Simon
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| posted on 2/11/08 at 05:30 PM |
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Oil pressure - aaarrrghhhhh!
Chaps,
When running car a couple of weeks ago I had very little oil pressure at tickover and a bit more at road speeds.
Today I fitted the higher pressure relief spring (from Rimmers) to pump and.....
I have what appears to be even less!
It's got a Mocal remote filter takeoff, so I'm wondering if Mocal already use a higher rated spring.
Suggestions and alternatives welcome please (I've just looked at DT site and electric oil pump is over £300, so that's a no-no).
ATB
Simon
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r1_pete
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| posted on 2/11/08 at 05:33 PM |
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Sound like something is holding the relief plunger off its seat, did you check and clean it while you had the spring out??
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Bigheppy
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| posted on 2/11/08 at 05:46 PM |
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Chop Shop had a similar problem on their RV8 and it ended up being the drive to the oil pump 
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rusty nuts
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| posted on 2/11/08 at 06:28 PM |
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What oil are you using?
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02GF74
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| posted on 2/11/08 at 07:47 PM |
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you're the rover v8 engine chappie?
from memory, the valve should open at 30 psi; rimmer uprate springs open at 10 psi more.
commonly people fit stronger spring or pack allen bolt to raise pressure but all that does is put further strain on nthe oil pump.
anyways, the take off plate is just that - there is no oil pressure spring. Some plates have thermostat fitted whcih is a thingy filled with wax that
melts are certain taemp to open port, normallly to oil cooler.
anyway, back to your problem.
what psi are you seeing at idle? 15 psi is not bad but anything less is a bit of a worry.
do you trust your gauge?
did you examine the pump gears for wear and check the rotor clearance?
the gears are cheap to replace.
also check the relieve valve - the thimble thing is not scored and free t o move i n t he pump - again cheap to replace- they can jam.
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mark chandler
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| posted on 2/11/08 at 08:14 PM |
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Take the bottom off the oil pump and flatten on a bit of wet and dry over glass and get rid of all the scores.
Next, get a straight edge, the oil pump gears should be very slightly proud of the housing, if flush the then whole front cover is knackered. You can
get around this by throwing away the oil pump gasket and using silk thread and blue hylomar (same as Rolls Royce use, its sounds horrible though) to
form a thinner gasket, make sure its not to thin and binds the gears.
If the pump is all within spec then its probally losing pressure at the rockers, if the rocker shafts are badly worn oil will escape up here.
If its only done this since fitting the remote have a look for poor alignment of holes etc.
Regards Mark
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02GF74
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| posted on 2/11/08 at 08:39 PM |
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quote:
Originally posted by mark chandler
Next, get a straight edge, the oil pump gears should be very slightly proud of the housing, if flush the then whole front cover is knackered.
as the top of the oil pump is formed by the timing cover, it is possible to correct the wear if you are able to skim the base of the oil
pump housing.
A piece of wet'n' dry on a sheet of glass may do it but you have to be sure it is sanded evenly, easier said than done.
I have never had to do this but reckon it shold be possible to take off up to 0.5 mm if you have a veriner caliper by this method; in any case the
gasket should take up any unnevenness.
nore: this ^^ is all conjecture.
If its only done this since fitting the remote have a look for poor alignment of holes etc.
not sure about that - the mocal cooler take off have a circular channel that should allow fitting in any orientation.
Regards Mark
Did this low oil pressure happen before you fitted the oil cooler?
Some things to try. remove cooler and fit oil fitler if you can - you can buy small v8 filters halfrods: HOF208 (?) and see if you haw low oil
presure,
then fit take off but connect oultets together and check again,
if the pressure changes at any one of these stages, then you know you have a restrition.
what size hoses are you using to plumb? 3/4 inch is recommended sized.
is the cooler high fited high up?
is it fitted so that hosesd enter at the top of it, of from the side?
hoses entrering from below is not good as it can cause air locks but I don'lt think that will cause low oil P.
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02GF74
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| posted on 2/11/08 at 08:44 PM |
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one more thing; when fitting remote oil cooler, the oil flows into the filter via the little holes around the circumference;
and the oil flows back into the engine via the central bolt hole.
unlikely you have have it wrong but check.
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mark chandler
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| posted on 2/11/08 at 09:27 PM |
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Generally when you look up inside the gear housing the top is scored and ruined, closing the clearence right up does restore things to a more normal
condition.
The oil pump shafts also wear due to lack of lubrication, you can attend to this in a couple of ways:
1 Drill and tap into the side of the shaft housing and take an oild feed from the old pressure outlet.
2 Much easier, when building the engine drill two holes from from the front of the block through to the base of the followers so that oil can drain
forward and splash down on the timing chain which also throws it around the top of the pump shaft.
Regards Mark
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Simon
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| posted on 2/11/08 at 09:38 PM |
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Chaps,
Thanks for all the replies, The o/p was fine before I stuck the turbos on, and I think that's the prob, hance the higher pressure relief
spring.
It took me three hours to get the pressure relief spring changed so not too keen to repeat the procedure.
I'm going to assume that something is sticking or scored and take cover off pump and have a look.
Engine is v low mileage so not really expecting trouble there.
ATB
Simon
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mark chandler
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| posted on 2/11/08 at 10:38 PM |
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Rv8's work on volumn of oil rather than pressure which is why they can last so long, lots of old ones have the oil pressure light flickering at
idle when hot.
Can you clamp off the turbo feeds in turn and see if one in particular is bleeding off the pressure?
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r1_pete
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| posted on 3/11/08 at 08:36 AM |
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If the pressure was ok pre Turbo's, then it would be logical to suspect something in the turbo's, or, you need a higher volume pump to
keep up with their apetite for lube and cooling. With the flow the two turbo's need its almost like adding a bypass in the lube circuit.
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02GF74
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| posted on 4/11/08 at 09:44 AM |
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quote:
Originally posted by Simon
The o/p was fine before I stuck the turbos on, and I think that's the prob, hance the higher pressure relief spring.
There is the answer. I know nowt about plumbing in turbos but think they use same oil supply as engine.
Oil or any sort of pressure exists if there is something restricting the pump.
Try this: blow air out of your gob then try again through a BIC biro.
The second case becomes harder as the biro is restricting air flow.
In your case I would say that the trubos are unrestricting flow so the oil takes the path of least resistance. It is irrelevant how much opressure
the oil pump can product is this occrus since there is not enough restriction for the pressure to increase and for the relief valve to open.
Or it could be somem other reason.
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