Dodge CTD vs Bus CTD

[jaynes]

So I just had a quick question. My school bus I drive (TC 2000, Blue Bird) has a Cummins 24v Turbo Diesel. Sounds just like the 24v dodges. Looking at it from the top side like I have to, I can't tell if it is the same 5. 9l or not, or if the turbo is bigger. What are the difference between these two engines? Thanks!



jaynes

 

[JLEONARD]

I'm guessing Greenleaf will jump in here and answer... he must be out at lunch... er, I mean workin' on a bus right now.

Wake up Scott..... :-laf

Jay

 

[TKingsbury]

We have a Thomas shuttle bus at work with a 260 hp 24valve in it. That bus is noticeably quicker than the ones with the p-pumped 190s. We have quite a few buses and depending on the year and brand of bus, they will have different turbo and exhaust manifold set-ups. I haven't given them a thorough looking over and compared them all as I rarely work on them personally. I would think engine-wise it's the same as a pick-up, just different hp rating and bolt-on accessories to fit a bus chassis.

Travis. .

 

[Greenleaf]

Huh?

Wha... What? Can't a guy get any rest around here! :-{} That TC2000 I just climbed out of sleeps well if'n one would set a board across two seats.....



What's all the fuss about anyhow?





GL

 

[jaynes]

bah... I'm making a fuss about what the difference between the 24 CTD in TC2000 that I drive versus that of a 24v Dodge Ram... got any info for me? Thanks y'all. I do like that bus though... it's nice



jaynes

 

[Greenleaf]

The engine mounts are entirely different. As the innards are concerned, I cannot say for certain however from what I "HAVE" seen, stuff is the same.



The valve cover has the oil fill and the hole to gain access to the pump's drive is covered with either a plain plastic cap or a breather vent.



There is a Bendix air compressor attatched to the engine where our power steering pump is located, and there may be some very slight difference inside the timing gear cover to beef it up a tad as I have never heard of a dowel pin problem with these bus engines. I have yet to pull a front timing gear cover, and untill I do I will not know for sure.



Only slight differences are noted. It's the same engine be it a VE power plant, P-Pump or ISB



GL

 

[jaynes]

thanks! What about the turbo? Is it the same size or bigger? I do know mine's an ISB...

 

[Dieselnutz]

The engine mounts are entirely different. As the innards are concerned, I cannot say for certain however from what I "HAVE" seen, stuff is the same.

Does this mean that they will not unbolt and then go in the Dodge?

 

[Greenleaf]

Just the engine mount is/are different. The engine BLOCK is the same, as in they all have the same mounting pads for various accessories and mounting fixtures.



The bus engine uses a very large cast-iron engine mount that bolts to the front of the block, surrounding the damper. Thus making R&R the surp. belt difficult as you have to snake and feed the belt in between very close quaters. Wears on my nerves some times. It is a single mounting point on the cross member with one very large rubber mount.



The rear of the engin is supported by means of the bell housing mounts. It's entirely different as one would expect, because we use the 545/630/World/2000 and some other trans, all Allison models.



Turbo is the HX-35 w/12 waste-gated housing on the newer units. The older bus, as JLEONARD affectionally dubed Old Smokey #3, because it has been, ah... . well never mind. It has the H1C with 18. 5 housing non gated.



One bus has the air to coolant aftercooler, thus the injection lines are routed differently.



Cooling fan is either a heat sensitive viscous clutch or the newer electric Horton.



Some of the engines have heat shields over top the exhaust manifold/turbo assy.



You can turn up then power just like any other CTD. But that's annother story.



-S

 

[tugboatphil]

Scott,



What size board do you recommend to make a full length seat bed? Is pine better than using hardwood?

 

[Greenleaf]

OK, what "I" did was to take a 3/4" sheet of plywood, rip it to... ... ... ... ... . ahhhh. Thought you'd trick me there did you? I'm smarter than that.



Go put your (perfectly good) shoes back on and leave us government workers alone.



GL

 

[jaynes]

haha, very interesting.

 

[MontyDyer]

The ISB's in RV, Fire truck, and all medium duty applications will also have a different cam profile for more low end torque as well as some other small differences in the head as well as the pistons.

 

[TKingsbury]

I have never heard of a dowel pin problem with these bus engines. I have yet to pull a front timing gear cover, and untill I do I will not know for sure.

GL

We had the cover off of one of our p-pumped shuttle busses the other day and the dowel pin was 1/8" or more unseated. Kinda surprising since the thing has a zillion miles on it and it's ten years old and the cover had never been off. All of the case bolts were loose, and the one behind the cam gear had come completly out and was getting hooked and banged by the gear. The bolt catching the gear cracked the housing (big oil leak).

Travis. .

 

[rkressg]

The ISB found in commercial applications (non-Dodge) all have 16. 3:1 compression. The Dodge ETC has 16. 3, the ETH has 17. 0:1. The ISB ECM has 2 50 pin connectors, the Dodge ECM has 1 50 pin connector. There are various different sensors, such as the APPS(TPS), but for the most part the internals are basically the same on the ISB as the Dodge ETC motor. The ETC Dodge and the ISB have the same injector pump (VP44) the Dodge ETH injector pump (also VP44) is slightly different.



The ISB engines came anywhere from 160hp to 300hp. The only difference in HP ratings was in what codes you put into the ECM. Of course, the Dodge came came as 235hp (ETC) and 245hp (ETH).



They share almost all the same internals as the ETC, about the only difference on an ISB and the ETH are the pistons and fuel pump.



Also, the ISB sets the rev limiter to 2600 rpm, the dodge models are limited to 3200 rpm. There are also many little differences, but they are nothing major.



The turbos on the ISB are almost always HX35w. The Dodge manuals came with HX35w, some of the autos came with HY35w turbos.



The 3rd gen motors, HPCFR motors, have major differences between the dodge apps and the commercial apps. The most major difference is where the timing gears are. On the commerical apps, the gears are on the back of the engine, on the Dodge apps, they are still on the front. They were moved to the back to make changing gears and camshaft simplier on larger chassis. But still, most of the internals are basically the same.



-Rich

 

[jaynes]

wow thats alot of good info, thanks fellers!



jaynes

 

[Greenleaf]

Bluebird no longer installes the Cummins B in a school bus... ... ... . They use CAT power now as Cummins went and redesigned the B engine for better emmissions etc. I guess I'll have to become a CAT guy. Yuck. That don't sound right does it.



I have nine ISB engines here. That's a lot of lift pump work... ... ... AHhahahaha I get my share. There is quite a few of the P-Pumped engines here as well. They keep going and going and going... ... .....



I have noticed that the ISB engine runs outta "R's" at around 2600 RPM. Seems low, but then we ain't in no race to get the kids into school either.



GL

 

[jaynes]

haha, yeah my bus tops out at 59mph. Kinda hell with traffic on the interstate, in which the speed limit is 70 mph! I'm glad mine still has the ISB, though!



jaynes

 

[bgilbert]

I'm starting to put two and two together here. :-laf Wants a newer turbo, wants info on bus turbos etc :-laf , now just need a story to tell the boss. 'Hmm boss, you're not gonna believe this. The turbo thingy on the bus just fell off!! :-laf ' Or, 'I just lost a bunch of power, and there is flames, sparks and smoke going everywhere under the doghouse '.

 

[Greenleaf]

I just drove a bluebird and it never hit it's top end out on the open road I use as my test track... ... ... ... ... ... ... oh... . your talking about an ISB powered unit. Yah, them pull hard up to about 65 (mph) then the fuel runs out.



GL