Hi,
Today’s questions. I am changing the current by-pass oil cooling system over to the later full flow version. Stripping down the oil filter assembly and removing the oil pressure relief valve I released I do not know how to tell if it is good or not? By shaking it I can hear what appears to be a ball bearing bumping about and am not sure if this is good or bad.... it doesn’t look if it comes apart to clean or inspect? What are people’s thoughts? It doesn’t look like you can get new ones any more?
Secondly, in the oil filter body of the full flow system, there is a bypass valve. What is not clear to me is whether the bypass valve in the sandwich plate remains or is removed when changing from bypass to the full flow version. I am thinking it is removed? Jaguar sell new bypass valves.... do they fail ever and would it be worth fitting new?

 

My parts drawings show that the by pass valve, #12 in the 3rd snap is ONLY for relief oil cooling, and I agree with the assumption it is omitted for full flow.

The rattle, NO IDEA, never shook one, and never had one fail, dunno.

 

Hi Grant, Yes that is the same route I took to come to the same conclusion. The jaguar parts catalogue lists that location as bypass only. I think it will be coming out!
I can,t find anything to say how to inspect, test, de-assemble the pressure relief valve unfortunately.

 

Ow... just looked at Rob Beere’s web site and they do a one day turn around on the V12 oil pressure relief valve rebuild! £95. A success!

 

I simply put all mine back in position, and moved on.

The $$$$ back in 1998 were STUPID, and I did not have oil pressure problems anyway.

Worst issues are the o/rings INSIDE the sump for the pickup and supply pipes, to and from the pump to the filter housings. They fail, shrink etc, and things kind of go AWOL slowly.

Never lose all the pressure, just the "up " of the oil pressure takes a few seconds longer. The pump is HUGE, as is its pressure and volume ability, so it can compensate quite well for about 500K miles, or about when the engine finally gets run in.

 

Thanks for the warning. I have ordered all new OEM ‘O’ ring from Jaguar. Hopefully they are post Ford input ones, so,quality may? Be better? A bit like the post Ford gaskets are meant to reduce oil leaks?!

 

Clouder
As and when I get around to rebuilding my engine, I was wondering whether to change to the FF system. I have all the bits in stock. Anyway, I tested the oil temps, and the in and out temps from the cooler on my OEM bypass system. I used k probes and stick-on temp strips
I found that oil temps never went above 87C, even on the hottest conditions and in the hottest part of the engine. I also found that the bypass cooler took 20C out of the oil temp across the cooler, so I wonder whether I shall bother or not.
The FF system does have a pressure relief valve (basically all oil pumps must have) in exactly the same place, with the same question-mark pipe on the end of it, as the bypass system. I say this because my spare FF filter head has all these bits on it. In addition, the FF system has a relief valve inside the oil filter chambers in the head unit, so that if the cooler gets blocked the oil can go direct to the engine oil distribution system.
I did take the relief valve apart once, from memory if just unscrews and it basically just a big spring holding a valve shut. When it opens the oil goes direct to the sump via the casting held by the triangular three-nut-fixing casting, not via the question mark pipe - which is there for I am not sure what, maybe to syphon off oil that creeps past the valve piston? Mine does not rattle, so a rebuild a good plan!

 

Greg, as I read your description of the pressure relief valve I was thinking it shouldn’t rattle then, and then you said yours didn’t! So yes, time for rebuild as you say.