In the quest to help eliminate wear and tear on the cam sensor gear, timing components and thrust surface of the block, I made a hybrid oil pump system for the Malibu. It’s a cross between a front wheel drive timing cover and a rear wheel drive timing cover. The gerotor type of pump like the ones used in the front wheel drive VIN3 engines drive off the crankshaft snout instead of the timing chain, cam and cam sensor gears. This alone relieves the high stress that is put on the timing chain or any of the related components when driving an external stock type pump. Looking under the hood keen eyes will recognize it's not the typical rear wheel drive oil pump assembly.

1.      1.  Reduces power robbing friction since it doesn't use the timing chain and cam/cam sensor gears to rotate the stock type oil pump assembly. Especially true if you use a high volume oil pump!

2.  Eliminates camshaft gear wear.

3.  Eliminates cam sensor gear wear.

4.  Eliminates block thrust surface wear.

5.  Reduces timing chain stretch.

6. It drives directly off the crankshaft.

7. Eliminates part of the stock inefficient oil passages that the stock timing cover is known to have.

The description I'm giving below is how I made this hybrid oil pump system for the Buick Grand National. There are other ways to accomplish the same thing and when I do another one I'll be making a few changes to simplify how it's done.  So this time, never mind the sloppy work because I never thought it would work in the first place.  I just bought a TIG welder when I done this job so I was just beginning to learn how to weld. To make matters worse, metal will soak up oil and when heated the oil comes back out making welding MUCH more difficult.  This is why you see the RTV silicone sealer on the inside.

To make a hybrid oil pump for the rear wheel drive engine, I cut an 86-87 front wheel drive timing cover and a rear wheel drive timing cover in half. I welded the top half of the rear wheel drive cover to the bottom half of the front wheel drive cover.  The red line in the picture below shows where I cut them. You can also see where I had to weld up a spot where the mating surface of the front wheel drive cover mates to the rear wheel drive engine. Slight casting differences on the front if the engine block would allow a MASSIVE oil leak if this wasn't welded. I marked the area that should be welded with the red square.

The late model Series II engine had a different style front cover than the older models. The inlet passage leading into the gerotor gears has a larger opening for more volume to enter the pump. I figured that wasn't a bad idea so I took a die grinder and opened up the passage way in my hybrid cover so it can have more volume also. You can see where I modified the oil pump slightly to increase oil flow into the pump.

Once the two covers were welded together I took the cover to a machine shop to have it surfaced flat. Also, since I used "used" timing covers instead of brand new ones it welded VERY poorly due to oil contamination. So, when I finished completing this project I applied some JB Weld over the areas where I welded to eliminate unwanted oil seepage. If I were to make another hybrid cover I'd start with two NEW timing covers.

During the test fitting of the cover, I installed the factory Grand National harmonic balancer and discovered the front seal was hitting the crank sensor trigger wheel on the hub of the balancer.  To make the factory VIN 7 balancer work I machined the sealing area (or snout) of the balancer a little deeper to help compensate. This also cut some of the interrupters "pressed fit" mount off. Even after that it still did not provide enough clearance for the balancer to slide all the way in against the lower timing sprocket. Since I didn't have any more room for machining on the balancer I now had to machine the seal area of the cover. The seal had to be relocated further back into the cover to gain more clearance.  This was accomplished by machining the the cover so the seal could be driven farther back. After several test fittings I had enough room between the seal and the crank sensor trigger wheel but it is VERY tight! (see picture below)

There is another area to watch when fitting the cover to the engine and that's between the timing chain and oil pump gear cover. You can see in the pictures below how different timing chains can have different off sets allowing more clearance between the oil pump cover and the chain itself. Since I am using the offset gears, my chain was very close to touching but it had enough clearance to still work fine. YOU MUST ALWAYS CHECK THIS AREA! If you still don't have enough room you can machine the oil pump cover in the area where the chain is likely to rub.

You can see in the picture below where the chain actually made contact with the oil pump cover while I was turning the engine over by hand. The use of a timing chain with the slight offset will allow more clearance in this area.

I didn't specifically order a set of timing gears with the offset. I just noticed that some sets have this offset already. Cloyes "TRUE" timing sets do have the offset needed...part number: 9-3132. I do know that Roll Master timing chains DO NOT have the offset...like in the picture below.

Although I haven't checked but if you are using a stock timing chain I think there would be plenty of clearance in this area since the stock chain is narrower than a double roller chain.

The VIN 3 front wheel drive crank sensor sits a little farther forward than the VIN 7's. You will notice the stock VIN 7 (RWD) cover is thinner in the area where the crank sensor sits. This hybrid cover is thicker in that area and requires machining or grinding down the VIN 7's crank sensor bracket to get it to align properly with the trigger rings on the Turbo Buicks balancer.  It was no big process to make this work. (These pictures are for reference only. Since I'm using a combination or "dual" crank sensor on mine I didn't have to do anything to make the crank sensor work on my engine. For more info on the Fast Start System click here: "Fast Start System")

I machined the cover, the front seal area of the cover and the crank sensor to work with the factory balancer. Now it was time to machine what I call "flats" on the "snout" of the balancer to fit into the pump gear. The first step was to install the oil pump into the cover and bolting the cover on the engine.  I then measured from the lower timing gear face outward until I was just past the oil pump "driven" gear. This is the total depth that the "flats" needed to be machined on the snout of the balancer. Mine measured about .600" deep. You only need enough depth to allow the snout to pass all the way through the pump gear and seat against the lower timing gear. See pictures below...

After the balancer was machined, I now had to machine the inside diameter of the oil pump drive gear so it would fit on the balancer. First I measured the outside diameter of the balancer hub. This will be the how much the  "inside" diameter of the oil pump gear will have to be machined.  The picture below will show how much metal was taken out to allow it to fit on the hub.

The use of front wheel drive gaskets are now required for installing the timing cover. You will need to use a kit from a 86-88 VIN 3 engine found in the full size Buick LeSabre.

Here is a picture of the oil pressure at an idle in gear. RPM was 730, the temp was 183 and the pressure was 40psi! This was taken after driving the car about 15 miles and running for 10 minutes at an idle while I was tuning on my FAST XFI. This pressure is on a fresh rebuilt engine.

Click here for a video of a hot start-up with coolant temps in the 180's.! Video was taken with conditions described above 2.5MB

MODIFICATIONS:

Port/blend oil pump passages in cover for better flow.

Port/blend oil pressure inlet on front of engine block so there is a nice turn towards the front cam bearing.

Drill .090" holes in cam bearings and re-clock them so oil pressure is limited to camshaft.

Drill out main bearing holes in the bearing to the size of the oil passage in the block.

Engine clearances are set at .0018" on the rods and mains.

Oil used is 20W-50

No other modifications were done!

This a VERY important step in the process of installing a gerotor oil pump front cover. Let me explain...the factory external oil pump is turned by the camshaft/cam sensor gears and timing chain. It rotates the oil pump in a manner that it "pushes" the camshaft towards the rear of the engine. This force will hold the camshaft back so it will not "walk" forward when the engine is running. This allows the use of a factory "spring type" thrust button on the nose of the cam. Since the gerotor pump drives off the crankshaft instead of the cam, the rearward thrust isn't there anymore. To hold the cam in place to keep it from "walking" forward will require a solid adjustable type of thrust button on the camshaft if you're using a stock cam. If you are using a billet cam like I'm using (see picture below) I'd recommend a bronze thrust plate that bolts directly to the front of the block.

NOTE: This is a VERY IMPORTANT step that CANNOT BE SKIPPED! Since there is no load on the camshaft thrust surface you will have to install a solid adjustable cam thrust button to keep the cam from walking forward. A STOCK THRUST SPRING WILL NOT WORK! IF THE STOCK CAM BUTTON IS INSTALLED THE CAM WILL WALK FORWARD AND THE LIFTERS WILL HIT THE ADJACENT LOBES CAUSING EXTREME ENGINE DAMAGE!  I SEEN THIS HAPPENING ON MY ENGINE WHILE I WAS USING THE STARTER TO CRANK IT ON THE ENGINE STAND.

Now you will have an oil pump that can pump 100psi cold or hot and not have to worry about putting stress on the timing chain, the thrust surface of the block or the cam sensor/cam gears. The original cam sensor will still be spinning off of the camshaft but there will be NO LOAD on the gears!

The completed unit works very well for a "stock" oil pump.  Now, I have no fear of wear and tear on the timing chain or any of the gears!

Here's a picture showing it in the car and where I mounted my transmission oil cooler. The trans cooler uses the factory crankshaft fan to draw in cool fresh air. (scoop not pictured).

With any kind of custom work problems do occur and a redesign is necessary. This fabricated timing cover/oil pump isn't without flaw either. Over the last 16000 miles I've had what I think "good" success with this oil pump assembly especially since it was made by me; a non professional machinist with inferior machines. It works really good! The oil pump gears and the welded timing cover is working great. It's what "drives" the pump that has given me trouble. I have always made periodic checks to make sure everything is still working as designed.  However, I've caught  something that would have caused a catastrophic failure if I had left it alone. Read on to see what happened...

First Design:

 The first design used a shortened harmonic balancer with a spacer to drive the oil pump. The spacer was machined down to fit into the stock gerotor gear and it cracked at the keyway. The balancer cracked at the keyway also. I think since the pulley that bolts to the balancer puts the belt so far away from the hub it was causing some flexing of the balancer that caused it to crack due to it's shortened hub. The front wheel drive cars do not have this problem since the belt is located very near the hub of the balancer.

Second Design:

The second design used a machined balancer without a spacer. The balancer hub was machined down to fit inside a stock gerotor gear but kept the stock length hub. I figured this would work better due to it being a "one piece" design. This design had the hub machined just as thin as the spacer was in the first design. I was not very confident that this would hold up either and I was right; this done the same thing...it cracked at the keyway and didn't last as long as the first design.

Third Design and Present Design as described on this page:

This design uses a stock diameter balancer with a machined gerotor gear that fits over it.  The stock balancer hub is 1.935” OD so the ID of the gerotor gear was machined out 1.937” to give .002” clearance. You can see in the pictures below that there isn’t that much metal that has to be removed from the gear…about .055”. This will allow the use of a stock diameter hub with machined flat spots that drives the gear. Since a stock Buick balancer doesn't give trouble I figured I'd be better off machining the gear to fit on the balancer instead of machining the balancer to fit in the gear. If this one cracks, I'm going to try to find a billet harmonic balancer and try this design once again. If that doesn't work, I'll go back to the stock oil pump set-up and call this is a failed project.