Author Topic: oil leak after adding oil  (Read 2265 times)

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Offline Striker

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oil leak after adding oil
« on: June 19, 2004, 04:26:59 pm »
Fellas,

When I bought my B2 it was coming of a fresh rebuild. After the car was delivered I put a fairly quick 300 miles on it over about 4 days (no big suprise). Anyway, I checked the oil and it it was rather low on the dipstick.  I thought this would be a good time to change the oil anyway so I ran over to the Valvoline for a quick change.  They put 5 quarts 10W-30 in it...looked a little low so they added another half, but it was still down around where the level was when I initially checked it (but we didn't want to overfill). I went home and got on the forum at which time I learned that I needed 7 qts. I ran out an picked up a couple qts and brought it up to a full 7.  Now everytime I take the car out and drive it, by the next morning, I have a puddle on the garage floor???  Previous to that there was nothing more than MAYBE a drop or 2 on occasion.

It appears to be coming from the rear main seal, but I was reading old posts that it could be a variety of other things instead. Any thoughts in the direct relationship between the extra quart and a half of oil?  Thanks.

Jason S.
2012 Boss 302 #1897 - Competition Orange, R/T, Boss Pkg.
1999 Mustang GT - Kenne Bell

Offline MarcusSimmons

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oil leak after adding oil
« Reply #1 on: June 19, 2004, 04:43:43 pm »
The dept of the standard 302 and the BOSS 302 oil pans are the same. The difference is in the calibration of the dip stick. If the level is low, not very much splash will get to the seals, either crank of oil pan. When the level was raised to the factory recommended level, splash becomes more apparenent. The fact that you had a little leak before adding the oil means the problem was always there. Check to determin if the oil is coming from the pan gasket of the rear main seal, then make the approiate repairs.
till together after all these years,
1970 BOSS 302, 1965 427 S/C Cobra replica
2002 F-350 Crew Cab DRW

Offline CLAYTON

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oil leak after adding oil
« Reply #2 on: June 19, 2004, 10:26:06 pm »
Striker. If your engine is a recent rebuild I bet the problem is your rear main. Felpro's new rear mains are screwed up. If you go and buy one you will see what I mean.
In the center of  each half there is a molded in "tab" for which I have know idea of its purpose. It is on the "lip" side of the seal and seems to hold lip away from crank surface when installed. I and a friend who builds lots of small block fords have had this problem. If you trim the tab off prior to installation it will then seal.
I know of three specific cases in the last couple of months where this was the case. My motor included. Hope this helps.
Clayton

1970 Mach 1 428scj 4 spd. / med. blue 70 Boss 302 SOLD / Sterling grey 2011 GT500

Offline BOSSTANG

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oil leak after adding oil
« Reply #3 on: June 20, 2004, 06:08:58 am »
I always read that you should use RTV around the rear main cap when replacing the rear main seal. I replaced my rear main on my 70 351 Mach 1 but forgot to use the RTV. It still leaks a bit even with the new seal which was a Ford replacement seal not a Fel-Pro. Maybe the old rope seals are better???

Offline MarcusSimmons

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oil leak after adding oil
« Reply #4 on: June 20, 2004, 10:16:29 pm »
Come to think of it, on one rebuild, I went to the rubber seal. And it leaked. The next time, I went back to the rope seal. That stopped the leak.
till together after all these years,
1970 BOSS 302, 1965 427 S/C Cobra replica
2002 F-350 Crew Cab DRW

Offline gsjohnson

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oil leak after adding oil
« Reply #5 on: June 21, 2004, 09:07:23 am »
You must remove the little retaining spikes when converting to a rubber rear main seal. The original rear main seals were of the rope design & the little spikes were designed to retain the rope seal. The newer rubber seals are far superior in design to the rope seals. If you forget(or don't know)to remove the little spikes & use the rubber seal, it will leak. No RTV or sealer should be used on a rear main seal. The technique is to "Clock" the seal when installing, so the two halves are not in direct alignment with the rear main cap. Let's say at 11:00 & 5:00. The dabs of sealer or RTV should be used at the corners of the front & rear of the oil pan gaskets where they meet both the side rail gaskets. Another apparent rear main seal problem I have seen is the cam plugs above the rear main leak & it is assumed it is a rear main, when it is not. Hope this helps.

Offline blueovalboy69302

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oil leak after adding oil
« Reply #6 on: June 22, 2004, 02:47:43 pm »
GS is 100% correct in his way of installing a two piece rear main seal.  not to many people know of this method but it works MUCH better.  make sure the two halves of the seal are not inline with the block!  also see if the end rails on the rear of the intake are eather the gasket or RTV.  if there is a leak coming from there pull the intake and use RTV and NOT the gastet.

Offline blueovalboy69302

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oil leak after adding oil
« Reply #7 on: June 22, 2004, 02:47:44 pm »
GS is 100% correct in his way of installing a two piece rear main seal.  not to many people know of this method but it works MUCH better.  make sure the two halves of the seal are not inline with the block!  also see if the end rails on the rear of the intake are eather the gasket or RTV.  if there is a leak coming from there pull the intake and use RTV and NOT the gastet.

Offline MD69Boss

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Re: oil leak after adding oil
« Reply #8 on: January 09, 2019, 08:19:49 pm »
Still looking to GS for sage advice...

I am pulling my motor next month and replacing the rear main seal to address the slow leaks since the new block; figure I will repaint the motor while I am at it...
In reference to his post above, the little retaining spikes are in the rear main cap?  Also, which is the preferred two piece seal these days?  Ford or FelPro, or...?
I am still considering a rope seal, as well, gathering info at this point.
As always, thanks in advance for your responses...

Offline David189412

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Re: oil leak after adding oil
« Reply #9 on: January 10, 2019, 06:06:51 am »
2901 Fel pro for rear main.
I think some of the problems are the oil pan seals now.

Also, make sure the PCV system is working. The replacment PCV hoses seem a little weak.
I have been installing a spring inside the hose so it does not collapse.

David






« Last Edit: January 10, 2019, 11:54:46 am by David189412 »

Offline swboss302

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Re: oil leak after adding oil
« Reply #10 on: January 11, 2019, 04:47:28 am »
I've battled the rear pan leak saga many times, David is right, use ONLY the 2901 seal as the worthless black seals that come in the gasket sets will leak. But before you blame the rear seal, as mentioned before, it could be the pan gasket and or rubber pan seal at the rear. The pan bolts will loosen up slightly after initial warm up and will normally need to be snugged up. My repeated path for success was to clock the 2901 seal, use anaerobic sealant on the main cap, seal the pan corners carefully and retorque everything after several warm ups. BTW you mentioned you had 10W30 Valvoline installed. If you still have the mechanical solid lifters, I sure hope it was Valvoline RACING oil as you need the added Zinc.

Offline MD69Boss

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Re: oil leak after adding oil
« Reply #11 on: January 11, 2019, 04:44:35 pm »
Thanks for the responses, gents.
Based on my research, I will go with the two piece FelPro gasket.
As I will have the motor out of the car, I am replacing the oil pan gasket as well.
@David, thanks for the screen shot you sent, very helpful!
I have been running Brad Penn 10w30 for years.  The Valvoline racing oil has plenty of zinc, but no detergent properties, not ideal for a street motor...

Offline crossboss

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Re: oil leak after adding oil
« Reply #12 on: January 12, 2019, 08:24:13 am »
Boys,
An old mechanics trick to help solve the oil leak(s), try pouring a small cap of brake fluid (DOT 3) in the crankcase. ONLY use a small amount from the brake fluid cap is sufficient. The cause of a seal leak can occur from improper placement as mentioned, and from shrinkage/dried out older seals. The brake fluid will not harm the engine, and will soften and expand the seals. It works wonders!
Current lifelong projects:
1969 Mustang Fastback/FOX chassis, 6 speed, 4 wheel discs, with a modern Can-Am 494 (Boss 429), Kaase headed, intake mounted with a 1425 cfm 'B' Autolite Inline carb, ala Trans-Am style…Whew!
 
Volvo 1800, being converted to Boss 302 power…coming soon!