Very Little Oil Pressure !

[beanpole]

Having sorted the electrics and my RV8 now starts and runs fine, I now find that I have hardly any oil pressure. I used to have 35 psi cold on the first couple of starts, now I have 5 psi at tick over, (light comes on), and a max of 10 psi 2500 revs or above. The engine has only run for about 15 mins total.

I have replaced the relief valve, spring and pump gears.

This is a recon engine and I removed the sump to check it did indeed have new bearings, bore etc, which it had, and the pickup pipe was cleaned before re-assembling the sump.

The pump just does not seem to produce more than 10 psi no matter how hard I rev.

Help….


:} :} :}

[Bernie]

Is it possible to have the wrong relief spring?

[TINKA]

Only thing I can suggest is that when I rebuilt my engine, I bought a completely modified oil pump unit from RPI. The firm who rebored my engine though said that in a lot of pumps, in the tube where the pressure relief spring goes, there is sometimes a casting line which stops the valve sealing properly. The solution was to use valve grinding paste to very carefully cut in a seat so that it will seal properly and then clean, clean, clean, clean x( x( x( x( .

I didn't fancy doing this due to the consequences if some of the paste is left behind, so I got them to do it and at the same time they honed the socket and made sure the face of the pump was completely flat reducing the end float in the gears at the same time

My car now runs 25psi at tick-over and when the engine is warm 50psi :tu :tu :tu :tu

Quite expensive to have done £65 I think but as this is one of the real weak points on a RV8, Money well spent. :tu :tu :tu

Hope this helps Martin :tu :tu

[beanpole]

TINKA

I have another second-hand oil pump on the way to verify if this is the problem. There is definitely bad scoring in the bottom part of the relief valve bore.

If this proves to be the problem I would like to invest in a new pump , modified as you suggested, did RPI do the honing work as well as supplying the pump ?

Steve


:tu

[TINKA]

Hi Steve, if you do decide to go this route then buying a new pump is not a necessarily the way to go. If when your old housing is stripped if there is no wear then as you already have the modified relief spring you will possibly only need the new gears. Your best bet is to talk to the people who did mine, they are Racemettle Engines In Gainsborough. Tel no 01427 616565 ask for Darryl.

The new modified pump which I bought from RPI I seam to remember was another £80 on top of having the mods done. Which is why I say check the condition of your old pump's first.

Hope this is of some help. Martin :tu :tu :tu :tu :tu :tu

[beanpole]

New oil pump arrived, fitted it , packed with vasaline and primed it with the electric drill,, OH NO I can’t belive it..no better, there is something funny here oil light only goes out when revved and max pressure reaches 10 psi !!!, and this is when cold !

I noticed the new oil pump came fitted with a new Rover Oil switch hmmm, so I moved the ETB oil light switch wire onto the Rover sender, guess what,,, light oil light goes out as soon as the engine fires up and does not come on until the engine stops.

Looks like my ETB sender is duff, (anyone want to buy a used oil pump fitted with high pressure spring and new relief valve).


:tu :tu :tu

I feel a bit of a prat now...

[Srv8]

50 psi ! mine is ~32ish on startup & normal driving, but drops when warm to almost 12. so low sometimes I have been known to stop the engine in traffic.
pressure surely wouldnt go UP when the oils warm ?!?!

Steve

[TINKA]

Steve, just reread my post and it is a bit vague.:} :} :} 25psi at tick-over when the engine is warm and 50psi when cruising also when the engine is warm. On startup it is about 70psi initially and then it slowly drops as it warms up.

Martin :tu :tu :tu :tu :tu :tu :} :}

[Dan]

It seems aas though this is a common problem. My engine is made from all new parts (The only original part is the casing). On startup the pressure is about 40-50 when idling, When hot it's about 30-40 @ 2k revs+ but drops to 5-10psi when idling (Warning light comes on). Once the engine cools and is restarted the pressure is back to 40-50.

I also have electronic gauges supplied by ETB.

I now ignore the warning light when the engine is hot - Which somewhat defeats the purpose... What sender units could I try with my ETB gauges to see if it is the cause.??


Dan ~ http://www.dan.uk.net/Projects/Cobra/

[russell_ram]

Dan/All,

the answer here is not necessarily that your engines have a problem - more that electric pressure guages are next to useless. I would never rely on one, let alone fit one in any car where I was worried about knowing the correct oil pressure. Fit MECHANICAL GUAGES wherever possible - after all they cost the same. If you're worried about the extra plumbing being on show, you can hide it inside the loom like I normally do.

Whenever I have someone complaining about oil pressure, the first thing I do is to hook up a calibrated mech guage - more often than not, there is nothing wrong with the oil pressure/water temp etc - it's the sender or guage that is U/S.

Russ