Replacing Oil Pan.

FFDP · July 22, 2011

Well its a 92 chevy 350 with 4x4.

It needs a oil pan, its got 2 small holes in it.

So the question is, does anyone got any tips or secrets to the removal procedure that may give me the upper hand when doing this.

I know pretty much everything that needs to be removed to get to all the bolts, but will the pan just slide out or does the motor need to be lifted a few inches for more room?? I am just wanting to be prepared thats all. Forgive me if this has already been talked about befor.

etex211 · July 22, 2011

I changed the oil pump on my '92 half ton truck a few years ago, and there weren't any problems. There was enough clearance between the pan and cross member to allow the pan removal without raising the engine. My truck had the factory engine oil cooler. Those lines, etc., had to be moved before I could remove the pan. It is pretty straight forward.

My truck was a 2wd and yours is 4wd. I don't know how much difference that will make.

These pans use a one piece pan gasket. My only recommendation is to get a high quality gasket, not a cheap one. I recommend GM or Fel Pro. The Fel Pro gasket comes with some plastic guides that screw into the four corners to help you align the pan and gasket and hold them in place during reassembly.

(When I pulled the pan off my truck, I was surprised to find a broken main cap bolt. The bearing on that cap looked good. I threw another main cap bolt in there, and that truck was still running fine when I sold it at 180,000 miles.)

FFDP · July 23, 2011

Thanks for the input man.

I also have the oil cooler lines on the side by the filter housing so those will come off and be moved to allow for room for the bolts. I am just waiting on parts to come in the mail and I got a felpro gasket and will be buying some RTV to help seal it.

wavery · July 23, 2011

Thanks for the input man.

I also have the oil cooler lines on the side by the filter housing so those will come off and be moved to allow for room for the bolts. I am just waiting on parts to come in the mail and I got a felpro gasket and will be buying some RTV to help seal it.

While you have the pan off, take the opportunity to torque the rods and main bearing cap bolts. Would be a good time to change the rear main seal. It's gonna leak sooner or later.

On a 20-year-old engine, a new oil pump might be a good investment (like $40). A new oil pump can add a lot of life to your engine. Those oil pumps don't last forever and they are a primary reason for major engine failures. All of this stuff will help you avoid having to take the pan off again for a more serious reason.

When you put the pan back on, screw in all of the bolts finger tight. Then x-cross across the pan as you tighten the bolts. Start with the middle side bolts. Get the torque specs and torque them evenly in a x-cross pattern a little at a time.

BTW...... make sure that you get off every speck of the old gasket. If you don't, it will leak.

etex211 · July 23, 2011

If you decide to change the oil pump, I would recommend getting the M55A. It has a different pressure relief spring than the standard M55. It should idle at 60 psi cold and 40 psi hot. Those trucks from that era tended to not have great oil pressure once they were warmed up.

wavery · July 23, 2011

If you decide to change the oil pump, I would recommend getting the M55A. It has a different pressure relief spring than the standard M55. It should idle at 60 psi cold and 40 psi hot. Those trucks from that era tended to not have great oil pressure once they were warmed up.

^ ^ excellent suggestion right there ^ ^

FFDP · July 23, 2011

Thanks a bunch for the help. I may end buying a new pump aswell, just so I know its gunna work good. And since its most likey gonna be a plow truck its going to get run long and hard so have good oil pressure and flow is key.

FFDP · July 23, 2011

If you decide to change the oil pump, I would recommend getting the M55A. It has a different pressure relief spring than the standard M55. It should idle at 60 psi cold and 40 psi hot. Those trucks from that era tended to not have great oil pressure once they were warmed up.

Where can I find this pump??? Does rockauto carry it??

And is it hard to replace or just a few bolts to take it off.

Also will upgrading the pump have any affect of the volume of fluid the pump sucks up. I dont want need a bigger oil pan over the stock 4qt pan.

wavery · July 24, 2011

If you decide to change the oil pump, I would recommend getting the M55A. It has a different pressure relief spring than the standard M55. It should idle at 60 psi cold and 40 psi hot. Those trucks from that era tended to not have great oil pressure once they were warmed up.

Where can I find this pump??? Does rockauto carry it??

And is it hard to replace or just a few bolts to take it off.

Most AP store either have them or can get them. You'll need a gasket as well. 2-bolts and the pump is out. The pump drive rod will come out with it. Be sure to line up the new pump drive key in the same position as the one that came out. It's a little tricky lining up the pump rod. It has a little plastic connector sleeve (if I remember correctly). Might be a good idea to replace that as well. (Boy...... it's been a long time)

Once the pump is out, you will have to pull off the old screen and clean it. It's just a press fit. When you push it back in, it should fit tight. If it doesn't, bend it slightly with channel lock pliers. It may be worthwhile to buy a new one and have it on hand, just in case. If you don't need it, you can always return it.

etex211 · July 25, 2011

If you buy a new pump, the pickup tube is only a few dollars more. To install the tube, just put the pump in a vice, and use a 5/8 or 11/16 (can't remember which) open end wrench and a hammer to put the tube in the pump. You'll see what I am talking about when you have the tube in your hand.

Then you'll need to get the tube rotated into the right position. Lay a straight-edge across the pan and measure to the bottom of the sump. Then, with the pump installed, lay a straight-edge across the bottom of the pickup tube and measure to the pan rail on the block. Rotate the tube on the pump to achieve about 3/8" clearance.

After getting the pickup tube in the proper position, I like to always tack weld them in place.

The little plastic sleeve that attaches the pump to it's drive shaft can be a little tricky, but you'll figure out what to do. When you install the pump, you are engaging the shaft with the bottom of the distributor gear.

The pump is held in place by one bolt going into the rear main cap. A gasket isn't really necessary.

The M55A pump is identical to the M55 pump in every way, with the exception of the relief spring. Like Wavery said, you can get it at any parts store. The price will be about double of the M55 pump. I don't know why they are so expensive. I usually just take a regular M55 pump and replace the $3 spring, but I'm sure you don't want to get into that. The M55A is sometimes referred to as a "Z-28 pump."

Doug_Scott · July 25, 2011

If you decide to change the oil pump, I would recommend getting the M55A. It has a different pressure relief spring than the standard M55. It should idle at 60 psi cold and 40 psi hot. Those trucks from that era tended to not have great oil pressure once they were warmed up.

Where can I find this pump??? Does rockauto carry it??

And is it hard to replace or just a few bolts to take it off.

Most AP store either have them or can get them. You'll need a gasket as well. 2-bolts and the pump is out. The pump drive rod will come out with it. Be sure to line up the new pump drive key in the same position as the one that came out. It's a little tricky lining up the pump rod. It has a little plastic connector sleeve (if I remember correctly). Might be a good idea to replace that as well. (Boy...... it's been a long time)

Once the pump is out, you will have to pull off the old screen and clean it. It's just a press fit. When you push it back in, it should fit tight. If it doesn't, bend it slightly with channel lock pliers. It may be worthwhile to buy a new one and have it on hand, just in case. If you don't need it, you can always return it.

I would not suggest you bend the pickup tube at all to make it a tighter fit. If the tube does not seal itself completely in the pump it will draw air instead of oil, or will draw air into the oil, causing aeration problems. Sort of like if you puncture a straw and then try to used the straw. If you are unsure if the tube is not round anymore, either replace the pickup, or once it is put in the pump, clean the area around the joint to remove all oil, and run a bead of silicone around the joint. Let it completely cure before putting oil in the pan. RTV silicone can take up to 24 hours to cure completely.

ChevyTech77 · July 25, 2011

I would NOT retorque the rod and main bolts as you will stretch them more than they have already been set to for years which could easily cause problems down the road.

I also, would NOT install an M55A oil pump in this engine as it will cause a bunch of oil leaks due to the insane amount of pressure that it can produce. Even a fresh engine with fresh seals can still leak from these pumps because under premium engine tolerances, this pump will produce 80 psi easily during cold engine start and high rpm usage. It's just not needed and I wouldn't waste your money on it. The stock pump is more than enough in any stock, and mildly modified applications. Not to mention that using rtv around an oil pump pickup screen to pump connection is certain to pull that rtv into the pump, possibly stick the pumps pressure relief valve, pump the rtv through the engine bearings and/or plug up an oil feed passage or the oil filter causing oil starvation and severe engine damage. Pump pickup screens should be a tight, press fit and a small spot weld can be used to ensure that it doesn't fall off/move under severe duty usage.

Lastly, you will only need a small dab of rtv in four locations to properly seal this oil pan up (at the gasket to front cover to block area and gasket to rear main cap to block area). The Fel-Pro gasket should come with a small tube of that rtv and if so, that is all you'll need. If not, Permatex Ultra Black is what you want.

Just remember to keep things clean and don't knock a bunch of stuff into the pan while you're trying to get it up into place on the engine. If you think that you may have gotten some debris in there during reassembly, a simple flush of oil using a quart or two of cheap, regular engine oil, should flush most all of it back out of the pan before you fill it up for good, after the repairs are completed.

FFDP · July 25, 2011

Wow, I didnt think it would make that much pressure, good thing I havent bought a pump yet.

On a little side note, do any of you know a really really good engine de-greaser, because will the oil leak and power steering leak it is pretty bad under the truck, and after the pan install I want to clean it up.

Thanks again for the help.

wavery · July 25, 2011

Wow, I didnt think it would make that much pressure, good thing I havent bought a pump yet.

On a little side note, do any of you know a really really good engine de-greaser, because will the oil leak and power steering leak it is pretty bad under the truck, and after the pan install I want to clean it up.

Thanks again for the help.

Wow!!!! It's nice to have lots of eyes on stuff like this.

In retrospect, I agree that the high pressure pump could cause issues on a high mileage engine.

DO NOT put RTV on the pick-up (for the reason previously mentioned). Pressing a new pick-up is quite adequate..... that's what they do at the factory. When you put a slight squeeze on the end of the old tube, it makes it slightly out of round. When it is forced into the perfectly round hole, the tube is forced round, only a tighter fit. When in doubt, install a new one....... cheap insurance.

You absolutely do need a gasket between the pump and the block. If you don't use one, you will lose pressure at that connection as it will leak (inside the engine where you can't see) when under pressure and the pressure will be less. It's sorta like not using a washer on your garden hose when you connect it to the faucet.

ChevyTech77 · July 25, 2011

Wow, I didnt think it would make that much pressure, good thing I havent bought a pump yet.

On a little side note, do any of you know a really really good engine de-greaser, because will the oil leak and power steering leak it is pretty bad under the truck, and after the pan install I want to clean it up.

Thanks again for the help.

Fresh engine, mid to tight bearing tolerances (.0015-.002") and that pump will run 90 psi, with 20w50 oil, cold (50*f ambient temperature). Blow an oil pressure sending unit at that pressure and ask me how long it takes for it to empty an 8 quart pan plus oil cooler. Trust me, I know.

Any of the store bought products that I have seen and used work well. Degrease it before you take it apart. You'll be happy you did.