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hoodeleydoo

your opinions on Fleetstar 6-71 with allison auto

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Hi guys,

I am looking at this truck to buy. I never owned a 2 cycle diesel before. I heard a lot about the 6-71. I heard there are a lot of parts available and are pretty cheap. I heard the allison auto trannys from back then werent so good. I have no actual evidence or experience.

The truck is a fleetstar 2070A that was a fire truck. the body is really nice, no rust on the frame either. The untility body woul dcome off and I will put a flatbed or small sided dump on it.

can anyone give me their experineces and advice on the engines and the truck. what to look for etc?

is the 6-71 any good? reliable? power? etc?

I think its came with the detroit from the factory. I would make it a flatbed dump.

I need to haula 10 ton trailer and put a dump on it.

thanks!!

Kevin

post-6834-1219142897_thumb.jpg

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If you understand the 6-71 is only good for about 210 HP without a turbo and about 250 HP with a turbo, the truck will most likely do a good job for you.

I have a GMC Brigadier 10-wheel dump truck with a 6-71/Road Ranger. When I get to any hill I have to start rowing through the gears. Even still, it will outrun anything of a like size with a gas engine.

It will certainly handle any load you can put on it in combination with whatever you can load onto a 10-ton trailer. Just be aware you won't be setting any speed records.

If the price is right, it should work really well for you.

Since it has seen fire service work it will most likely have had good maintenance and will not have been abused too severely. In other words, it should have a lot of good life left in it.

Good luck.

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thanks for the notes mark.

can you slap on a turbo without changing pistons or upgrading anything else?

I'm not sure extra power will be noticed but maybe the efficiency would in fuel mileage.

thanks again

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If that fire truick was a pumper it could have 1000's of hours on the engine.

Even a 6-71 can be worn out with use.

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I guess the top speed is 50-60, so more like 50.

would it be a good hill climber? with a top speed geared so low like that I would suppose it would accelerate relatively quickly and be ok on hills. where I am moving to in NY and going to be driving around in has a lot of steep grades. some very steep.

any input would be appreciated.

thanks

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Keeping in mind the 2-cycle DD's have a very narrow power band, a truck equipped with a 6-71/Allison will climb fairly well if the RPM's are kept in the power band. Lugging is very easy to do if the transmission isn't shifted down manually in order to keep the RPM's up.

Other engines of the same relative size would include the Cat 3208 and the Cummins 555.

Compared to them, the 6-71 will pass them like they were stopped.

The most important thing to remember is the 6-71 is only rated up to 210 HP naturally and 250 HP turbo'ed. It will not keep up with a big cam Cummins or any -92 series DD.

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We had a 2010 Fleetstar that had a 549 Gasser and a 5+2.............Worked pretty well until it cooked a head gasket and cracked the block............So we bought a 2050 Fleetstar that was shot for its 555 Cummins to put in ours..........Ended up not much swapped without mod's and in the end we had a 2010 powered by a 555 that was gutless. Had we known that I'd had put a 6-71 in it we had access too. Detroits may make alot of noise and leak oil, but they are running fools!

Only issue I see is the Allison, don't know how well that would preform doing heavy work behind a DD.

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We had a 2010 Fleetstar that had a 549 Gasser and a 5+2.............Worked pretty well until it cooked a head gasket and cracked the block............So we bought a 2050 Fleetstar that was shot for its 555 Cummins to put in ours..........Ended up not much swapped without mod's and in the end we had a 2010 powered by a 555 that was gutless. Had we known that I'd had put a 6-71 in it we had access too. Detroits may make alot of noise and leak oil, but they are running fools!

Only issue I see is the Allison, don't know how well that would preform doing heavy work behind a DD.

yea, I'm not too keen on auto's, I would prefer a stick. If something sends the allison packing, then maybe I put a stick in?

It looks like a 4 speed tranny. I havent gone up to see it yet or drive it.

I don't even know how to drive it, would it be like a pick-up truck.....put it in "D" and step on the throttle??

thanks again!

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Short answer, put the lever in "D" and take off.

The AT/MT/HT series of Allison transmissions are fully automatic and don't normally need to be manually shifted.

Having said that, most of the time they will shift when the shift package tells it to do so. Sometimes that is a little early on the upshift and and a lot late on the downshift.

It isn't a problem if you are unloaded or on the flat. It becomes a problem if you are starting out with a full load or you are climbing a hill. In those instances, manually shifting allows you to get the maximum RPM's before the transmission shifts.

If the middle number of the transmission model is a '4' the transmission is a four speed. If the middle number is a '5' it is a five speed.

If the transmission is an AT model (not likely), it will lock up in fourth gear.

If the transmission is an MT model (most likely), it will lock up in third and fourth gears.

If the transmission is an HT model, it will lock up in second, third, and fourth gears.

On a hard pull, it will act as if there is half a gear between those gears when the transmission goes into lock up.

Once you get used to an Allison it is very hard to go back to being shifty. They are particularly nice if you ever have to do much urban/suburban driving requiring lots of stop and go.

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well, I went and looked at it and drove it (could't go any faster than 1st gear or reverse due to the utility body not being completely removed).

runs nice, looks nice, cab and chassis are in good shape.

the trans is a HT 750 CRD.

the engine is non-turbo.

well see if I get it.

thanks everyone for all the help!

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The HT-750 CRD is the ultimate tough transmission from Allison.

It has a deep low first gear and lock up in the top three gears.

Behind a 6-71 non-turbo you will never wear it out or break it unless you really abuse it (like going too fast when you try to lock it into deep low).

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The HT-750 CRD is the ultimate tough transmission from Allison.

It has a deep low first gear and lock up in the top three gears.

Behind a 6-71 non-turbo you will never wear it out or break it unless you really abuse it (like going too fast when you try to lock it into deep low).

I bought 15 1987 Ih s-2200 single axle trucks and resold them back in 2002 and they all had the 6-71 detroit with turbos and the hp rating on them were 330hp. They had alot more pep and power than the standard non turo 6-71. I really like them.

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I purchased a 6V-53 Series that was removed from a fire truck. It was factory set (injectors, cams, etc) for much higher horsepower than a standard 6V-53. It would really pull and had much more lugging power than most Detroits. I also owned a 6-71 in a 18 wheeler grain truck and grossed 73,280. It was slow on the hills but would run 70 on the flat streches. The 6-71 with the allison would be a great combination. I would also suspect that it is setup with a fire truck application package which increases the horsepower and torque.

David

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that good news....

When I drove it, it didnt have a load other than the utility bed. I guess that weighs about 2-3 tons with all the junk in it. if it doesnt hhave enough power (which would be doubtful) I could always swap a turbo engine in it.

one thing I couldnt find and the owner didnt know, was how to turn thte pto off for the generator (off the tranny).

he has to get the title squared away before I can consider buying it. NY wont let me register it (1972) is the cut off.

thanks again for the advice!

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