427 - can't stop oil pan leak! (continued)

[Jack O.]

Hi,

I still have an oil leak in the rear area of my oil pan. I originally posted in 10/2003 "can't stop oil pan leak!" and at that time replaced my rear main seal and put on another new FelPro one piece gasket (#OS30061T). I'm about to go in again and at least replace the gasket with another new FelPro one piece and was wondering if anyone had any further ideas. I know I should put sealant in the corners around the rear main cap but should I be using sealant anywhere else with this particular gasket? I also had to use slightly longer bolts on the pan at the rear main cap because I couldn't get the originals started because the gasket is so thick. With this said, should I be torquing the pan to the original spec's when using the one piece gasket?
Thanks,
Jack

[Phil P.]

sealant between the rear main cap and block *NM*

[Dick W.]

Re: sealant between the rear main cap and block

Jack, I would check the pan surface where the bolts come through also. If the bolts have been over tightened at some time it is possible that they are dimpled inward. If so, you can take the pan, turn it upside down, use an appropiately sized socket and dimple the pan outward using a small ball peen hammer.

[Terry F.]

Re: 427 - can't stop oil pan leak! (continued)

Take everything apart and clean all the gasket material off the surfaces. Also, clean out the bolt holes. It is an absolute must if you want it to seal well and for good. Use lacqure thinner on a Q-tip and compressed air. Bone dry be best! Make sure the oil pan surface is flat. Everything must be bone dry.

I use copper permatex silicone sealant. Put a thin coat on everything and slap it together. Don't use too much because it will squeeze out and potentially brake off and clog something up. Don't get any sealant on any of the bolts or they will loosen. Get is all back together and let it sit for a week, especially in cool weather. If you fire up the engine too soon, it will blow out. If it is done right, the permatex will hold it nicely and you don't have to crank down so tightly on the bolts. Actually, it is best to not super tighten the bolts because it will squeeze all the sealant out. Just my humble opinion. Good luck, Terry

[Joe L.]

Re: 427 - can't stop oil pan leak! (continued)

Jack------

A small instruction sheet is packaged with the OS30061T gasket. It instructs that a small dab of silicone sealer should be applied to the gasket at the corners (the ends of the pain rail section of the gasket where it joins the end seal section). Also, the proper torque specifications are provided on the sheet for both the 5/16" and 1/4" bolts.

As others have said, the oil pan rails must be flat.

Considering that you have the leak at the rear, I'm going to speculate that the most likely source of it is from an improperly installed rear main seal or the lack of sealant in the required areas of the rear main cap.

[Mark #28455]

Can you see the leaking area?

If the engine is still in the car, you can easily chase an "oil pan" leak for a long time when the leak is really at the cam plug or the oil gallery plugs.

Mark

[Verle R.]

Re: Can you see the leaking area?

Also check the back of the valve covers, intake manifold and distributor. A bad distributor gasket will leak a significant amount of oil. Don't ask how I know.

Verle

[Timothy B.]

Re: 427 - can't stop oil pan leak! (continued)

Jack,

Check the valve covers also to see if this could be the leak.

[Terry F.]

Re: 427 - can't stop oil pan leak! (continued)

Yes, by all means check for other sources of oil leakage. Look very closely at the rear edge of the intake and make sure that gasket did not slip inside the engine. With either too much sealant or if the gasket gets squeezed too hard, it will want to slide out. Clean oil can be hard to detect. Start at the top and work down. Take your time. Terry

[John M.]

Re: Can you see the leaking area?

I hear you Mark. I have the same problem as Jack, engine in car. I replaced the pan gasket and it seemed ok for a few miles; now leaking badly again. I did the job laying on the garage floor. I have a lift now and will be very careful. Do you think the guy who built my engine (professional)would have just forgot the sealer at the rear main cap or is this wishful thinking? Should I replace the rear main seal while in there? I'm not going to be happy if I have to take this engine out to fix an oil galley or cam plug. BB with 850 miles on it. Any ideas on how to see if this is the problem with the engine in car?
Thanks,
John McRae 30025

[Terry M.]

Re: 427 - can't stop oil pan leak! (continued)

I don't see anyone addressing the possibility of excessive pressure build-up in the crankcase as a cause of oil leakage. It is at least something worth checking, and ruling out.

Be sure you have the proper, functioning PCV valve and system. Clogged hoses in the PCV system (I know one wouldn't think that with a freshly rebuilt engine, but check anyway), or a leak in the hose(s) on the suction side of the PCV valve. This vacuum leak ought to manifest itself in other performance issues, but is still worth checking IMO.

If the rings have not yet seated an engine can make more blow-by than the PCV system can handle. I suppose if this is the case (may be checked with a cylinder leak-down test) one can either choose to live with it in the hope that the rings eventually seat properly, or re-ring the engine – not a pleasant thought either.

[Mark #28455]

Re: Can you see the leaking area?

Start from the top down to look for the source of the leak, or start from the bottom up to track it back to the source. Take off the sheet metal shield on the lower part of the bellhousing and carefully take white TP and touch it to various parts of the engine block around and above the rear main cap. Each time after touching, look at the paper to see if there's oil there. On one of my engines, the entire back of the engine inside the bellhousing was coated with a fine oil spray - turns out the professional engine guy used teflon tape on the oil galley plugs. That happened about 20 years ago and ever since then, I have requested all my blocks BARE so that I can insert all the plugs myself. I use Permatex Avation Form a Gasket (brown sticky, snotty stuff that stains your hands really well and seems to never leak).

If still having problems locating the leak, you may need to pull the bellhousing to get a better look.

Good Luck,
Mark

[Clem Z.]

clean the engine down with brake cleaner

buy the chemical,auto parts should have it, to put in the oil that shows up yellow with a "black light" run the engine with out going out on the road as the wind will blow the oil around and use the light to look for the leak.