Thomas 3800 Dt466 speed restricted

[expat explore]

Hi guys,

Thanks for all the threads and real world information.

My name is Joel and I have been living in the US with my family all the way from Australia for the last couple years. We will be heading back home in the next 12-18 months and are in the process of buying and converting an old school bus and do the complete lap of this amazing country over a 3 month period. Starting and finishing here in sunny Corpus Christi.
We will offload or Skoolie (at a steal no doubt) upon our return and head back to Oz with some amazing stories and memories.

Why a skoolie and not a motorhome is what every one asks me and my answer is just because....Just because I can is the answer Motor home probably would be easier, just not near as fun.

So I am just about to pull the trigger on 1998 Thomas 3800 DT466e. I'm not sure which gearbox it is running and I don't want to bother the seller for the hundredth time just yet.

I test drove the bus and around town it was fantastic but when I got it out on the HWY I was not able to go any faster than 55mph. Not that I want to go much faster but it would be nice to be able to do 65mph on the large open stretches.

My question is... Is there a governor that can be adjusted or any other way of boosting the speed up a little with out the need of adjusting the gearing or tire sizes?

Thanks for all you help

Joel

 

[EastCoastCB]

It could be limited by the ECU. It could be limited by gearing.
Does it cut out or just run out of breath?
55 sounds reasonable and safe till you try driving through Atlanta. I NEED 70mph at least the capability for short durations.
Either way- if its gearing you can fix that for a grand or two, and if its the ECU that's a couple hundred or free if you know someone with Navistar service software.

 

[cadillackid]

ECCB has it pretty dead on... except normally when I go through atlanta im lucky to drive 20 let alone 70!!!



alas what are your RPMs at 55... if the RPM goes up to 2600 and stays there at 55 you are mechanically limited... gears, tires, and the like..



if your RPM either drops off when you hit 55 or stays steady at less than 2600 then its a computer program change to lift the speed...


that year, engine, and being in corpus christie is very well possible the transmission is the AT545 auto which isnt a great highway trans. but is very workable if ytou dont try to haul ass in the mountains... ...


-Christopher

 

[expat explore]

Thanks for the comments guys. I never really paid to much attention to the RPMs in the way you mentioned. I'm guessing that 2600 RPMs is the magic number and I don't really want to be heading up over that by pouring in more fuel or switching out the gears, tires etc.

During my test drive I noticed the engine sounded really tight and the gears shifted smoothly. I didn't notice any oil around the engine at but the tranny was quite dirty and oily. I was thinking from possibly the rear main seal? Would this be fairly normal or should I be a bit concerned? The bus had been sitting in the same spot for some time and there was no sign of oil on the ground.

Thanks again for the help and I will keep you all posted.

 

[ermracing]

I think you would notice if the engine was spinning at 2600 rpm, even if only for a few miles. Ours was limited to 55mph initially and was turning around 1850 rpm at that speed. Like EastCoastCB said, the ECU fix is simple, but the cost is variable depending on who you know. Ours was done for free when it was inspected, but had to replace the air bags so we dropped a few $$$ anyway.

 

[cadillackid]

2600 RPM is a hard stop... even if we crank up the computer to give it more fuel. the RPM limit is going to be there... I might be able to raise it but I surely wouldnt try it.. thats how you bang valves with pistons..



MANY busses come shipped from the factory with a computer limited speed of 55.. if the RPMs are below 2600. then its easy to just turn the speed limiter off.. you can drive the bus against the rev limiter.. it wont go over...


I never recommend driving any engine at its maxx. . but the engine manuals state that its continuous duty at the max RPM...



a leaky valve cover gasket or dipstick tube are common places for oil to leak on a DT... also the road-draft tube can blow oil everywhere if the oil has been over-filled. which is easy to do...



I was SURE i had a rear maion seal leak on my DTA360. and in fact even had the part ready to install when I did my trans swap.. only to find that my rear main was dry as a bone but oil was leaking around my dipstick tube... i looked it up and found that to be somewhat common.. the oil runs down the side of the block and gets blown back all over the transmission..

-Christopher

 

[cadillackid]

I travel alot and have the full featured software.. i will program anyone;'s engine. that ends up near me wherever that may be... most I might "charge" is a Doppio-Espresso at a local coffee shop
-Christopher

 

[expat explore]

Thanks Christopher...That is very helpful and puts my mind at ease. I will check the bus out this weekend again with some better understanding and knowledge of what to look out for.
Regards Joel