Oil Pump

[BillW103]

Is this the proper bolt combination to hold on the oil pump?

 

[jlaird]

I expect it makes no difference. All bolts all screws some of each. Important thing is for them to clear the cover.

Sure is a rusty lump on the outside, where did you have it hidden, under the back porch step. LOL

 

[smaceng]

Make sure you replace that leaking rear freeze plug.
Scott in CA

 

[BillW103]

It's a 12V motor that sat in the car for 30 years. Are the two diferant bolt heads stock. This is a 74 block and the last licence on the car was 76.

 

[Gerard]

Yes. As I recall. the panhead screws hold the cover to the pump, the hex bolts hold the pump to the block.

 

[jlaird]

Take it apart and check the insides. Your shop manual will tell you how to determine if it is good.

 

[TulsaFred]

Here's a question:

Is it smarter to replace the oil pump, as usually advised

or to reinstall the original if in good condition?

Given the problems I've so frequently had with repros, I think keeping the original is probably better

Fred

 

[JPSmit]

Here's a question:

Is it smarter to replace the oil pump, as usually advised

or to reinstall the original if in good condition?

Given the problems I've so frequently had with repros, I think keeping the original is probably better

Fred

I replaced the original - should have bought a new one. IMHO oil pumps are consumables like water pumps and thermostats. It's not that they stop working but after 40 years the tolerances aren't there.

 

[Spridget64SC]

Take it apart and inspect. Check the housing clearance to scroll. If more than 0.006", toss it. If the rotor and scroll are scored from debris, toss it. You won't know what you have unless you open it up and inspect.

The two screw heads just hold the cover on the pump. The two 7/16" bolt heads fix the pump to the block.

The after market oil pumps I've been getting from Gordon at the B'hive in SC are good quality parts. My favorite oil pump used to be the FAI brand, but haven't been finding them too much anymore. I'm sure BPNW can set you up with a good quality pump if you so choose. The biggest issue with oil pump wear will be the pressure drop when the oil is hot and the rpm's drop to idle. Usually, when running the engine at speed, the oil pressure is just fine, it drops due to the excessive internal clearances when idling.

Good rusty block cleaning procedure. Alternate using Naval Jelly and oven cleaner. Wire brush/scrub with cleaners on the block both times. Wear protective gloves, goggles and apron. Does a good job, but acrid and messey. Hose off with hot water and clean block using plenty of hot soapy water. Use a good stiff 3" cup brush in a 4-1/2" side grinder to clean all the flat machined surfaces.

Mike Miller

 

[Spridget64SC]

Worn Oil Pump from race engine. Debris from sump passed screen and entered pump. Gives an idea of oil pump wear.

Another picture:

HTH,
Mike

 

[TulsaFred]

Great info, Mike
thanks

Fred

 

[TulsaFred]

Mike,
Can you show a pic of how and where you take the .006 tolerance measurement?

Fred

 

[Spridget64SC]

I'll see if I can do this tonight. The 0.006" is measured between the aluminum housing and the steel scroll. Much more that 0.006" and the pump is getting too loose. Time to renew.

Mike

 

[Spridget64SC]

All:
Here are some pictures I took last night of the oil pumps. Got a used one from my landlord at the shop. His area is behind mine and we both are total Spridget addicts and racers.

This picture shows oil pumps in row. Starting at the left; New "concentric", then old/used Hoburn Eaton, then new "Powertune", and last one is a three bolt fixing 948/1098/Cooper 'S' 1275 type. Note the different type of bolting to the block. 4-bolt and 3-bolt fixings usually use metal lock tabs. 2-bolt is usually a lock washer.

This picture is of the old used HE pump showing the worn out rotor. See the scores from debris caught between the rotor (cam driven part) and the scroll. Also look at the flat worn on the rotor face. The trailing face as the same wear. This pump goes in the recycle barrels. Aluminum in one and steel in the other. Beer money when full.

Here is the money shot. The one showing where I measure for scroll to housing clearance. 0.006" in my upper limit.

This is the last one showing the Powertune oil pump with measurement. This oil pump appears to be the County brand offering and looks to originate in the UK at a oil pump manufacturer who makes pumps for a number of applications and suppliers. I've got the same pump in a different box without the "Powertune" in the body.

Hope this benefits all viewers. Oil pumps are the heart of the engine. Finding a good used pump in a 36+ year old engine happens, but not often. Usually, debris and use has taken its toll. A new one is cheap insurance for an engine and the typical enthusiast rebuilder who isn't into engines on a weekly basis. I usually have 3 or more engines going at a time.

Take care and enjoy,
Mike Miller

 

[dklawson]

With new pumps, make sure that the pump's steel plate is flat before installation. If it is bowed, you loose some oil flow capacity. The plate can be sanded flat using a piece of coarse wet dry paper on top of a piece of plate glass. Likewise, you can sand down the aluminum pump housing height a tiny bit to set the rotor to housing clearance to near zero. That will also slightly improve the amount of oil flow.

 

[TulsaFred]

Highly educational, thanks

Fred

 

[Hap Waldrop]

It might be worth mentioning, you also need to measure the distance between the points/lobes of the drive and the scroll when they at their closest position, your manual should have a photo and talk about this, I know the MGB manual has this in it for sure, and as far as this goes it's the same deal. Alot of the time a old OEM pump may very well be in absolutely lovely condition and if so, and they pass the clearence chack and has no deep end play scratches to speak of, there is no reason not the reuse the original pump, these day sort of a common pratice with 948 oil pumps coming to the US, as the new ones offered are for the later Minis, and come no where near fitting the older inline 948 engines.

 

[Spridget64SC]

As Hap points out, there are other clearances that can be checked in the oil pump. What I've pictured is the first one to perform and gives you a real quick assesment of the housing condition. Next do a visual on the rotor and scroll and inside surfaces of the housing. Scoring and gouging can eliminate the pump here. Then look at the clearance the shop manuals show. Look for a heavily worn flat on the meeting surface of the two steel pieces. Wear here will open the clearances and hence the measurement.

So, now its back to the replacement question. If you have doubt, then renew with a good quality pump. Loose clearances mean the pump will lose flow mostly at idle when you really want some pressure (like 20-25).

Take care,
Mike Miller

 

[rkep01]

Well, after reading this post, I determined to take a look at my oil pump, since my engine (948) is out of the car and discovered that its pump is a Burman type. :confuse: Not sure of how to check for wear, but the vanes seem to be where they should be; up against the cavity wall. I would assume that each vane should be checked against the cavity wall after the pump shaft has rotated 90º in turn. Should there be some clearance or should the vanes be tight against the cavity wall with no clearance at all? Note that in the WSM clipping, there is a write up for checking the Hobourn Eaton type, but nothing for the Burman.

 

[bug_sixty]

all I hope is your paying yourselves for all this effort because the brandee new ones are around forty big ones.... and agreed the oil pump is one of the most important items of a great engine