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I am in the process of replacing the crankshaft oil seal (p/n 399781S) on a B & S 12S512-0118-E engine. The engine is leaking oil on the floor from that seal. I had purchased a used Troy Bilt pressure washer last summer. The engine runs really good but the oil leak is annoying. I decided to replace the seal. When I removed the water pump from the bottom of the engine I saw that someone had apparently installed the oil seal upside down and apparently the cause of the leak. I could not remove the oil seal the traditional way because the seal was pushed all the way down and into the recess where the camshaft passes through the oil sump. So I removed the sump and with a lot of difficulty I was able to remove the upside down seal. I cleaned up the oil sump and when I attempted to install the new seal it appears the seal is too large to fit into the opening. I am attempting to install the new seal with the sump removed from the engine. I checked the parts diagram and it shows I ordered the correct seal. The parts diagram shows the sump is part number 498983. I tried to gently tap the seal into the opening on the sump but the seal's diameter is a little too large. I am hoping to get some advice or tips on installing this seal. Is it better to re-install the sump onto the engine and then install the seal using a proper diameter piece of pipe or socket? I used lube on the outside of the seal and the opening in the sump. Thanks!

Warm the sump on our BBQ
Ovens work better but sleeping on the front porch for the rest of your life is not fun.
And put the seal in a zip lock bag in the freezer.

Before you start measure the hole & the seal.
Any more than around .002" would mean you have the wrong seal

bertsmobile1 said:

Warm the sump on our BBQ
Ovens work better but sleeping on the front porch for the rest of your life is not fun.
And put the seal in a zip lock bag in the freezer.

Before you start measure the hole & the seal.
Any more than around .002" would mean you have the wrong seal

Click to expand...

Thanks for the great advice and laugh about having to sleep on the porch! Using a digital caliper to measure, the opening on the sump is 1.617" and the seal's outside diameter is 1.693", so about .076 inch difference. In the videos I have watched the person installing the seal can start the seal in the hole by pressing with both thumbs. I am definitely unable to do that. At this point, I am ready to try the method you mentioned to heat the sump and freeze the seal. If I use the oven what temperature would I set it at and how long would I "bake" it? Thanks!

Pan of hot water works for me.

Russ2251 said:

Pan of hot water works for me.

Click to expand...

Thanks for that tip!!

.076" is WAY too much press fit.

You've got the wrong seal.

I wonder if that sump base is different for the washer vs a mower? There are various changes for that service.

OP, what's the digit after the E in the model number.
Should be E1,E2 etc.


EDIT. ( I looked up both variants e1&e2, sump part number is the same)

cpurvis said:

.076" is WAY too much press fit.

You've got the wrong seal.

Click to expand...

I am thinking the same thing.

tom3 said:

I wonder if that sump base is different for the washer vs a mower? There are various changes for that service.

Click to expand...

I searched on the internet and found several photos of sumps with the same part number and they all appear to be identical to the one I have. Of course, there could be a difference in the diameter of the opening.

Scrubcadet10 said:

OP, what's the digit after the E in the model number.
Should be E1,E2 etc.


EDIT. ( I looked up both variants e1&e2, sump part number is the same)

Click to expand...

It is E1.

cpurvis said:

.076" is WAY too much press fit.

You've got the wrong seal.

Click to expand...

Yes You have the wrong oil seal
Oil seals should be a class IV transitional fit or a class V interfearence fit
A type IV should be able to be fitted with finger pressure or a light mallet
A type V should be able to be fitted with a "Light Press" or heavy mallet.

Oil seals should be around these tightnesses
https://www.engineersedge.com/class_iv.htm

GO down the table and for the seal diameter of around 2.5" your crush should be between 0.0002" to 0.0024" .

This is a tad looser than the measured 0.067"
With oil seals , the crush is generally the thickness of the rubber that coats the steel case so removing & replacing it will not damage the hole ( in theory ).

firedawgsatx said:

I searched on the internet and found several photos of sumps with the same part number and they all appear to be identical to the one I have. Of course, there could be a difference in the diameter of the opening.

Click to expand...

If the hole was a different size it would be a different part number

bertsmobile1 said:

Yes You have the wrong oil seal
Oil seals should be a class IV transitional fit or a class V interfearence fit
A type IV should be able to be fitted with finger pressure or a light mallet
A type V should be able to be fitted with a "Light Press" or heavy mallet.

Oil seals should be around these tightnesses
https://www.engineersedge.com/class_iv.htm

GO down the table and for the seal diameter of around 2.5" your crush should be between 0.0002" to 0.0024" .

This is a tad looser than the measured 0.067"
With oil seals , the crush is generally the thickness of the rubber that coats the steel case so removing & replacing it will not damage the hole ( in theory ).

Click to expand...

Yes, it does appear the seal I was sent a genuine B & S 399781S is not the correct seal for the sump. It is neither a class IV or class V fit.

Scrubcadet10 said:

If the hole was a different size it would be a different part number

Click to expand...

That is what i figured to be true. While searching for photos of the sump on the internet there appears to be two different versions of the sump with part number 498983. They look extremely close in appearance except for a slight variation of the pattern of the casting on the exterior side and one version has a collar around the opening and the other version does not. My sump is the one with the collar.

I would email or call Briggs with your model and code date numbers.
They should tell you

You have already measured the hole diameter and shaft diameter so just measure the thickness and order a new oil seal from a bearing supply shop.
All seals used on mowers are a common size.
They have to be in order to reduce costs.
Just go to a real bearing store and not some fly by night online shop flogging junk from 3rd world countries.

Scrubcadet10 said:

I would email or call Briggs with your model and code date numbers.
They should tell you

Click to expand...

Thanks for the suggestion. I will contact Briggs to see if they can assist me. I will post what they tell me.

bertsmobile1 said:

You have already measured the hole diameter and shaft diameter so just measure the thickness and order a new oil seal from a bearing supply shop.
All seals used on mowers are a common size.
They have to be in order to reduce costs.
Just go to a real bearing store and not some fly by night online shop flogging junk from 3rd world countries.

Click to expand...

Thanks for the info!

I am a small fry and independent so all of my oil seals are in the oil seal box
Thus you walk in and ask for an oil seal I ask have you got the old one then match it with what I have in the box.
Mr big multi franchise usually has no oil seals and orders them in as required.
If they do they are in bins according to the size of the part for most efficient storage so unless the computer gives them a bin number they can not find a suitable match.

My parts suppliers only carry a very limited range so I get most of them from an engineering supply company.
A pack of 10 is about the same price as 3 single so I usually get a pack.

Most "cities" with businesses that actually produce something, will have what I call 'bearing supply houses.' That's because the machines that produces things have bearings and bearings eventually wear out.

They carry bearings, seals and the assorted paraphernalia that goes with with bearings.

bertsmobile1 said:

I am a small fry and independent so all of my oil seals are in the oil seal box
Thus you walk in and ask for an oil seal I ask have you got the old one then match it with what I have in the box.
Mr big multi franchise usually has no oil seals and orders them in as required.
If they do they are in bins according to the size of the part for most efficient storage so unless the computer gives them a bin number they can not find a suitable match.

My parts suppliers only carry a very limited range so I get most of them from an engineering supply company.
A pack of 10 is about the same price as 3 single so I usually get a pack.

Click to expand...

Unfortunately, I destroyed the seal during the removal process because someone has installed it upside down and it was pushed down too far. Because the seal was upside down I couldn't even look for numbers on it to identify the seal. I have submitted a request for assistance on the Briggs web-site.

cpurvis said:

Most "cities" with businesses that actually produce something, will have what I call 'bearing supply houses.' That's because the machines that produces things have bearings and bearings eventually wear out.

They carry bearings, seals and the assorted paraphernalia that goes with with bearings.

Click to expand...

Thanks for that tip! I live in San Antonio so I am relatively sure there are some local bearing supply houses that I will seek out.

firedawgsatx said:

That is what i figured to be true. While searching for photos of the sump on the internet there appears to be two different versions of the sump with part number 498983. They look extremely close in appearance except for a slight variation of the pattern of the casting on the exterior side and one version has a collar around the opening and the other version does not. My sump is the one with the collar.

Click to expand...

I contacted Briggs & Stratton about the issue I am having with installing the oil seal. They stated that there was only one version of the #498983 sump I have on my engine and advised me to contact an authorized B&S service center. Well, on my sump I have a ring/collar (maybe a spacer) insert around the hole that is keeping the oil seal from going in. Looking at on-line photos of the sump with p/n 498983 there is no ring/collar on the sump like the one on my sump. I am wondering is there is a version of the sump that incorporates the ring/collar that appears to fit inside the opening of the pump on the pressure washer. The OD of the oil seal the parts diagrams show is the correct seal for the engine is 1.693". The bore where the oil seal seats (below the ring/collarinsert) is only 1.430". I have attached a photo of my sump (with the ring) and a photo I found on-line of a sump #498983.

In the first photo the oil seal is way too deep.
Usually they would go in about 1/16" or so below the top edge of the hole so they are just not flush with the face of the hole to avoid mechanical damage.
The Briggs man would have looked up the parts file and seen that your engine number has only one sump, ie there are no alternative ones on the file.
Weather there were previous versions that superceeded to the current one is a different story.

bertsmobile1 said:

In the first photo the oil seal is way too deep.
Usually they would go in about 1/16" or so below the top edge of the hole so they are just not flush with the face of the hole to avoid mechanical damage.
The Briggs man would have looked up the parts file and seen that your engine number has only one sump, ie there are no alternative ones on the file.
Weather there were previous versions that superceeded to the current one is a different story.

Click to expand...

Thanks for the feedback! This issue is extremely frustrating. It appears that at this point I will be forced to purchase a new sump with the oil seal already installed. The problem is that sumps with the listed part number don't have the raised ring/collar. So far, I can't determine if that is actually even a concern. When I started I thought it was going to be an easy operation removing and installing a $5 part.

Usually sumps don't come with the seal installed

You may have to bite the bullet and order one. And find out.
Be sure returns are accepted though.. IMHO:confused3:

Is there anything left of your old seal to measure the OD and width? It ID will be determined by the crankshaft.

You are making a mountain out of a mole hill.
Take the sump along to your local bearing supplier alone with the measurement of the crankshaft
Ask them for a seal to fit.
If you ask them nicely a lot will actually push the seal in
As mentioned earlier the seal goes just below the very end of the hole
From your photo it looks like the sump has a larger hole , which is where the seal would go then a step then a smaller hole then an even smaller hole for the crank shaft to run on.
People do all sorts of strange things to engines for all sorts of reasons so unless you have owned this one from new anything could have happened.
IT was not uncommon for machinists to buy junked engines that have siezed then machine the cases for a bush.
Of junked sunps plates and machine the opening larger for an oversized seal because the sump plate was damaged.

bertsmobile1 said:

You are making a mountain out of a mole hill.
Take the sump along to your local bearing supplier alone with the measurement of the crankshaft
Ask them for a seal to fit.
If you ask them nicely a lot will actually push the seal in
As mentioned earlier the seal goes just below the very end of the hole
From your photo it looks like the sump has a larger hole , which is where the seal would go then a step then a smaller hole then an even smaller hole for the crank shaft to run on.
People do all sorts of strange things to engines for all sorts of reasons so unless you have owned this one from new anything could have happened.
IT was not uncommon for machinists to buy junked engines that have siezed then machine the cases for a bush.
Of junked sunps plates and machine the opening larger for an oversized seal because the sump plate was damaged.

Click to expand...

I am probably making a mountain out of a molehill. I posted my issue hoping someone had come across this same issue in the past. I do appreciate all the tips and information provided.

Thought I would post a followup to my issue so it can possibly assist others in the future. I was finally able to figure out how to properly install the oil seal. I had contacted Briggs & Stratton, posted on numerous forums, called small engine repair shops, searched the internet for hours and was still totally unable to find the answer I needed. In the end it turned out the solution was extremely simple. I kept studying the illustrated parts diagrams to see if I could figure out what I was missing. I kept seeing a part #1102 (p/n 691255) called a pilot-guide. What is confusing is that on the parts diagram #1102 is not shown to be where the oil seal is shown. I searched and searched the internet for a photo of this pilot-guide but I could not find one photo. So, I narrowed down #1102 to be the steel ring/insert I have in the bore of the oil sump. I used a small pry bar to remove the ring/insert (pilot-guide) and my problem was solved. It actually popped out quite easily. So, I lubricated the new oil seal and bore and got it started uniformly in the hole. Then I used the ring/insert to push the oil seal down to the proper depth and ensured the pilot-guide was fully seated. Apparently this pilot-guide's only purpose is to install the oil seal to the proper depth. It is amazing to me I was unable to find one photo, one article, one service manual instruction or even a mention of this since at least 150 engines use this part.