OBS Cummins Steering Issue

powerstroke95 · Nov 9, 2016

Hello all!

Just wanted to get some opinions before I start throwing parts at my truck trying to solve a problem. I have a 95 F-350 that I recently put a Cummins in. This swap was done with a 96 12 valve engine. I ended up using the entire Ford steering system, except for the pump. I made my own lines and adapted the Cummins P/S pump to the Ford gearbox.

My first time driving it was at a sled pull. I had some issues with steering. The steering wheel felt very jerky, at times it was all i could do to hold it straight. At the end of the track it felt as if the steering was locked up (which I blamed on my welded front diff).

I tried drag racing a couple weeks ago on a short dirt track and as I was building boost, I could actually watch the steering wheel jerk back and forth (while sitting still).

To me this sounds like the systems got excess pressure or something. Is there a relief valve in a dodge steering box, but not in a Ford box maybe? I believe dodge started hydro-boost in 1996, could that pump be causing the issues? I'm hoping maybe someone else has encountered a similar problem...

79jasper · Nov 9, 2016

Have you every seen a duramax sled pull? That's not the pump that causes that.

You have play somewhere.

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gwunter · Nov 9, 2016

Is the steering stabilizer in good shape? I use the cummins vac/ps pump combo on my 4bt expedition. I resealed it when I got it, simple and cheap. I don't remember an excess flow valve or anything like that when rebuilding. I think the only difference from non hydro to hydro boost pumps are an extra return tube on the pump reservoir....i.e. there's one high pressure outlet and 2 return inlets. The pumps are very simple and can be resealed in a few hours on a Saturday and a 15$ kit.

powerstroke95 · Nov 10, 2016

79jasper said:
Have you every seen a duramax sled pull? That's not the pump that causes that.

You have play somewhere.

Sent from my SAMSUNG-SM-G935A using Tapatalk

I'm going to say my problem is definitely not play. The fact that as i sit still and build boost, and the steering wheel jerks back and forth tells me there might be a pressure issue.

I resealed the Vac pump but not the P/s pump. Looking in the pump while its running, the fluid looks very aerated. Are there internal seals that may cause issues?

6.0 Tech · Nov 10, 2016

You didnt put any hoses on backwards did you? First 6.4 i pulled the body on i got the hydroboost lines backwards. Did kinda similar, but with the brake pedal. Was hard then soft, the kinda pulsey, and went back and forth from there. Made for an interesting test drive...

powerstroke95 · Nov 11, 2016

6.0 Tech said:
You didnt put any hoses on backwards did you? First 6.4 i pulled the body on i got the hydroboost lines backwards. Did kinda similar, but with the brake pedal. Was hard then soft, the kinda pulsey, and went back and forth from there. Made for an interesting test drive...

I'd like to think not, but I guess anythings possible. I'll double check tonight.