HWH tank

[Tom and Pam Brown]

There is a tank behind the front access door in my 1999 Marquis.  It is attached to the hydraulic pump.  It has a silver cap on it and I cannot remove the cap.
Is this the hydraulic fluid reservoir?  If so is this cap a vent?  Is there somewhere else to,add fluid?

Thanks.

[Edward Buker]

Mine is black and it is a vent cap that unscrews if it is the same configuration. A photo may help.

Later Ed

[Jeremy Parrett]

Silver cap is vented and the only place to check (it has a dip stick) the level and add fluid if necessary.