Mystery Mower


Old 07-29-05, 01:03 PM
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Arrow Mystery Mower

I just purchased my first riding lawnmower...used, for $200. It's a little ugly, but seems to do the job, which is all I need.

However, I'm pretty sure that at some point in the near future I'm going to have to do some maintentance on it, and for that, I need to know what the thing IS.

The only identification on the mower is the serial plate on the back. I don't have the serial number itself handy (I'm at work) but I wrote down everything else.

Model # A3812001
Code # 0030M
Manufactured by Noma Outdoor Products

It's a 38" mower, and originally had a 12hp Briggs & Stratton engine in it...the previous owner replaced it a couple years ago with an 8hp Briggs that someone gave him (it's a little pokey, but does the job). It's red and black (as MANY brands seem to be), has a five-speed-with-reverse transmission, and has the gas filler on top through a hole in the hood.

The guy that sold it to me said that it was an MTD mower, but there's nothing on it to indicate that this is true. I did a BUNCH of Internet research last night and today, and have come up with a few things that all seem to contradict each other.

1. Noma was bought by Dynamark, who was then bought by Murray. True?
2. Dynamark built mowers for a LOT of different brands (including Craftsman?), and they are all more or less interchangeable. True?
3. Murray doesn't know what this thing is.
4. I found ONE reference to the model number on a 3-year-old used mower listing, but the model number was associated with Dynamark, not Noma, Murray, or MTD.
5. When searching for similar tractors on eBay, I found both Dynamark and MTD mowers that looked VERY similar (but not exactly) to mine. Is there any correlation?
6. When I search for Noma parts, I either come up with nothing but Noma blades or else I get directed to Murray parts.

I'm going to take some pictures tonight and post them on a'll be at (not until after about 9pm Mountain time).

Basically, what I need to know is...who DID make this, what other brands is it parts-compatible with, and where can I find owner's/service manuals? I feel comfortable working on it myself (can't afford to take it to a shop, anyways), but I need information and guidance for finding parts and procedures. I've already exhausted the obvious resources that I can find online, and what info I've found only seems to muddy things up further.

The engine itself won't be a problem...I've worked on pushmower engines since I was a kid, and Briggs & Stratton has all sorts of documentation for their engines online. It's the rest of the drivetrain and the mower deck that I'm afraid to touch without a manual.

Thanks in advance for any help.

Last edited by arex; 07-29-05 at 02:01 PM.
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Old 07-29-05, 03:55 PM
Join Date: Dec 2003
Posts: 105
re: noma mower


Not sure how old it is and don't have time to do research on that, but my guess if it is less that ten yrs old it was likely manufactured by MTD.

I have an MTD 38-12 lawn tractor with a 12 HP Briggs I bought 9 years ago.
Fortunately, I still have the manuals as I bought it new. I'd guess the mower deck etc are identical to yours if it's of the same vintage or newer.

Companies like MTD may change the "tin" or bodywork to make a unit look sleeker..but the guts are usually the same.

If you have no luck I can scan in the manual and email it to you as a PDF, or compy it and send it snail mail.

Good Luck,

Snowman 53
Old 07-29-05, 04:15 PM
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Originally Posted by Snowman53
Not sure how old it is and don't have time to do research on that, but my guess if it is less that ten yrs old it was likely manufactured by MTD.
I think I came across something last night (I found SO many little tidbits of information that I couldn't sort through) that seemed to imply that it could have been built in 1990. Very little plastics on it, mostly sheet metal.

[EDIT] Pics are up.

Last edited by arex; 07-29-05 at 09:29 PM.
Old 07-30-05, 08:42 AM
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I have just aqquired an MTD that looks very much like your mower. I think it older as it has the 11hp which I think was superceded by the 12.5. Check the MTD archive, it is down often it seems as it is now so I canot look
MTD says their lawn tractors model # starts with 13..... so that keeps the mystery on. Here is a link for the deck manual on mine 38"
and here is the one for my mower

Compare to yours and see if similar enuff or we can keep lookin...
Here is a pic of mine or rather my daughters heheheh...

P.S. Just rethinking and noticed your transaxle...that configuration for shifting is the same as I see on Masterkraft and some craftsman. Again tho the model # starts with a 13...
Old 07-30-05, 02:25 PM
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and Murrays home page, the search shows nothing with those #'s but there is several support contacts listed.
Old 07-31-05, 11:36 PM
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Okay...I spent a good part of today cleaning, tuning, and figuring things out. Still have questions, but those will follow.
  • It is almost certainly a Dynamark 12/38, no idea of the vintage.
  • The replacement Briggs & Stratton 8hp engine is 17 years old, based on the model number. It starts and runs quite well after a tuneup, and didn't bog down hardly at all, even in the tall heavy grass.
  • I suspect that the mower deck isn't original, either. It looks much newer and more "modern" than the rest of the mower, and there's a wiring pigtail on it that doesn't appear to have anything to attach to on the tractor itself.

My questions now are fairly generic:
  • The mower deck drive belt jumped off several times during mowing. When engaged, it seemed reasonably tight, but I don't know what the tension ought to be. Are there any general criteria for this, and how do I measure the tension, by inches of deflection? All the metal tabs next to the pulleys to keep the belt in the pulley groove are there.
  • The level of the pulleys on the deck (at its highest lift) is significantly lower than the level of the drive pully on the engine shaft (I don't have any measurements, but an eyeball guess is about 1-1/2 inches). This doesn't seem right, and I suspect that it's at least part of the cause of the belt jumping off. When I set the deck to its highest level, I was then able to get almost all of the lawn mown before it jumped again. Why would there be such a large difference in pulley alignment?

I have some ideas about this second question.
  • The tires (not original) may be larger than the originals, lifting the frame of the tractor higher above the mower deck, causing misalignment (I consider this a bit unlikely, but conceivable).
  • Since the engine isn't original, it's possible that the shaft doesn't extend down far enough for proper alignment. I have no idea where this engine originated from. Is this shaft solid all the way through to the crank, or is there an "extension" mounted on the driveshaft between the top pulley and the bottom, and can a longer extension be obtained and installed, thus restoring proper alignment?
  • Since I suspect the deck of not being original, might the pulleys on IT be aligned for a different mower? How interchangeable are the mower decks? They all seem more or less the same in design and attachment...the guy that sold this to me also gave me another old deck (blue, faded and chalky) that, while obviously MUCH older and more "primitive" in design than the one on the mower, otherwise seemed very similar.

Any thoughts on all of this, or do you know of any reference books that could give me some answers? Even though I've finally figured out the manufacturer and model, I'm having NO luck finding any documentation.
Old 08-01-05, 12:06 AM
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Oh boy, yes, you have an old noma product and are finding out how difficult it can be to keep one going. You'll probably have to find most parts for the mower itself used on ebay. I don't think there is much if any support for noma products at all anymore. They did make some sears products many years ago, but there are few that still survive. (this was over 20 years ago). To worsen matters, it sounds like yours has been cobbled. The crankshaft has no extension. The pulley is bolted directly to the crankshaft. It could be that your pulley is wrong. It could be that the deck is wrong. It coulb be both or neither. The thing to do here is either engineer to make it work the way it is or with modifications of your own design; hope to find an old lawnmower shop that might still have literature about this mower and maybe view some manuals and try to get it back to operating the way it was designed; or bail out of it before things get hairy.

It's normal for a blade belt to be slanted downward toward the deck pulleys when the deck is down, but not more than the sheave on the engine pulley or blade pulleys will allow without rubbing the belt edge too much.
Old 08-01-05, 06:33 AM
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Murray link is provided...a phone call may be a bit much trouble theese days...but I have had excellent support when speaking with Murray support folk via landline. If they have hard copy documentation not available online, they have scanned and mailed

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