m543a2 wrecker boom lowers by its self any ansewers

[standardaero]

My boom on my wrecker lowers by its self, have already had both cylinders rebuilt by a national company, think the problem is the boom control lever. What is a snubber valve and where is it located? do you have any suggestions?

 

[OpieNoTool]

Dont feel bad mine does too! i have a leaky hose fitting.

 

[nf6x]

If there's no obvious fluid leakage, it might be the control lever. I haven't had to rebuild one yet, but I would think that a bad internal seal in there could make the boom lower without any loss of fluid. Although I haven't had this problem myself (so I'm talking out my back end to a certain degree...), that's where I would look next since there's good reason to expect that the lift cylinders are in good shape now.

 

[nf6x]

Oh, by the way, I just noticed your post count... Welcome to the board! We'd all love to see pictures of your wrecker!

 

[Recovry4x4]

I'd bet on a valve issue for sure. My wrecker cylinders leak like a seive but the boom stays put.

 

[DaveP]

isn't there check valves? seems to me i remember someone talking about the checks failing. then when they tried to remove them for repair they cracked. seems like they were made out of aluminum and deteriorated. then again i could be all wet as this was a while ago

 

[Recovry4x4]

There are restrictor valves on the lift cylinders. They are there in the event of a hose failure, the boom doesn't come crashing down.

 

[CCATLETT1984]

its a valve issue, its not completely blocking off flow once the piston is extended, so fluid is bleading back through and the boom is lowering. It would be the valve that controls the upward motion of the boom most likely. if the valves are connected to each other it might be easier to just rebuild them at one time.

 

[vtdeucedriver]

YEP this thread is worthless without pics............................!!!!!!!!

 

[DaveP]

There are restrictor valves on the lift cylinders. They are there in the event of a hose failure, the boom doesn't come crashing down.

thanks for clearing this up for me Kenny. are these made of a light metal?

 

[63H20]

Check the snubber valve. Look in the TM for the location, think its in the bottom of boom lift cylinders.........RVN wheel & track mechanic..........

 

[standardaero]

took cylinders back off and went to hyd. shop. I explained and they tested and disassembled found that a spacer was missing in the cyl's , must have been missing from previous owner.