oil pump

[upnorthelan]

Can anyone tell me if it's possible to extract the oil pump while the engine is in the car? I'm in the process of installing a high pres. kit and have the pump w/in 1/2in. of coming out when it hits the frame. Might it be possible to unbolt the motor mounts and hoist the engine up slightly? Looks like what I thought would be a plesant afternoon job is getting more serious.
Thanks,
Mike

[upnorthelan]

If I'd have been in less of fuss I would have searched the archives first. It looks like I'll have to hoist or lower the opposite side of the engine to pull her out!

[CBUEB1771]

Place a floor jack with a wood pad under the sump, then unbolt the carburettor side engine mount. Elevate the engine with the floor jack and you can remove the oil pump.

[upnorthelan]

Thanks,
The job went well after the initial confusion.
mike

[peterako]

Hi Mike,

Well done on the change.

Any particular reason you're changing for a High Pressure pump/kit??

I changed my pump about 18 months ago (engine in situ) on my +2 froma a high pressure pump to the normal pump and the engine has never been happier.....

Peter

[upnorthelan]

Hi Peter,
I have an S4 I've been working on a few years, preparing as a mild street/ vintage car. Since I've owned it, I've always gotten 35 lbs cold, droping to around 20 lbs. oil pressure hot. I recently added an oil cooler and accusump, but still wanted to see more pressure when warm. I ended up using Dave Bean's replacement spring rumored to achieve around 60-65 lbs oil pressure cold. Hopefully it won't be too much work for the engine,
Mike

[msd1107]

There are two interrelated factors at work here. Oil volume and oil pressure.

You are looking for sufficient oil volume to insure lubrication of the engine and at the lowest pressure to minimize losses.

Generally speaking, anything over 30 or 40 psi at medium to high rpm should ensure adequate oil volume. Unless you have exceptional circumstances (a restriction somewhere), higher oil pressures just leads to higher losses.

At low rpm, oil pressure may droop, sometimes to as low as 5 psi. Generally speaking, low pressures are indicative of increased bearing clearances (which flow more oil at a given pressure) or of oil pump leakage. Increased bearing clearances are generally indicative of a well run in engine, which generally produces more power than a new green engine. For oil pump leakage, you can tighten up the clearances in the oil pump or replace it.

Modern oils will run at lower pressures than what was considered "normal" when the car was new in the '60s.

So if you can be comfortable with the lower pressures, learn to live with it. But it is your mental health and engine. To be really comfortable, you can do a bottom and top end rebuild to get new bearings and tight clearances and install a new oil pump with new tight clearances and then be really happy with 50-60 psi and 40 at idle.

David
1968 36/7988

[Carlos A]

Hi Mike,

I changed my pump about 18 months ago (engine in situ) on my +2 froma a high pressure pump to the normal pump and the engine has never been happier.....

Peter

Hi Peter. What do you mean? How was it runing before "downgrading" to an standard normal pump?

And for the rest of the crowd: What do you think about HP / HV oil pumps for street cars? Any advantage?

Carlos

[rgh0]

Volume flow to the bearings is whats critical, pressure is just whats required to get that volume flow

For road use the standard pump is fine you just dont use the engine hard enough for long enough to run into problems.

For race use with a wet sump to maintain sufficient flow at a constant 7000 to 8000 rpm on the track with potentially very hot oil you need a high volume / high pressure pump and oil cooler. A top quality synthetic oil with extreme temperature tolerance such as Redline helps also. This setup also helps you have some oil pressure at low revs when you return to the pits at the end of a race.

A high pressure standard volume pump will get a little more volume in circumstances when the standard pump is relieving ( i.e. any time the guage indicates 40 psi). This may help in some circumstances but wont help hot idle or other circumstances when the pump pressure is less than the 40 psi of the standard pump and the standard pump valve would not be relieving.

cheers
Rohan

ps 2000 posts!!! -I need to spend more time building engines and less on the computer

[elans4dhc]

Rohan
Please tell us you don't mean that, please.

[Leo Leentvaar]

For what it's worth here's my tuppence.
Last year I've had a full engine rebuild on my Sprint's Big Valve engine, it's been run in now and clocked about 1500 miles so far while runnning in.
I just took the car for it's first spin after hibernation last Sunday.
The engine has the standard oil pump and shows about 20 psi while hot and idle and goes up to 40 psi under acceleration and higher speeds, the needle remains stable FYI.
The oil used is the Penrite classic

I am not as well versed into car mechanics as some of you are but to me the sole purpose of the oil pump is to pump around enough oil for cooling and lubrication.
So the emphasis is on flow as the pressure yielded is only there to mostly overcome the pressure drop of the channels in the engine( yes I admit some pressure is generated by the flow of oil as well). I concur that since the inception of the Elan in the 60s oil technology has changed dramaitcally as well with the development of synthetic oils.
For a driver like me, that only takes his car for drives in the countryside, an oil like Duckhams or Penrite has a good enough viscosity and properties to keep the engine in good shape.
I am led to believe that the kent engine like any 60s engine does not take thin oils that easily(like the modern 5W oil that currently is used in my turbodiesel company hack)

[Dag-Henning]

Hi Mike,

I changed my pump about 18 months ago (engine in situ) on my +2 froma a high pressure pump to the normal pump and the engine has never been happier.....

Peter

Hi Peter. What do you mean? How was it runing before "downgrading" to an standard normal pump?

And for the rest of the crowd: What do you think about HP / HV oil pumps for street cars? Any advantage?

Carlos

- as already said ; - street car - std. oilpump. Anything else is waste of effort. Another thing to remember is that a hp/hv pump puts a lot of strain on the jack-shaft gear, and pump gear. You will need a selected jackshaft with minimum run-out ( they all have to some extent...) , and a hardened gear on the pump. A misfit here, and the jackshaft teeth may strip in very short time. (!) A lot of work for nothing on the street!
Dag

[skelteanema]

When I bought my car, it had only covered about 1000miles from engine rebuild, and it leaked oil from nearly every possible place. I had always wondered why the oil pressure needle was at the max on the guage (>60psi). I realised that my engine probably had a high pressure oil pump installed after hearing that the normal pressure should be about 40psi. After reading a few threads on this site, and the Miles Wilkins book on the pros/cons of a high pressure oil pump, I replaced the HP pump with the standard oil pump. The pressure now sits at a nice 40psi and oil leaks were substantially reduced, but did not disappear.

[Carlos A]

Thank you very much you all for your informed answers.

I changed the original oil pump for a standard aftermarket because I suspected the old one.

This is how the oil pressure changed, with a new pump, fresh oil and the same gauge (which is about 4 psi off)

OLD/ STANDARD ORIGINAL

IDLE
cold / hot / after a 2 hrs run
55 / 15 / 10


3500-4000 RPM:
warm / hot /
32 / 30 /

NEW STANDARD (from RD)

IDLE
cold / hot / after a 2 hrs run
45 / 30 / 20

3500-4000 RPM:
warm / hot / after a 2 hrs run
45 / 40 / 40


Best

Carlos A