Jump to content

Mystery dead battery solved


Recommended Posts

Our Scag Cougar mower was outside in a torrential rain while we were at a graduation party. The next day when I went to use it the battery was flat. It started ok with a jump pack and the battery came back after hours on a charger and then on a bench power supply where I could force feed it. Mower started and ran ok for a day then wouldn't start so I trouble shot it to a bad interlock relay. I happened to have a few of those generic relays on hand and that fixed it. I remembered that I heard the starter solenoid click when I applied the jumper pack so decided to dissect the relay and puzzle solved. The interlocks - seat switch, parking brake, and blade switches all are in series and supply the ground for the relay. The key start switch supplies power to the relay coil and if all the safeties are made it'll crank. Always hot power is available to supply the starter solenoid.

The relay corroded, closed the contacts, and the machine sat and cranked until the battery gave out! The starter motor must have loved that but is still working. I have a spare on the engine I took out of that machine when I repowered it with the larger EFI engine. Obviously the corrosion had been going on for years before it mysteriously cranked the engine on its own.

Scag corroded relay.jpg

  • Like 2
Link to comment
Share on other sites

Interesting post 

Link to comment
Share on other sites

2 hours ago, New Englander said:

Our Scag Cougar mower was outside in a torrential rain while we were at a graduation party. The next day when I went to use it the battery was flat. It started ok with a jump pack and the battery came back after hours on a charger and then on a bench power supply where I could force feed it. Mower started and ran ok for a day then wouldn't start so I trouble shot it to a bad interlock relay. I happened to have a few of those generic relays on hand and that fixed it. I remembered that I heard the starter solenoid click when I applied the jumper pack so decided to dissect the relay and puzzle solved. The interlocks - seat switch, parking brake, and blade switches all are in series and supply the ground for the relay. The key start switch supplies power to the relay coil and if all the safeties are made it'll crank. Always hot power is available to supply the starter solenoid.

The relay corroded, closed the contacts, and the machine sat and cranked until the battery gave out! The starter motor must have loved that but is still working. I have a spare on the engine I took out of that machine when I repowered it with the larger EFI engine. Obviously the corrosion had been going on for years before it mysteriously cranked the engine on its own.

Scag corroded relay.jpg

Case 70 and more so 90 series tractors are bad for that. The starter relay is on inside frame and over years moisture can accumulate. Buddies tractor was in his yard running one morning after setting for a while. Local dealership told him a few times a year they sell starters and whatnot for same thing occurring.

  • Like 1
Link to comment
Share on other sites

1 hour ago, yellowrosefarm said:

We had a 90's ford bucket truck years ago that did the same thing. It was manual trans and got tangled up in a chain link fence over a weekend.

Funny! Remember the Ford trucks that sometimes popped out of park and into reverse? I was working for Eastern on an L1011 when a TWA mechanic came up the Jetway and into the cockpit, HOT!. It seems one of our water service trucks had popped into reverse and was jammed under one of their 707s. That was in PHL. In Boston a lavatory service truck went missing. Who would want one of those? Well, it apparently popped into reverse and crossed all the runways and taxiways in the middle of the night and ended up in Boston harbor, spotted under water by a landing plane in the morning. After that and several other runaways and the edict to always chock them failed they removed all the stock shift levers and put a simple FWD N REV pedestal on the floor. Parking brakes and chocks mandatory.

  • Haha 1
Link to comment
Share on other sites

I had a 74 F250 in the mid 80's and had gone downhill skiing, parked in one of the upper parking lots, got all my gear on and as I shut the locked door I heard click and it started rolling ahead. I had truck camper hooks on the box pockets so I grabbed on, dug my ski boot heels in and played human anchor, went a couple feet and bumped into the vehicle ahead, then this crusty voice pipes up from an unknown observer, yup dem Fords are bad for that 🤣

  • Haha 3
Link to comment
Share on other sites

We had a 2000 F550 with a six speed manual transmission and a bale bed. My brother was opening a gate while the truck was idling. When he got to the gate, the truck jumped forward and almost pinned him against the fence before it died. The line to the transmission cooler had gotten a hole rubbed in it and leaked all the oil out. Some internal parts welded together and it tried to take off like it was in gear. He could have been badly hurt. 

Link to comment
Share on other sites

10 minutes ago, hardtail said:

I had a 74 F250 in the mid 80's and had gone downhill skiing, parked in one of the upper parking lots, got all my gear on and as I shut the locked door I heard click and it started rolling ahead. I had truck camper hooks on the box pockets so I grabbed on, dug my ski boot heels in and played human anchor, went a couple feet and bumped into the vehicle ahead, then this crusty voice pipes up from an unknown observer, yup dem Fords are bad for that 🤣

Was in Saskatoon one day and had took some grain samples in. Parking lot was on a slight downhill slip towards the street. I came back out to get something out of the truck and the truck was no longer there. Here it had rolled down the slope and was parked nicely out in the street. Someone must’ve pushed it to the side as it wasn’t siting along the main traffic lane. It had been out in 6th gear without the parking brake in. Slope was steep enough that gravity overtook the transmission. Was still in gear when I got back in. No one hurt or anything damaged thankfully.  

  • Like 3
Link to comment
Share on other sites

Our RV based on a Gillig Transit bus has a Voith 4 speed automatic (with it's own ECM that is CAN bused to the Cummins ECM) there is no park on that tranny, must use the bus air brake  parking system, for you non air brake guys, the parking brake is just a big-a$$ spring held away from the brakes by an air cylinder, when the air pressure  is less than 70 PSI it sets automatically. So the parking lever just drains the brake-cans to set to park. I never worked with air brakes before we got the Gillig, interesting systems to learn about and use.

Link to comment
Share on other sites

17 hours ago, oleman said:

Our RV based on a Gillig Transit bus has a Voith 4 speed automatic (with it's own ECM that is CAN bused to the Cummins ECM) there is no park on that tranny, must use the bus air brake  parking system, for you non air brake guys, the parking brake is just a big-a$$ spring held away from the brakes by an air cylinder, when the air pressure  is less than 70 PSI it sets automatically. So the parking lever just drains the brake-cans to set to park. I never worked with air brakes before we got the Gillig, interesting systems to learn about and use.

All the older medium duty trucks with Allison automatics I've ever seen are like that, no park but maxi brakes. My C70 has an Allison, air brakes, and maxis. Driving a wrecker when I was a kid I carried a couple of release screws for them as in the salt belt the ones on the brake cans were often rusted beyond use. Towing any truck with air brakes that wouldn't run it was hook up and crawl under and release the brakes. I was always towing with juice brakes. Some outfits with bigger wreckers that had air would run an air hose to the broken trucks system and let them off that way - no good for a wrecked truck. I think there's an actual way to control the towed truck's brakes as trailer brakes but don't know exactly if or how that works.

Link to comment
Share on other sites

33 minutes ago, New Englander said:

All the older medium duty trucks with Allison automatics I've ever seen are like that, no park but maxi brakes. My C70 has an Allison, air brakes, and maxis. Driving a wrecker when I was a kid I carried a couple of release screws for them as in the salt belt the ones on the brake cans were often rusted beyond use. Towing any truck with air brakes that wouldn't run it was hook up and crawl under and release the brakes. I was always towing with juice brakes. Some outfits with bigger wreckers that had air would run an air hose to the broken trucks system and let them off that way - no good for a wrecked truck. I think there's an actual way to control the towed truck's brakes as trailer brakes but don't know exactly if or how that works.

RE: controlling the service brakes of the truck that is being towed.  Fairly easy to do with just a little bit of knowledge and effort.  The tried and true standby was to use a “Brake Buddy”, a pneumatic cylinder that clamped to the brake pedal and the steering wheel.  An air line hooked to that and run through the vent window to the Service (blue) gladhand.

From the Emergency/Supply/Red gladhand an air line is run to the air drier or wet air tank.  Without air supplied to the system pressing on the brake pedal, or tapping directly onto the service relay valve, will have no effect.

 

Again here I am with random factoids that are of little interest to most……..

Link to comment
Share on other sites

17 minutes ago, 1586 Jeff said:

RE: controlling the service brakes of the truck that is being towed.  Fairly easy to do with just a little bit of knowledge and effort.  The tried and true standby was to use a “Brake Buddy”, a pneumatic cylinder that clamped to the brake pedal and the steering wheel.  An air line hooked to that and run through the vent window to the Service (blue) gladhand.

From the Emergency/Supply/Red gladhand an air line is run to the air drier or wet air tank.  Without air supplied to the system pressing on the brake pedal, or tapping directly onto the service relay valve, will have no effect.

 

Again here I am with random factoids that are of little interest to most……..

I'll likely never tow anything with air brakes again but it's nice to know that what I remembered from my teens is accurate. Getting into aircraft mechanics and piloting was an extraordinary career move!

  • Like 1
Link to comment
Share on other sites

I helped tow an old KW (1952 I think it is) that had maxis and a bad engine. Used old Ford F600 farm truck and a Emglo compressors with a Honda on the truck bed to tow with tow bar. Just the compresser plumbed into a glad hand hose.  Had a driver in the KW to steer and apply brake at intersections. All went well 140 miles or so.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...