low oil pressure? - try this

[McBreadhead]

My crossflow has been suffering low oil pressure ever since I swapped in a higher power unit of 1993 vintage that, when I test drove it in another car, had good OP of circa 4 bar on cold.

 

I had 'professionals' install it but from day one I had to check gauges, renew switches, PRV springs, did a mechanical test but couldn't fathom why the pressure would go down when revs rose and was generally 2 bar or worse.

 

I've just had it rebuilt and again on start up had poor OP. This was baffling as we'd replaced the pump with a new hi pressure hi capacity item, oilways all checked, no obvious leaks etc.

 

I then recalled the 'professionals' had swapped the 1993 sump with the 1996 item from my original xflow on the grounds that it looked better.

 

Fortunately my engine builder spotted the potential conflict and found the collector plate grounding on the bottom. A quick tweak on the collector to provide a few mm clearance and hey presto 4 bar!

 

It seems as if the sump heights vary so if you are considering swapping sumps do check this tiny detail.

 

Don't ask me to recommend a certain well known 7 specialist.

[Paul Richards]

Glad to hear you've found the problem. It's quite common.

With a steel sump, if you ground it, it can bend up and block the pickup. We used to braize 3 nuts on the pickup so that if they touched the bottom of the sump there was still sufficient room for the oil to pass. If you see what I mean.

 

Paul Richards

Area Representative - L.A.D.S. (Lancashire and District Sevens)

LADS Website

Growing old is compulsory - Growing up is optional

[McBreadhead]

Paul,

 

Now that is a sensible little mod and a half.

 

The older sump seemed to be a pressed steel item and 'tougher' wheareas the younger one seems fabricated. Will have to watch grounding out then.

 

Thanks

[Nick Chan]

Nick,

 

Glad to see that you are getting to the bottom of things with the engine - now if you had only just had the engine dropped in without "improvements" it might have been easier!!

 

Cheers

Nick

 

The BEC has gone - now onto an R400!!

[McBreadhead]

Nick,

 

As the Beatles once said,

 

"..........long, long winding road............."

 

I will update you with all the history once RR (No 3) is sorted

[DaveMorris]

Well, not only did you get there in the end, you found the root cause of the problem.

 

Just a pity that you were forced on the circuitous route by a person or persons unknown who could possibly have been a little more thorough.

 

The engine certainly went well enough before teh transplant and the "improvements". With my track record with x-flows I should have bought it from under your nose anyway 😬

 

X-flow(er) power now resting. Trying Vx for a change.

[Englishmaninwales]

Nick

Glad you' ve got it sorted at last. Those North Wales roads are still empty..... 😬

 

Malcolm

[McBreadhead]

Hi guys,

 

I need to put 130m on the car to bed in the engine before the RR session but Horseshoe Pass may tempt me beyond my 5k rev limit so am reluctant.

 

Unless I bring it up to do both............

 

Hope all's well in Rhyl meester English 😬

[stevefoster]

I had a similar problem on my 1st XF in Sweden back in 1997.

Oil pressure dropped as revs rose.

Turned out the engine / car builder had used a sump / pick that were not compatible.

The strainer mesh was pushed hard against the bottom of the sump causing the oil to have to flow through the thickness of the wire of the mesh that was obscuring the pickup - pipe shortened problem solved.