not a r/r problem

hi peeps,I know this isnt a r/r problem but i have posted on the jag forum with no sucess,not one reply in five days.Its an oil pressure problem on a XJ40 3.2s the aj6 engine.When started it shows just over 4 bar on the gauge,when you increase the revs,oil bursts past the filter o ring.I have checked the pressure relief valve in the filter housing and this is ok.The filter has been changed in case the problem was the filter valve.The filter was tight and the housing is not cracked.Any help would be appreciated.regards

sounds like a blockage if pressure relief valve is ok, did old filter break up? can you find an oilway diagram from engine-lubrication diagram.

Also not knowing the setup- is the relief passages clear

have you fitted proper oil pressure guage in place of oil pressure switch and read pressure as you raise revs 65 psi is alot for idle but not unknown but if rises too high will blow filter,vms diesels are high at 90 psi

thanks for your input,will put a gauge on tomorrow.This is the third new filter to be fitted,the first lasted a run down to Cardiff and nearly home.This had not broken up.Second fitted and lasted until car revs were raised.Third was sourced from a different supplier.all were genuine jag filters.

if pressure is too hign probably is relief valve sticking

jamesmartin said:

if pressure is too hign probably is relief valve sticking

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thought that myself,there is one in the filter housing which appears to be operating,pressurised it with an air line at 60 psi and it worked ok.This makes me think there is a blockage on the return side.I will have to obtain a flow diagram.I have also pressurised the delivery side of the filter and air pressure is felt at the filler cap.Do you think it could be the oil cooler sludged up,i know im grasping at straws.regards

return side is out of bearings and rocker shaft,have had cam brgs spin out of line of feed holes before ,but that had other symptoms as well ,normally cooler is on bypass meaning not all has to go through it but flow diagram would be good,i would expext relief valve to be next to pump on direct outlet ,it may have valve that doesnt allow cooler flow till pressure or temp reached

jamesmartin said:

return side is out of bearings and rocker shaft,have had cam brgs spin out of line of feed holes before ,but that had other symptoms as well ,normally cooler is on bypass meaning not all has to go through it but flow diagram would be good,i would expext relief valve to be next to pump on direct outlet ,it may have valve that doesnt allow cooler flow till pressure or temp reached

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cheers mate,will get a flow diagram,thank god for this forum,ive had no reaction at all from the jag forum

tomcat59alan said:

cheers mate,will get a flow diagram,thank god for this forum,ive had no reaction at all from the jag forum

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fix this fault soon as, you will destroy your engine,the seals will blow,and you will have wallet trauma.

jamesmartin said:

if pressure is too hign probably is relief valve sticking

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Hi James,Had another look and I think the "o/p relief valve"I found is actually a balance valve to bypass the filter in case of blockage.It looks like Ive got to drop the front suspension to remove the sump to gain access to the relief valve.Its a long time since Ive wielded a spanner to this model hope my thinking is right but I cannot see any other answer.Thanks again for the input peeps,it got my old grey matter working regards Alan

Hi There, I have some xperience of Jags.
The valve in the filter housimg is a bypass valve for if the filter becomes blocked in order to prevent oil starvation. Yu need to work on the pump pressure relief valve, this will be set higher than the filter housing valve but still not as high as to blow the housing.

wantaquad said:

Hi There, I have some xperience of Jags.
The valve in the filter housimg is a bypass valve for if the filter becomes blocked in order to prevent oil starvation. Yu need to work on the pump pressure relief valve, this will be set higher than the filter housing valve but still not as high as to blow the housing.

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thanks for the confirmation,am i right the pump p/r valve means the sump has to come off regards

I believe so - part of the oil pump

wantaquad said:

I believe so - part of the oil pump

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cheers pal

Hi people,just an update.Posted this problem on jag forum,67 viewings one reply who suggested an oil change,great.The problem was the oil pressure felief valve. This sits in a steel sleve which should be tight in its aluminum housing.This sleve had become loose over time and when the valve lifted the sleve lifted as well and effectivly blocked off the drillings that allow excess pressure to vent to the sump via the pickup pipe.The engine has done 140,000 miles so this may become a more common problem.Regards and thanks to those that contributed