OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Removing booster fan/starter pulley from old B&S

Hi all,
Am pulling down this old motor hoping to get it running again. I cannot find any stampings on the cowl but I understand it is a 16HP and is in an MTD 990 CUT. I need to get the pulley/fan off and am wondering if anyone can tell me what size bolts to use? I am assuming of course that the two extra holes in the boss are for the purpose of attaching a puller but am happy to be corrected if there is a different way of doing it.

There are several different ways to remove Briggs flywheels, depending on the model. We need the Model, Type and Code information, which should be stamped on the side of the cooling air cowl above and forward from the intake port, at the tip of the yellow arrow:


You may need to polish up the cowl in that region. The tractor seems to have been made in the early 1970s, unless it is a 990A, which would make it even later. By then, all Briggs engines had the required information stamped on their cowls.

Thanks for that. I have sanded the cowl back to bare metal in that area but there are no markings punched into it.
What are the alternative methods of removing the pulley? There are no lips behind the centre boss to use a three jaw puller on so I thought it would probably only leave using a harmonic balance type puller as the only alternative.

It looks to me as if the 4-hole flange on the crankshaft is neither on a taper, nor keyed on. If that is correct, it is probably a light interference fit on the shaft, and you would remove it by cleaning the rust and crud off the shaft, tapping it inward toward the flywheel slightly to break it loose (use a piece of tube or pipe that barely fits over the shaft) then pulling it off with a flat plate puller. It may be that only two of its four holes are currently used, but the remaining pair could be tapped to the same UNC size as the two that are already tapped. You could then make a very simple 4 hole flat plate puller and draw the flange off.

So far as the flywheel is concerned, Briggs lists 4 different flywheel pullers:


Here is the way the most common flat-plate pullers are used on flywheels pre-drilled with two holes:


Note that for the small engines the pre-drilled holes are ready for tapping with a 1/4" UNC thread.

Here is the corresponding instruction for some of the larger flywheels which look more like yours:


The manual notes that on the larger engines (22 to 28 cubic inches displacement), which require puller 19203, you can use a couple of cylinder head bolts in the puller:


Obviously if we had the engine model number, we could go straight to the correct instruction rather than posting a whole bunch of them like that. I'm guessing your engine may require the 19203 puller, after you tap the flywheel to suit cylinder head bolts. Essentially, the predrilled holes will probably turn out to be the correct tapping diameter for either 1/4" UNC, or the larger UNC thread for the head bolts. The size of the holes tells you which flat plate puller is required. It is the work of a moment to make up a flat plate puller by drilling two holes the required distance apart, in a piece of steel plate of suitable thickness.

Thanks for all the info. I locked the output shaft by sliding a big screw driver through the universal joint there and tapped the fan pulley with a drift and turned it slightly then jiggled it forward a bit using a couple of large screw drivers until I was able to get the tangs of the three jaw puller behind it and then just pulled it off. It is probably meant to be a slide on fit but as you say, rust and a bit of aluminium growth made it overly tight. I'll clean it all up before it goes back together.

I checked the cowl from the inside, no layers of paint there, and there is no sign of any punching anywhere for ID numbers. I hosed all the crud from around the engine, the machine went through the floods, and then whacked a pipe wrench on the front and it is turning over pretty easily with plenty of wheezing coming from the ports so there is a chance I can get the old girl running without too much problem.

Not bad for $20 from the tip shop hey?

It's probably a decent engine, but unless you know what it is, it is inconvenient every time you need a part for it. The numbers must be there somewhere.

I am not enthusiastic about pulling a square flange with a three leg puller - it increases the chances of bending or breaking the flange. Usually three leg pullers come with a two leg center spider as well as the three, and it is easy to change them over.

It's only square looking on the front, the back of the hub is circular. I've degreased and hosed down the engine and will go right over it trying to find any numbers although from a first cursory look I cannot see anything that looks like a good spot for them to be.

Thanks so much for your input.

Sorry about the round versus square issue, I missed that.

Your machine does indeed seem to be a 1973 MTD 143-990, which was a 16 hp machine.


It also seems to have come with hydrostatic transmission, 3 point linkage, and a disengageable Power Take-Off for driving implements:


This was a serious garden tractor, not a simple ride-on mower. It would have been nice to see it restored.

Well it has been a long time since it looked like that I think. Yes, it has the hydrostatic drive and the PTO and at some stage had a mid mounted mower but all that remains of that is the lift frame. They also came with a two speed diff. To restore this one, even if everything else could be unrusted, it has the right side axle tube smashed off at the diff housing and no wheel on that side. I did a quick search for spares but the only one listed was a guy wrecking the same model in America and freight is way over the top. I'd also need a complete rewire as it really is a rats nest in there as well as some serious panel beating on the bonnet. Oh, and the steering wheel is missing also.

Of those items only the rear axle tube replacement sounds like a machine-shop job, and most ordinary ride-ons need to be re-wired after the previous tenant has had his way with them. There is a full wiring diagram, and an Illustrated Parts List, in the rather impressive on-line owner manual. However you might find that the hydrostatic drive is worn, and a rebuild kit, if available, might be expensive. There's no telling what other parts would turn out to be worn or rusted badly.

You didn't mention it having the 3 point linkage. To me, that was the most impressive feature of the thing. Most of the fun you can have with a tractor involves the linkage, and having one on a ride-on mower implies that it was capable of pulling ground-engaging implements such as a plough, or handling a small scraper or grader blade, even a little front-loader bucket perhaps if the front end was strong enough.

Here's a picture of the linkage, from the manual:

The axle tubes unbolt from the main housing and are in two pieces that slide allowing you to adjust the rear track by simply undoing a lock nut. Unfortunately the broken piece wasn't with the machine at the tip otherwise it could probably have been tigged back together. The front end is quite substantial and could probably handle a small bucket.

I am actually thinking about dropping the front end onto my Rover Rancher. I live on 100 acres and have tracks all through the bush which are a bit rough in places and the Rover has quite a light duty front end. It was also a dump find, swapped some Ironbark fence posts for it. 17HP B&S, Autodrive. The pin through the bell crank that operates the drive discs was sheared so replaced it with a 20mm Grade 6 bolt. New battery, oil filter, oil, one front tube and a bit of welding and it goes like a rocket. All up less than $200, big part of that for the new battery.

Realistically, getting the MTD back into really good shape would probably be expensive and time consuming. It seems way too elaborate either for mowing or for a runabout on your property. It's the sort of thing you rebuild as a hobby I suppose, unless you actually need a miniature tractor. I'd say it's in a different class altogether from a Rancher. If you don't need it, and don't want a hobby job, I don't suppose it makes sense. It's just the kind of thing an old tractor fancier like me can enjoy, even if he doesn't need it. Personally, I don't even have a place to keep a tiny tractor, let alone drive one. It takes me 15 minutes to mow the place with a 19" push mower, including my neighbour's nature strip as well as my own.