MEP002A just stopped running

[Guyfang]

An even easier way to determine if one of the switches is bad, is to take a wire, with two roach clips, oops, alligator clips, and hook it up to TB5-8 and TB5-9. This jumps the whole safety circuit. The TB and terminals are plainly marked. Hook it up, start set. If it runs, pull one end of your jumper off, and see if the engine dies. Then jump just the S5, (oil press) switch and fire it up. If it dies, its the S-4, (over temp). Better to check the S-5 first, as its easier to get at, then the S-4

No toolbox should be considered complete, without at least two of these simple jumpers. I have a short one, maybe 20 cm, and a long one, about 2 meters long. You can do a lot of testing in the control box, instead of all over the gen set.

 

[Light in the Dark]

As I get more time playing with these toys... I am finding little bits of info like this to be indespensible. Hope Lowes has some (on my way to/from work).

 

[Light in the Dark]

and I need to provide an image of my S1... because I think its #13 which has no screw or lead at the moment (and from reading above... thats the run circuit). Which doesn't make sense, as it has ran just fine.

 

[Guyfang]

I do seem to remember that yes, there was at least one position on the S-1 that was not used. Having said that, is that one hole suposed to hold down a jumper? What number is next to the hole? Look at the S-1 terminal schedule on the schematic. I seem to remember stealing a screw from the S-1 on occasion, but its been a while!

 

[Guyfang]

Yes, 13 should be one of the jumpered terminals. do take a picture.

 

[Light in the Dark]

Here you can see S1, as well as the disgusting condition of the OPS. Whoever previously serviced this set cared little about cleanliness.

 

[Light in the Dark]

As an aside, whats the preferred method for degreasing these things? Will the wiring stand up to a degreaser? I want to clean this entire area up as part of my testing of the OPS, but dont want to mess anything else up as I go. Thanks

 

[Light in the Dark]

In looking up a replacement OPS, I came upon the folks over at Green Mountain. They are nice enough to give manufacturer details on some items... and it appears that this model is also an appropriate replacement.

http://www.alliedelec.com/honeywell-76052-15-01/70111623/

Yes, no, maybe? The design is a little bit different than the unit on it, but that doesn't mean much on something like this. Just don't want to buy something thats wrong (on purpose). Going to jump the OPS when I get home later and see (or I'll bypass the whole circuit if I can find the TB items Guy mentioned).

 

[Chainbreaker]

and I need to provide an image of my S1... because I think its #13 which has no screw or lead at the moment (and from reading above... thats the run circuit). Which doesn't make sense, as it has ran just fine.

Pin 13 on S1 Master switch is NOT used. The schematic does indicate that pins 13 & 14 are internally connected within the switch internals (bussed together by virtue of the line on schematic within the switch outline between those pins, if it were a jumper it would be shown outside the switch outline). S1 Pin 14 is the pin used for the safety circuit.

 

[Chainbreaker]

Here you can see S1, as well as the disgusting condition of the OPS. Whoever previously serviced this set cared little about cleanliness.

View attachment 657626View attachment 657627

In looking at your OPS picture it appears that it is dripping oil (drop on bottom). If that is the case, then the pressure within the switch itself is fluctuating. It probably leaks less when oil viscosity is thick (cold) and leaks more when oil viscosity is thinner (hot). Anyway that's my theory and I'm sticking to it. Hope its that simple as just replacing that switch. Just a 5-10 min job not including cleanup!

 

[Chainbreaker]

Yes, the Honeywell 76052-15-01 N/O (normally open) is a suitable OPS replacement.

 

[Chainbreaker]

An even easier way to determine if one of the switches is bad, is to take a wire, with two roach clips, oops, alligator clips, and hook it up to TB5-8 and TB5-9. This jumps the whole safety circuit.

Thanks Guyfang, that is a GREAT tip! Hmmmm...I might just wire up a Battle Short switch that way. If during the heat of battle (Civilian version = Power outage during cold rainy/icy/snowing darkness) my unit shuts down unexpectedly yet has oil pressure and only runs in Start position, I could simply flip a toggle switch to quickly troubleshoot & temporarily bypass the safety circuit if necessary and make repairs later.

 

[Light in the Dark]

Came home and isolated the OPS... bingo bango she purrs in both run settings! Time to replace that part, and clean up that area on the block. Thanks for all your help everyone.

 

[Light in the Dark]

Yes, the Honeywell 76052-15-01 N/O (normally open) is a suitable OPS replacement.

Thank you

 

[Light in the Dark]

Thanks Guyfang, that is a GREAT tip! Hmmmm...I might just wire up a Battle Short switch that way. If during the heat of battle (Civilian version = Power outage during cold rainy/icy/snowing darkness) my unit shuts down unexpectedly yet has oil pressure and only runs in Start position, I could simply flip a toggle switch to quickly troubleshoot & temporarily bypass the safety circuit if necessary and make repairs later.

An excellent idea to make a killer design platform just that much better.

 

[Triple Jim]

From your description and photo of the oil pressure switch, it seems likely it was leaking oil, which may have lead to its self destruction. I'm glad you found the problem!

 

[jamawieb]

http://www.mixerandplantparts.com/Terex-14242-NO-Pressure-Switch-Set-at-15-PSI-p/14242.htm

Here's a link to a place where I buy replacement oil pressure switches. I'm glad you found the problem.

 

[rustystud]

In looking up a replacement OPS, I came upon the folks over at Green Mountain. They are nice enough to give manufacturer details on some items... and it appears that this model is also an appropriate replacement.

http://www.alliedelec.com/honeywell-76052-15-01/70111623/

Yes, no, maybe? The design is a little bit different than the unit on it, but that doesn't mean much on something like this. Just don't want to buy something thats wrong (on purpose). Going to jump the OPS when I get home later and see (or I'll bypass the whole circuit if I can find the TB items Guy mentioned).

That oil pressure switch will do fine. As far as cleaning the unit goes, I just use brake clean. It cuts the grease real good and doesn't hurt the wiring.

 

[Guyfang]

Rustystud is right. The wiring is aircraft grade, and very tough. We used some cleaning compounds that I hated to use without gloves, and the wire harness was not affected.

The only problem with a battle short, is what happens when you do lose oil pressure? Or it overheats? But yes, it can be handy, in a pinch. I only had to use Battle Short a few times, and we would check the set lots more often. I never understood why the 002 and 003 never had a battle short.

In the old days, before the 002 and 003, the sets had lots of relays in them. About 5-6 on a terminal board. We often had several jumpers on them, as the early 70's was a bad time for getting replacement parts. The money was all being spent in Viet nam. On the 45 KW Stewart and Stevens, we could never have provided air defence in Europe without them!

 

[Guyfang]

Yes, 13 should be one of the jumpered terminals. do take a picture.

When I wrote used, I ment it is part of the common. It should have a metal strip between #13 and #14. If the screw in#13 was missing, you could get an intermittent contact, or no contact at all.