| Author | Message | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 545 Registered: 9-2007 Posted From: 96.42.5.35  Rating: N/A |
4107-8 V 71 n I have what I think is a broken water temperature sending unit. My Schrader valve would not function and this sending unit had the wire and top part of the unit corroded off. It was in the water pump housing and stands up about 2 inches tall and goes into the water housing about the same. On the 3 flats (15/16) of the brass portion it has the initials BK DG R. On the sensor portion (in water) its says 18 M4 and 210 X. Can someone tell me if this is the temperature sending unit for the guage on the dash or is this an on/off switch for overheating.I am going to try the local parts stores tomorrow to see if I can match it up, but it would be helpful if I knew its function. Thanks, John | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2133 Registered: 10-2003 Posted From: 71.58.71.157  Rating: N/A |
what does your gage on dash read now? With ignition on,ground the wire leading to the sender and look for either a hot light,buzzer to come on,or the gage to move to full cold or hot. | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 546 Registered: 9-2007 Posted From: 96.42.5.35 Rating: N/A |
The guage on the dash seemed to work correctly and stayed about 180 although so I am not sure that this sending unit even goes to the guage. I had taken the air line off the Shrader valve and plugged it so I was able to run, although when I had to shut if off I had to snub it out with the clutch. | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 1244 Registered: 8-2006 Posted From: 184.10.191.147 Rating: N/A |
1 wire would be a sending unit for the dash gauge or light or maybe a buzzer, the Kysor/Cadillac shut down will have 3 wires, the sending unit has to match the gauge and that model shows to be a VDO gauge it doesn't mean much on a old bus so match it with you gauge brand in the dash fwiw the sending unit for the gauge is usually on the thermostat housing good luck (Message edited by luvrbus on August 22, 2011) (Message edited by luvrbus on August 22, 2011) | ||
| Sam Summers (Greyghost)
Registered Member Username: Greyghost Post Number: 85 Registered: 4-2011 Posted From: 166.231.31.196  Rating: N/A |
John let me know what you find out, I'm wanting to replace mine also. Sam | ||
| Brian Evans (Bevans6)
Registered Member Username: Bevans6 Post Number: 71 Registered: 5-2009 Posted From: 65.92.51.90 Rating: N/A |
I don't understand the connection between the temp sending unit and the schrader valve - can you explain that for me? Thanks, Brian | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 547 Registered: 9-2007 Posted From: 96.42.5.35 Rating: N/A |
The way I understand it, the schrader valve operates when all the peramiters are met. Engine coolant level, engine temperature, trans temp, and oil pressure. If any one of those fails to be in the proper range the valve responds and shuts off the fuel flow to the engine. It also operates in an "override" manner during cranking and thats why my bus would run as long as I was cranking the engine. As soon as I would let off on the key it would die. I may be confusing two different systems though. There was air behind the valve which was keeping it in the closed position. I removed the air line and closed it with vice grips. The bus then started and ran fine except as indicated it would not shut off with the key. Very confusing! There are two sending units in the "water jacket" for lack of a better term. I am just trying to determine which is the shut off circuit and which is temp to the dash. John | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 1245 Registered: 8-2006 Posted From: 184.10.191.147 Rating: N/A |
Shouldn't work that way the skinner valve controls the shut down on all the GM I worked on,then the safety systems and alarm stats are 3 wires I don't know what you have there,a one wire sending unit cannot supply power to anything it only reads the skinner valve that controls the shut down is mounted on the firewall overhead has a hot lead and a ground most cases the ground is lost on skinner valve causing the problem good luck (Message edited by luvrbus on August 23, 2011) (Message edited by luvrbus on August 23, 2011) | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 548 Registered: 9-2007 Posted From: 96.42.5.35 Rating: N/A |
Well then I am totally confused and may be using the wrong terminology. As I look at the engine on the left side is a plate with a air cylinder . This valve either allows the engine to run or not depending on its position. When there is air supplied to it it extends and shuts off the engine. So in most cases when I turn on the key. The cylinder retracts and stays that way during the run cycle. When I shut the key off, the cylinder extends and shuts off the valve. The air is supplied from a bank above the engine with at least 3 solonoids all in series so any one of them could cause the "shut down valve" to operate. When I remove the air line and blocked it. The cylinder was no longer extended and the valve was in a position that allows the engine to run, however when the key was shut off and the engine normally would have shut down, it no longer did and I had to "snub" it out using the clutch. I thought when I found the wire broken on this sending unit that it would be what was causing this to fail into the default mode of "no run" but I may be way off. Also in my previous post I labeled it Schrader valve when I meant to say skinner valve. No wonder I am not making any headway! (Message edited by bigrigger on August 23, 2011) | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1281 Registered: 8-2006 Posted From: 99.37.28.23 Rating: N/A |
John, Now we gotcha! The Skinner valve on the bulkhead is described as "normally open," in other words with no electricity to it, air will flow thru it to the STOP CYLINDER. The rod on the end of the stop cylinder pushes the shutdown lever on the governor. You can stop your engine the way it is now by walking to the rear and pushing on the lever that the rod would push on if the air line were connected. The engine stops when you turn off the master because electricity is turned off to the Skinner valve, so it lets air into the stop cylinder, which pushes the rod on the end of the piston out against the shutdown lever. John Roan was exactly correct above in how to locate what your wayward wire does. Since you say that your temperature gauge works properly, the loose wire may be for a hot engine shutdown? As John said, ground the wire with the engine running, and see if you get a hot engine light or buzzer. If not, check for 24 volts across the Skinner valve terminals with the engine running and the wire grounded, as it could be a low-water protection device. As the engine will start and run with the shutdown cylinder connected, the Skinner valve is OK, and the problem is electrically elsewhere. Turn on the master and see what lights and buzzes without starting the engine, besides the low air warning. Make sure it lights and buzzes, and you should also see no charge, and low oil pressure. Neither low air or no charge will prevent the bus from running, only continued low oil, or hot engine, or maybe low water. Hopefully another Buffalo owner can tell us if they came equipped with a low water shutdown? I hate to ask this, but is the rear stop switch in the run position???? Don't ask several of us how we know to ask! G | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2136 Registered: 10-2003 Posted From: 71.58.71.157 Rating: |
Ok, I dug out my manuals...Picture shows two sending units. One is the temperature gage sending unit. The other is the overheat sending unit which connects to a light and a warning buzzer.The part # in the book is 6402829-switch, engine temperature. No other numbers. The description in the maintenance manual: "A tell tale light in the instrument panel and alarm buzzer are used to warn driver of overheated engine. Overheat switch is installed in thermostat housing and is connected to wiring harness. Engine overheat switch has internal contact points which are open at temps below 210 deg F. If engine temperature rises to 210 to 214 deg F, the contact points close close and complete the electrical circuit, which causes tell tale to light and buzzer to operate." There is also a low coolant sensor system on the coach that turns on the same warnings if coolant drops approx. 8 to 9 quarts.If you have difficulty locating a replacement sensor, Most good auto parts stores and NAPA have a book with sensor specifications to match up a switch. Since it is a grounding type switch, voltage rating is not an issue. | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 630 Registered: 10-2003 Posted From: 66.165.176.62  Rating: N/A |
Based on the number 210 on the probe part of his sendor I suspect that is the overheat warning one. | ||
| John & Barb Tesser (Bigrigger)
Registered Member Username: Bigrigger Post Number: 551 Registered: 9-2007 Posted From: 96.42.5.35 Rating: N/A |
After spending yesterday covering half the state and talking to various "experts", I found out exactly what your saying is true. However NAPA or anyone else I contacted cannot get that switch. One place has a source that will custom build a switch with a 2-3 week wait. Anyway when I got home I had an email from one of the busnuts (thanks Gus) that he had a new switch extra from an earlier "bulk purchase" so i think I am going to be good as gold. I will bypass it for this weekends band excursion and replace it when I get the part. Thanks all for your help! When I look back and think of all the times I could have used the support of a group like this (ie. trucknuts,taxnuts, buildingnuts)... Thanks again all, John | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 1258 Registered: 8-2006 Posted From: 184.10.191.147 Rating: N/A |
I have a 4905 here for engine work and have no idea the difference between the 4107 and 4905 but the 4905 does not have a high temp shut down just a buzzer and light. I find that part strange as it has a shutdown for low oil pressure mounted on a manifold with a oil sending unit for the dash gauge good luck | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 2139 Registered: 10-2003 Posted From: 71.58.71.157 Rating: N/A |
a high temp shutdown was optional on these coaches and can be easily be wired for it. | ||
| Brian Evans (Bevans6)
Registered Member Username: Bevans6 Post Number: 73 Registered: 5-2009 Posted From: 65.92.54.23 Rating: N/A |
My MCI has two over-temp switches, one in each thermostat manifold on each head. Two part numbers are called out, one for 210 degrees and one for 220 degrees. Maybe if you call the usual bus supply places or MCI, you can get one. It's just a switch to ground, and probably a 1/2" pipe thread. MCI part numbers are 8C-28-12 for the 210 degree, and 8R-28-5 for the 220 degree. MCI calls it an "alarmstat" and the respective Kysor numbers are 1002-24200-34 and 1002-24200-36. Maybe those will help. Brian | ||
| Derrick Thomas (Thomasinnv)
Registered Member Username: Thomasinnv Post Number: 26 Registered: 10-2010 Posted From: 107.38.103.97  Rating: N/A |
mohawk has them in stock. If i remember correctly they are around $30 or so. |
