Can't go faster than 60mph max...30mph on hills

[Spinksmatt]

Trying to figure out why my 2000 Thomas Saf-T-Liner will not accelerate properly. It has the Cummins 5.9 ISB in there. I am a newbie, just bought the bus two months ago, no prior bus or Diesel engine experience. I just changed the fuel filter, and have checked the fuel lines. The fuel injection pump was replaced a couple years back...although I've heard that these buses often have problems with those...uhhhgh.

I do have a leak coming from the fuel tank area that I need to fix. Would that cause this issue? I don't hear any unusual noises or jerks or anything like that. I can hear the turbo working. It seems like so many things might be the cause. Anyone experienced that could point me in a good direction?

Got the bus for $2700 and already put $1200 into repairs.

 

[Elliot Naess]

60 MPH may be all it is supposed to go. Remember, this is a school bus.

For someone without heavy vehicle experience, it can be quite an adjustment to accept how heavy vehicles operate. (No offense intended!)

When I bought Millicent, she struggled to reach 55 MPH. Then we turned up both the fuel (power) and the governor (RPMs). Now she accelerates right thru 55 and tops out around 64, at the official redline of 2,600 RPM.

Still, I see 20 MPH at times on steep grades with (very) heavy load.

Obviously, fix any leaks and such real problems.

Can you recruit an experience driver to evaluate her?

You bought a 16 year old bus for $2,700. I bought a 14 year old bus for $5,500, and I'm quite happy with her, even though I paid "full retail".
10 years later I put $2,000 into her for front end repairs -- king pins, rod ends, and brakes. In the interval... a few hundred here and there, and two or three $500 dollar bills -- maybe (very rough estimate) an average of $600 a year in repairs and fluid changes.

In these ten years we have spent several times the total of all that on fuel. All soooo worth it!

 

[Spinksmatt]

I thought it was a pretty good deal. I'm happy with it. I wish I knew any experienced drivers though. I removed all the seats, and feel like this load shouldnt be too heavy, couple of futons and one bunk bed. I do plan on figuring out the fuel leak situation, for sure. But, it just seems like there must be something else happening...it hits 60 only on the highway after like several minutes of acceleration in perfect conditions... thanks for the encouragement though

 

[Elliot Naess]

Well, that's as empty as it can get, so it should "fly". But "flying" is still relative. "Several minutes" from 0 to 60 may be normal if you are accustomed to a peppy automobile.

Maybe you could swing by a nearby school bus barn and chat up the drivers and/or mechanics? Not to test drive your bus on company time, of course, but on his personal time. You wouldn't need more than ten minutes of his time. The bus mechanics I have met have all been wonderfully friendly and helpful.

 

[Spinksmatt]

Thanks, Elliot. Will do that.

 

[Kubla]

You need to find out more information about your bus, like which transmission, rear end ratio and engine horse power and if it is speed limited by a governor, really common in school buses

 

[cowlitzcoach]

Which transmission and rear end ratio can also determine how long it gets up to cruising speed.

Try locking it in a gear until it gets to the redline and then manually upshifting to the next gear. You may have a transmission that has been programmed to shift up as soon as possible. If you have a MD3060 that has five usable gears and it shifts into 5thOD at 35 MPH it could take you next to forever to reach 60 MPH. On the other hand, if you keep it locked down you may find it is relatively peppy when the throttle is stomped.

I have driven several different models of the Saf-T-Liner FE that had various models of the 5.9L Cummins. They ranged from 190 HP to 250 HP. All of them seemed like hot rods compared to Cummins C-190 equipped Gilligs and GMC OEM vendor supplied chassis buses with gas V-6 Type 'D' buses we had back in the day.

You may also want to determine that all of your brakes are releasing completely. Some brakes adjusted to tightly can really slow you down while accelerating.

 

[Spinksmatt]

Thanks everyone for the help. If it has a governor, what would that make the engine sound like or do when I hit 60? Also, how would I remove it? It just doesn't seem like the brakes idk. Also, it just doesn't feel like this is all the faster this bus should do. Obviously, I'm no expert, but something doesn't feel right. I'm going to try to find an experienced bus driver this week to test drive it.

 

[gbstewart]

what's the rush? my bus tops out about 110kms around 65 miles an hour, I like to run about 95kms . best fuel mileage , nice relaxing drive, less noise etc.
gbstewart

 

[prof_fate]

I've driven newer Saf-t-liners and OMG..i can run faster carrying the kids on my back I think.

IC's can be had with 220 240 and 260 hp motors and different gearing and even transmission. It can make a HUGE difference in the performance of the bus.

We have an 11% grade in town that I drive daily and the older IC i've had this week is fine empty..put 60 kids in it and OMG..it won't hit 25 on the uphill..can do 30-35 empty.

The saf-t-liber is 31k GVWR, 220hp and a '13 with 70k miles on it. Loaded (60-70 gradeschool kids) it will not get to 35mph between stops (speed limit is 35, road fairly level, 1/4 mile between stops). Our newer IC 260hp buses cna do it no problem.

As for hiway, haven't had the thomas on the hiway. Had several of the IC buses and no problem doing 55, 65 even 70. Empty or less than 1/2 loaded.

Govenor limites max RPM of the engine - all the ones iv'e driven seem to top out about 2500, 2600 rpm. Not sure what trans or engines are in all of them..the IC's have cummins and probably 2500 or 3000 trans (i can ask). I know the older IC/BB buses (we have both) have 545's in them and our transits have the 3060s

 

[Spinksmatt]

Yeah. I do need to figure out more of the specs on this bus. Previous owner didn't know much, he got it from an impound that he worked at.

Here's why I want it to get a little more power. We are planning to drive it all the way from Indiana to Nicaragua. And want to be able to make it, with my family and possessions, over hills or even mountains if need be (of course avoiding them when at all possible, but have you ever driven Guatemala? We did it last year and OMG). Anyways, I've got a lot to learn, but it just feels like it should have more power...

 

[Tango-SKO]

If you are going to be driving in Guatemala, keep ground clearance in mind. The few folks I have chatted with that took their buses through Mexico & Central America all discovered that tail dragging was one of their most common problems. One was stuck blocking a muddy, bouncy road for nearly two days because their drive wheels were lifted off the ground. Their tale of jacking and rocking it back into contact was pretty scary.

 

[Spinksmatt]

The bus has lots of clearance underneath, thank God. I definitely considered that when making the purchase.

 

[prof_fate]

he's talking more about 'departure angle'

I've only scraped the rear of a bus once - but my camper and cargo trailer (in particular since it's very low at the rear) i scrape often.

The bus has lots of clearance underneath, thank God. I definitely considered that when making the purchase.

Save​

 

[prof_fate]

 

[Spinksmatt]

Oh, thanks for the pic. I see what you're saying. Anyone who has travelled Guatemala and Central America have a recommendation on measurements for that? Will I be ok?

 

[Hank's P-O-S]

First off, there are two different kinds of governors. There are "speed" governors and "engine" governors. One limits vehicle speed with the transmission and the other limits the engines rpm to the manufactures top "safe" RPM.
You do not want to increase your engines top rpm, it is there for a good reason. It is there to prevent unnecessary engine wear and unreasonable engine temperature.

Have you ever gone faster than 60MPH in a school bus? If you have, I would guess you wouldn't ever want to again. I have, and they don't drive real straight above that.

I have spent time in Guatemala in a 10 window bluebird with a 4+1 manual and a 200 HP DT466. We dragged rear several times and spent a lot of time in 2nd or bull-low.
I think you haven't considered where you are going. Either you are going uphill, and will run out of power. Basically you WILL be going 15-20 MPH in second gear, or you are going downhill at 15-20 MPH in second gear to avoid catching the breaks on fire or falling off the road. Supposedly the steepest interstate grade in the us is 8%, expect grades of 15% and on real shitty roads.

I'm sure you have seen the local "chicken" buses. They may make 55 MPH uphill but they go though a lot of fuel, like 4 MPG with a DT466, black smoke all the way. The do go upwards of 50 MPH downhill, but I saw a lot of buses with smoking breaks. Several times I saw one of the front tires come up off the pavement!

Take it slow, take it safe!

---> for the record, my original "dirty Canadian" With 175 HP and a top speed on flat ground of 55 MPH was going to, and probably still will, go on a trip from central Canada all the way to Guatemala towing a 25 foot 10k trailer, although without me.

 

[DoubleO7]

If you have any kind of rear overhang, it would help to add some structure and sheet metal to the underside from the tires to outer edge of the bumper.
Making a nice smooth, full width skid plate.

 

[Kubla]

If you are not at engine recline at 60 mph (around 2700 rpm) then you Have an electronic governor that limits engine speed when you hit 60, you need a computer and the right software to change that

 

[AlleyCat67]

<snip>Supposedly the steepest interstate grade in the us is 8%, expect grades of 15% and on real shitty roads.

I think the final descent to the Yukon River on the Dalton Highway in Alaska (AK 11) is like 12%, then the same on the other side of the bridge. Also a few other places along the road that have in excess of 10%. Though it is not an interstate highway so you are correct on that, I reckon I've covered every mile of interstate in the 48 states and can't call any grades that were more than 8% on any of them.