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Playing with flywheels and taking some measurements to design the flexplate.

PTT on the left, QMI on the right. QMI should be much easier for adding the flexplate.

Oh yeah, good thing I measured. The QMI flywheel is actually 0.837 or so... a little short even for a nominal 0.850, much less 0.890.

Time to snag an oil pump...

GM's had a couple iterations of the oil pump and the harmonic damper. The harmonic damper squeezes the oil pump drive sleeve against the shoulder that carries the crank timing sprocket. There is no positive drive of the oil pump... drive from the crank to the oil pump drive sleeve depends only on the clamp load from the damper. That's a little scary, but millions of engines work fine that way. While GM also put the LS oil pump concentric on the crankshaft in front of the timing drive, they DID make a positive drive from the crankshaft to the oil pump in that engine.

RockAuto lists the Melling M188 for the '09 DTS (FWD/WWD).





The '09 STS (RWD) gets the Melling M488. I contacted Melling about the difference. The only info that department had is that both met GM specs, which is unusual for Melling... they usually have more technical details about their products.





I just checked this morning and the '09 STS-V gets yet another oil pump... the Melling M489





The standard FWD pump is actually the most expensive, with the RWD pump being about *half* and the -V pump being a little less than the FWD. That kind of pricing is practically begging me to drop the -V pump in.

I think I'm supposed to install new oil pump bolts as well... I guess I need to order those from the dealership as Rock doesn't have a listing.

Also need to figure out if I want to do something fancy for the front cover bolts... probably not. I am considering either ARP Stainless or titanium for the external case half bolts... purely because I can.

years ago a boss I had told me that when you want to know where the issues are with a product you need only look at the drawing revision number....nobody changes things that work fine. All the pump version are kind of tell the story. I think the early one was a cost savings but I assume they had trouble with tolerancing...the more expensive added spline allow the the pump gears and housing rear face to not need to be exactly in the same location/fixed offset. I'll bet they had pumps that galled with that original design.

The FWD pump drive sleeve has flats that drive the gerotor inner component. There's nothing in the interface that locates that sleeve axially relative to the pump, so there's no tolerancing problem with the pump location. The sleeve is just clamped in place by the balancer.

That being said, there is some fretting/wear of the flats on the pump I pulled out, so that may be why GM went to the splined interface.

ahh, it looked like there was no sleeve on the early one....but still design changes mean they had a problem so buy the newer design would be my thought.

I get what you're saying about revisions... that actually happened with the harmonic balancer. There was a design change because sometimes they'd see a balancer bolt back off and the balancer would relax its squeeze on the oil pump drive sleeve, and poof goes the engine. That's why I'm looking up the most recent balancer revision. Beyond that, they ran the FWD pump from '93-'11... Although I'm not sure what revisions GM themselves put in place over that period.

The RWD engine has four cam VVT, which requires a lot more oil volume than the fixed cam timing FWD engines. The supercharged engine doesn't have any extra oil demands, but does use a different pump, so that intrigues me, as GM must have improved it somehow for the higher performance engine. I guess.

so the RWD pump is out...is the oil spec different SC to FWD version? that might answer your question.

Ooops, I guess my post wasn't super clear.
FWD/WWD engine was developed in '93 and incrementally improved through '11. It never had VVT.
RWD engine was introduced in '04 in the SRX (SUV) and XLR (Corvette C6 platform), then '05 in the redesigned STS (Sedan)
The Supercharged engine was introduced in '06 as a sub-model of the XLR and STS, so the supercharged engine is a RWD engine. I meant that the supercharged engine doesn't have any additional oiling needs--

Err... wait a minnit... It *DOES* have additional oiling needs. The SC engine has piston oil squirters, while the RWD engine does not.

Got to play with the V series oil pump over the weekend.

Both pumps:



Look at the width of the gerotor element in the FWD pump:



Now look at the width of the gerotor element in the V pump:



And here are the drive sleeves compared:



Here's galling on the OD of the drive sleeve:



Here's fretting on the drive flats:





Block sides of the pumps. Inlet on the right, outlet on the left. Note the small hole right next to the inlet with the groove around the inlet. That is NOT and o-ring groove. Do not put an o-ring there.



I was not going to take my brand new V series oil pump apart, but here are the guts of the FWD pump
Note that it has basically a large spring pin between the two halves and only two bolts holding them together until the oil pump mounting bolts go through both halves into the block. The FWD pump also has a nice smooth die casting, while the V series pump appears to be sand cast. The V series pump has five bolts plus the three mounting bolts holding it together.



In this photo, the inlet is on the left and outlet is on the right. Note the tiny grooves that go from the high pressure outlet around the pump housing to the hole drilled through to the groove around the inlet. I'm not sure if that acts to wet and seal the pump housing halves and the pump-to-block interface or if it's something to do with noise, stablity and/or resonance of a gerotor pump. Both pumps have the groove around the inlet, so I @$$ume they both have the groove around the joint.





GM specifies to pack the inlet of the pump with vaseline to aid in sealing so it can prime. I have never done that before. Also, my engines have not been able to build oil pressure from extended cranking. They do fine one first start as the lifter noise goes away in ~3 seconds, but did not indicate any pressure on the gauge from any amount of cranking.

This time I packed the pump inlet with vaseline. We'll see if this engine can build oil pressure cranking.

If you try to install the pump straight, the (larger than FWD) regulator boss runs into the lower crank case



If you rotate it up to clear the crank case, one of the upper bolt bosses runs into the right bank timing chain. I took this photo after I had removed the chain to install the pump, so you'll just have to take my word for it.



However, with the right bank timing chain removed, it goes right on and rotates down into place. It is temp installed with old oil pump bolts in this shot.



If you're eagle-eyed, you may have noticed "Shim to center on crank" cast into the front of the V series pump. After inspecting the unit, I determined that this is to make sure that the housing is positioned such that it is centered on the gerotor.
After carefully measuring it, I think I need three 0.059-0.060 gauge pins (or a comparable sleeve) for this. I was able to scrounge two 0.058 and one 0.059 pin. I snugged the bolts and will get either gauge pins or a custom alignment sleeve this week. Then I'll install new bolts. The oil pump bolts are 8x1.75mm (!) or so and have threadlocker pre-applied by GM.



The stamped steel front cover doesn't *quite* seat, but the gap is thinner than the gasket/seal, so this should go together just fine.



You can see the pump *right there* behind the front cover. GM really made the packaging on this engine tight in order to fit it in FWD engine bays. Whether that was a good product decision when BMW & Benz were RWD is debatable, but it *DOES* let me install the engine in a Fiero without much fuss.

If it helps, .058" is a standard wall thickness for 4130 tubing so you could just buy a foot of something close ID/OD and make a slit-sleeve