Briggs Vanguard Main Seal Oil Leak??

I have a 16 HP Briggs Vanguard engine on a Simplicity Landlord tractor. The engine is about 15 years old and has 460 hours on it, if I can believe the hour meter. I bought this used 5 years ago so I don’t know the earlier history. I appear to have a lower main seal oil leak. I put a new O-ring on the lower end of the plastic dipstick tube where it enters the engine. I also replaced the O-ring on the dipstick itself. I see no leakage in the areas where I replaced the O-rings. Oil leaks down onto the two pulleys that attach to the crankshaft and then gets flung onto the underside of the tractor and whatever else is nearby.

Someone told me that the whole engine needs to be torn down in order to replace that seal. Uggh. I was wondering if I might get lucky and have a problem with a clogged breather or something similar that ends up creating pressure in the crankcase that then forces oil past the main seal. So I removed the reed valve breather assembly and blew and sucked air through the port. It seems fine; I sloshed some gasoline around in it anyway to clean it. Can I do a pressure measurement somewhere to see if I have pressure in the crankcase? Is there something else I can check? What’s involved in replacing the main seal? Is there a reason I can’t pull off the bottom of the crankcase, replace the seal, and reinstall the lower crankcase without touching the crankshaft and camshaft? Failing all of that, is there some way I can build something to catch or capture the oil before it drips down on the pulleys?

BTW, the engine starts and runs just fine, summer and winter. The problem seems worse in the winter. I think that may just be because there’s no sand/dirt/grass clippings blowing around to stick to the oil and make an oily mass so more of it drips on the floor after snowblowing.

 

If you will post a model and type number of engine, it would be more helpful. Yes the engine would have to be removed to gain access to that seal.

 

Briggs Vanguard 16 HP twin cylinder. Model 303777. Type 1111-A1. Code 96112011.

I realize the engine has to be removed to access the seal. My question is can I replace the seal by taking only the lower crankcase/oil sump off the engine?

 

Yes you can, here is a link from Briggs with part break down. Illustrated Parts Lists | Repair Parts & Maintenance Products | Shop | Briggs & Stratton
Some have even used a cotter key tool and just popped out the seal and have been lucky enough to put a new seal in without taking engine apart at all. Feeling lucky?? Just clean the crankshaft (PTO end) really good with emery cloth. Makes sure you also get seal in square and not to deep,,study old assembly. Good luck

 

I nearly always change the bottom seal without removing the engine. I've never had a problem doing it, but you have to be careful and know that any metal scraping on the crankshaft is going to scratch it and make it leak. I raise the mower, remove the clutch and pulleys, then use a seal puller to carefully remove the seal. Install the new one, being careful to keep it straight, not one side down further than the other, reassemble. Turns a several hour job into a few minutes job, just be careful and don't nick the shaft or the block. The crankshaft is softer than you think.

 

This is sounding much better. I like minutes better than hours when it comes to projects. Is there adequate room to get a conventional seal puller in there? How do you drive the new seal in place? I see there's a Briggs tool for that purpose called a support cylinder (maybe cylinder support?) but it sells for $40 plus. I was wondering if I could find a chunk of PVC pipe of the right diameter that I could cut with my chop saw to make a driver. I assume this seal is not too hard to drive into place.

 

It's not hard, just be sure to be easy getting it on the shaft so that it doesn't pop the spring out from inside the seal. If you can find the right size pipe, it will work. I use a slide hammer to pull the seal out, but there are probably other tools that will get it out just as well.

 

Since I didn't have a seal puller or cotter key puller I tried a trick I read about on an Audi forum website. I drilled two small holes in the bottom of the old seal and threaded two small sheet metal screws into the holes. I then used a pair of pliers to pull out the seal. It worked like a champ. I used a length of PVC pipe as a driver to install the new seal. That also worked just fine. Total cost: $6.33. No engine removal or dissasembly. This is really the way to go.

Thanks so much to mowerdude and cheese for your valuable help with this. It saved me a ton of time.

 

Great! Glad we could help, and thanks for the update. I use a screw also, as you did, but I have it chucked in the slide hammer so that it yanks the seal out. Pretty much the same thing you did. Sure beats the heck out of doing it the hard way.

 

That is really good to hear BikerBill,,also have taught me a new way also. Glad to help