Emeightch

Old build but only a couple hours of total run time. It’s a reconditioned 2-pc rear main seal 400 block. New Eagle rotating assy at time of rebuild. Same for the new Hamburger 7qt Oil Pan. It had a small leak from the beginning of breaking it in and slowly getting worse. Every time I run it I get an oil stain.

Is there a way to tell if this is an oil pan just needing reset or if it could be the rear seal. I’m assuming mains were align honed because the bare block was covered in surface rust when I gave it to the Engine builder. Here are a few pics from the bottom side.

cv67

Hard to tell, check the bolts in the rear to see if they need snugged down some?

cardo0

Clean the affected areas and throw some white flour on them. Then test drive and reinspect.

4-vettes

Clean it up real good with some aerosol brake cleaner. Then spray it down with aerosol spray foot powder. Run it on your ramps. Watch for the first place the white powder turns brown.

71chimera

find the leak as above

unrelated to leak, but run a little longer filter e.g. WIX 51060

Tampa Jerry

It should make no difference if the leak is from the rear main seal or oil pan. In order to change the pan gasket, you must remove the pan. Once the pan is off, the rear main change out is a 10 minute job. Get a Fel Pro one piece pan gasket and rear seal. Don't forget your torque wrench for the rear main bearing cap. Jerry

DC3

Before going to too much trouble with the oil pan or rear seal, make sure you don't have a valve cover leak that is dripping down the backside of the block.

DC

Jebbysan

100% in agreement with this......if I have the car in the air and am going to reseal the pan, not knowing if the seal or pan gasket is leaking, then replace both.
A couple of things going on here though:
1) It has a crap 4 piece paper gasket on it.....I would change it, just to change it.
2) Make SURE you know whether or not this engine was line honed.......when a 400 is line honed, the seal lip is opened up to the size of the main journals. There is a specific seal for this that Fel-Pro and other manufactures use......

Jebby

7t2vette

OMF

Have a look to see if the oil is coming from the dipstick tube, it does look a little wet in the head /block seam there.
That's where I found my leak.....

Emeightch

Cleaned everything up. Torque’d the pan Bolts to 15 ft/lbs. Not sure if this is normal, but the 2 forward and 2 rearward bolts are a different size than the ones in the middle. Wondering if I should torque those higher?

So it Appears the leak is coming from the passengers side rear most bolt and not the rr seal. Is there a way to fix this without removing and resetting the oil pan? I’m thinking it’s never that easy - lol.

I also found a minor one by the oil Pressure sending unit. Should I be using a thread sealer? I thought that it needed to ground and didn’t put anything on.

71chimera

Put some pipe dope or tape on sender; the threads will easily cut thru & ground AOK.
Torque all pan bolts to spec. Google's your friend.

Emeightch

I had some time today to finally pull the oil pan off. One thing I noticed is the gasket had black Silicone a white’ish silicone too. Any reason why there would be two different ones?

Also, doesn’t appear to be sealer on the pan side of the gasket. Only in the corners near the mains. I thought you need to put gasket rtv on both sides?

Lastly, does anyone have any tricks of the trade to removing this old gasket without scratching the block surface all up?

cardo0

Everyone has their own way to seal a oil pan. My thinking the sealer was used to hold the gasket up in place to get the pan on. I see a 4 piece gasket and those require sealer in each corner. Have you considered a one piece oil pan gasket? I really like mine and they are reusable. Read theinstructions as the one piece gaskets still need sealer just in the corners IIRC.

Just use a gasket scrapper. It shouldn't mark the blocks cast iron oil pan rail. I have a Craftsman gasket scrapper with a screwdriver handle but a putty knife works too.

Have fun.