1975 L8000 Power Steering

[Makensmoke]

I have been searching online and am coming up empty handed. I'm attempting to trouble shoot what looks like a fairly simple power steering in a 75 L8000 cab over fire engine.



Does anybody have any ideas where I can find some breakdown pictures of the system, or some tips of what commonly fails with this system? It has a traditional pump, a what i'd imagine proportioning valve and a hydraulic cylinder piggy backing the drag link. Before I start pulling things apart, I'd like some heads up... much like why I joined the TDR

 

[mwilson]

What's the issue??? Little or no power steering assist??



Is the cylinder leaking??



Where is the valve located??

 

[Makensmoke]

No power assist is the issue. The cylinder is not leaking, the only leak seems to be spirting out of the vent in the pumps fill cap when driving. The valve is located at the end of the steering shaft. The steering is so hard to turn, I must be fighting that cylinder.



Thanks for the reply!

 

[mwilson]

If it's like the GM set-up of that era the spool at the input shaft of the steering box has gone bad and you are doing exactly that, fighting pressure from the cylinder.



GM was a huge fan of that set-up on Brigadiers and Astro Cab-Overs.



There is a locating pin that can shear off in there as well.



I don't know if that stuff is still available or not.



Can you post a few pictures, interested in the top portion of the box where the valve is and the cylinder as well.

I can see if any of that stuff is still obtainable when I get to work tomorrow if you want and maybe point you in the right direction.



Mike.

 

[Makensmoke]

Looks like my info on the proportional valve was a bit off... the "throttle" for the pressure flow is located directly in the drag link, not at the end of the steering shaft as I first indicated.

I sure appreciate any info you can provide.

 

[mwilson]

That's a C-8000 cabover, right.



3208 smokin' smellin' Cat power!!!!



I have a parts buddy at a local dealer that has peddled Ford parts for 30+ years. I will call him in the morning.

Do you have the VIN? I might need it.



That is different than the Saginaw GM set-up I had pictured in my mind.



There was a company called Air-O-Matic that used that same type of drag link trigger for power steering but that used air pressure and an air cylinder. Principle is the same though.

 

[Makensmoke]

It could be a "C" for all I know, for who knows why I always called it a "L". I'll attach a couple pics of it here, the black and white one is when she was delivered brand new! Again, I appreciate any help!

 

[Makensmoke]

A couple more... hasen't changed much in 36 years!

 

[Hoefler]

That is a power assist type power steering. Pull the lines loose from the cylinder, here is where it will get messy, with the engine running slightly turn the steering wheel one way and observe if you have fluid coming out of one of the disconnected lines, then turn the wheel the other way and check the hoses. You don't need to turn the wheel very far, it should squirt fluid out of the line. If you don't get fluid from one or both lines, the spool valve is bad, the piece in the drag link with all the lines. If you get fluid flow from both lines, but it is not the same or very slow, you have a line that has come apart internally, replace all lines. If the flow from the lines is strong, hook one line up to the cylinder, now turn the steering wheel, you want to turn the wheel in the direction that makes fluid go to the cylinder, not the disconnected line, see if you get any fluid flowing out of the fitting the line is disconnected from, if you do, the cylinder needs rebuilt, the seal on the piston is bad.



One other thing you might check, jack up the front end and place jack stands under the axle keeping the wheels off the ground. You should be able to turn the steering wheel lock to lock with out much trouble, engine running or not. If you get a lot of resistance or you have to put a bit of muscle into it, most likely you need king pins.

 

[Makensmoke]

Thanks for the help!



Is the spool valve very easily rebuilt?



Also, with the wheels off the ground is the steering to turn easily even with the cylinder plumbing attached? Not sure if there is supposed to be some reliefs in there somewhere in case the power dies... or in this case something else faults and the assist fails? Its darn stiff, dumping the water didn't help, like I thought it might.

 

[Hoefler]

Should be able to turn with some resistance, but you should not have to really work at it. Check the king pins for any movement. Just another thought, is the pump any good? You could have a bad relief valve.



That power steering setup is weak to begin with, it was an add on from the get go. Ford used the cab from 1959 to the 1990's. If you can find a steering setup off a newer model with the Ross gear box, it will all be internal in the box and a better setup.

 

[mwilson]

Hoefler,

That is one the best troubleshooting write-ups I have seen!! Nice job!!!



The plumbing looks a little funky, maybe has been molested in the past. 90 degree elbows at the hose connections do not make a lot of sense.



Maybe it was added at the body company. A lot of fire trucks were and still are born from stock chassis, have caught Freightliner doing that several times.



One notable example was from a local town, they came to me as they could not get the seatbelts latched if they were wearing Scott Air Packs. The truck had seats that were hollowed out for the backpack/tank unit to rest in but belts were too short. Come to find out the chassis was a stock unit and had been converted. Nobody thought about the Scott Packs pushing the firefighters further away from the seat backs. Couldn't get help from anyone on that fiasco due to liability. Finally found a fire truck serial number that was properly specced and ordered seat belts that did fit. They all do it. #@$%!



I think your suggestion about a newer box is a great plan, there should be an ample supply of those trucks at the salvage yards. That model was the city tractor of choice for LTL carriers for many years and also were used for refuse, beverage delivery, etc. .





Let me know if it turns out to be the spool valve and I will see if any can still be had

 

[Makensmoke]

I will check all the above. THANKYOU for the replies!



I did some quick research about the Ross stearing box. I found some 76 trucks with them installed. This makes me think it would be a direct bolt on replacement, if the cab ran in production for x amount of years, I doubt they changed the bolt up of the steering box in one year... did they? My luck, yes they did... can anyone confirm this?

 

[Makensmoke]

Some troubleshooting decided that my kingpins are not seized, wheels off the ground it turns with expected resistance. The pump however is not pumping. I will start here and see where it takes me!



The relief isn't plugged, or at least wouldn't open with 100psi of shop air. There is a few teaspoons of what looks like anti seize in the bottom of the tank... I suppose I have a shaft seal or similar thats out of tolerance due to this wearing.

 

[JoshPeters]

Isanti... wow it's a small world! I grew up in Cambridge.



It looks to me like the "anti-sieze" type stuff is the guts of the pump. I'm guessing the pump or something that moves ate itself. All those metal shavings can't be good.

 

[Hoefler]

Looks like fluid break down from heat. You need to do a little research and find out if you system is supposed to have power steering/atf fluid in it or 30w non detergent motor oil. I noticed while looking at your pictures, it looks like you don't have a cooler on it, it is supposed to have one! While your at it, install a cooler on the return line. A small transmission cooler will work the best.

 

[Makensmoke]

I'm searching for a pump... I have Catco looking up a price for a new or reman one, but these things aren't that readily available. I am finding out it's dwarfed by a pump that would hang over a 12,000 lb axle now a days .

 

[mwilson]

I have a customer that is a Ford Truck guy from way back and has many in the fleet where he works now. He has old Ford parts books that cover your truck and is looking it up now.

They used that pump for many applications if it is what he thinks it is and simply put different cans on the back to suit the application.

He has several newer Ford trucks that take the same pump cartridge and gets them from Power Steering Supply Company.

This is good news so far.

I am e-mailing your pictures to him and will let you know what he comes up with.



Mike.

 

[Makensmoke]

Excellent, thank you very much.



There is a paper "build sheet" on the passenger door. Its pretty wore out, but it shows the power steering pump number as a 4HA3A691CA. Google gives me nothing...



Maybe this will help him pin point what exactly it is.

 

[mwilson]

Here is a simple way to identify it, we think... ...



See here.