genster

i need some input/help. so i want to crank it up some. do i loosen #2, turn #1 to move the slider towards the front of the truck? what is #3 for? im currently running about 16 psi @ 825*. thanks guys.

Which injection pump? ambac or bosch.? try a moderate amount first.

I often wondered why somebody doesnt make an after market aneroid device that has a longer travel than the factory bosch one.... allowing for a greater increase in "turning the pump up" without getting all the black smoke..

bosch pump. is there an easy way to check for air leaks? can i take the intake tubes off from the turbo to the manifold and plug the ends and psi test it? is that basically how they do it?

So i got to running my 88 Dm the other day with the new boost gauge and pyro on it. we changed the max rpm from 16-1700 to 2100. it has decent power, but only makes about 16 psi @ 800 degrees. is this about normal? i want to crank the pump up a little, so how many turns of the screw would you guys start with? thanks.

a little update, i got all 3 crossmembers in and bolted up, should be all ready to go now. it actually wnet much easier than i thought, the worst part was getting the old bolts out of the frame.

i wish mine were in 3 pieces....the old ones were 3 piece design with the center sction welded to the 2 brackets on the side. the new ones are 1 piece 32" wide shaped like a "U" so i think im going to have to spread the frame a little to get them in.

anyone have tips or tricks for getting the new ones in place??? they are the "u" shaped members that bolt together back to back. $250 a piece, and i need six of em!@!@!@@ they better not break again! oh well, gotta spend money to make money i suppose. i had alot of fun getting the old bolts out....torched the nuts off, and the 3/4" impact wouldnt budge them, so i got to stand on the fram rails with a 3/4" breaker bar and 4 foot pipe to get them lose so i could hammer them out. i only smashed my hand 3 times (i wore a welding glove, really helps to lessen the impact!!)

I have a DM897 with 22.5. I'll trade you what ever is necessary for the swap.

what for axle is it? 22.5 daytons?

on the axles, where the 7/8" bolts hold the shock insulator caps onto the axles, is the axle flange threaded? i ask because all 4 inside bolts are broken on both axles on the passenger side of my truck (2 broken bolts per axle). where the bolts would come through from the bottom up, it looks like the holes are threaded on the square flange on the axle where the shock insulator caps bolt on. i hope you can follow what i am saying, as im sure some of my terms are incorrect. and my next question, how to get them out? i suppose my 1 inch impact should be able to spin them out if they are threaded. thanks.

Austin

1988 DM 690 SX with a 17-18K front axle. I'm wanting to do the front axle at least to get more flotation, since its a 5,000 gallon tank spreader and I dont want as much compaction. I'm thinking the tandem rears have a fairly decent sized foot print because of the large tire diameter.

on another note, are super singles (385, 425 etc.) sizes made or popular in a 24.5 rim?? I've only seen them in 22.5 rim size.

Maxville, that looked like a nice rollover on that tank spreader of yours .....and i think you guys had a few solids in the lagoon too!

so is there a reason mack made the 1750 rpm engines?? are the 300L's built any different than the regular 300's? i think it would run great if it would wind to 2100. i'll have to get a boost gauge, and a pyrometer for it....ive got a pyro gauge but no pyro or boost gauge. anyone know where to get them reasonably priced?? thanks all!

hey guys, ive got an EM6-300L and was wondering if putting a 350 turbo on it and turning the pump will give me more power. i am sure it would, but i wanted to ask since it is a low revving (1700 rpm) engine and i wanted to make sure it would work. i have the t2070 behind it and just need a little more power and acceleration.

'88 DM690SX with a 5,000 gallon manure tank. 4.5-5 gal/hr....dont wanna think about the MPG!

Actually, you'll need 20" Dayton 6 spoke hubs to go with 22.5" (tubeless) Dayton rims.

Be sure to get the rims with the proper offset, as there are frequently clearance issues between the inside edge of the wide rims and the tie rod ends on certain front axles.

As stated previously, unless you want to stay with the spoke hubs for appearance reasons, a set of 10 stud unimount hubs would enable you to use any 10 stud unimount wheel of any diameter or width (of course you'd have to also use the unimount type brake drums with the unimount hubs).

if i went to the 10 stud, then i would need new brakes totally, or just brake drums?? im assuming just drums which would mount thru the studs. but if i went with the 20 inch dayton spoke hubs would i need new brakes also? my drums currently measure 18 inches in diameter, and that seems pretty big for a 20 inch hub to fit over for clearance issues.

is that the 2.5 inch rule? a 20 inch spoke uses 22.5's tubeless, and a 22 inch spoke uses 24.5 tubeless?

thanks to all for putting up with my ignorance!

hey, the brakes will be the same no matter what size wheel you run, unless you have roto chambers? what you need to find out is the inner bearing set number, and cross reference it over to the smaller hub. any parts jobber can do this for you. why stay with the spokes? why not change over to a hub pilot? the hub pilot will most likely be cheaper to buy. tire size you might want to run would be 385, 425, or 445, But they are not cheap!! Ive done a number of hub/wheel change over ask away!

what are roto chambers?? ive never heard of them before. i'll just need to find out what is cheaper, changing hubs and running a 20 inch dayton, or changing hubs and running a hub pilot for 22.5 rims. i would think open 22.5's would be cheaper and easier to find, but i could be mistaken. hub pilots are nicer in that the rims wont spin, and you dont need to make sure its centered. i know those tires arent cheap, at work we put a pair of 385's on a truck and they were $7-800 a piece. ahhhh, its only money!....

hey guys, i currently run 12r24 tires with 6 spoke hubs on the front axle of my mack and am wondering what all would be involved in swapping them to 22.5 6 spoke hubs to run a wider super single or flotation tire. the current height is 48 inches tall, and i want to stay at that height if possible. will the brakes be too large to fit the 22.5 hub and would it bolt up?? any help will be greatly appreciated.

how does a 2070 compare to a mack 12 speed?? i currently have a 2070 behind a EM6-300L and there is another truck with an E-6 300 with the 12 speed for sale. the problem i have is i either run out of RPMs with the low speed engine, or am in between gears while running loaded. (could use a 3.5 gear!) i would assume the 12 speed gears are closer together which would be ideal for me.

just wondering, does $12,900 sound reasonable for an

1989 MACK DM690SX. E-6 300 Mack 300 HP, 12sp, Camelback Suspension, 12R24.5 Tires, Spoke Wheels, Tri Axle, 58,000# RA, 75,000 mi.

im not sure what the condition is, but i think they mean 12R24 rubber, and it has a concrete mixer on it.

Thanks guys!

Austin

Hey everyone, Im new to the site and new to macks. I bought a 1988 DM690SX, which was formerly a concrete mixer truck. It now has a 5,000 gallon tank on that I use to haul manure. Its a 10 wheeler, EM6-300L, 54K rears, 17-18K front (i think, if i remember correctly) camelback, with the t-2070 tranny. The engine runs strong, although I could use some more gears, or a higher reving engine. Im sure i will be asking questions as i get more involved with the repairs and maintenance.

Austin