[dknelson]

I have pretty much answered this question for myself but would like you opinion.

I live on 5 acres and less the house and a couple of outbuildings and a 1/2 acre pond, I mow it all. I estimate that I mow 3 1/2 - 4 acres total.

I bought a new Snapper HZT21480BV zero turn mower either 11 or 12 years ago. They promoted this model as a "commercial grade zero-turn for homeowners". I would say that was a pretty good description because it does have a 21 HP Vanguard Briggs engine, a fabricated steel deck, etc. Not sure about the Hydros. The specs say they are Hydro Gear/10A and Hydro Gear HGM-12P wheel motors. I don't know if those are decent models or not.

This mower now has just shy of 2100 hours on it. I don't know a lot about mowers but I figure that is decent for a residential zero turn.

Now my issue. The motor appears to be pretty much shot. I am getting a LOT of oil blowing out. It has the engine case vent made into the top of the right valve cover and it first started by blowing oil out around the rubber o-ring where the breather bolts to the top of the valve cover. Also a lot of oil in the air breather. It still ran and mowed fine but blowing a lot of oil. I was hopeful that perhaps it was just a bad o-ring but I replace it and now it's blowing out around the other valve cover. I can replace that one too but I know that it will just find the next weakest place to leak. I have not done a compression test but I think it's fairly obvious that they rings are likely shot.

I can buy a new Vanguard engine for around $1,000.00. They no longer make this 21HP but they have a 23 that will replace it. My feeling though is that a residential grade mower with over 2,000 hours is going to start needing other things replaced also. If I spend $1,000.00 on an engine, how long before I will also be spending big bucks on deck spindles, hydro pumps, etc. I don't know anything about hydro pumps but would they likely be getting close to needing replacement also?

I've been pretty lucky with this mower. I've never replace a spindle or anything expensive. Belts, one idler pully, one front tire, a couple of batteries and I think a regulator, is all I've ever had to replace on it.

So what do you think? Chance it and replace the motor or is it time to move on? I won't replace it with another Snapper because even though it has served me pretty well, the local Snapper dealers have not. I bought this mower from a Snapper dealer, not a large box store, but I have never needed a single thing that I have not had to order. They haven't even stocked belts for it.

 

[TobyU]

Compression tests are not very informative on mowers as most have a compression release at cranking speed that lowers it.
Vanguards are the Briggs top dog! What kind of oil have you run in it and how often did you do oil changes? Has it always had a proper air filter filtering air?
Have you smelled the dipstick oil to make sure no fuel smell from gas getting pooling through carb into crankcase? This is common. Then they will leak, smoke, have low power.
How do plugs look? Even? Put a fresh set in and read them after a couple of hours.
Make sure dipstick oring seal at bottom is perfectly sealed. This can cause oil in air filter housing.
You might take off crankcase vent/breather check valve and clean or replace with new. These can cause oil leaks and into air filter area.

I would hate to junk a vanguard. They are one in the few I would actually hone and put new rings in if ever needed it. Most of the rest are too common to find good running used ones cheap to bother with the time and parts prices to tear into.

 

[dknelson]

I appreciate the response. I've run Mobil 1 10w/30 in it for the most part. At least as long as I can remember. It has always had the proper air filter including the foam pre-cleaner. Haven't smelled the oil but will do that when I get back home from the business trip that I'm on. Put new plugs in at the end of last season but haven't looked at them lately. I'm sure that they are all sooted up at this time. Pulled off the crankcase breather to replace the o-ring. While I had it off, I cleaned it very well and made sure that the check valve was working properly. It seems to be. I can suck air through it but it closes when I blow into the hose.

Not sure what I will do with it. I ended up buying a new mower this week so it is no longer urgent. I may keep my eyes open for a used motor on Craigslist or something. Wouldn't mind getting the old Snapper going again for a backup.

 

[TobyU]

Check the ring around the dipstick to make sure it is sealed as I mentioned before. I had one that suck quite a bit of oil up into the air filter when this was leaking. Then I would try some of the restore engine treatment. It is the only rejuvenation style oil additive that I have ever seen work. It works well. They sell in for 6 & 8 cylinder size cans. If it were my engine I would put 6-8 ounces of restore in it with a fresh oil change of Valvoline VR1 racing oil straight 30 or straight 40. Then keep using it and see if the oil consumption Blow by gets better. In many lawn mower engines Mobil 1 10 w30 leaks and disappears a lot more than it should. Might be fine for a new engine that's nice and tight with excellent compression and perfect gaskets put on an older one I would rather see 15w50 red cap mobil 1in it or a non-synthetic with high zinc content like Valvoline VR1 racing.

 

[dknelson]

They are supposed to deliver the new mower today but as there was an 80% chance of rain, and it is raining like crazy this morning, I mowed yesterday evening with the old mower. I had just changed the oil over the weekend though it was before I read your response and used the Mobil 1 synthetic again. I did stop and pick up a can of Restore. I added about half a can of the 4 cylinder amount to it. That alone did not help and by the time I finished mowing, it was smoking like crazy but I did get finished. Haven't checked the dipstick ring but will do so when I get a chance. It feels tight, no wiggle and etc., but I'm not sure how to check it without removing it I suppose. Will look at it closer. Motor sounds strange when mowing. There is a specific rhythm to the sound. Not sure I can describe it but it sounds strong and normal for maybe 15 to 20 seconds and then almost like it "gasps" for 3 to 5 seconds and then sounds normal again. Very little smoke at all and then suddenly a blanket of smoke, almost seems to coincide with turning or being on some type of small slope. As much as it smokes, it probably only used about a pint or a little more oil after 2 1/2 hours of mowing. Grass was pretty high and thick because it has been too wet to mow but it plowed through it pretty well with little to no abnormal bogging down.

 

[TobyU]

That's head gasket symptoms. One plug should look much more oily than the other. Put two new ones in if you want then kid and look at them.
The restore takes many hours to work. For cars it says 500 miles.
Classic blown head gasket symptoms is it smokes like a mosquito fogger when you go in a tight Circle 3 or 4 times to the left and three or four times their right or get on an angle.
Then it will clear mostly completely up after you straighten back out. They will consume oil because it's burning it and will get the plug nasty and eventually foul out the plug. The coming and going of power and sound you're hearing is that plug not firing properly because of the oil on it so the power from that cylinder comes and goes.
I've never personally had to replace a head gasket on a Vanguard. There is the old design which is the thin stainless metal head gasket and the new design which is the Graphoil ike most Briggs use. I had to pull a head off of mine to fix a slid valve guide but my gasket was perfect so I just sprayed it with the Permatex copper gasket spray and reinstalled.
Vanguard's are absolutely awesome engines. And as I said before, I highly doubt yours was worn out even with 2500 hours on it. I think you just need a new head gasket and you'll be good to go for many years on that one.
I think there's only 4 bolts to hold those heads on. I always take that head and lay it on a flat please of glass or flat metal with some 80 grit to 120 sandpaper and usually end up giving it four or five hundred strokes until I can tell it's being sanded down evenly. Since I don't have a mill. Then clean up block surface with a razor blade or some Scotch-Brite until it is absolutely clean also. I'm betting yours has the new style gasket like most Briggs have. Those are the ones that will burn through and leak. The thin stainless steel like on mine are kind of hard to burn through so unless it is loose or the head gets so warped so there's no longer pressure the gasket is not going to blow.

 

[dknelson]

Thanks. I'll take a look the first chance I get. If that is it, it will be a pretty easy fix.