1986 TMC 102A3 - Slow Take off

jraynor · August 06, 2018, 06:57:37 AM

Good morning all,

I took the bus out for a maintenance run this weekend to celebrate finishing the new subfloor throughout the bus and installing my drivers seat. I haven't driven the bus in quite a bit (1.5 Months) but I did start it up last weekend and let it run for about 45 minutes - hour. When driving this weekend, it seemed that it was really slow taking off from stopped. It would go slow through 1st and 2nd gear, pretty much skip 3rd gear, only heard it for about 5 second if that, then gets to 4th and seems to have more speed to it and gets on up to 50 MPH.

I was looking through some of the oldest posts just for browsing and saw one where someone mentioned that a customer complained about slow take off and the intake was clogged. Could this be my issue as well or does someone might know what the issue is?

Thank you,
Jonathan

chessie4905 · August 06, 2018, 07:02:42 AM

How are your fuel filters? If intake plugged, you will get a lot of black smoke from exhaust. If filters plugged, you will see much less smoke on acceleration than you are accustomed to.

luvrbus · August 06, 2018, 07:15:53 AM

Fuel delay is probably sticking from lack of use or the fuel filters

jraynor · August 06, 2018, 07:40:11 AM

I honestly don't even look to see the amount of smoke that comes out when accelerating. Just not something that I have been looking for when I drive it. as far as fuel filter, the one in the back that you can see the fuel level is still in good condition as far as I can tell (only a small portion up the filter is covered in fuel so its pretty new still?)

Iceni John · August 06, 2018, 07:42:41 AM

You're letting it idle for 45 minutes to an hour? That's not the best for the engine. It won't get up to temperature, even at fast idle (unless something's seriously wrong with the cooling system!), with the result it can wash unburnt fuel into the oil, or worse. Incomplete combustion can also leave carbon on the rings and valves. It's best to not start a big diesel unless you plan on getting it up to full operating temperature, and that takes at least fifteen minutes of hard driving. If you need to charge batteries, buy a battery charger, but leave the engine off unless you'll be driving it. It's better to not start a diesel at all for several months instead of idling it monthly: there are some RV owners in the RV yard where I keep my bus who do that every week or two. Ouch!

John

jraynor · August 06, 2018, 08:10:22 AM

Thank you for that information John,

I was not aware that it does more harm than good to have them idle monthly. I don't start it up to charge the batteries, when I do want to start it, I charge the batteries in advanced. Ill keep that in mind and only start the bus when I plan to drive the bus.

eagle19952 · August 06, 2018, 09:07:06 AM

Quote from: jraynor on August 06, 2018, 08:10:22 AM
Thank you for that information John,

I was not aware that it does more harm than good to have them idle monthly. I don't start it up to charge the batteries, when I do want to start it, I charge the batteries in advanced. Ill keep that in mind and only start the bus when I plan to drive the bus.

Setting the "idle" at 900-1000 rpm does no harm.

jraynor · August 06, 2018, 09:23:17 AM

Quote from: eagle19952 on August 06, 2018, 09:07:06 AM
Setting the "idle" at 900-1000 rpm does no harm.

Only hard part is that I have no Tachometer. Im looking to get one so I can watch the RPMs but I just have a large speedometer and air pressure, then small hourmeter, fuel, temp and oil gauges. I plan to add a large size tach when I can find one.

eagle19952 · August 06, 2018, 04:03:09 PM

Quote from: jraynor on August 06, 2018, 09:23:17 AM
Only hard part is that I have no Tachometer. Im looking to get one so I can watch the RPMs but I just have a large speedometer and air pressure, then small hourmeter, fuel, temp and oil gauges. I plan to add a large size tach when I can find one.

about 1/4 1/3 throttle

just not "none"

Geoff · August 06, 2018, 04:29:57 PM

I know of a few people that used to start their buses monthly without driving them and their mufflers got plugged up with oil. Same symptoms as your bus when they finally drove them. It just takes a while to blow the oil out
Worse if you have a catalytic muffler.

OKIE9ERS · August 06, 2018, 04:40:49 PM

I remember someone mentioning idling was bad a while back and meant to ask about that. Because I remember as a kid going to the Greyhound terminal and they never shut those things off...8 or 10 Detroits rumbling was so cool to me...
But now Im gathering its just idling without getting to operating temp thats harmful?
Ive been starting mine every weekend to either move it into the shop(halfway all that fits), or to mow where its been sitting, or just to air it up...
So, if I take it a few spins around the section line each time it'll be ok?
Dieing to drive it anyway, and practice shifting thay funky 4 speed...
Thanks

Geoff · August 06, 2018, 04:50:43 PM

Well. Idling Detroit's in the old days wasn't as bad for Greyhound since they were always on the move.
Do your air box drains go to the ground, back into the engine, or to a collection tank?

buswarrior · August 06, 2018, 05:00:13 PM

Here we go again with the religious observances of false prophets...

Do you idle your car for certain purposes?

Then idle the bus for the same.

Certain purposes.

The busnut who renders the coach undriveable is statistically putting the project in great peril.

No driving means no fun, and if there's no fun, the project hits the wall, and then we never hear from 'em again.

Everything goes to hell in a sitting coach. What worked when parked, doesn't after extended sitting.

Keep driving it, and it will keep driving.

Stop, and it will exponentially add to your repair problems.

The tired old whore lost her virginity long ago. This ain't no concourse worthy vehicle due this sort of idling fanaticism.

It's leaving the air system valves sitting that will cause more grief than most others.

My only issue with idling, is that you are spending fuel money and not going anywhere...

But when there's a reason, run the engine and carry on.

Happy coaching!
Buswarrior

DoubleEagle · August 06, 2018, 07:28:58 PM

Quote from: OKIE9ERS on August 06, 2018, 04:40:49 PM
I remember as a kid going to the Greyhound terminal and they never shut those things off...8 or 10 Detroits rumbling was so cool to me...

Chances are those Greyhounds were running at fast idle to keep the A/C running, not at low idle. Extended low idle in a 2 cycle is a no-no, and not healthy for the engine for reasons that have been well documented.

jraynor · August 07, 2018, 05:35:49 AM

Quote from: eagle19952 on August 06, 2018, 04:03:09 PM
about 1/4 1/3 throttle just not "none"

So leaving the bus at fast idle when I'm doing work should provide a save idle?

Trust me, I love driving the thing around. Who doesn't love driving a 18 ton beast around town just because you can. I would drive it every weekend on my runs to lowes. It has plenty of space to put everything that I could possibly buy.

If oil has possibly clogged the muffler, how much driving should clear it out? I can use this as an excuse to go drive it to town this weekend so my wife wont be annoyed at me