I thought I had it conquered...I fixed the constant hydraulic booster pulsing and have made it only happen when the engine and outside temperature is cold. Before I hook up the pressure gauge again..has anyone had hydraulic booster pulsing when the outside temperature is about 5C or less. (Approx. 40F) This disappears once the engine is warm or about 20 blocks whichever comes first? To give the background, Pressure regulator switch changed with aftermarket-see previous post "ABS with a twist" if you want past adventures. The over pressure valve has been removed, cleaned and new o-rings installed. I did reinstall it. The spring does not appear to be weak but I have not tested compression pressure. The SLS is no longer with us. It was removed by a dealer some years ago, BTO. (Before this owner). The system only boosts the brakes. The overpressure has been adjusted to 120Bar. The run pressure (when warm) has been adjusted to 75 Bar. I was not able to adjust to 80. I had the choice of 75 or 90 due to the threads on the aftermarket pressure switch adjuster. Has anyone had this problem? Is it normal that the hydraulic oil is too thick at 5C and the system can't relieve the pressure? By the way this is a low mileage (69K km/40Kmi) car and has spent a lot of time sitting in garages (personal not mechanic's). Thanks for any assistance. Ron.

 

Ron,

I can't help on your hydraulic issues, but in the event others may be able to, it will be helpful to be reminded of the year of your car and engine displacement. It's a good idea to add that information to your signature so it appears in all you posts.

Cheers,

Don

 

Further to the above cold temp hydraulic pulsing. It is just that. Hard to believe that the system cannot control run pressure until the fluid warms. I am using the correct Castrol fluid from the Jag dealer. Maybe I should blame that pesky ,new & non OEM pressure control valve. Now that spring has sprung here in the Canadian prairies the pulsing is a distant memory. Teach me to drive the Jag in cool temperatures.