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post #1 of 73 Old 10-24-2018, 02:39 PM Thread Starter
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Difference Between a 16G and an 18G?

I just bought my neighbors 16G. Can anyone tell me the difference between a 16G and an 18G?

The tractor is currently bone stock. Anything I can do for improvements? I am currently making my way through Sheldon's improvements post but I haven't gotten much further than the readings on his steering brake setup.
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post #2 of 73 Old 10-24-2018, 03:30 PM
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Re: Difference Between a 16G and an 18G?

They both have the same motor. Kohler didnít offer a 16HP Magnum twin, so Gravely used M18s and called them 16HP. There is evidence that the slot in the dashboard for the throttle lever is shorter, and/or the governor is setup differently, to lower the output of the motor on the 16-G. Sheldon will be along shortly to expound on that.

There are only three other differences:

-16-G could have manual or hydro lift (18-G was always hydro)
-18-G has heavier steering tie-rods (shared with the 20-G)
-18-G always has wider tires on wider rims, front and rear (also shared with the 20-G)

Caveats: Sheldon has evidence that some 16-Gs had wider front tires than the smaller-engined tractors. Also, I have seen some 16-Gs that had a smaller steering wheel (and definitely had the shorter slot in the dash).

I have also seen 16-Gs with and without oil pressure senders and low oil lights. The 18-G always had them.

Gravely 18-G * 50" MMM * 48" Snow Blade / Gravely 816 Project * 30" Tiller * 48" Blower / Custom Trailer

Last edited by yamato72; 10-24-2018 at 03:38 PM. Reason: Clarity
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post #3 of 73 Old 10-24-2018, 09:41 PM
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Re: Difference Between a 16G and an 18G?

Not intending to quibble as I agree with you. But your post points up the essential fact: They Are The Same Tractor. Sure, one has a wider racing stripe and the nifty chrome door handles, but they are the very same thing.

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Gravely 16G (1998)
Gravely 16G (1994)
Gravely 16G (1991)
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post #4 of 73 Old 10-24-2018, 10:07 PM
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Re: Difference Between a 16G and an 18G?

The only difference in the engines is the lack of an oil filter on the 16G and the stickers on it.

As for the the throttle slot, that was a running change in the design of the dash board and throttle cable. If you have the right throttle cable for the right dash panel, you will get full throttle operation with no problem. Older G tractors used a plastic "T" handle throttle, with a smaller dash slot, newer ones (after about 1994?) used a metal "L" handle with a rubber cover and a longer dash slot. The early cable could be serviced piece for piece, the later one must be replaced as an assembly. Obviously they changed vendors and had to adjust the dash slot for the new throttle handle design.

Now for the important part, 16G or 18G, GRAVELY decided to set the governors on these engines at 3300 RPM, so actually as delivered both were only about 16 HP. But Kohler designed the engine to run at 3600 RPM, with a very flat torque curve, so to get max power, reset the governor to 3600 RPM - you will not hurt the engine and you will really have 18 HP. Kohler designed the engine to run generators and welders, constant wide open throttle at 3600 RPM.

None of the internal engine parts that would effect HP production are different between the spec numbers of the Kohler M18 engines delivered to GRAVELY. 16G or 18G, they have the same cam, heads, pistons and governor. The original carbs have different part numbers, but they all crossover to the same replacement carb. And carburetors do not by themselves change HP. They can only limit max RPM, but we are talking two carbs that are the same bore, take the same rebuild kit, on engines that never see the max air flow the carb can deliver.

All G tractors got wider front rims about 1994, but 14G and 16G still had the smaller 16 x 6.50-8 tires. 18G and 20G had 16 x 7.50-8 tires.

Rear tires - early G's all had 7" wide rear rims, again, about 1994, 18G and 20G tractors got an upgrade to wider rear rims, I think 10". This is a known fact but not documented by GRAVELY. And again, 14G and 16G had 23 x 8/50-12 tires, 18G and 20G had 23 x 10.50-12 tires.

Steering - 14G and 16G tractors had lighter duty tie rods and shorter/lighter steering arms. 18G and 20G have very heavy duty steering parts - this is well covered later in my improvement thread.

Early 16G tractors did not have low oil pressure lights or hour meters, by 1994 both were standard.

These minor differences are subject to exact year/model, but the major differences are as Yamato pointed out:

Steering linkage

Wheel/tire size

Availability of the manual lift only on 14G and 16G

The shorter/taller steering wheel shaft is also an early/late issue with all G tractors, early = short, late = tall.

Important thing to understand - GRAVELY never went by any kind of "model year". Model numbers stayed the same until a change was made to the tractor, which could be mid year, or not for many years....so knowing your actual model number, like 987061, tells a lot about your specific tractor, and can make a big difference when buying some parts.

I know, I have likely bored you to death by now.

Feel free to ask any specific questions you may have.

Sheldon


Last edited by ATLANTIC CENTRAL; 10-24-2018 at 10:27 PM.
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post #5 of 73 Old 10-24-2018, 10:23 PM
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Re: Difference Between a 16G and an 18G?

Quote:
Originally Posted by Mikey4 View Post
Not intending to quibble as I agree with you. But your post points up the essential fact: They Are The Same Tractor. Sure, one has a wider racing stripe and the nifty chrome door handles, but they are the very same thing.
Mikey, true enough but I do consider the difference in the steering to have some merit.

In fact, after making the following list of changes, the steering effort of my tractor was noticeably lower:

Upgraded to 18G linkage with longer steering arms.
Upgraded to tie rod ends with grease fitting and seals.
Replaced the flat wide original Turf Chief tires with the rounder current Turf Master tires, staying the the smaller 16 x 6.50-8 size that came on the 16G.

So I have a hybid, 18G steering linkage, 16G tire size w/round profile, grease-able tie rod ends = lower steering effort

I also added the oil filter to my tractor later the same week I bought it.

And when I needed rear tires, I split the difference on my 16G 7" wide rims - 23 x 9.50-12 also a better choice than either factory size for the 7" rims.

But the steering brakes are the big deal - I could never go back......

Sheldon

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post #6 of 73 Old 10-24-2018, 10:42 PM
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Re: Difference Between a 16G and an 18G?

Oil filter. I knew I forgot something. I've had two 16-Gs come through, one with, one without.

The rear wheels on my '91 18-G are 8.5" wide with 23x10.5-12 tires. Front wheels are 5 or 5.25" wide. I love the wide wheel and tire combo that came on the 18/20-Gs. Like Sheldon said, the wheel sizes are poorly documented by Gravely.

Gravely 18-G * 50" MMM * 48" Snow Blade / Gravely 816 Project * 30" Tiller * 48" Blower / Custom Trailer
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post #7 of 73 Old 10-24-2018, 11:50 PM
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Re: Difference Between a 16G and an 18G?

Quote:
Originally Posted by yamato72 View Post
Oil filter. I knew I forgot something. I've had two 16-Gs come through, one with, one without.

The rear wheels on my '91 18-G are 8.5" wide with 23x10.5-12 tires. Front wheels are 5 or 5.25" wide. I love the wide wheel and tire combo that came on the 18/20-Gs. Like Sheldon said, the wheel sizes are poorly documented by Gravely.
Somebody added that oil filter. My dealer told me about it before I left the showroom, I bought the parts later that week.

8.5" rims, that's the number I could not remember. Earlier they all had 7" rims. I'm very happy with the 23 x 9.5-12 tires on the 7" rims, that worked out well.

I never liked the look of the 10.5 tires on the 7" rims of the older 18G/20G tractors.....

Sheldon

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post #8 of 73 Old 10-24-2018, 11:57 PM Thread Starter
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Re: Difference Between a 16G and an 18G?

Everyone,

You have not bored me the slightest bit and I appreciate every bit of your input. Thank you.

Ironically, I walked over to the neighbors late tonight to pickup the tractor and drive it home. It would not start... we heard the starter motor spinning but it would not engage the flywheel. We gave it a quick jump with his battery pack and it fired right up. At that point, my 6 year old was tuckered and had to be put to bed. I will walk back over tomorrow evening and bring it to the house.

It is a late 80's model. I will report back with more specifics when I get them.

Thanks again everyone for the information. Greatly appreciated.
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post #9 of 73 Old 10-25-2018, 09:41 PM Thread Starter
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Re: Difference Between a 16G and an 18G?

I brought the 16G home this evening. It does have a bit of dust and grime but it actually shows pretty well in my opinion. Rust is very minimal.

A few things I noticed...

There isn't and doesn't appear that there ever was an hour meter installed on the side panel of the firewall.

The fuel tank is metal... I was under the impression the G series had plastic tanks?

It does have mechanically actuated hydraulics.

The clutches appear to be in great shape. It is very smooth in forward and reverse and the plates look like they have a lot of meat on them.

It seems as though someone has bypassed the seat safety switch and some other sort of safety switch (i'm assuming the second bypass is for the pto or neutral but havent had a chance to look)

As Yamato and Sheldon mentioned in regards to oil filter.... this machine does not appear to have an oil filter. Is this something I should add? If so, any ideas where I could get the parts?

Do you guys have a preferred battery size you like to use?

Well, outside I go now to give her a bath. I'm sure she has a few more secrets that I'll uncover....
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post #10 of 73 Old 10-25-2018, 09:42 PM Thread Starter
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Re: Difference Between a 16G and an 18G?

Also, does anyone have any idea what year this may be according to the serial number?
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post #11 of 73 Old 10-25-2018, 10:43 PM
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Re: Difference Between a 16G and an 18G?

That's a nice looking 16G.

Nice, neat deck repair.

Generally clean.

There were two kinds of hydraulic systems. Yours is the earlier one with the filter serving as the oil reservoir. Later versions had the electric system (using bits borrowed from the boatbuilding industry).

The debris basket is a nice accessory to have.

Hour meters were not all that common on 16Gs of that vintage. Easy enough to add one, but the only real value is to monitor hours between oil changes.

I'd get a new seat, That crack can pinch tushies, especially when you're wearing shorts or thin pants in the summer!

All you need to add the oil filter is the adapter, a gasket to mount it, and the filter itself. Here is an eBay ad for the adapter. Search for KOhler M18S oil filter adapter - not for Gravely. The one in the ad is from a John Deer. No worry. Just be sure it is for a Kohler M18S (it also fits other motors).

https://www.ebay.com/itm/Oil-Filter-...xojF:rk:3:pf:0



There are several filters that will fit. You want the shortest one as the space where it fits is pretty tight. I installed filters on two of my 16Gs. I don't recall which one, but on one of them I had to rotate the exhaust a few degrees to get things to fit.

You're going to like that tractor.


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Challenge Met


Gravely 16G (1998)
Gravely 16G (1994)
Gravely 16G (1991)
Gravely 48" Snowblower and Cab (for the 91 16G)
Gravely 816S (1976)
Gravely 38" Snowblower (for the 816S)
Gravely 812 (1975)(mine since 1982)(Rolled over in 2016)
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post #12 of 73 Old 10-25-2018, 11:04 PM
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Re: Difference Between a 16G and an 18G?

I'm thinking now that the 16-G I'm thinking of (neighbor's) has an oil filter because I had previously bought the adapter off ebay and we added it to his M18.

I like the tractor, looks to be in good shape. A shame that the safety switches were bypassed, they're not hard to troubleshoot.

I just buy the Kohler filter from TSC.

EDIT: I just looked back through my previous posts, and determined that my neighbor's 16-G came to us with the filter installed. So I may have a housing for you. I'll have to check.

Gravely 18-G * 50" MMM * 48" Snow Blade / Gravely 816 Project * 30" Tiller * 48" Blower / Custom Trailer

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post #13 of 73 Old 10-25-2018, 11:18 PM
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Re: Difference Between a 16G and an 18G?

Based on what I have access to and knowledge of, it is somewhere between 1989 and 1994. The important number is the model #47578

Here is a link to your IPL: https://www.gravelymanuals.com/pdf/P...s_IPL_0889.pdf

One of the guys with access to the ARIENS/GRAVELY dealer network can and may look it up for you. That will tell us when it was shipped to the dealer.

Yes you can add an oil filter, Kohler kit #82 755 23S. You will have to modify the right side exhaust, keep reading my thread you will get to the part where I put the older style exhaust like yours on my tractor.

All GRAVELY's had metal tanks until about '94.

Batteries - the correct and best battery is a group 22F - which you will not find at WalMart or your local auto parts store. But if you have a good tractor dealer near you, they will likely have them. Why are they special? They have the correct mounting ears at the bottom for the factory hold down, they have the correct terminal orientation, and they are a deep cycle tractor/equipment battery. In my tractor, bought new in 1996, each battery has lasted 7-8 years. I have never charged a battery, or used a battery "tender", tractor starts every time until it does not, then I replaced the battery. Only on my third one counting the factory battery.

Your tractor is too early for a factory hour meter, but you can add one.

Looks like you got a great machine there, congratulations, welcome to the club.

Sheldon

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post #14 of 73 Old 10-25-2018, 11:26 PM
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Re: Difference Between a 16G and an 18G?

It is possible only the seat switch is bypassed and the PTO and neutral switches still prevent starting in gear or with the PTO engaged.

If you need help with the safety switches, sent me a private message and I will help you trouble shoot them.

Honestly, my tractor has not had a seat switch for a very long time.....

But I know in great detail how that wiring works, and the GRAVELY wiring diagram is not very helpful.....

Sheldon

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post #15 of 73 Old 10-26-2018, 05:18 PM Thread Starter
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Re: Difference Between a 16G and an 18G?

Wow. This is all great info fellas. Thanks again.

I was able to blow off most of the fluffy grime with compressed air last night and it's cleaning up really nicely. I'm going to go after her with a bucket of warm water with some Dawn detergent it along with a few rags and a bottle brush tonight.

I got the oil filter adapter ordered earlier today. I'll probably order a seat in the next few days.... even if my bum cheeks were to survive a pinch or two, my ocd would not let me live too long with that torn seat cover.

I picked up a 22F battery at the local lawn and garden dealer.

The seat safety switch would drive me crazy if I hooked it back up so I think I'll leave that undone but I will test this evening for proper functionality of the pto and neutral switches. Sheldon, thanks for the offer to help. I'll look you up if I get jammed up with the wiring harness.

I'm not feeling a dying need to add an hour meter. I tend to over maintain anyway. I usually change oil twice a year because of temperature. It looks like the Kohler manual specifies straight 30 above 32 degrees and 10-30 or 10-40 below 32. The tractor will be used mainly to mow in the warm weather and push snow in the winter so I will definitely be using it in sub freezing temperatures. Sometimes as low a 5 degrees but that's rare. 15 to 20 isn't too uncommon though. So i suppose 10-30 beginning in the winter and switching back to 30 in the spring would be a good plan?

Sheldon, do you have a preferred model for oil filters to make things fit nicely?
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