1975 RS685LT

[Hobert62]

Polished aluminum looks good on any truck.  All painted up or not.   

[j hancock]

12 hours ago, Quickfarms said:

Does anyone have any experience with the hydraulic steering boost

It looks like the drag link is the control valve, there is a ram on the front axle and it looks like there is a reservoir above the engine by the firewall. The pump appears to be located on the passenger side low

It does not appear to be working at idle. Does it need some rpm to work?

I have a similar Garrison power assist on the B75.  Mine seems to work at idle. 

I can't say that I have tried turning the steering wheel at idle while not moving the truck.  That puts a lot of stress on the front end.  Shuttling the truck in the yard at idle seems to be fairly effortless.

Couple of ideas might be dirty fluid in the system which is overcome by more rpm, pump itself may be a little tired, a seal or o ring may be bypassing some fluid so you are not getting full pressure.  I might start with a drain and fluid change.  My system uses engine oil not power steering fluid.

[HarryS]

I've got that system on my B model except the pump is driven from the back of the generator. Mine works at idle not effortlessly but better than manual. Check your fluid reservoir, mine has a filter in it about the size of an old school auto oil filter.

[mackaholic]

On 10/2/2018 at 10:29 PM, Quickfarms said:

I took a little road trip this week to visit my daughter at college because two of my chocolate labs died in the last week and this morning I bought this truck

I did a double take when I saw your post. I looked at that truck a month ago. Never thought to ask if it was for sale. I was visiting a buddy who has a business down the street from where it was parked. Nice clean truck! Congrats

[Quickfarms]

I did a double take when I saw your post. I looked at that truck a month ago. Never thought to ask if it was for sale. I was visiting a buddy who has a business down the street from where it was parked. Nice clean truck! Congrats

Thanks, that's such a coincidence the owner put it up for sale about a month ago.

From what I can tell it has not been registered since 2009

[Quickfarms]

I have a similar Garrison power assist on the B75.  Mine seems to work at idle. 
I can't say that I have tried turning the steering wheel at idle while not moving the truck.  That puts a lot of stress on the front end.  Shuttling the truck in the yard at idle seems to be fairly effortless.
Couple of ideas might be dirty fluid in the system which is overcome by more rpm, pump itself may be a little tired, a seal or o ring may be bypassing some fluid so you are not getting full pressure.  I might start with a drain and fluid change.  My system uses engine oil not power steering fluid.

My fluid is low and red, how do you drain the system?

I've got that system on my B model except the pump is driven from the back of the generator. Mine works at idle not effortlessly but better than manual. Check your fluid reservoir, mine has a filter in it about the size of an old school auto oil filter.

I have one of those filters that you describe, it is in the upper right of the picture of the ram that I posted, but it is not connected to the steering system. It is connected to the supply oil side of the turbo.

[ranchhopper]

On ‎10‎/‎3‎/‎2018 at 6:14 PM, Quickfarms said:

Both of the battery box covers are missing. Are the aluminum covers available?





Since this is a California truck, is there an issue with only running two batteries? If I continue to run two batteries would it be hard to put both of them in one battery box?

I have a pair of hayward mack battery box covers sitting in the shed.

 

[Quickfarms]

I have a pair of hayward mack battery box covers sitting in the shed.
 

I am interested

Pm sent

[terry]

2 hours ago, Quickfarms said:

 

My fluid is low and red, how do you drain the system?



I have one of those filters that you describe, it is in the upper right of the picture of the ram that I posted, but it is not connected to the steering system. It is connected to the supply oil side of the turbo.

 

Never heard of a filter at that location, can you post a pic?     Terry

[HarryS]

The filter cartridge on my system is located inside the power steering reservoir.  I didn't realize there was a filter until I happen to see the lifting ring when the fluid level had gotten low.

[h67st]

4 hours ago, Quickfarms said:

My fluid is low and red, how do you drain the system?

I have one of those filters that you describe, it is in the upper right of the picture of the ram that I posted, but it is not connected to the steering system. It is connected to the supply oil side of the turbo.

I drain PS systems by pulling the lowest hose and letting it drain out there.

[Quickfarms]

Never heard of a filter at that location, can you post a pic?     Terry:MackLogo:

This is a closeup of the filter



This is a wider angle shot



I will take a closer look at the hoses to confirm where it goes

[terry]

Thanks for posting the pic, but that is something I have never seen !! Is it actually tied in to the turbo supply?    terry

[keg1]

looks like the oil filter i had on a 52 willys jeep

[Vladislav]

On 10/7/2018 at 7:54 PM, keg1 said:

looks like the oil filter i had on a 52 willys jeep

Yes, that's what I thought. And probably the same thing was used on GPW (Willis) during the war times.

[Quickfarms]

Yes, that's what I thought. And probably the same thing was used on GPW (Willis) during the war times.

Yes it is very similar


But the jeep fittings look like 1/8" or 1/4" pipe and these look like 3/8" or 1/2"



And I did confirm it is hooked to the turbo

[terry]

Guess somebody wanted to filter the oil before it hit the turbo.   terry

[Quickfarms]

Since Mack only started using spin on filters in 1971 it is not surprising to see an old style cartridge filter on a 75.

But why filter the oil to the turbo?

[Quickfarms]

Does anyone have a wrecked fiberglass hood laying around?

The passenger side metal piece that the rubber bumper rests on is missing on my hood

[terry]

6 hours ago, Quickfarms said:

Since Mack only started using spin on filters in 1971 it is not surprising to see an old style cartridge filter on a 75.

But why filter the oil to the turbo?

It is a first for me, and I have been around a lot of the older macks.    terry

[h67st]

On 10/9/2018 at 11:40 PM, Quickfarms said:

Since Mack only started using spin on filters in 1971 it is not surprising to see an old style cartridge filter on a 75.

But why filter the oil to the turbo?

Since the turbo spins so fast it would be more sensitive to dirt & debris in the oil. Maybe they wanted a little insurance for those turbo bearings.

[Vladislav]

On 10/11/2018 at 7:29 AM, h67st said:

Since the turbo spins so fast it would be more sensitive to dirt & debris in the oil. Maybe they wanted a little insurance for those turbo bearings.

A friend of mine has old Scania with V8 14 liter engine. The basic block is the same to what Mack used in 865 or 866, never mind. He said me that his engine had spin on filter to supply the turbo only. The main oil filtering system utilizes a centrifuge.

[Quickfarms]

The truck currently has the ENDT675 with a 5 speed direct transmission and a R170 rear axle with 4.33's in it according to the tag.

I have been running some ideas through my head on some options for the truck to make it more drivable on today's freeways

Option one is to simply change the gear ratio to 3.90 and service everything including having the radiator cleaned out.

Option two is to swap in a EM6-300 and a T2070 seven speed

Thoughts for a hobby truck that would probably never top 40,000 lbs and probably be at around 25,000 lbs most of the time.

One of my issues is when ever I go anyplace I end up running trough one of the mountain passes or at least a big long grade.

[terry]

I don't think a 2070 with a 4.33 rear is a good combo,  that trans is usually used with around a 5.50 rear. You will top out around 85 or more, And it has real wide gears, 4th to 5th is a real high overdrive. probably stay in 4th in mountains. Why not leave that engine and rears and go with a 13spd fuller? it is real nice having the splits in high range. And the fuller overdrive would work good with the 4.33's      terry

Edited October 21, 2018 by terry

[Maxidyne]

The Fuller is an inferior transmission, stick with Mack. Besides, the Fuller will need different mounts and driveshaft. Unless the components are worn out, stick with stock and change as little as possible. Changing to a different ratio in the Rockwell rears may make sense though, not so much to get more speed but to get the cruising RPMs down which will really help your cruising MPG. IIRC, they offered 3.90, 3.70, and 3.55 ratios in that R170 rear end.