Oil Pressure Problem?

[Pete Boole]

These are the parts involved Phil:

This is the casting that mounts on the end of the pump and also supports the distributor:



These are the oil pressure relief valve components after pressing out of the housing (big thanks to Dave at Lotusbits for showing me the internals of the valve recently!):



The plug with the o-ring simply presses into the housing with an interference fit.

Pete

[CHRISYD]

could you not just use an engine oil system flush or cleaner?

[Tanz]

These are the parts involved Phil:

This is the casting that mounts on the end of the pump and also supports the distributor:


These are the oil pressure relief valve components after pressing out of the housing (big thanks to Dave at Lotusbits for showing me the internals of the valve recently!):


The plug with the o-ring simply presses into the housing with an interference fit.

Pete

Thanks a lot Pete for taking the pictures. At least I can see what i'm looking for. I don't have a press but guess I could flush it out with brake cleaner and check it moves OK. To be honest I think my high pressure reading is down to the sender which according to the service history was replaced by UK Sports cars in 2005 for £82.76 plus labour by the previous owner. But I will pull the pump when i change the cam belt this month if the weather is resonable.

This sender looks cheap compared to UK Sports Cars in 2005 (Edited to say it now shows none available)
https://www.ebay.co.uk/itm/VDO-Oil-Pres ... ctupt=true

[Tanz]

could you not just use an engine oil system flush or cleaner?

Thats another option but if the oil pressure still reads high, you dont know if you have eliminated the pressure valve from a possible cause or not. Plus you need to change the oil a couple of times to get the oil flush out of the oil cooler.

[Lotus-e-Clan]

Phil,

I now run two 7-bar oil pressure senders into the OE VDO gauge to compare pre and post oil filter pressures. The senders are selected from a dash switch linked to a changeover relay. The old sender is in the std location and it does 'jump' from time to time - a bit like yours only less so - but at least I have data from the other sender to compare. I have vowed to recondition the old sender when time allows. I think, as has been said on here earlier, it could just do with both an electrical and physical clean.

When I set up this system I wasted money buying a so-called universal 'VDO' sender off ebay only to find that the resistance values ran inversely to the OE sender - ie OE sender max full scale deflection = high resistance ...duff ebay universal VDO sender max full scale deflection = low resistance d'oh - now used as a paper weight!

However, that said, I found VDO 10 bar senders were easiest to find, VDO 5 bar senders were a little less-common and OE 7 bar senders were ultra-rare/impossible...even the 7 bar universal 'VDO' wrong-ones are rare!

I eventually bit-the-bullet, gave-in and forked out the big money for probably what was the last 7 bar sender in the country at that time from SJS. The high price is largely forgotten now. The important bit is I have a pair of OE 7-bar senders that are more or less 'matched' - which is what's needed when comparing pre and post oil filter pressures.

In short I'd buy the 5-bar from a Lotus specialist (after first attempting to refurb your old sender) ...you'll soon forget about the expense and the stress caused by unreliable oil pressure values.

[Tanz]

Is this where the oil pressure relief valve lives?



If I poke about in there with a blunt screw driver I can feel a spring loaded valve moving.

Edited - Just looked back at Pete's picture - That shows the opposite end - so yes that's it. Not brave enough to press it out though. It moves freely so will leave well alone.

[Hawaiis0]

Just watch the threaded stud for the Dizzy lock doesnt get damaged.

[barker_001]

Yes Phil, that's it. You need to press it fairly hard to get it to move, but that's because of the spring rather than it been stuck. If I recall from mine, your photo shows the view looking towards the distributor?

[Tanz]

Just watch the threaded stud for the Dizzy lock doesnt get damaged.

Do you mean the bolt that locks the dizzy when adjusting the timing? Why is that likely to get damaged?

[Tanz]

If I recall from mine, your photo shows the view looking towards the distributor?

Yes thats right. Guess if you want to press it out (Pete's pictures above) you would have to push it out down this hole and out the other end. I think mine is working OK. When I put it back together and there is no change with the oil pressure reading I will get a new sender from SJ's.

[Tanz]

Just to bring this thread to a conclusion - I purchased a new sender unit from JG Supplies Part no 970946 £24.99 and all is well. Thanks for all the help and advice.