Deck corrosion kills a lot of otherwise perfect lawnmowers. I see it all the time; It seems such a shame to chuck a mower when she’s got so much more to give.
So, are lawn mower decks interchangeable? Lawnmower decks are largely interchangeable. Engines will swap without issue. However, blades and drive systems may differ.
I’ve been a mower mechanic for over twenty years, and I’ve changed lots of decks. In this post, I’ll give you the heads up on changing your deck. You’ll learn common mistakes to avoid and tips for a successful engine swap.
If you need video help, check out the “Mower repair video library”, it walks you through a ton of common mower maintenance and repair jobs like blade sharpening, pull cord repair, no start trouble-shooting, carburetor cleaning, self-drive faults, etc.
Old grass clippings are a deck killer.
Evaluate Your Mower
OK… so what does that even mean? It means we’ll need to make sure the other components of your mower are OK. Anyway, since it’s your mower, you probably already know it pretty well, how she starts and runs.
But it’s worth checking over the mower, not much point in changing out the deck to find a drive system is failing, or worse, an engine. Getting this wrong will be a waste of your dollars and your time. Make sense? Since the engine and drive system are the most expensive components to repair and replace, we’ll look for possible problems there first.
The following should be considered before swapping out a deck:
- Is engine swap is straight forward
- How’s engine health
- How’s the oil quality – very black or grey oil isn’t a positive sign
- How is the oil level? – low level may indicate engine wear and a high level could indicate a carburetor issue
- Any oil leaks around or under the engine? – crankshaft seals are a common source of mower oil leaks
- Start the engine – does it start easily? – hard to start mower could indicate a tune-up needed or a replacement carburetor
- How does the engine run? – misfiring or spluttering means it may need a tune-up, but it could equally mean a more expensive repair is needed
- Does the engine rev cleanly without surging? – surging could mean a new carb needed
- Does the engine run without smoke? – smoke is a sign of engine wear, however simply overfilling the oil will cause the engine to smoke too
The most common non-critical lawn mower engine faults I see include:
(Link to video repair)
Drive System Health
Drive systems can be expensive to repair. If your mower is self-driven (most are), you’ll need to ensure the drive system operates well.
Leaking drive system
Some higher-end self-drive mowers are hydro-static transmissions and are hugely expensive to buy, they don’t offer spare parts, and they’re a real pain to fit. I wrote a post about trans-axles here.
So that said, let’s look at some drive system probing questions.
- Does the application of drive happen smoothly?
- When driving, does the mower pull well, is the action constant and smooth?
- Does the mower pull well on hills, or do you need to help by pushing it?
- Any grinding, squealing or otherwise strange noises when drive is applied?
- Is the trans-axle free from oil leaks?
- Is the drive belt in good condition?
The drive system includes a transaxle, wheels, pulleys, and belt.
Common Drive System Faults Include:
- Worn belts
- Frayed braided drive cables
- Damaged pulleys
- Worn drive pins
- Worn wheel drive gears
- Worn wheels
- Worn out transmissions
Check out the drive system repair video here “Video repair library page”.
Everything Else On The Mower
Under this heading, we’ll include:
- Blade boss
- Grass flap
- Grass bag/box
Replacing drive controls can be expensive too.
Most of these components generally don’t cause many issues and are low risk. However, it’s often items such as these that make a mower uneconomical to repair. The blade and blade boss are the components from this list most likely to need attention but are easy to fit and not expensive.
Deck Replacing Tips
Is it worth it?
When it comes to replacing your lawn mower deck, there are a few mission-critical factors. Here’s what you need to know. All lawnmower engines are interchangeable. The engine mounting points are standard. So you can easily remove any engine and fit it to another deck.
However, while all engines are interchangeable, it doesn’t follow that all mower decks are interchangeable. While mower engine manufacturers agree on standard engine mounting specs, no such agreement is in place for any other mower component.
The easiest swap is either find an identical deck match for your old deck or – find a perfect pre-loved mower (same type deck or different) with a blown engine (check the length and width of crankshafts match) and swap over your good motor.
Either of these strategies will almost guarantee success. I’ll explain in further detail below.
Important Engine Specs
Crankshaft size is mission-critical – Get this wrong, and your blade won’t fit.
OK, so you know you can swap out any engine, and it will bolt to any deck, so what’s the problem? While all engines mounting points are the same, not all engine crankshafts are the same length or diameter.
So what does that mean? It simply means your engine crankshaft size (length and diameter) is paired with both your self-drive pulley and your blade boss (blade mount). These components must be swapped out as a set.
Important Deck Specs
You already know that lawn mower deck manufacturers don’t operate standards apart from the engine mounting points. So what does this mean to your deck swap? It means unless your new deck is a match for your old one, it’s unlikely your drive system will transfer across.
Other issues like handlebar mounting points will most likely also differ. And yes, of course, you can go all MacGyver on it and make them fit, but getting the drive system to fit and operate correctly probably won’t be worth all the effort. Deck widths also vary, and so obviously, your blade width will need to match your new deck width.
Although manufacturers don’t hold standard deck specs, they will very often share designs. So it is very common to find your identical deck fitted to a different brand. Generally, you won’t have a problem finding a new or used donor deck for your mower.
I’d avoid attempting to re-engineer a drive system.
Can I put a bigger deck on my mower? Yes, you can fit a bigger deck to your mower, but engine power and deck size are often proportional.