P/S pump swap

[Higgins56]

Hi Guys,
I have 429 engine with AC in my 71 Mach 1.
I bought a rebuilt Thompson pump 7 years ago and recently rebuilt the Saginaw gear ( 3 turns lock to lock)
When reassembling the gear the pump was untouched but changed a new belt with 1/2 inch "play" and tried to top the fluid level right there was a new noise attached - this whine that is almost unnoticeable when idling but when increasing rpm and turning the wheel the noice is too well audible.

I know that the noise is typical to some extent with these pumps but mine was satisfactorily silent before .
Maybe the pump is just worn out with the critical parts as it is not leaking and it powers the steering well....

I happen to have another Ford pump available type RF D8AC-3D609-AC which was used in the late seventies/ early eighties.

Has anybody tried that to swap the original Thompson to that ?
The pulley shaft seems to be the same but I have not tried the bolt pattern yet but it looks the same so I might use the original bracket to install that.
If it fits can I use the original pulley ( diam. 6 ") with that pump
Otherwise the pump is smaller in size than the original so it should fit well

Attasched two photos of the "new" pump - which I think was used in 70's Broncos and some commercial vehicles?

 

[Stanglover]

I'll never claim to be an expert, but I have rebuilt a couple of pumps recently. In my case, it was leaks that needed to be fixed, but in the process, I went through the entire pump inner works. There is not much to these, but tolerances are very tight between the eccentric cam and the top/bottom plates and I believe that might be were the noise comes from. It is that or the pressure relief valve sticking and that was something I didn't get into.
If you're interested in attempting a rebuild yourself, there are several posts on the forum as well as lots of help from others who have done rebuilds. The only special tool you need is a pulley puller/installer that can be bought quite cheaply at Harbor Freight.

 

[Higgins56]

Thanks Stanglover !

I will first try with the other Ford pump I have on the shelf - its newer and I thought to give it a try.
I managed to take the pulley out from there Thompson pump tp be able to check if the bracket fits with the newer Ford pump - and it does !
So - I can install the new pump exactly where the old one was.
I was a bit sceptic regarding the pulley / belt line - not installed the pulley yet - but I measured the distance from the pulley axle bottom to the bracket bolts center and it was the same with both pumps - so the belt line should be OK.

The only head ache will be the adapter to the original hose line....
The original pump has 15.7 mm = 0,618 " connection and the newer has 14,1 mm= 0,555" - so I have to find an adapter with the bigger dimensions on both side.

Attached you will find photos with the new pump installed and the adapter that was in it but does not fit the original hose connection

 

[Stanglover]

Thanks Stanglover !

I will first try with the other Ford pump I have on the shelf - its newer and I thought to give it a try.
I managed to take the pulley out from there Thompson pump tp be able to check if the bracket fits with the newer Ford pump - and it does !
So - I can install the new pump exactly where the old one was.
I was a bit sceptic regarding the pulley / belt line - not installed the pulley yet - but I measured the distance from the pulley axle bottom to the bracket bolts center and it was the same with both pumps - so the belt line should be OK.

The only head ache will be the adapter to the original hose line....
The original pump has 15.7 mm = 0,618 " connection and the newer has 14,1 mm= 0,555" - so I have to find an adapter with the bigger dimensions on both side.

Attached you will find photos with the new pump installed and the adapter that was in it but does not fit the original hose connection

If it works, job done!
However, being as you have the old pump basically stripped, why not pull it apart and see if it's ok inside. I suggest taking pics as you go through it so you assemble it correctly. However, if shaft steel bushing is worn, i.e. the shaft can move (other than go round of course) I have not found a source for replacement bushings. Bronze will not stand up to the side load.
As for the relief valve, if the plunger moves in and out without sticking, it ought to be ok. That was not something I wanted to mess with.
There are several post on pump rebuilds and I have quite a few pics that might help. To help me, I found a blog on rebuilding Thompson pumps that was very helpful so I don't claim any kudos for anything.
Any question, just ask. Several of us have done this.

 

[Higgins56]

Hi folks,
to end this little project I have now bled most air out of the P/S system - this can take time - even days to settle down and to get all air out but so far situation is that the newer Ford pump which fortunately matched the bracket holes is working. At the far end both left and right there is some noise but only at the extreme end and if you force the steering wheel to turn at the lock. This newer pump is a bit smaller that the Thompson som it is easy to fit. The downside was that the output is 9/16 thread and the Thompson has 5/8". No proper adapters were available here in Finland so I decided to cut the original high pressure hose and make two extensions - on with 9/16" connection and the other was the original 5/8" in case I decide to replace the new one with the old.
By the way I let one mechanic check the original pump and he told me that the rotor is worn out and cannot keep the pressure so I managed to find a NOS rotor from eBay and now waiting for it to complete the original pump.

 

[Stanglover]

Hi folks,
to end this little project I have now bled most air out of the P/S system - this can take time - even days to settle down and to get all air out but so far situation is that the newer Ford pump which fortunately matched the bracket holes is working. At the far end both left and right there is some noise but only at the extreme end and if you force the steering wheel to turn at the lock. This newer pump is a bit smaller that the Thompson som it is easy to fit. The downside was that the output is 9/16 thread and the Thompson has 5/8". No proper adapters were available here in Finland so I decided to cut the original high pressure hose and make two extensions - on with 9/16" connection and the other was the original 5/8" in case I decide to replace the new one with the old.
By the way I let one mechanic check the original pump and he told me that the rotor is worn out and cannot keep the pressure so I managed to find a NOS rotor from eBay and now waiting for it to complete the original pump.

That's great news. Well done.