Starter issues resolved

Just Dallas · June 29, 2011, 08:34:21 PM

With a 2 stroke Detroit, which is the most prevalent engine in our buses, there can be no fuel pressure if the engine isn't running, (or in start mode). The fuel pump is mechanically operated and the fuel pressure switch is only there to to disable the starter if the engine is already running, so the operator cannot keep cranking after the engine is running. Remember, the engine is 30-40 feet away.. and some of those drivers don't care if they burn out a starter... they couldn't hear it anyway, (Ask Bryce or RJ or Runcutter or any number of others).
That switch is there to save the company money. Nothing more, nothing less.
A starter that goes bad can be changed in the shop for under $300. A starter that goes out on the road with a load of passengers can be in the $2000+ range, figuring towing, repair and rape of an owner.

Quote from: artvonne on June 29, 2011, 08:20:17 PM
Quote from: Just Dallas on June 29, 2011, 07:33:12 PM
I'm with Clifford. All it does is remove the starter solenoid from the circuit, so the driver can't engage the starter while the engine has fuel pressure.

The only safety feature it provides is to guard against a stupid operator.

Please explain? What would disabling the starter accomplish if it still has fuel pressure, and why would you not want it to start while it has fuel pressure?? I am trying to understand the problem this is trying to solve.

Chopper Scott · June 30, 2011, 05:09:09 AM

But Dallas that also allows the operator to over ride the shut down by pressing the start button in case the engine shuts down in an area not safe to pull over. I had to use it several times a couple weeks ago running into a pretty tough cross wind and some hills. She heated up, shut itself down and I pushed the start button to get over the hill and all was fine again. If it was just saving the starter I wouldn't have bothered.

ake1994 · June 30, 2011, 09:47:54 AM

Chopper scott,

Thanks for posting this! When I first got my bus 6 years ago I replaced the dash temperature gage and sending unit. That gage and the gage in the engine compartment have never read the same. After some testing and time I realized how much the dash gage was off and have just lived with it that way. After reading your post I realized I had installed the temperature sending unit with Tape. It is a one wire unit. While I have not had a chance to pull it out and get rid of the tape, I have measured the resistance to ground and it is NOT a dead short to the block of the engine. I believe this additional resistance is what might be causing the error in the gage. Hopefully this weekend I will remove the tape from the threads and will let you know for sure.

Thanks, I believe your post may have fixed my temperature gage.

Breck

rcbeam · June 30, 2011, 10:50:08 AM

Scott: You are right about the pressure switch being an "overrule" for the engine shutdown feature. Not sure if all buses have the automatic shutdown for temp or oil, but if they do then this switch will allow you to overrule the shutdown long enough to get the bus out of the street... of course if you don't have the shutdown feature then I guess it doesn't do much in that case.

Anyway, here is the part number from my packing list from MCI, dates, 06/06/11... part # 6463109, item: pressure switch. What I received was a two terminal switch.

Russell

luvrbus · June 30, 2011, 11:09:40 AM

You guys are telling me if the oil shut down stops the engine you are going to override it and keep driving the bus why not just read the gauges and pullover before it shuts down ? in the middle of a train track with the south bound heading your way I can see it
I have a friend that kept over riding his system when his MCI would overheat cost him a 15,000$ for a 8v92 so we removed his override he pays more attention now not saying you guys don't

good luck

Len Silva · June 30, 2011, 03:37:16 PM

The "Over Rule" switch is for exactly that purpose, to get off the tracks or some other situation where safety is more important than the price of an engine. On modern engines it is in the computer and should be labeled "Warranty Void" switch.

Chopper Scott · June 30, 2011, 04:55:44 PM

Thanks Russell. I'm going to get one ordered. I don't think anyone is over riding a loss of oil pressure Cliff, at least not me. I actually have 2 Murphy gauges installed in the back which are adjustable and I have them set at 205 replacing the original sending units. I've had 3 occasions now as I was about to crest a hill and the shut down occured so I just hit the start button, topped the hill and released it. All was fine. It's a nice feature to have in case of an emergency such as train tracks also. The point that you are missing Cliff is the fact that when the shutdown is tripped you have no more power and all you can do is coast to hopefully a convenient spot to stop, if you are lucky. Now stop and think. What's the first thing the sending unit does when you lose power? It gets hotter without any circulation and you sit by the side of the road waiting. With the overide feature I can let off the power, hit the overide, keep the engine moving fluid and it immediately cools back off and I adjust my speed accordingly. It's suprising how fast the temp can drop if it's still running and how long it takes to cool off if it's just sitting by the side of the road. A valuable feature to have and I'm not about to eliminate it. If your buddy kept overiding his shutdown then he is an idiot and would have found another way to screw things up. Don't blame it on a safety feature.

luvrbus · June 30, 2011, 05:23:06 PM

You should get a warning buzzer at 205 on 8v71 not a shutdown 215 is shut down and I do agree with you about water circulation cools one down faster but you have a long way to go to prove how valuable that feature is lol.
They are nothing but a problem to me and you probably would not run one with shut down from low oil pressure being a farm boy but I have 3 engines here welldone that people used the override to keep it going.
I read here all the time the MCI guys looking to buy that switch Eagle tried it for a short time, on both of my MCI's those things were always leaking or grounded out causing me nightmares so I done away with it on both but if it works for you stay with it never did for me very long

good luck

Chopper Scott · June 30, 2011, 08:15:32 PM

It works for me and I'm sticking with it. The original one I took off was covered in crud so I'm assuming it wasn't short lived. The temp gauge in the dash, after all my attempts to make more reliable is still a pos plus the fact that it only goes to one head. I watch my gauges constantly. For the MCI guys that know their gauges, if mine gets over the F, I know I'm close. But Cliff. I'm trying to help other MCI owners out with a problem that cost me some bucks. That is all. We want to retain that feature. Evidently you think we are wasting our time. Now a warning buzzer is your suggestion? Wonder how that would have worked with your buddy who fried his 92? I know you have a lot of knowledge about busses and such but I didn't ask if it was worth keeping. I just stated my experience, got a part number I wanted and am going on. If you wanted to help you would have had the number for me instead. Never once in all my posts about starter problems did you reply with the fact that MCI had a problem with the fuel pressure overide switches and they were junk....... until now. So give it a rest.

luvrbus · June 30, 2011, 09:05:27 PM

Sorry if I offend you Scott but you find very few of those still in the electrical circuit and most of these guys shutdown are not 205 it is 215 on a 8v71 and doesn't take but very little to push it over the top kinda like peeing in a cup and they get in trouble,
I have taken dozens out of the circuit for Indians here because the dumb @$# drivers melted the engines now when they shut down they don't go till they are cool it probably works good for a owner that pays his own bills and you are lucky yours is a 8v71 on a 92 series like the Indians have a few degrees will kill it I just always had trouble with those on mine and fwiw Napa sells that switch BTW my friends was 8v92 in 102 MCI

good luck

Chopper Scott · June 30, 2011, 09:31:32 PM

I'm amazed at your knowledge Cliff and your contacts and such. Just call this one a draw if need be and hope others learn from what college I went to... Hard Knox. I'm not offended. Just wanted to let others know what happened to me and get the right numbers for the 2 wire switch. Sorry that eagles don't have such.

I'm still not backing down on this feature. It's something worth saving. If it wasn't I would have just left it plugged off and bypassed it. I don't need it but occasionally when I do..... worth it's weight in something. A lot of folks on this forum consider your answers as gold. I have learned so much from you and others. If I have an issue thinking you are wrong however I am not shy about expressing my thoughts and generally will come prepared. But for me.... it ended up costing me a lot of cash and I'm still keeping it. I just hope others, as you have shown, will learn from my experience.