1984 M936 issues and upgrade?

[Sniper2323]

This truck was bought by a VFD and converted to a fire tender. Stainless tank, 2600 gal and change. I believe it has the cummings 240 or 250 in it. Needless to say, with a load of water on pulling a hill is a slow task. They smoked the brakes coming down a hill with a load of water on. So... We bought it, and converted it to do more. But we are looking at the engine. It has issues starting. We installed a anti drain back valve (works correctly). But it appears that the fuel pump on the engine is leaking (and in my mind possibly drawing air into the fuel system).

So....

Being it lacks Jakes
Lacks power to pull hills
parts might be difficult to find (per boss)

We have a 3406B. How difficult would it be to transplant?
Will the Allision handle it? or should we look at dropping a 13 or 15 speed into it?

What are we facing?

Thank you for your time, and yes I searched as I'm sure I'm not the first one to look at doing this, but results came up with c-12's and c-15's.

 

[98G]

The Allison is close to maxed out with the NH250. I believe its rated for something like 800 lbs/ft of torque.

Wreckers are known for early transmission demise due to the weight.

 

[NDT]

Lose the 250 In a heartbeat and the Allison with it

 

[simp5782]

This truck was bought by a VFD and converted to a fire tender. Stainless tank, 2600 gal and change. I believe it has the cummings 240 or 250 in it. Needless to say, with a load of water on pulling a hill is a slow task. They smoked the brakes coming down a hill with a load of water on. So... We bought it, and converted it to do more. But we are looking at the engine. It has issues starting. We installed a anti drain back valve (works correctly). But it appears that the fuel pump on the engine is leaking (and in my mind possibly drawing air into the fuel system).

So....

Being it lacks Jakes
Lacks power to pull hills
parts might be difficult to find (per boss)

We have a 3406B. How difficult would it be to transplant?
Will the Allision handle it? or should we look at dropping a 13 or 15 speed into it?

What are we facing?

Thank you for your time, and yes I searched as I'm sure I'm not the first one to look at doing this, but results came up with c-12's and c-15's.

Put a big cam in it with an ht754 from an m915a1. Move the transfer case back 4 inches. About 3 weeks worth of work

 

[Sniper2323]

so.. putting in a 3406B and replacing the trans with a manual 13-15 speed is not a good plan? We have a 3406B on the shelf with transmission is why I asked.

 

[Jbulach]

Unless you have good fabrication skills and or a donor truck, and retarder setup for the Cat, I would go with a higher HP 855 with jakes. The 3406 will fry the stock Alison the first trip out, so yes a manual would be a good upgrade for the mountains as well. All this will still take a considerable amount of time an skills though. Think the Cat is longer as well, so you may need to graft a couple hoods together.

 

[simp5782]

so.. putting in a 3406B and replacing the trans with a manual 13-15 speed is not a good plan? We have a 3406B on the shelf with transmission is why I asked.

You could. Someone just did a 13speed swap into one. Gotta raise the cab and new frame to engine mounts for the sae1 housing. Problem also is that the engine has to sit offset to one side of the frame and high in the frame or you have front driveline issues and a pumpkin into an oil pan too

 

[Jbulach]

Oh yeh good point. Probably have to modify or build a new pan as well, but sounds like a fun project!

 

[Sniper2323]

Thank you everyone for your insight.