usdmholden

Anyone had to fix an oil pan that warped after welding the notch?

I notched my f body oil pan to fit over the steering rack in my fox Mustang swap. I moved the engine as far back and as low as I could, and therefore had to cut a notch for steering rack clearance. I also have the steering rack relocated upwards to improve bump steer. The slot is in a location with is probably abnormal for most swaps. See pics.

After welding the front of the pan warped upwards about .030-.040". The rear of the pan sits perfectly fine. The warpage begins right around the bolt holes holes directly below the notch.

My first fix attempt was to bolt the pan down to the block and try and stress relieve the area with the acetylene torch. This made the warpage pull in and decrease the gap to about a .020". I suspect the pan will seal if I just run it as is, but I don't know really. Also I don't really want to worry about long term failure because the pan is under stress from the warpage. I'm not sure I can get enough heat with the acetylene torch to heat the whole area at the same time, so my second try will be with a propane weed burner.

If that doesn't work, then I guess I will be:

1) cutting a slot down the center of the notch, bolting the pan down, and then welding the slot closed.
2) OR: have pan milled flat by a machine shop
3) OR: both

This whole thing is kind of annoying because after the external weld was done I got pan sealed up and the external weld pressure tested to 70 psi without having any bubbles in the soap solution. I did check flatness after welding the external joint and flatness was OK. After welding the plate to the inside of the pan, the pan was warped. I guess I should have left it well enough alone.

Anyone else run into a problem like this? What did you end up doing?

Thanks

19wagon63

Good luck with your fix. I don't have and experience with that but hope it works out for you.

Project GatTagO

iTrader: (7)

Have you tested the pan with the gasket? The oil pan gaskets are aluminum with rubber o-rings on both sides. I bet it will seal.

Andrew

usdmholden

I didn't pressure test with the gasket. My weld pressure test was only to strap the oil pan down on a sheet of cardboard on the flat bench top. It doesn't really seal against the cardboard at 70 psi, but the cardboard does not leak fast enough and holds pressure in the pan to test for leaks at the weld.

I plan to pressure test the oil pan on the short block but I need to get the engine reassembled first.

LLave

iTrader: (3)

I doubt you have a real problem there. The gasket will take up a fair amount of the gap and the bolts all the way around the perimeter are going to apply much more even pressure and will probably flatten it right out. I bet if you did you cardboard and ratchet strap test to the pan before modification you would end up with the same result. Of course this is all based solely speculation and I am be completely full of ****.

Good luck!

usdmholden

I understand that it will probably work. What I am looking for is if someone had a similar problem and how they fixed it. Or if they didn't bother to fix it, did they have problems down the road?

I can always:
1) cut a slot
2) buy a junker iron block
3) clamp the pan down to the iron block
4) weld the slot while it's clamped down.
5) take to machine shop and have milled
6) OR - spend A LOT of time tramming my Bridgeport spindle to the oil pan sealing surface and mill it flat myself. Granted milling it myself is a little scary because my Bridgeport is 52 years old and isn't really the most precise machine tool anymore.

If I do all the above, guaranteed, no leaks. However, it's long and time consuming and I have to buy a block and maybe pay someone with better machinery than I have to mill the surface flat.

I'm hoping someone has done something more simple.

Thanks.

97FormulaWS-6

iTrader: (1)

If I were in your shoes... I'd just have it milled at a machine shop. Best way to get a perfectly true surface.

fieroguru

iTrader: (1)

You could bolt it to the iron block with a .020 spacer under the bolt hole that the warp begins with, then tighten down the front while heating up the welded area.

4x4head

What kmember are you using? I used a ctsv pan and grey86hatch mounts with a teamz kmember and it worked perfect.

E.rodz

iTrader: (4)

easy fix just use some sand paper preferably stick it paper put it down on a flat surface like a mill table or a table saw table stick the paper to the table and sand tell flat. hope this helps.

BigEd_72455

iTrader: (7)

.030 isn't really that much of a warpage, unless its like going through the hills of the Ozarks and the warp is between two bolt holes. I would initially say mill it, but you risk reducing the stress the pan can take by thinning down the rest of the lip of the pan for that one area. I would secondly say to grab the block on a stand, put the pan on the block WITHOUT the gasket in place, and heat the area with ALL bolts in, but loose, then tighten the warped area and let cool for a while, going in stages. If you are so inclined, grab some flat washers for the area of the pan that is not warped, and place them between the pan and block. That will give a bit of a rise and allow for the warped area to flex a bit beyond the rest of the pan and when it cools, it may turn out better than you think.

Whichever that case is, let us know how it turns out...

usdmholden

I looked at it again last night and the oil pan gasket has a .150" thick o ring sealing surface, so it should take up the gap from the warpage with no problems at all. My primary concern is stressing the aluminum casting and cracking it after a long period of usage due to the load from the bending.

After looking at it last night I'm going to cut the slot and weld it back up after tightening the oil pan flat to a "junker" block. I don't think I will bother milling it afterwards, given the thickness of o ring in the gasket.

usdmholden

I thought about that, but it's a whole lot of sanding. An hour or two of setup in my milling machine and I could cut a nice, flat, smooth, surface. Relatively speaking of course.

usdmholden

I have a Maximum Motorsports k member with motor mounts I built myself. The motor mounts drop the engine at least 1.45" and set it back towards the firewall at least .600". There were no clearance issues with the modified 4.6L motor mounts on the MM k member using the f body oil pan. I want mass center as far back and as low as possible. I'm not building a drag car, and the 4.6L k member sets the engine very high in the chassis.

BigEd_72455

iTrader: (7)

So what did you get figured out with the pan?

usdmholden

I haven't done anything with it yet. I spent the last couple nights figuring out what's wrong with my timing chain:
https://ls1tech.com/forums/generatio...s-typical.html

I need to pick up an iron block before I re-weld it, and I'll cut the slot with it bolted to the iron block.

pan58head

Might sound funny but how about using a air board file (for doing body work) with 36 or 80 grit paper. I took .014 out of flatness out of a ford escort cylinder head using this method, car is running today!!!! I know kind of redneck but it's a beater

usdmholden

Long ago, I knew guys who used to tear down engines after every pass. They would occasionally, in emergency type situations, surface a block with a portable belt sander between passes. Granted, they had a whole lot of budget to throw around.

I still think my best bet is cut, weld, mill, so that is what I will be doing when I pick up a block to camp the pan down to. Thanks though.

usdmholden

For some reason I remember the wrong numbers in my first post. The warpage was actually .080" after my first round of heating.

So instead of buying a scrap block I just set up the 3/4" aluminum plate on my drill press and clamped it to that. I cut the slot and re-welded it with everything rigidly clamped, and ta-da, it made no different at all.

What I did which worked better was to clamp it down on the old oil pan gasket so the warped portion overhung the gasket and I could bend the pan down a little. I heated the pan with the acetylene cutting torch. I actually melted the aluminum in the pan with the torch across the whole width of the pan. If you do it correctly, you can make the aluminum melt with the torch, but the outer surfaces hold together and the puddle is in the center of the two surfaces. Doing this I got the pan to come down to .030". I will probably try this again and see if I can improve it more. If I can get it to .010" I'm just going to install it and leave it as is. Otherwise I'll mill the surface flat.

usdmholden

So its been a while, I've been fabricating other parts for the swap since my last post. Over time, the warpage has climbed back up to about .060" from .030" last time when I measured it.

I put the oil pan on the Bridgeport table and I shimmed it until I got a measured flatness value of .001" over 14" of surface travel on the non warped surface of the oil pan. There is some waviness between the beginning and end points, but the flatness never goes past .004" and comes back to .001" total across 14". My 14" number is arbitrary, since it is as far as I can go before the warpage screws with the reading, and also I run out of table travel since I didn't remove the vise for the test measurement.

Given the ability to get it that flat over the long span, I think I will use some aluminum brazing rod, build up the warped surface, and them mill the brazed surface flat in the mill. I'm not planning on milling the whole surface, just the part where I braze it to build up material. I believe I can get it close enough milling only the warped surface, so that I can clean it up with some 600 grit sandpaper and make everything nice and smooth, while not screwing up the flatness.

I'm working on designing a fixture now to clamp it to the milling machine table while being able to adjust it for flatness in the x and y axis prior to clamping it all down.