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MG MGB Technical - Auxiliary oil pump?

So while I'm in grad school here, I really don't drive my '73 RD very often. The engine doesn't have many miles on this rebuild. Oil pressure is good. But when I first crank the car, especially after it sits for a week or so, the bearings wanna knock like a platoon of vacuum cleaners salesmen. I know, it's because the oil filter has a lousy anti-drainback valve.

Is there such a beast as an auxiliary (electric?) oil pump, to get the oil system going before I try to crank? It's worse in the (poor substitute for ) winter we get around here, because It has to have a spot of choke to start but that makes it rev to 3K or whatever with no pressure.

Help. My baby begs you.

Rob
Rob Olsen

I would switch your brand of oil filter to one with a better drain-back valve first. I believe that Wix is a good one. Others have said good things about the Volvo 240 oil filter as well.

I would try cranking the car over without the ignition (without choke may work). You just want to spin the engine over long enough to get some oil flowing without it actually starting.

Your engine shouldn't spin too long without oil pressure unless something is badly wrong.

Tyson
Tyson Sherman

Rob,

For a start, sounds like your choke needs adjusting! Shouldn't go higher than 1300-1400rpm IMO. :)

Call me crazy, but I'll admit to something. I never start my V8 cold, unless I've cranked her over till I see pressure register on the gauge. I do this by way of an ignition cut out switch (mainly for security purposes). It's a lot better than the cold clatter you experience even with anti drain back equipped filters. All of my 4 MG's do it when cold. It's not a nice thing at all. So I'll probably kill a few starter motors over my lifetime, better than the engine bearings I figure. <VBG> :)

There are electric pre oilers or whatever they are called, Summit Racing sells them, but they aren't cheap and I wonder what would happen if one of them malfunctioned..?

I'd still get that choke fixed.. :)

Cheers,
Neil
Neil Cotty

Rob ...First, you gotta get a better oil filter. It's cheap insurance (under $5 bucks). Some folks distain
the units from Fram. Wix, Purolator, etc. seems to get higher praise. Some owners run with a big
Motocraft filter from a V8 Ford (FL-1A) as it has a lot more filter surface area as well as a fairly good
anti-drainback valve.

Before starting the engine after a long sleep - pull the spark plugs, shoot a few squirts of oil into each
cylinder and wait a few minutes for the oil to flow to the piston rings. Then, spin the engine until oil
pressure registers on the guage. Put the spark plugs back in and fire it up.

--------

Instead of an auxillary oil pump...years ago...I remember a gizmo called an "Accu-Sump" or "Accusump", or something spelled like that.

It looks like a small aluminum scuba tank cylinder with a pressure guage and hose. I think it holds
about 6 quarts of oil. Inside, is a nitrogen gas-loaded piston. The hose is connected from the tank
to somewhere in the engine oil system (nearest the main gallery). Pressurized oil from the running
engine is pumped into the Accu-sump cylinder and is held there in reserve. Return pressure is
supplied by the gas-loaded piston.

In the event of a disasterous oil system malfunction (bad pump, blown oil cooler hose, hole in pan,
etc...), pressurized oil in the Accu-sump cylinder is fed back into the engine oil system - giving you
enough time to limp to the roadside (or a nearby pit stop) without bearing damage.

Before shutting off the engine - there's a valve on the cylinder that you close to hold the reserve
oil in the Accu-sump.

Later, before you start the engine (cold) - you open the valve on the Accu-sump...and pressurized
oil flows out and primes the engine oil system.

One "hitch" to this is the cylinder is rather large to just mount anywhere. Most racers mount it where
the passenger seat used to be. It positions the pressure guage and the valve within easy reach.

I believe that Accu-sump is still in production. Maybe a web search will turn up some info.
Daniel Wong

Hi Rob

My daughter has the same problem with her 1500 midget.

She just cranks it a bit with no choke or accelerator until the oil light starts to flicker.

Cheers
Ian f
Ian Fraser

Daniel

You are quite correct about Accusump; here is the URL:-

http://www.accusump.com/index.html

One would use one as a pre-oiler, prior to starting, but also to combat oil surge in high G manoeuvres, such as long fast sweeping corners, or prolonged hard braking. It will also protect against low oil levels caused by high oil consumption on long non-stop runs.

As you say the Accusump is a "hydraulic accumulator". It is available on three sizes 1, 2 or 3 US Quarts, all of which are of similar design. The cylindrical reservoir, which can be mounted anywhere convenient under the bonnet (hood) contains a free-sliding piston.

On one side of the piston, the cylinder is closed, with air filling the enclosed space. The other side of the piston is full of oil, pressurized by the engine’s oil system.

As the oil pressure increases, oil is pumped into the reservoir and the air on the other side of the piston is compressed, the piston slides towards the closed end of the reservoir which is charged with oil.

If the oil pressure drops, the air expands and forces oil back into the engine. This has the effect of damping out sharp changes in oil pressure. Should the oil pump suck air, due to a prolonged high G manoeuver the Accusump provides 10-30 seconds of oil pressure, which is usually sufficient to finish the manoeuver without harm.

Prices are, IMHO, reasonable, a 3 quart unit with an electric valve is $285, whilst a 1 quart unit with a manual valve is only $150. I would go for the largest reservior which would fit in the available space with an electric switch.

Years ago a couple of friends fitted them to B V8's and were delighted with them. I keep meaning to fit one to my BGT V8 and your post has got me thinking again.

Nigel
MGA 1600 Roadster
MGT BT V8
MGR V8
Nigel Steward

Carquest filters are made by Wix, I'm using one now and no problems.
I have used Motocraft FL300 and Unipart filters with good results. I think
it was suggested in an earlier thread that it's best to use a short filter
because there is less area above the filter adapter pipe to fill, resulting
in quicker oil pressure build up. My 74 roadster has a hangdown filter
and is a lot less messy to change. It uses a different filter and is a little
harder to find, but I never have to worry about oil filter leakdown.

I used Fram on my daily driver cars for years with no problems. But about
two years ago I put a Fram Supergard on my Nissan PU and it leaked down.
I complained to Fram and they wanted the filter, they tested it and agreed that
the anti drain valve failed. They sent a claim form but I took the filter off when
I heard the engine rattle the first time so there was no provable damage.
Fram sent me three new filters and I threw them away.

FWIW Clifton

Clifton Gordon

You could also just run a dry sump, which like the accusump is an external tank with an electric pump that basically replaces your oil pan and mechanical pump. These can get expensive, but check all the racer out fits, Summit, Jeggs, racer wholesale, pegasis etc...
Bill
Bill Mertz

Thanks to all.

I'll try the Wix. I'd heard that the Volvo 240 filter was good... (Mann? Is that the mfg?)

I've been hesitant to sit and crank the car in the parking lot for 30 or 45 seconds to get pressure up, simply because I'm getting a bit sensitive about people making reliability jokes near me. Not that my 'B is unreliable, far from it! I just hate *looking* like my car won't start. Ah, well. Don't wanna go through another rebuild, either.

Found the oil reservoir thingie in a Summit Racing catalog - it was a Moroso, 1.5 quart for $59.95. Not too bad. They also had electric pre-oilers - $450!

Thanks again to all.

Rob
Rob Olsen

This thread was discussed between 20/01/2002 and 24/01/2002

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