How to fix an early oil pan?

[djwarner]

Putting my engine back together after an overhaul and finally turned my attention to the oil pan. I found lots of RTV on the pan and after cleaning it became very clear that someone over torqued the bolts warping the pan. 

 

Tom Monroe says to place the pan face down on a flat surface and to use a hammer and a large punch to flatten the re-enforcing beads.

 

This being an early pan, it has no doubler plates, but rather a raised boss about 8mm wide and enlarging to a circle around the bolt holes. Most is not all of the distortion is dimpling around the bolt holes.

 

Does anyone have a better technique for removing the dimples? The only reasonable flat, hard surface I have is the engine block currently inverted on an engine stand.

[rossiz]

i've had to do the same thing - much easier than it seems.

 

the pan is made from thin sheet metal and it will flatten as easily as it distorts due to overtorquing. if you have nothing flat to use as an anvil, go to the hardware store or home depot and pick up a piece of 1 1/2" or 2" x 1/4" steel flat bar - they sell 4' lengths pretty cheap, and it will be useful to have around. lay the bar flat on a concrete surface and put the pan upside down on it and use a ball peen hammer to work your way around it. lots of light taps are better than a few big hard ones... you'll get a sense for it pretty quickly.

 

it will get nice and flat and you can run a sanding block over it to knock off any peen marks or texture from the steel flat bar, then a fresh coat of rattle can and you'll be good to go.

 

fun! 

[siteunseen]

The jaws of a small bench vise? Or something similar?

[Patcon]

Rossiz is correct. Lots of light strikes, they will tend to put the metal back without additional stretching. The sanding is a great idea too. A small wooden block or a piece of the steel bar would make a good sanding block as opposed to a foam sanding block. The hard surface will help knock down high spots.

[240260280z]

I've used concrete floors in a pinch.

[Chickenman]

I've used concrete floors in a pinch.

Works just dandy.

 

I've also used a body mans dolly and a body man hammer. Use the dolly on the non-engine side and tap the high points flat with the body hammer. You can also use a regular Ball Peen hammer. Don't worry too much about getting it " perfectly " straight. The pan has enough flex that it will pull down straight when you tighten the bolts. Just get rid of the high points on the mounting surface around the holes.  Old oil pans on SBC's need this all the time.

 

FY in generaI....never use silicone as a sealant on gaskets. This is advice direct from Permatex . It allows movement ( from vibrations ) between the two parts and will " fret " the gasket causing it to fail. Use a sticky adhesive on gaskets such as Permatex Aviation Cement ( Brush on Can ) or a Spray such as High Tack.

Edited April 27, 2015 by Chickenman

[Careless]

lucky for us series 1 guys, the raised bump that is on the pain rail is closer to the folded over outside edge. A small maple or oak or other hardwood piece to smack on the rail just inside the bump is all that is needed. As Chickenman stated, the pan will conform the rest of the way.

 

Now I'm not sure for the later pans, but if you have a raised boss that is right in the center of the rail, what you want to do is get some hard wood like maple or oak, and make a small wedge that fits in between the pan rails, and has TWO tips, with a small section cut out of the middle- just about the width of the raised boss. the thickness of a generic mitre saw blade has been enough for me in the past on other nissan pans that I've fixed. The same can be done with a throw-away cold steel chisel and a grinding disc with a couple of keen slices- but I find it's a bit too heavy or aggressive for nissan pan rails. They tend to be on the thin side.

Edited April 28, 2015 by Careless

[djwarner]

Thanks for all the help. I saw several YouTube videos on the subject as well. It is easy enough to see light under straight edge. What no one said was how big a gap was tolerable. Even our heads have a feeler gauge tolerance.

I quit with no gap as large as 0.005" (how flat is a concrete floor) and used a thin coat of non-hardening Type 2 gasket sealant and a Beck Arnley cork gasket. Set the bolts to 6 ft-lbs with a torque wrench, repeating several times as the gasket took a set.

Keeping my fingers crossed.

[Careless]

it'll be fiiiiiiiiiine!