Volvo L90E powersteering pressure way down

[Volvomad]

Driving L90e today myself when all of a sudden the steering seemed a bit slow ,if it is not going back or forward it will hardly steer at all .The orbital unit seems to work as it should but when the steering load increases the steering wheel stops going round as if it is not getting sufficient pressure . I am just going to check the pressure now ,but was wondering has any one seen this before

 

[Volvomad]

25 bar is all i am getting to the danfoss unit . Book says 210 . I cant figure if it is a loadsensing or priority valve issue . Both go through the main valve block (central block) not the spoolvalve block

 

[Volvomad]

I changed the central block (pain in the ass of a job) and that sorted the problem . If any one has info on the central block ,I am hoping to try and repair my old one .

 

[funwithfuel]

Between lsw and lss port there is a check valve that may be obstructed. It is an Alan plug, unscrew it, there will be an o-ring and a ball seat. You will see the cross drilling. Check it all for any damage. Check and verify no debris. The tip of the valve has been seen chipped in the past. Each passage should blow clear to law. Lastly, the pressure reducing valve for steering is the short one. Remove and check for damaged seat or face. Verify no spring damage. Good luck

 

[Volvomad]

Thanks funwithfuel . Just the kind of info I am looking for . Wont get near it for a long time ,but when I get time I will follow what you said and will report back .

 

[Volvomad]

A long time is up. I think my current block is cracked. Must go ripping tomorrow.

 

[funwithfuel]

It's only been 5 years, why do you think it's cracked?

 

[Volvomad]

I pulled the check valve, the relief valve and the priority valve . I saw no dirt or anything broken. Blew every item and bore with compressed air, stuck them back in and fitted the block (a lovely job) and prayed to the devil. Works perfect so thanks a mill for your help. As for why it cracked, it did it once before around 12 or 14 years ago in the same place, in a line between the ports that feed the steering and main spool valve chest.