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SMI 7200 blower.

Aerospace Eng

2000 Club Member
Zelienople, PA
The fleet is complete, at least for now.

Ex Indy airport blower that Terre Haute had bought as a backup.


I did run into an issue. The blower showed up at about 7:00 last night, but when we went to lift the blower to drive it off the truck, a hose blew, putting fluid everywhere.


I did not have a spare hose. To get it off, I lifted the blower head with the telehandler, suspending it from chains off the carriage, and had the truck driver slowly drive off, with the telehandler in neutral.

Unfortunately, when the front wheels got to the end of the RGN, the angle changed too much, and one fork got hit by the cab. Fortunately, the window didn’t break.

A block and hammer sometime this summer should fix it adequately.


I got the hoses changed today, and tested the blower motor. It smokes more than I would like on startup, but it did start without ether, and it was below freezing


Everything seems to work, which makes me happy.

The blower head is very heavy, and actually rides on solid steel wheels at the moment. It is clearly designed for straight line work only.


Like the other blower the airport has, the tires are the old 10.00x20s dual size.. I might change to a super single type in the future, since the rear axle bearings can’t be happy with only a single wheel in the back. Good tor snow/ice traction but the wrong offset.
Aerospace Eng

Aerospace Eng

2000 Club Member
Zelienople, PA
Like most of my fleet - a utilitarian cab. Based on condition, it looks like the <5K mileage and <1000 hours is correct.



The blower up/down is annoying, since down is back and up is forward. I think the reason they did it that way is so there was more room to put it into float, as shown above.

There are 5 valves in the stack. The leftmost is chute direction. Of the other three, two go to ports on the front of the machine, to be used for a truck loading chute if installed. The fifth one does not have any hoses attached and does not go anywhere. Maybe for a steering blade on the blower?

I took it out and ran it today, on some snowbanks that have turned into ice, just to see if everything worked. I did not try to drive it straight into the banks, since the ribbon won't chew ice like a solid auger. I took slices, and then the truck didn't want to ease forward at 1000 RPM, I just reversed and went to a different location.

It did, and it throws snow (or semi-ice chunks) 150' or so, but there were some issues I have to correct.

I need to use an aviation headset the next time I am using it. The cab is somewhat noisy when everything is revved up.

The transfer case does not want to shift from low to high, so I need to investigate that to see if it is just a frozen linkage or something more serious. I did not put a lot of force on it.

I had to hold up the clutch lever for the blower to stay engaged. I believe this is likely just an adjustment of the over center mechanism in the PTO.


I tried to take a picture of the dataplate on the PTO so I could order a manual, by holding my phone up while crouched under the truck, but it was too dirty, so I had to crawl inside to clean it off.



Fortunately, Cotta is still around, although they are no longer in Rockford. Hopefully they will help me out. 3.92:1 gives 540 RPM at the impeller, or about 6,000 feet per minute at the tips of the blades.

The blower motor responded well to the throttle once it warmed up. After I was done at the snowbank, there was no more smoking.

The truck engine is under the cab, sort of like an old van. The covers give decent access, to linkages and the top of the engine and are removable by thumbscrews. The sides under the cab come off as well, so access is better than I thought, but still not very good. You have to remove the side plate to check the oil, which is dumb. The cap on the side of the cab, by the driver's door is an oil fill tube.


Unlike my other airport purchases, I have no records (Terre haute never got them from Indianapolis, and the filters aren't marked, so I will do a complete fluid and filter service. I should start buying the straight weight oil for these 2 strokes by the 55 gallon drum, like I bought hydraulic fluid.

The fuel tank looks like an old home heating oil tank, and the fuel cap is on the top of the truck. I don't get it. It's like they expected you to add fuel by driving under a tank, like a steam locomotive taking on water.



Aerospace Eng

Aerospace Eng

2000 Club Member
Zelienople, PA
Here's the fuel tank....


The radiator shutters for the blower motor were stuck open. However, I found that the handle was in manual override. I rotated it and the shutters closed. They still work, and should help the engine warm up more quickly and smoke less.


Last night I had e-mailed Cotta about the transmission. By 9:00 AM this morning, I had manuals and a parts breakdown in my inbox. Very happy with their technical support for a machine that is 42 years old. Their manual let me know that the over center force on the clutch (actually a twin disc unit that Cotta mates to their reduction gear) should be 150 lb.

So, this evening, I went up to the hangar, disconnected the linkage to the clutch, lubed it up, and made sure it was moving freely. Then I grabbed the clutch lever and put a bunch of force on it and it popped. I haven't measured it, but it felt right. I had just wimped out during my testing yesterday. After reassembling it, it takes about 70 lb on the lever in the cab to lock the clutch in. I haven't figured out how I'm going to check the oil yet, since it is rotated so that the output driveshaft runs forward along the right frame rail.


I also made sure the push pull cable to the transfer case moves freely, but the input to the case is not moving (Rockwell T226). I will probably defer a disassembly for now, since the truck moves at a decent blowing speed. If I start the blower motor as I start crawling toward the berm, It should be warmed up by the time I get there.

The air filters on both machines are old Farr units. The elements are still available, but I'll probably buy two sets to have a spare just in case.



I was puzzled at a black button right in front of the driver's seat.


I traced the line, and it went to what looks like an IV bag hung on the side of the engine cover, but is actually the windshield washer fluid reservoir. To get fluid sprayed on the windshield, you stomp on it.


I think this might be carrying the utilitarian motif a bit far.

Now I know what those hex head bolt looking things are - the windshield spray nozzles.




PlowSite Veteran
Southern WI
Haha this is fun. I would have no idea on fixing anything, but I enjoy seeing how it’s put together and how it works. Great job with pics and videos.
@Mr.Markus please don’t post videos without tagging me in. @Ajlawn1 said I’m the resident expert so I need to be made aware of these things...Thumbs Up
Aerospace Eng

Aerospace Eng

2000 Club Member
Zelienople, PA
I downloaded the parts book for the transfer case today and studied the mechanism.

While I was at the airport tonight, I decided to take a look at it, because there weren't many ways it could be hung up.


I re-disconnected the linkage and removed the top cover to access the shift mechanism. I removed the spring and the other parts of the ball detent that go in the hole on the left except for the ball itself, which wouldn't come out.

In this picture, it is in low range, where the gear under the shift fork is meshing with a larger gear, providing a reduction. In high range it nestles into the inside of the gear on the right, driving the output at 1:1. The control input just moves the fork which engages with the input gear and slides the gear along splines to be in mesh or inside the 1:1 gear.


I reached down and grabbed the gear, to make sure it would at least slide on the spline. It did, to within the tolerance allowed by the shift fork.

With that established, knowing that no harm could come to the gears, I got out a 1 lb deadblow. A light tap on the control input popped the ball loose and freed the shaft. I don't know if it was just oil that had turned gummy in the shaft bushings or the ball was somewhat stuck, and I don't really care. It's free.

I slid it back and forth a bunch of times.

High Range


Neutral. There is no detent.


I put the linkage back together and tested it from within the cab. Worked fine.

I will get a gasket and replace it, but for now, I just put the cover back on.
Aerospace Eng

Aerospace Eng

2000 Club Member
Zelienople, PA
Friday and yesterday I undertook to ensure that everything had adequate lube. For example, I didn't change the oil in the blower head, I just made sure it was up to the fill plug, which took about a quart. The transfer case took a pint. The 6V53 chassis motor was about a gallon low, but the oil looked clean.

I did decide to change the oil and filters for the blower motor, since although the oil was clean, it was actually overfull on oil and it felt like a 15-40 or similar, rather than a straight 40W.

I need to find a better pail pump. The one I have is from tractor supply, and in addition to not being very efficient, leaks at the top guaranteeing a mess.

If a reader knows of a pail pump that will work well on heavy engine oil or gear oil, please let me know.


Another issue was that when I got to the rear differential, I couldn't feel any fluid near the fill plug, so I thought I would loosen the heat indicator plug and see if were at least up to there - it was, but I didn't see any seepage until the plug popped out, overwhelming the drip pan (a paint tray) I had under it before I could get it back in.

I decided to just go ahead and change the oil in the differential.

The drain plug was stiff coming out. The threads were not in good shape and the magnet was broken.


I ran to Tractor Supply, got a 3/4 NPT tap, and cleaned up the threads in the housing.


Fortunately, Penn Diesel had a magnetic drain plug for the Detroit 2 strokes which was the same thread. I like the fact that the magnet doesn't stick up.


Using the pail pump, I refilled the differential. Hand pumping 6 gallons with a leaking pump sucks. I need to figure out a cleaner way.




I then proceeded to contribute even more to the mess by changing the oil filter on the engine. It is in an awkward place, and as soon as it leaked oil as I spun it off, I lost my grip and dropped it.


Refilling complete, but what a mess. The little pieces of straw are from a bird's nest I found on top of the radiator while I was checking it (It was about a gallon low)


Nothing a bunch of Speedy Dri can't fix.

Aerospace Eng

Aerospace Eng

2000 Club Member
Zelienople, PA
I also installed bottles and checked the ether injection systems. I disconnected the lines and then had a friend check whether ether came out while cranking (there is an interlock with the starting circuit)

The front one (chassis engine) works.


The rear one (blower engine) does not, so it will take some further investigating.


I didn't get to the filters on the front engine or the hydraulic system filters yet.

The transmission has an external filter on it, an AC PM-16 (Used by Chevy from 1958 to 1967) that takes a PF-141 element. I have to decide if it is better to track down the obsolete element or just replace the whole housing/filter with something more modern.