How to replace oil pump 6.2 L86

kgkern01 · August 17, 2022

So while doing the cam swap on my L86, I accidentally cracked the timing chain tensioner while trying to pin it. To get to the tensioner bolts to replace it, the oil pump has to come out. So on the 4x4 trucks, what’s involved with replacing the oil pump? Is it as easy as dropping the pan, or do I need to lift the engine, or is there a better way to do this? I can’t seem to find any good tutorials or videos online that show dropping the pan on a 4x4 L86 or L83?

JONBLARC7 · August 17, 2022

I replaced mine on my L86 on the engine stand but i don't see why you couldn't do it in the truck. If your using a new oil pump there is no need for alingment tools. The new pump seats to the crank. Just make sure you have a good seal between oil pan and the bottom of the oil pump. So the O ring on the front of the pan for the pick up tube doesn't suck in air.

kgkern01 · August 18, 2022

Yeah the main thing I’m looking for is what I need to remove, loosen, move, etc to get to the pan while it’s in the truck. Heads are off, exhaust is out, radiator is out, picked up a new GM oil pump today, just need to pull the old one, install new tensioner, then finish my cam install and reassembly.

kgkern01 · August 18, 2022

5 hours ago, JONBLARC7 said:

I replaced mine on my L86 on the engine stand but i don't see why you couldn't do it in the truck. If your using a new oil pump there is no need for alingment tools. The new pump seats to the crank. Just make sure you have a good seal between oil pan and the bottom of the oil pump. So the O ring on the front of the pan for the pick up tube doesn't suck in air.

At this point I almost wonder if it would be easier to just pull the engine and finish it up on the stand?

CamGTP · August 18, 2022

I can't view a service manual but if it's anything like the other trucks you need to drop the front diff out and the steering rack needs to be dropped down, then the cross member unbolts so you can get the oil pan down far enough to remove the pan.

It's like an 11 hour labor job or something crazy.

Watch this video if you want, youtube always has video if you do some research.

JONBLARC7 · August 18, 2022

Pull the motor. If your 4x4 it's going to be more of a pain to drop the pan than it is to pull the motor. You already got everything you need off to get the motor out.

kgkern01 · August 18, 2022

I was able to get the pan out by removing the cross member, sway bar, removing the lower pan, then lifting the motor up from the front with a cherry picker to give more clearance from underneath. Cam, oil pump, etc is all out. Once I clean everything up if I determine the engine has to come out to reassemble, I will, but it appears I’ll have enough room to finish reassembly as is. To be updated as I reassemble…

kgkern01 · August 22, 2022

I got the oil pump and pan in this weekend, and while it wasn't the easiest thing to do, I will add a few notes as to what I did to not have to drop the front axle and steering rack completely out of the truck. Hopefully this helps the next driveway jackstand mechanic a little bit.

To get the oil pump and pan out, as mentioned before, I drained the oil, unbolted the engine mounts, 3 15mm bolts per mount, and raised the engine up with a engine hoist. I remove the lower oil pan, which is 10 10mm bolts, then removed the trans cooler lines from the trans to move them out of the way, and disconnected the oil cooler lines from the pan. Then unbolt the pan from the block, remember the 2 10mm long bolts at the back and the 2 15mm bolts going through the bellhousing. Once the pan is loose, you can remove the pump, 4 13mm bolts, and disconnect the solenoid plug. This gave me just enough clearance I needed to remove the pan out of the truck. Once the pan was out, I also remove the long stud that is on the drivers side mid/front half of the pan to get a little more clearance for re-installation.

Putting the pan back in, however, you need more clearance than you did to remove it. This is because the pan is sealed to the block with RTV and not a gasket, so you cant just slide it in, you have to make sure the RTV bead stays where you put it on the pan and doesn't scrape off when re-installing. To get the extra room that you need, you will need to drop the steering rack, front axle, as well as the front sway bar. However, they do not need to come out of the truck completely as in the video, that is unless you feel you need all the room you can get. If you want that extra room, the front differential unbolts pretty easily from the axle shafts with I think 6 or 8 bolts. If you want to do that and give yourself just enough room to get the pan back in, they just need to be lowered, I used a HF low lift transmission jack, but a floor jack with a board may work as well to support the steering rack and front axle. For the steering rack unbolt the bolt that connects the steering column to the rack to allow it to drop. 4 bolts to disconnect the rack from the frame, and 4 bolts to disconnect the axle from the frame and you will gain another few inches of clearance. This gave me the room I needed to get the pan back in with a bead of RTV/gasket sealer on the pan. Make sure you also put in new o-rings while the pan is out. Do not put the bead on the front rail of the pan yet, as it is only needed on the sides and back for now, since the timing cover will need sealed to the front of the pan. Before I put the pan back in, I had the new oil pump primed and ready but did put it on the crank yet. With the RTV on (I would recommend the GM or Ultra Grey sealant, Right Stuff while seals great, it also only gives you a 5 min working time), I carefully put the pan back in sitting on the front diff, but did not put it on the block yet. With the pan resting on the diff, I slid the oil pump on the crank, and plugged in the solenoid plug. Then went back under the car and raised the pan into place on the block and torqued it down. RTV stayed on where it needed to and never touched anything but the pan and block. Once the pan was bolted up, I torqued the oil pump to 18ft/lb. Went back under the truck, raised the diff and rack back into position and re-installed the sway bar, transmission cooler lines, and oil cooler lines, and their associated mounting brackets. At this point you should be left with just the timing cover and front rail of the oil pan to seal back up.

In hindsight, honestly, just removing the front differential would make it a little easier and give a lot more room, and you can leave the axles in and steering rack in (just lowered down, to do that. If you want to try it without doing that, then it is possible, just take your time, double check everything, and practice sliding the pan into place a couple times without RTV first to make sure that you have enough room to do so without touching anything before you try it for real. Having to pull the pan again because you scraped off RTV while putting the pan in is not worth it.

JONBLARC7 · August 23, 2022

Glad you got it back together. It seem the 8 bolts holding the bell housing would have been easier.

kgkern01 · August 26, 2022

On 8/23/2022 at 1:58 PM, JONBLARC7 said:

Glad you got it back together. It seem the 8 bolts holding the bell housing would have been easier.

In hindsight with everything involved with a cam swap, removing the heads, oil pump, etc, I would have to agree, on an engine stand would be much easier than in the truck.

JONBLARC7 · August 26, 2022

I've had the head off twice on my L86. Once for the stuck lifter and the last time for the rebiuld becasue of the spun rod bearing. While it can be done in the engine without dropping the oil pan. If you have the time and a stand. It is much easier just to pull the motor since everything you need to get the motor out is already off.

I'm real bad at thinking "I can save time by not doing all the steps." and in the long run I end up fighting something that should be easy to get to. If I just removed everything.