1989 K1500 oil pan R&R using BBC oil pump

[n2xlr8n]

I'll add pics next week, but I wanted to post this while it was still fresh in my mind-

In my opinion, the best way to R&R the oil pan in our trucks (at least a 1989 K1500) is as follows, as removing the engine mount bolts will not allow the engine to get high enough:

-Put vehicle on jackstands
-Disconnect battery obviously
-Remove upper front diff mounts on either side of engine (2 bolts/nuts)
-Remove front CV joints bolts on each side (6 bolts each)
-Disconnect front diff actuator (2 electrical plugs)
-Disconnect front driveshaft (4 bolts)
-Remove pass side diff mounts nuts, leave bolts in place (2 nuts)
-Remove driver's side diff mount bolt (1 bolt/nut)
-Remove torque converter / flywheel cover (4 bolts)
- I used a transmission jack to lower the diff, but one could use a floor jack and a dolly- it doesn't need to come all the way to the ground.
Now one has all the room to work you need.

If one is installing a BBC Melling MV99HVS- there are things you need to consider:

-The BBC pickup tube (oil pump outlet on the BBC pump body) is 90 degrees CW from the stock SBC oil pump, and the pump housing is thicker. I used a ARP stud (finger tight; it's through hole- the last thing you want to do is deform the bearing shell by over tightening the stud).
-The stock oil pan will need to be modified (sorry, I intended to snap a pic, but a description will have to suffice) in the sump area: if you're oriented looking at the sump (viewed from the rear of the truck), the "oval shaped windage" portion of the sump will have to be trimmed at the 2:30 to 3:00 clock position- it's not a lot; I cut away less than 1/2" strip in a curve from 2:30 to 3 o'clock. My stock pump pickup measured 6-1/2" from the oil pan rail to the bottom of the pickup; I put the 3/4" OD oval BBC pickup at the same distance.

BBC pumps provide more advantages than just volume. I usually install restrictors and a higher capacity pan with his pump, but I'm not doing wheelies or spinning this stock-ish 350 more than 5500 rpm, so...anyway.
BBC oil pumps have larger rotors and aren't as prone to spark scatter- there are reasons hotrodders have used them in SBCs for years- not least of these were the engines destroyed by the various Melling model / revisions of the stock SBC oil pumps. Used to be, one could simply replace the M55 with another. For the last 15 years, it's rolling the dice, in my opinion- ymmv.


Hope this helps.

 

[L31MaxExpress]

I'll add pics next week, but I wanted to post this while it was still fresh in my mind-

In my opinion, the best way to R&R the oil pan in our trucks (at least a 1989 K1500) is as follows, as removing the engine mount bolts will not allow the engine to get high enough:

-Put vehicle on jackstands
-Disconnect battery obviously
-Remove upper front diff mounts on either side of engine (2 bolts/nuts)
-Remove front CV joints bolts on each side (6 bolts each)
-Disconnect front diff actuator (2 electrical plugs)
-Disconnect front driveshaft (4 bolts)
-Remove pass side diff mounts nuts, leave bolts in place (2 nuts)
-Remove driver's side diff mount bolt (1 bolt/nut)
-Remove torque converter / flywheel cover (4 bolts)
- I used a transmission jack to lower the diff, but one could use a floor jack and a dolly- it doesn't need to come all the way to the ground.
Now one has all the room to work you need.

If one is installing a BBC Melling MV99HVS- there are things you need to consider:

-The BBC pickup tube (oil pump outlet on the BBC pump body) is 90 degrees CW from the stock SBC oil pump, and the pump housing is thicker. I used a ARP stud (finger tight; it's through hole- the last thing you want to do is deform the bearing shell by over tightening the stud).
-The stock oil pan will need to be modified (sorry, I intended to snap a pic, but a description will have to suffice) in the sump area: if you're oriented looking at the sump (viewed from the rear of the truck), the "oval shaped windage" portion of the sump will have to be trimmed at the 2:30 to 3:00 clock position- it's not a lot; I cut away less than 1/2" strip in a curve from 2:30 to 3 o'clock. My stock pump pickup measured 6-1/2" from the oil pan rail to the bottom of the pickup; I put the 3/4" OD oval BBC pickup at the same distance.

BBC pumps provide more advantages than just volume. I usually install restrictors and a higher capacity pan with his pump, but I'm not doing wheelies or spinning this stock-ish 350 more than 5500 rpm, so...anyway.
BBC oil pumps have larger rotors and aren't as prone to spark scatter- there are reasons hotrodders have used them in SBCs for years- not least of these were the engines destroyed by the various Melling model / revisions of the stock SBC oil pumps. Used to be, one could simply replace the M55 with another. For the last 15 years, it's rolling the dice, in my opinion- ymmv.


Hope this helps.

My 5 qt pan did not have to be modified but my OE windage did reguire a slight amount of trimming.

The last L31 I pulled a part with the stock oil pump and stock bolt had contact with the main bearing that distorted it and caused a round wear spot visible on the bearing face.

The later small blocks actually use a M155 pump with a higher pressure spring and a 3/4" pickup. It is still the same thin wall junk casting though.

 

[L31MaxExpress]

Hard to tell in the picture because it was a bit blury, but the oil pump bolt damage on the bearing shell from distortion is circled. It was a mostly round, discolored spot on the bearing face inline with the bolt contact.

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[Schurkey]

The stock oil pan will need to be modified (sorry, I intended to snap a pic, but a description will have to suffice) in the sump area: if you're oriented looking at the sump (viewed from the rear of the truck), the "oval shaped windage" portion of the sump will have to be trimmed at the 2:30 to 3:00 clock position- it's not a lot; I cut away less than 1/2" strip in a curve from 2:30 to 3 o'clock.

My 5 qt pan did not have to be modified but my OE windage did reguire a slight amount of trimming.

Yup, it's the windage tray, not the oil pan that needs to be modified.

My concern is that merely "cutting/trimming" the windage tray without reinforcing the cut edge, will lead to cracking of the tray. I'll add some material to mine so it's not just a sharp, trimmed edge subject to vibration.

The later small blocks actually use a M155 pump with a higher pressure spring and a 3/4" pickup. It is still the same thin wall junk casting though.

My understanding is that the weak pump bodies aren't a problem any more with the aftermarket Melling pumps. They may be a continuing problem with the OEM pumps sold to GM.

However, for at least ten years if not longer, Melling sold the weak, easily-broken SBC pump body over the counter; and expected that any "performance" application used the more-expensive pumps.