveling in.

I don't reccomend modifying controls without getting the OEM to sign off on the change, because you could incur liability on yourself, even if some accident has nothing at all to do with the change you made. Liars, oops, I mean LAWYERS will distort anything if they think they can win a judgement. Draw it up, then send it to the OEM for an offical blessing.

In lieu of adding an oil cooling unit in the machine room. Did you ever try forcing the car to park at the bottom landing which would put most of the oil back in the tank. Due to the sheer volume of oil in the tank it may have aided in the oil cooling capacity. I've had to do strange things when for example you have 16 90s in the oil line from machine room to the jack. Another unit that came to mind was a duplex years ago which was a rarely used office building parking garage during the day but at night it took a huge amount of people up and down to a cinema. In these cases the solution was a larger oil line. I had one recently that is a very busy medical clinic during the day but basically vacant at night. The building engineer decided to turn the machine room ac unit down to about 50 degrees every day before he left because he would walk into the machine room and it seemed hot. Needless to say the unit had leveling problems every morning until we got on to what the guy was doing.

Hey Vic, I was on to the heat expanding things , just not the right thing, that's a good one. What in would like to know, is why didn't anyone suggest a oil cooling unit, considering it was that hot? I have seen quite a few of these units here in California where some of the machines get extremely hot with constant use.

Smitty, I can't remember if I tried that. Thanks for adding your experiences. Interesting. Nowadayz, if I suspect a temperature issue, I place these "bugs", smaller than an old pager, that record tons of temperature data. You can download them after a month, or whatever, and print out a graph, to prove to management if there is an issue.

Scott, a cooler would have been a much better idea in many ways. When I was younger, I thought everything was "up to me", to find a solution to every problem. It never occured to me back then to hold my ground, and force a cooler into the mix. Now that I'm older, hundreds of elevators later, I wouldn't hesitate to quote code to them, and stand my ground. "Too soon old, and too late smart!" Well, it's not too late, just an expression. But if I was to go through that again, I definitely would go the cooler route.

great stories Vic. I havent been on the site in awhile but I enjoyed following the logic and brainstorming.

I'm so glad to hear that! I hoped that the reader would feel like they were part of the troublshooting process. Sort of like reading an adventure novel. I was going to be a writer, ended up here! 8*)

ooohhh too much posts,,mmmmm i think you have hydraulic line problem....not electric.
Recheck all the hidraulics,lines,tank,filters and connections,"you have obstruction in some area" and this generate the noise like when you change the sequence ABC or CBA.this means because the pump take air not oil(because have obstruction) and the interior metal in the pump generate the noise.This need minucious check of the hydraulic lines because the pump can stuck inside.

Too much posts? Uhm hum, ok. Obstruction, oh, ok, uh huh.

Ok, so here I sit, coffee at the ready, getting set to get outta town on vacation...YAY!!! Finally! Now, this thread has been an enjoyable one with the info/symptoms of trouble given, and watching the detectives go to work theorizing and thinking. But what I can't figger is this; Of the twenty something posts, three were, it seems, logged during working hours (that being M-F 8am to 4:30pm). Not that I'm a boss, or even really giva a rip, but it just caught my eye. Like I said, sittin' at home, to much time to think as I'm not being pushed by the tracker or shoved along by the clock. Just an observation...but to humor you is the motive...really.

I'm always on my own time, self-employed! 8^)