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Author Topic: Lots of smoke  (Read 2658 times)
wagwar
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« on: November 12, 2012, 04:47:24 PM »

I had to start the bus today after it sitting for about 3 weeks. It was a little below 50 degrees F. It just did not want to start and I had to bridge the house batts to the start batts and crank it 4 or 5 times. Normally it starts and dies on the first try and starts and runs on the second. I was careful not to crank it more than 5 - 6 seconds at a time. Finally, it caught and belched out a big cloud of white smoke. More than I have seen it do before. It ran a little rough for a few seconds and continued to smoke - then it cleared up and ran fine. We went for a nice drive and all seems well. I have a few questions:

Is it normal for a 6v92T to be a little hard to start at 50 degrees?  I would have expected that at 30 degrees, but I was a little surprised at this temp.

The water temp (at the dash) registered about 160 degrees. It never got above that. Isn't that a little low even in 50 degree weather?

Should I expect to have to preheat the engine at this temp?

Would it have been better for me to give it a little shot of starting fluid?

Thanks,
Jim

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luvrbus
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« Reply #1 on: November 12, 2012, 05:04:57 PM »

Just pre heat the engine they are all different some worse than others the turbo engine is a lower compression engine below 50 some are hard to start, what was the low of the night when down to 30 or 40 at night it will take nature awhile to heat that piece of iron at 50 degrees 

If the 160 degree reading is accurate that is to cold check the thermostats and the seals in the housings replace if necessary with 175 or 180 t stats  with new seals 
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buswarrior
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« Reply #2 on: November 12, 2012, 07:56:24 PM »

Three weeks sitting, busnut duty cycle...

Might need a little cranking?

The more you crank, the more smoke you'll get on starting.

What was the battery voltage? How strong was the spin?

Cranking speed is EVERYTHING to get these started. A weak spin in an excellent engine will produce a no start when it is cool out.

happy coaching!
buswarrior
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skihor
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« Reply #3 on: November 12, 2012, 08:16:03 PM »

When I start mine @50 or below, I start from the rear and hold the fuel shut-off in the off position for two or three cranks, then DURING the next crank let-er go and it fires every time with minimal smoke.

Don & Sheila
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RJ
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« Reply #4 on: November 12, 2012, 10:32:56 PM »

Jim -

I agree with Don.  Hold the fuel shut off in the "off" position while cranking from the rear for two/three times.

I used to do that on charters when I didn't have the opportunity to plug the coach block heater in somewhere.

Difference was that I'd let it crank for 10 seconds, then let it sit for 30 seconds, repeat.  90% of the time it would fire on the third go, on the fourth if it was below 35o or so.  Usually got the loopy idle for about a minute before smoothing out, too.

With your MCI, you should make yourself a simple tool to hold the fuel shut off, rather than running the risk of hurting yourself with the blower fan belt.

FWIW & HTH. . .

 Wink
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RJ Long
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luvrbus
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« Reply #5 on: November 13, 2012, 05:52:45 AM »

He could have a little injector problem also setting that long some dribble and takes a few turns to get the fuel back and the excess smoke could be from that if it starts easy today I would pull a oil sample and take to Cat it will tell if they are dribbling or not  fwiw
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TomC
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« Reply #6 on: November 13, 2012, 08:02:51 AM »

A little comment on starter cranking. The hardest cranking part on the starter is from a dead stop. Once the engine is turning over, the starter has very little to do but to keep the engine turning.  Every time you stop and let the starter rest, it takes a tremendous amount of torque to get the engine and transmission spinning again. Long starting cycles, like pushing a minute, are done all the time in our shop to get engines started after fuel injection work.  ALL the mechanics know that continuous starter operation isn't what burns out a starter-it's short bursts that will toast the starter.

I agree with cold starting.  My engine is still fairly fresh. But when it is below 40, I will start from the back.  Turn over for 5 seconds holding the fuel lever shut, then with the engine still turning over release slowly and the engine just comes up to speed with minimal smoking.  Now you with electronics can't do this, but should have the advantage of the electronics adjusting the timing to compensate.  Good Luck, TomC
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wagwar
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« Reply #7 on: November 13, 2012, 09:02:27 AM »

Thanks, all of you for your help.

I was under the (mistaken) impression that it was better for the starter NOT to crank it very long!  I was always careful to release the start button as soon as the engine started firing - so that the starter was not engaged with the engine running. I thought that would prevent damage to the starter and flywheel.

So, it is OK to crank it for longer periods of time - up to a minute?  That is really good info as I want to avoid damage to the starter or engine at all costs.

One question about starting from the rear - my house batt to start batt switch is a momentary on, so I have to be up front to use it. How can I use it if I start from the rear?  Would it be OK to use a simple tool to hold the fuel shut off, crank from the front and then remove the tool and crank from the rear?

Unless the engine is already warmed up, I always use the bridge just to ensure that there is plenty of power for the starter. Is that a mistake? 

My start batts (four Type 31) are strong and will usually crank for a good while, but I was under the impression that low voltage was more damaging to the starter than anything else. So, I use the bridge to ensure full voltage.
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luvrbus
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« Reply #8 on: November 13, 2012, 09:11:08 AM »

Low voltage is hard on the MT starter so are high CCA spin it for 30 seconds and let cool for a minute
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bobofthenorth
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« Reply #9 on: November 13, 2012, 09:50:41 AM »

Low voltage leads to higher current draw which is what is hard on the starter.  Why not replace your battery bridge switch with one that isn't momentary contact?
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R.J.(Bob) Evans
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Oonrahnjay
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« Reply #10 on: November 13, 2012, 09:55:57 AM »

  Low voltage leads to higher current draw which is what is hard on the starter.  Why not replace your battery bridge switch with one that isn't momentary contact? 

     Or add a second (parallel) momentary switch at the rear?  (I agree with your intention to feed good voltage to your starter - it's a good idea; just don't overcook the CCA's.)

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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
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wagwar
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« Reply #11 on: November 13, 2012, 03:58:38 PM »

How would I know if I'm overcooking the CCA?  I may be doing that as my house battery bank is six 8D AGM deep cycles in a 24 vdc arrangement. I calculate 730 AH, but I don't know how to calculate CCA?

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luvrbus
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« Reply #12 on: November 13, 2012, 04:05:06 PM »

Deep cycle batteries are not rated with CCA that is only for starting batteries so don't worry about it fwiw a 24 volt system will only have the CCA as the first 2 batteries you can add as many as you like it won't change the CCA same with a 12 volt system the 1st battery with the CCA rating never changes with the addition of batteries

good luck
« Last Edit: November 13, 2012, 04:27:03 PM by luvrbus » Logged

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Oonrahnjay
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« Reply #13 on: November 13, 2012, 05:34:05 PM »

   Deep cycle batteries are not rated with CCA that is only for starting batteries so don't worry about it fwiw a 24 volt system will only have the CCA as the first 2 batteries you can add as many as you like it won't change the CCA same with a 12 volt system the 1st battery with the CCA rating never changes with the addition of batteries
good luck   

       Exactly.  To not change the voltage, you have to have batteries in parallel (unless you WANT to change the voltage).  As Clifford says, you don't change the CCA from the closest battery in parallel; it's series that can change it.  Don't worry if you change the number of batteries; be aware of what you're doing if you change the configuration of your batteries.
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

(New Email -- brucebearnc@ (theGoogle gmail place) .com)
wagwar
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« Reply #14 on: November 14, 2012, 04:58:06 PM »

just a quick update:

Took the bus out again to day for a 40 - 50 mile ride. The dash temp gauge looked like it was around 160 F (it is hard to tell as there are only marks at 150 and 200). So when I got home I shot the thermostat housing w/ an IR therm.  Temps were a little under 170 F but above 160 F. This was after a few minutes of engine idle.

So can I conclude that the thermostats are working properly?  Or that they are even there?

Jim
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