4 cyl big block oil pumps - how many versions? FAQ added p2. Updated p4.

Correct Chris its hydraulic .

 

Interesting thread ......for engine geeks !

since that includes me i have a couple of observations to add,



I reckon the waisted section is simply grinding clearance, the middle one is ground all along, but the one on the right looks turned on the spline and waisted bit, and only ground where needed for the bearing surfaces, for cost probably. Is one of the ground sections slightly larger diameter than the other?

I appreciate this is a possible leak path if things aren't working properly, which isn't ideal. But since the shaft isn't grooved at the oil hole, the flow of oil would be very limited as you mention, the oil path is only open once an engine cycle.



That hole in the middle looks a lot like a check valve to me, as Chris mentioned. Would be interesting to take that thing apart, see if it is.



Is that one sprung loaded? Can't see the oil hole in that pic.

Mike

 

well at 6000rpm that hole in shaft is opposite the hole in block 60.4 times a second, which is enough for me!!
Keep in mind thats fully opposite, oil would flow in hole I dunno, 15 degrees before and after it was directly opposite too.
Its not a check valve, just a hole. Ive one split here.
I dont think any were sprung loaded, and I dont know why not...
Ill shoot up a pic of the cap split.

 

maybe its not sprung for the same reason a hydo follower isn't sprung......it doesn't need to be as its 'sprung' by oil pressure

 

Maybe, but, the oil cannot pressurise it if its say 1mm off pump gear face if for any reason it gets lifted off it as I mentioned above, remember, my one was jammed up with gunk.

And heres the cap split, very simple inside, plunder is quite heavy.



Brian.

 

It would be very difficult to work out the flow of oil, but i suspect it would be low or comparable to an oil fed bearing in the engine.

Hydro followers are sprung - tappets are and the cam chain tensioner i've been working on is. The spring force is about the same as the force provided by the oil at idle on that.

No check valve and no spring, its a new one to me, i suspect its a solution to some NVH problem from those gears, which is massively flawed from the start - same number of teeth is a big no no on a gear pair.

Mike

Edit: misread one of your posts earlier, they don't have the same number of teeth - 17-19?

yeah even with the thing stuck up i really don't think much oil will flow. Not got anything to base that on other than speculation.

 

When you say flow of oil Mike do you mean with everything ok, or are you talking about if the cap got stuck in the ''up'' position?
Surely the flow of free oil out a 5mm hole 60.4 times a second would have an effect on oil pressure if the cap was faulty as in my picture above taken in through the hole thats normally capped with a frost plug?

All 4 gears being discussed have 17 teeth each.

 

No...it is not works just as Brian described.I pulled out the plunger. Yes the hole is in the middle of the plunger.

 

I want to mention a bit about the pressure relief valve too while were on this subject, ill take a few pics and do up a post.
Chris, feel free to split off what ever replys you want into another thread if you want to keep this one just on different pump types.

Brian.

 

All fine for now - can split at any point, so keep up the work!

 

Below Ill be taking a look at the pump itself and explaining different bits and how they work, and a few things to note in respect to wear issues.
(2.0l 36mm 16v pump)

Here you can see the pump as it is in the engine but with the outer casing removed for clarity.
You can see the feed hole up from the pick-up to the left of the rotors, and the hole down on the right to the by-pass pressure regulator.


Below is the bottom housing but with the rotors removed so you can see the feed hole up the from pick-up, and the hole on the right down and across under rotor seats and onto to the by-pass pressure regulator.



And a picture with the cap removed and the spring and piston withdrawn.
The cap has a small hole in it in order to let pressurised air escape from the area behind the piston(spring side) so that the piston can move freely to the left as the oil pressure comes against it. If the hole was not there, the air behind piston would become pressurised once the piston moves to the right and would give inaccurate rates.


Lets take a look at the route the oil takes inside the pump itself.
When the engine is off there is no oil pressure in the pump so the release valve is closed.
Once the engine is started the oil takes the path shown below, up pick-up, gets drawn in between rotors and casing, around, and up to the filter, as shown by the yellow lines and arrows.


Once the oil pressure is reached up top in the engine after starting, the by-pass pressure release valve opens letting any excess oil under pressure back out of the pressurised circuit and around to the pick-up or low pressure side of the rotors, as shown below by the red line and arrows.



Now, lets take a very close look at the by-pass release piston.
Below is the piston, its made of steel and has a hollow centre, the reason the centre is hollow is because a longer spring can be used and therefore a more constant and uniform pressure can be applied to the rear of the piston.


A close up of the top of piston, showing angled seal face, much like a cylinder head poppet valve. Flow is more controlled at small opening rates, and the flow is directed out the orifice better, and of course, an angled nose leads to a greater sealing face area.


A shot of the bore where the piston normally resides.


And one of the angled sealing face. Take note of the partial drilling too in the base(bottom of bore), this acts as a mini sump and always contains a small quantity of oil in order to lubricate the lower portion of the piston.


The by-pass release and its operation.

If you look at the few close-up shots below you can see how the piston movement changes in respect to engine temperature and rpm, and of course what happens it if the worst should happen and your oil pressure drop due to bearing failure.

Here you can see the piston in its rest or closed position, engine is off when piston is in this position. The pump is not turning, therefore no oil flow, or excess oil to be re-routed.
Its also important to note the scoring on its surface, a direct indicator of piston travel during its operation period/cycle.


With engine started oil starts to flow and pressurise.
Engine is cold in this instance and although there is the correct oil pressure in the oil gallery's there is a higher volume of oil being re-routed through the by-pass.
There are two reasons for this, the bearings and caps throughout the engine have not yet expanded to their full operating tolerances, there is a thinner space between parts for oil to flow so there is a ''surplus'' of oil in the system and it has to get re-routed.
The second reason is down to cold oil being thicker or said to have a higher viscosity.
This in turn limits oil flow through the engines critical bearings because oil with a higher viscosity has a higher resistance to flow, and again, as above the by-pass return opens.
The above is why you should never drive a car hard from cold.
Its important to note under normal conditions and with a healthy engine, the by-pass return regulates this pressure and flow at various degrees of engine wear, temperature and rpm and in turn keeps the gallery(s) pressure and flow volume at the correct equilibrium.

Piston position in the picture below, just after starting from cold, a small amount of oil is passing through the by pass.
Engine speed is very low and therefore pumping volume is low too.
In a healthy engine even at low rpm the tolerance between bearings is small enough to limit this low flow and pressure will increase.
This pressure build up is solely governed by the pre-load force of the spring acting as a by-pass in the system.
At very low pump speeds the pumped volume is low and therefore the piston needs only to open a small amount to ''bleed'' of this small oil flow surplus.
On a worn engine the flow resistance is lower through the bearings, the low flow generated by the pump at low rpm can actually make its way through these bearings with the result of the pre-set psi set by the by-pass return spring-rate pressure never being reached, and therefore turning on your oil buzzer or oil light.
This is often why on a worn engine when revved above idle will extinguish the oil light.
Higher flow is generated, it overcomes the flow resistance in the worn bearings, and has then the power to produce pressure at the by-pass and in turn open enough to set/govern the required psi throughout.


Piston position in the picture below shows the position it takes at higher rpm, the greatly increased flow overcomes the flow resistance at the bearings by a large amount so therefore the piston has to move back more in order to ''vent'' this extra oil.
The spring is compressed more due to higher flow but still keeps the required psi in the gallery's, a slightly higher psi is normal up the rev range than at idle because as the spring is compressed pre-load is increased and therefore more force is required.


If we take a really close look again at the piston we can learn alot from the wear lines created by the end edge of the bore on the left side of the orifice.
If we look at the yellow line on the left it shows where the wear starts, wear here is when the piston is almost closed, or time spent at idle, and approaching or near 0 rpm.
If we look at the red line in the middle where the most wear has occurred, we can tell that this is the main approx position and therefore the most common rpm which, Im going to say on this engine would be 3000rpm, it seems to have spent alot of time in this range and would sound correct looking at piston wear.
At the yellow line on the right we can see less wear than in the middle, this wear occurs when piston is farthest left or ''full open'', higher oil flow causes this and would indicate that this engine dident spend too much time at high rpm(raised oil flow) as scoring or time spent in this area is minimal.


One more thing I want to mention is the rotors.
The two rotors sit on the bottom casing, there both spinning and made of steel the casing is alloy.
The rotors are lubricated by a thin film of oil within the pump body.
Where the rotors sit on the casing they rely on a thin film of oil to prevent wear, keep in mind that this film of oil is not pressurised in the normal way a bearing would be, take for example a main bearing, where it is totally enclosed inside an oil film and the pressures all around bearing are the same and the crank becomes ''suspended'' within the shells.
Well in the case of the rotors they are not suspended between top and bottom thrust faces as oil pressure is not acting uniformally in both areas but flowing from right to left across thrust faces from a high pressure area to a low pressure area.
Therefore wear occurs on the bottom thrust face, gravity and the weight and end shape of the rotors play a big part in this wear.
Its obvious in the pictures below that more wear occurs on the heaver rotor and thrust area.
This is due to increased weight of the drive shaft integrated with the drive rotor acting down on it.
The drive rotor and thrust face.


And the driven lighter rotor and thrust face.


The difference in rotor weight is obvious from the close-ups and does play a part where wear is concerned.
I feel it is this wear or incorrect operation of the by-pass/release/relief valve leads to pump failure, poor performance more-so than rotor flank wear.

The newer 06A oil pumps do not have this problem, I know they are of different design but the basics are the same, but in the case of the newer style pump the centre rotor is sitting horizontal and therefore no thrust forces come into play.

The design of the old style pump could perhaps be improved in this area by cutting a small groove beneath the rotor on the thrust face in order to supply adequate oil to it, but instead with the groove coming from the high pressure side.
Similar in size of course to the groove supplying the driven rotor fixed centre shaft.
See yellow line below.


One last thing I want to mention which Ive been asked once, it relates to the three tabs on both pump castings.
They look like tabs used as lever points to aid separation but actually there not.
The tabs come into play at the time of machining and are used in the jig fixture for the hold-downs to clamp against, given its an odd shape these tabs are necessary in order to mount the raw casting as level as possible on the milling table.
Three datum tabs are nearly always chosen to be used on parts that require machining, Three tabs self level and require no setup or adjustment of fixture jig.
Ever seen a 3 legged stool rock? No you havent.
Ever seen a 4 legged stool rock? Yes you have!

I think that just about covers the actual oil pump.

Brian.

 

Thanks Brian. I'd yet to think the oil flows fully through, so that clears that up.

I can vouch for more visible casing wear from the heavier co with the driveshaft on it.

As that an ABF pump or 2 litre 8 valve pump?

Question from previous posts above: does any oil flow through the 8v pump driveshaft (the one with a distributor?).

What happens internally on the diesel pumps (the ones with the vacuum take off, taken where the C-clamp is positioned on KR/9A/ABF etc). Is a hydraulically pressured cap present?

 

Its the aeb pump, the very same as the abf.
I cant comment yet on the 8v pump as I havent got one to look at.
I have never worked on the diesels as I am a pertol man to the bone so I cant comment on that either.

Chris as a matter of interest, does the dissy type pump have a hollow shaft at all?
If not I have to figure out how the gears get oiled.
Its hardly run-off from the intermediate shaft end bearing???

 

i don't think there's any oil flow up the oil pump shaft as such, just a feed to a hole in the top bushing from a drilling off the feed to the filter (blocked with a ball bearing at the other end).
the 8v dizzy gear has an oil feed from a slot cut in the intermediate shaft bearing, this is enough to direct a little dribble onto the drive gears, the oil then runs down onto the top of the upper oil pump shaft bush to lubricate the bottom of the dizzy shaft where it drives the oil pump.
how the internals of the dizzy get oiled i don't recall exactly, but there is a hole on my k-jet dizzy just above the drive gear. this may receive an oil jet from somewhere? i'm curious now. i might nip out tomorrow and have a look to make sure..

 

''i don't think there's any oil flow up the oil pump shaft as such, just a feed to a hole in the top bushing from a drilling off the feed to the filter (blocked with a ball bearing at the other end).''

Can you explain what you mean by that and what shaft type your implying it to.
Of course theres flow up the shaft? its tapped into a live oil way.

 

i have run a 9a 2litre oil pump on a 1.8 kr for ages ,worked well, . the early kr converted 2 litre engines ran a 1.8 pump, and worked even with out oil squirters . i have also tryed 1.6 diesel oil pumps on 1.9 still worked , none have blown due to lack of oil

 

2dubnick has measured up 9A and G60 pumps:

9A

• 36mm gears
• Waisted stem
• ABF-style spline, not KR
• Large pump outlet / ABF housing appearance

G60

• 36mm gears
• Non-waisted stem
• Distributor-drive style driveshaft
• Pump outlet is larger than basic 8v, but smaller than ABF

 

sorry brian g, you asked about the dizzy type oil pump in your last post, so i was talking about the oil feed with regards to that. i should have made it clearer what i was referring to.

 

Sorry to post here; if innapropraite perhaps the mods can move to a new thread?

Been chasing an intermittent light metallic chatter (only at idle) for ages now and it seems to be located in the oil pump/gearbox end of the block. Guessing either the plunger is seized or some other dark shenanigans is at work. Top end is really quiet (even after leaving for days before starting) so I don't think the oil pump is on its way out. Wondering if the plunger is the culpirt; looks v easy to remove and I have some parrafin doing nothing which I could use to clean it. Is it easy to remove the plunger once the retaining fork is removed from the block?

Sump will come off next oil change for a closer look but guess it cant hurt to check the shaft plunger.

 

oil change

hi g60, don't know if this is good or bad! lol, forum advice from non professional bull talker!
even tho i had no symptoms such as you describe, and possibly the actions of an idiot, i filled my engine with diesel, and ran it for a few minutes before removing the oil filter , and dong a full oil service. some say, - if it aint broken- dont fix it. however, i personally didnt see the risk!