93 4.0 Oil Filter to Block Adapter leak - Ford Truck Enthusiasts Forums

93 4.0 Oil Filter to Block Adapter leak

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Old 06-24-2005, 01:36 PM
Jharger Jharger is offline
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93 4.0 Oil Filter to Block Adapter leak

Here's my first string I posted in the Explorer forum. Got no response so I'll post it here in engines with an update that could help others.

Hey Guys - and the 2 or 3 gals that track this forum (I know you're out there).

I just R & R the oil filter adapter on the 4.0 L and changed the O-ring to the block. I suspected a leak from there since the oil filter itself is constantly dripping and I couldn't see any trace of fresh oil leak above the adapter.

I was a bit miffed this morning when I realized that I had to pull my header off (yes header - Borla stainless steel - not stock cast iron) in order to get the adapter off. All's good there since I found the exhaust gasket was leaking and had to be replaced anyway.

So when I take the assembly off I quickly realize the , yes bonehead, Ford dealer didn't tell me there are actually 3 seals in the assembly. 1 goes to the block (~2" diameter) and then the mounting bolt for the assembly has 2. 1 ~1.5" diameter and one ~ 1" diameter.

So OK, I didn't get all the o'rings from the aforementioned dealer but I did get the suspect leaking one. But I noticed an odd thing. The 1.5" one was OK - it was your basic rubber compound - you know - you could stretch it , mush it down... But the smaller 1" diameter one was hard as a rock. I did break it off the little shaft in 3 pieces - it was like a cast piece of bake lite, thermoset plastic. So to call it an O'ring at that stage would be just wrong.

I went to Autozone and found the right size O'ring out of Viton Rubber - which from my engineering profession days was a higher temp material from Buna-N. All is installed and no leak so far.

Not sure with this thread if I have a question but I guess I'm just curious what others have found around sealing this oil filter adapter housing.


Well 2 days later I noticed a puddle of oil on the garage floor. Glad I kept the cardboard on the ground. Clean all the oil off with Gunk, hosed it all off, dried the entire area with carb cleaner, started the engine and saw the block to oil adapter seal still leaking.

Mind you, when I discovered all this I was on a mission to get my battery cables and go jump my wife's car who's battery had just died. She was stranded in 108 degree Arizona heat with my 2 small children. Now both cars are down - I didn't want to risk driving the Explorer with this size an oil leak right over the exhaust header. Well tow truck showed up, jumped the Durango and she got home so I went off with that to get a new battery - no one got heat stroke.

So that night I go at it again and rip the wheel well cover out, pulled the header, dropped the oil filter and then saw the new problem. The o'ring I paid $6 for at the dealer was smooshed outside the o-ring groove and sticking out from behind the adapter itself, about 3/8 inch of length. O'rings are supposed to be behind the seal surface, not protrude beyond it.

On goes the engineering hat again. Upon inspection and mic'ing out the oring groove, it doesn't size to any standard SAE o-ring size. The old o-ring has to be a square section as it was too square to have been compressed into that shape. New o'ring from Ford is round. So I'm thinking the German built engine came with a metric, square section O-ring and Ford US can't source that as a replacement part, economically that is. So they find something that kinda sorta works in a round cross section. Well that is a -230 SAE sized o'ring.

A -230 O'ring is a nominal 1/8 cross section and 2.5" inner diameter. The diameter of the groove in the adapter was about 2.5" ID - close enough for this size O-ring to work. The depth of the groove was right at spec for a 1/8 o'ring. But the width of the groove was at spec for a 3/32 diameter o'ring - too narrow.

So when the adapter was installed with the new o'ring, it began to moosh down and spread out in the groove as it is supposed to. But then because the groove was too narrow, it popped out at one point and got between the block and the adapter and smooshed outside the groove where I saw it on the car. Prime candidate for a leak right where oil pressure is the highest.

Also, all the way around the oring, in a circular direction, it had a shred of material cut off. All the way around the o'ring. Like a thin slice from a razor blade.

Inspecting the adapter groove, I noticed the groove itself wasn't deburred. had sharp edges all the way around. So again, as the o'ring expanded, it had no where to go and when the adapter finally met he block, the o'ring got cut, all the way around.

Now it is 6:30 at night and my wife is out with the Durango. I call around and find a -230 o'ring at one of the ACE hardware stores. She finally gets home and I make it to ACE 1/2 hour before closing. For 94 cents, I get a new o'ring.

But not wanting to see a repeat event, I got out my dremel with a 1/4 ball end cutter and chamfered the o'ring groove to about .04" on both sides. This will give the o'ring some where to go when mooshed down and also make sure there are no sharp edges to get cut on.

This would be a good time to mention too that on the first go around on this thing, I had also chamfered the internal bore of the adapter where the center bolt insets. Remember there is a o'ring there in the middle that separates the oil pan side of oil flow from the clean filtered oil side of the flow. The o'ring slides into and seals on a inner diameter of the adapter. Well that edge of the internal bore was not chamfered either and would have cut that o'ring up too upon install of the center bolt. So I caught one but missed the other. 50% ain't bad.

And since I was paranoid about the large o'ring popping out of the groove again, I installed it into the groove dry so it wouldn’t pop out. I did lube the outer side once inserted. But I figure the oil from the system will get to the backside of the o'ring and seal it once installed.

Slapped it all back together and 2 days later it's oil drip free. I have a couple photos if anyone is interested.
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Old 05-20-2014, 11:05 PM
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asavage asavage is offline
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I had posted the below over in the Aerostar forum last week, but got little response.

For the 4.0l OHV in the '97, this is the line drawing that the Ford manual shows.

Click HERE for larger

Notice that it shows only two o-rings: the big one that seals the adapter to the block, and the small one that is an intermediate on the adapter bolt.

The following pic is from an eBay seller, purportedly for a 4.0l OHV.

Click HERE for larger

Lastly, this is for a SOHC. Notice three o-rings in this drawing?

At first, the dealer couldn't find a listing for that under-the-bolt-head o-ring, but when I showed the SOHC drawing, he used that group number to find it. This was sufficiently difficult to figure out, that I'm posting it for future Googlers.

Adapter Filter Adapter Mounting Bolt o-ring:
E9TZ-6749-A ---- 26.5mm

Internal seal o-ring:
E3TZ-6749-A ---- 17mm (or Victor Reinz 72115)

Oil filter adatper-to-block:
Fel-Pro 72884
Inside Diameter (In): 2.482 Inch
Width (In): 0.141 Inch

So, now that I kind of know what I'm fighting (I have the too-typical oil weep at those o-rings above), I have a question for those of you who may have already been down this road.

I am installing a dual-filter remote (one full-flow, one bypass) in the usual location (for Aerostars) of outside the right frame rail. I assume that I can remove the OEM oil filter adapter entirely and bolt my filter adapter directly to the block, but that I'll need the double-ended threaded insert that screws in the block, and to which an oil filter would normally thread. Something similar to this:

Does anybody know either the 4.0l OHV's thread size/pitch, or a part number for that adapter?
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