Felpro Rear Main Seal BS40012 (Cadillac 368/472/500)

I know it needs to be trimmed, but its the one I've been using for the last dozen years or so (with good results) because it was easily sourced from the local parts store but it appears Felpro has recently changed it from a 2-piece rubber seal to a rope seal. I ordered two from Amazon.com and one from the local NAPA and all three showed up as rope seals. I finally got one from E-bay that was the 2-piece rubber one I was looking for.

I figured I'd post this up to warn any others that may have used this seal in the past that it appears to have been phased out. I see TA carries a "no-trim" one for essentially the same price, but I expect shipping to be ridiculous (as is for all their small parts).

The easy way to tell if the part in the box is a rope seal is all the make and engine information is missing on the box. Just lists the part number and that is it. The boxes containing the 2-piece rubber seal has all the Cadillac engine information on it.

 

Try Fel-Pro 5116. It is a 2 piece rubber rear seal that does not need to be trimmed.

 

Things like this need to be a sticky.

 

I just ordered 2 from auto-zone using that part#, one came as a 2 piece and the other rope???? sent the rope back. counter guy can't explain it.
gary

 

Boxed wrong for sure. The 5116 is a straight 6 Ford 2-piece rear main seal.

 

Its not boxed wrong, its a part Felpro changed. One I could believe a wrong box, but three? Four counting Gary's experience? Its a systematic change.

 

I agree, the one box indicated the application on the box,correct one, the other had nothing on the box except the part #.
Unless the ones without the part # are real old ones that they're are grabbing before the neoprene ones came out. I've been using this part for years, I prefer to file fit them myself.
gary

 

I liked fitting them myself as well (I've been driving the car with the pictured seal for the last two days and no leaks :TU: ). By the appearance, I'd say the ones sans application data, are the new ones. The labels are printed on an actual label and not on the box. Here is a picture of the "old style" boxes and labeling. I'm kicking myself for not getting a picture of the new style labeling, but its basically a large white label running down the whole side of the box and all printed information is on the label and not on the box.

 

I did some checking and it would appear that the supplier for the Caddy seal is no longer producing them for Felpro. So for whatever reason, Felpro elected to stuff rope seals in the boxes and call it good. It will be "pot luck" if you order the seal and it comes as the correct 2-piece rubber seal, no matter the vendor. In 30 years in the auto repair business, I have never heard of anything like this. Typically if a manufacturer changes a part, they will reassign it a new number or put some sort of suffix on the original part number. This stuff is certainly getting harder to find at the regular parts houses.

Victor may still have the correct ones. May want to Google a part number and see what happens. And there is always the BOP seal, but that is a few dollars more.

 

while we're on the subject of seal , does anyone have a part # for the neoprene front seal.
I have always used a National front seal, but no parts store can get it anymore and they don't have a cross???
gary

 

If you want the best and know what you are going to get. https://www.bopengineering.com/buick_v8.shtml

 

$40 isn't terrible, but I'm used to paying $15 p ($10 for the E-bay ones). Certainly a solid alternative and I was strongly considering it if the ones I ordered came in as rope seals.

 

For me it is how much is it worth to not have to pull the motor again. ou: Viton is a much better material for a seal than the rubber used in most seals.

For me it was a case of pulling my brand new build out because of the rubber rear main leaking. BOP seal and leak is gone. What's the old saying "you pays your money and takes your choice."

 

Mine leaked because I over RTV'd the main cap side of it causing the RTV to go under the lip. The exact same result would of happened with a $40 seal. The current $10 one that has been in the car since Monday, with around 75 miles is still keeping all the oil in And until this most recent case, I've had excellent luck with the BS40012 since I installed my first one in 2002.

 

Installation is more important that which seal you use.

In short..

On a perfectly clean block, cap, fit the seal so there is about .020 crush, and offset the ends. Do not line it up with the parting line of the cap.

Then put a very thin line of sealer behind the seal.. in the cap and block.. use a q-tip to remove any excess.. you just want a smear in the seal grove. and then that same smear on the cap mating surface around the seal.. just the right amount is critical, more is not better.. and too much is a problem starter.

I have installed the caddy seal, the Ford seal (no trim) and the BOP seal now for some time, enough to get a feel for each. 30+ installs of each seal, at least.

The caddy seal has no real downfall, just old-tech materials, and fitting required. And apparently going to be no longer available.

The Ford seal has a smallish ID when installed.. I never really had a big leak problem but we would actually melt out the seals a little on the dyno.. there would be a little pile of "seal goo" under the crank in the drip pan, just like with a rope seal, after the session. This was from the rubber seal melting a bit. The seal groove ID and crank OD do vary a little bit on these motors, so some would do that, and some would not.. it was a little hit and miss.

Like I said, never a real big problem.. but the BOP seal is a better material and has a bigger ID when installed, crank drag is noticeably less.. just ignore the Pontiac specific instructions that come with it, and install it as instructed above.

As was stated, cost should not be a consideration here.


JW

 

Jim, thanks for the write up! Next time you install a BOP, would you take a pic or two with the cap off and silicone applied?

 

sure..

JW

 

Rob,
I did mine the hard way. Did not disassemble the motor. Removed the pan and rear cap, loosened all of the mains and snaked out the half of the old seal under the crank. Trimmed the seal halves using the cap (JW would have better advise here.) Oh, also cleaned the snot out of everything I could get to. Then feed in the first half under the crank with no silicone, and like Jim said offset slightly. Put a tiny dab on each end, did the groove on the cap as described then put it all back together. Do not know if I was lucky or good but it worked.

Also, used a pipe cleaner to clean out the groove under the crank.

 

What my problem was and the reason I've always used it.