Pitman Arm Won't Come Off - PeachParts Mercedes-Benz Forum

Skippy · #1 11-14-2021, 10:36 PM

(2nd try posting)

I'm changing the steering box on my '83 300D and I've already broken four pullers trying to get the Pitman arm off the old steering box. Any ideas?

martureo · #2 11-15-2021, 02:42 PM

Quote:

Originally Posted by Skippy

(2nd try posting)

I'm changing the steering box on my '83 300D and I've already broken four pullers trying to get the Pitman arm off the old steering box. Any ideas?

Here's what I do. I remove these on a regular basis.

Clean off any visible grime, dirt, oil with a wire brush.
Heat the output shaft and pitman arm with a propane torch for ~30 seconds, moving the torch around.
Install the puller and turn it as much as I can with a long handled wrench.
Shock the pitman arm with a mini sledge.
Tighten the tool a bit further if possible.
Beat the pitman arm with the mini sledge.
Apply more heat with the propane torch.
Beat the pitman arm more with the mini sledge.

I don't usually get past step 4 on the majority of the boxes I recondition, but there's always a few stubborn ones.

Junkman · #3 11-15-2021, 03:13 PM

Pitmans are frequently a hassle. Does the beating damage seals or bearings? I ask because the box on the truck needs to come out but not be rebuilt before reinstall.

BillGrissom · #4 11-15-2021, 05:18 PM

What type of puller? Are you using a special "Pitman Arm Puller"? I have 2 different sized ones and use them for more than just Pitman arms. I recall the smaller one is from Harbor Freight and has even fit some ball-joints or tie rod ends (forget) in my various vehicles. I recall the larger one was a name brand and would probably fit my M-B. I have removed 2 steering gears, but recall leaving the Pitman arms on. Heating with a torch usually helps and if you pull it fast the heat may not have time to conduct up the shaft to burn the output seal rubber, though likely you would change that anyway. Did you spray penetrating oil a few days before trying? Hammering the arm as you load it seems to help, probably by hyrdo-shocking the penetrating oil to help flush rust loose.

Diesel911 · #5 11-15-2021, 06:36 PM

Quote:

Originally Posted by Skippy

(2nd try posting)

I'm changing the steering box on my '83 300D and I've already broken four pullers trying to get the Pitman arm off the old steering box. Any ideas?

What make of tools are you using?

This thread has a pick of the original Mercedes Tool. It also shows the OTC one that is similar. The OTC took comes in 2 sizes and the smaller one can also be used to separate the lower front Ball Joint. The OTC OT 8149 is the smaller one and the OTC8150 is the larger one.

https://www.benzworld.org/threads/pulling-the-pitman-arm.1654399/

I go by 300Dman on the benzworld.org forum. One of the posts has the dimensions for the 8149.

https://www.benzworld.org/threads/lower-ball-joint-separator-for-w123.1669576/

I think the OTC Tool is longer then the Mercedes one. It could be there is not enough room for it or you my need a shorter Bolt.

Diesel911 · #6 11-15-2021, 10:51 PM

Story concerning heat. I had put a gear puller on a gear and put considerable tension on it with no movement. I heated the gear with a propane torch.

I turned the torch off and walked away to do something else and there was a pop sound. When I came back the gear was off of the shaft and lying on the floor.

Heat can work wonders. It also facilitates the wicking in of penetrating oil if you don't get the part too hot to evaporate it fast.

Skippy · #7 11-16-2021, 01:21 AM

Thanks all.

The first three pullers were a Harbor Freight 2-jaw puller set. The last one is similar to the one linked below:

https://www.oreillyauto.com/detail/c/performance-tool/tools---equipment/mechanics-tools/pullers/pitman-arm-pullers/692e9db8fec4/performance-tool-pittman-arm-puller/pfm0/w142/v/a/3215/automotive-car-1981-chevrolet-corvette?q=pitman+arm+puller&pos=0

I've plasticaly deformed it, but it isn't all the way broken yet. I'll try again tonight with the hammer and more penetrating oil. I'll ask around some people I know for a conical puller if I can't get it with the current one.

Diesel911 · #8 11-16-2021, 06:09 PM

Quote:

Originally Posted by Skippy

Thanks all.

The first three pullers were a Harbor Freight 2-jaw puller set. The last one is similar to the one linked below:

https://www.oreillyauto.com/detail/c/performance-tool/tools---equipment/mechanics-tools/pullers/pitman-arm-pullers/692e9db8fec4/performance-tool-pittman-arm-puller/pfm0/w142/v/a/3215/automotive-car-1981-chevrolet-corvette?q=pitman+arm+puller&pos=0

I've plasticaly deformed it, but it isn't all the way broken yet. I'll try again tonight with the hammer and more penetrating oil. I'll ask around some people I know for a conical puller if I can't get it with the current one.

Not the ones in the set but the single harbor freight Pitman Arm Pullers; years ago I was looking single bubble packed larger ones and saw someone had put some broken ones back up for sale. In this case they appeared to be brittle because they had one of the hook/projections broken off.

Junkman · #9 11-17-2021, 08:06 AM

@Diesel911, I've used mostly rented pullers but have a few picked up at random places. Pitman arms have been more of a hassle than say tie rods which only need a hit or 2 on the knuckle.

Pitmans are similar being press fit and tightened down. Beating on them would put sideways pressure on the shaft and seals. I'll look for a decent puller and have a good heat source before tackling the next one if that is what works.

Diesel911 · #10 11-17-2021, 03:31 PM

Quote:

Originally Posted by Junkman

@Diesel911, I've used mostly rented pullers but have a few picked up at random places. Pitman arms have been more of a hassle than say tie rods which only need a hit or 2 on the knuckle.

Pitmans are similar being press fit and tightened down. Beating on them would put sideways pressure on the shaft and seals. I'll look for a decent puller and have a good heat source before tackling the next one if that is what works.

I did not mention beating on it.

Skippy · #11 11-18-2021, 10:46 PM

I tried beating with a 2 lb hammer. No joy. I put some Aerokroil on it last night and again today before work. I may try again tonight or wait until the weekend.

martureo · #12 11-19-2021, 10:08 AM

Quote:

Originally Posted by Skippy

I tried beating with a 2 lb hammer. No joy. I put some Aerokroil on it last night and again today before work. I may try again tonight or wait until the weekend.

How are you hitting it?

Hit the pitman arm where the numbers are stamped on it. It shouldn't take more than a few blows.

BillGrissom · #13 11-20-2021, 05:05 PM

All I have is the puller shown in post 7, in 2 different sizes. I might need to buy the conical type puller, though might not be able to still whack it with that on. I would try, loading the puller, then propane (or MAPP) torch on the Pitman arm, whack with big hammer, try to tighten more, keep repeating. If you can get it red-hot, it should break free.

Skippy · #14 11-24-2021, 11:46 PM

I took the steering box out with the pitman arm still attached. Tomorrow I get to take it outside and use the propane torch I just bought. I'll also be able to get a much better swing at it with the hammer than I did with it in the car. I was so happy to get the box out I made a quick and dirty Youtube video about it:

https://youtu.be/PEHXs6B7a3w

Skippy · #15 11-26-2021, 07:17 PM

I followed Martureo's eight steps. It finally came off after about 45 minutes of heating and beating. Thanks to all for your suggestions.