Mountfield HP185 139cc lawn mower: a hero for bargain-hunting petrol heads

Perfect for powering over larger lawns, the Mountfield HP185 lawn mower is a robust workhorse that can mulch, collect or discharge grass to suit all needs

Mountfield HP185 lawn mower on a lawn
(Image credit: Linda Clayton)
Gardeningetc Verdict

If you are looking for the strength, power and flexibility of a petrol mower – without splashing all your cash – then the Mountfield HP185 lawn mower is an excellent choice for larger lawns. It started first time, every time, during our test period, and made our clover-infested lawns look very smart indeed.

Reasons to buy
  • +

    Auto choke

  • +

    Easy height adjustment

  • +

    Robustly built

  • +

    Big grass box

  • +

    Superb value for money

Reasons to avoid
  • -

    Hand-propelled

  • -

    Hard to read the oil dipstick

Why you can trust Gardeningetc Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

With a large lawn to keep tidy, testing the Mountfield HP185 lawn mower at the start of summer when the grass was long and in need of a trim was the perfect opportunity to put this petrol mower through its paces. 

Mountfield is a UK manufacturer, now based in Plymouth, that has long been associated with reasonably priced, well-made rotary mowers. My parents still use the one they bought when I was a gawky teenager. Established in 1962, the brand became part of the Stiga Group in 2000, and Stiga now makes many of the engines for Mountfield mowers, including the entry-level model I tested for this review. 

Our garden measures somewhere around 1,000-1,200sq m, the majority of which is at the rear and side of the house, with a smaller, more recently laid lawn at the front. That’s quite a lot of grass. My husband Nick and I usually tackle it in tandem – him on a ride-on and me sorting out the edges and hard-to-reach parts with a cordless strimmer and mower.

For the purposes of this review, I took over the whole shebang for six weeks in late May/June. Great for my step-count, not so great for my leisure time – Nick was delighted. As the grass was growing like billy-o, I was able to alternate the Mountfield HP185 lawn mower with another mower I was reviewing, cutting twice a week (once with each mower). 

The overall terrain is mainly flat, with a fairly mild slope at one end. In the front garden, I needed to mow as close as possible to a drystone wall, raised flower bed and a cobbled garden path. 

In our verdict, this is one of the best lawn mowers around. See how this four-star model fared in our testing.

Mountfield HP185 139cc lawn mower product specifications:

Why you can trust Gardeningetc Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

Mountfield HP185 139cc lawnmower

(Image credit: Mountfield)
  • Deck cutting width: 46cm
  • Engine power: 139cc 4-Stroke
  • Power source: Petrol
  • Cutting height range: 22–65mm (six intervals)
  • Fuel tank capacity: 0.75 litre
  • Engine oil Capacity: 0.44 litre
  • Grass box capacity: 60 litres
  • Weight: 23kg
  • Dimensions: H110cm x W54cm x D148cm
  • Lawn size suitability: Up to 1500sq m
  • Warranty: 2 years

Unboxing the Mountfield HP185 lawn mower

Mountfield HP185 139cc lawn mower in box

Box with handy carrying holes

(Image credit: Linda Clayton)

Arriving in a substantial cardboard box (measuring H49xW56xD82.5cm), I don’t think the Mountfield HP185 would fit in the boot of my car, so delivery to my door (they brought it inside the hallway in fact) was perfect. I mention this because Mountfield sells a version of this mower (same size, different engine) in B&Q and I’d recommend double-checking your boot capacity before buying in-store. 

Inside the box was the main mower, the handle, grass box and mulching plug, plus an instruction manual and a few bolts to get it all together. There was also a single A4 page with assembly instruction with bigger, better illustrations that were much easier to understand! 

Lawn mower instructions

Brochure versus leaflet assembly illustrations

(Image credit: Linda Clayton)

Assembly was pretty straightforward and essentially involved attaching the handle (in two parts) with the easy-screw motion-head bolts and quick-release clips supplied. Then I had to build the grass collector box, inserting a metal frame and screwing it into position. The latter was a tad tricky as the angle of the screwdriver was awkward in relation to the screwheads, but I grabbed the electric screwdriver for extra power and soon had the frame locked down. The netting grass-box sides then clamped onto the frame with relative ease. 

Finally, the pull cord needed to be hooked onto a keeper on the handle so it’s closer to you when starting, or you can leave it where it is if you don’t mind bending down. If you are struggling with the print instructions, it is well worth checking out this assembly video (opens in new tab) by Mountfield. It's also worth noting that some gardening specialists stocking the Mountfield HP185 lawn mower offer pre-assembly as part of their delivery service (the mower is assembled and tested before it’s delivered on a pallet), which could be worth considering if you’re not confident with a screwdriver/too busy.

What is the Mountfield HP185 lawn mower like to use?

As with any petrol mower, before I could start thinking about how to mow the lawn with it, I had to add petrol and oil, neither of which are supplied. The Mountfield HP185 runs on 4-stroke oil (we had some universal SAE 30 4-stroke engine oil in the shed that was compatible) which, obviously, goes in the oil tank. Then you just need to add unleaded petrol, taking care not to overfill or overtighten the cap. A small amount of air comes in through the cap threads and overtightening can cause the engine to fail.

Starting
As the choke is automatic, there’s no need to prime the engine or adjust the throttle, you simply hold the brake lever into the handle and pull the cord sharply towards you. On my very first pull, the engine started with a slight puff of smoke and a heartening roar! Happy days.

The grass was pretty long on first use, which was during the first decent spell of summer sunshine after far too many weeks of rain, so I notched the cutting height quite high to prevent the long grass clogging everything up. I loved that the height adjustment was all on one handle – I’ve tested mowers where you have to adjust at all four wheels, which is tiresome – and found it very easy to change through the six levels.  

I’m not going to lie, that first mow was hard going, but more down to the length and wilderness of our grass than the Mountfield HP185’s cutting prowess. Saying that, I would have given my back teeth for a self-propelling mower (or ride-on) and ended up with a blister in the middle of my right hand when the job was finished, a couple of hours later. Subsequent cuts were significantly easier, and blister free, so I won’t hold it against the Mountfield HP185.

Cutting
Overall, the Mountfield HP185 lawn mower did an admiral job on our lawns, which, I may have mentioned, are not perfectly kempt. It is fitted with an anti-scalp plate at the front that is designed to prevent that scalping effect you can get when you hit uneven ground and it worked really well. None of those mad bald patches and alarming grinding noises I’ve experienced near the edges of the lawn with past mowers. 

I never got down to the lowest height setting, as that would have left us with scrappy, brown lawns, but there was definitely plenty of adjustment for my needs to allow me to keep on top of our lawn care. I also liked how close the Mountfield HP185 could get to the walls and borders, which minimised the need to use a strimmer

Mountfield HP185 139cc lawn mower on the go

Mowing tight to the raised beds.

(Image credit: Linda Clayton)

While a self-propelled or riding lawn mower is always going to be my preference, after that first hellish cut, pushing the Mountfield HP185 along really wasn’t hard at all, even on the part of our lawn that slopes. This smooth ride is most likely due to the robust 20cm diameter wheels and also the lightness of the mower, which makes it almost effortless to push along, especially when on level ground. It looks a lot sturdier than its 24kg weight, and I could just about lift the whole thing to get it off the steps of the patio (where I built it), using the chunky handle at the front.  

Emptying
Moving on to better news. Grass box emptying is very easy – the usual lift up and shake out technique – and the grass compacts well inside so you don’t have to empty it with annoying frequency, even when the grass height is insane. The flapper-style ‘box full’ indicator (when the flap shuts flat, it’s time to empty) was simple but very effective, too.   

Grass discharge
During the mowing test period, I also tried out the Mountfield HP185’s other two grass dispelling options. The first is rear discharge and involves removing the grass box, popping a pin under the guard to stop it blocking the exit point and allowing the grass to belch out the back. Rear discharge is generally aimed at rougher ground or really high grass, perhaps an orchard for example, where you just need the grass cut without getting blocked in the chute and don’t mind raking it up or are happy to let it rot down. I can confirm it worked as it should, but I’m not into raking and don’t like the kids traipsing dead grass into the house so this option was not for me.  

The second option, the mulching plug, slots easily into the grass chute under the guard and then the mower cut the grass into fine blades before blasting it back down into the lawn. Much more useful, especially if you are cutting, as I was, twice a week. Not having the dead weight of a grass box to push along was very welcome, and I also appreciated not having to empty said grass box. Luckily, there wasn’t much evidence of the mulched grass coming into the house (via small feet and paws) and I think I noticed the lawn was greener looking a couple weeks along, too. We’re not talking verdant fertilizer-induced green with brilliant lawn mowing patterns, just a little healthier.

rear of the Mountfield HP185 139cc lawn mower

Mountfield lawnmower with mulching plug inserted

(Image credit: Linda Clayton)

Cleaning the Mountfield HP185 lawn mower

As you can’t tip the Mountfield HP185 lawn mower, or any petrol lawn mower to be fair, onto its side, keeping the undercarriage (cutting deck) clean isn’t terribly easy. I went with a slight backwards tilt and then used the garden hose at full pressure to wash off any pulped grass post-mowing. A wooden stick also works. If you don’t then the grass will harden in storage, making future cleaning a whole new ballpark of awkward lifting and scraping. A lesson learnt the hard way. 

Image showing the underneath of a Mountfield HP185 139cc lawn mower

Clearing grass from the cutting deck underneath

(Image credit: Linda Clayton)

As mentioned, the grass collection box is very easy to empty and it’s also no biggie to pull out any lingering grass from the chute before you store the Mountfield HP185 lawn mower away. I did give it a bit of a hose down one day, after noticing the mesh was clogged with grass. Blocked mesh is something to be avoided as it reduces how much grass the box will hold before the ‘box full’ indicator comes on, and ultimately increase the number of times you’ll have to traipse to the compost heap. 

Storage and maintenance

The handle folds down easily using quick-release grips at the side. This isn’t a huge lawn mower but nor is it targeted at compact, space-saving storage so you’ll need a decent size shed or garden storage to house it. There is a large handle on the front of the blade deck, which is helpful for lifting the Mountfield HP185 over small obstacles or up steps.

handle folded down on the Mountfield HP185 139cc lawn mower

An easy fold-down handle makes it easier to store

(Image credit: Linda Clayton)

I didn’t really need to do a lot of maintenance during the test duration, but I did attempt to check the oil levels, which is good practice. Being black, the oil dipstick isn’t very easy to read but I could see that it hadn’t raced through the oil and there was still plenty in the tank after several weeks. 

The fuel is easy to top up if you have a petrol can with a flexible hose, and the fuel consumption also seemed fair. It’s hard to quantify without the kind of stats you get on a car, but, roughly speaking, I was refilling the 0.75 litre tank every other time I mowed.

Lubricating all moving parts is an essential longer term maintenance chore that you’ll need to be willing to do before buying any petrol mower.

checking the oil levels on a Mountfield HP185 139cc lawn mower

The oil levels aren't easy to read

(Image credit: Linda Clayton)

How does the Mountfield HP185 lawn mower rate online?

First up, when checking out reviews, it’s important to make sure they are for the right Mountfield HP185 model. The one I tested had a 139cc Stiga engine, but there also seems to be a slightly cheaper 125cc model with a Briggs & Stratton engine out there.   

Once I’d tracked down the correct reviews, I couldn’t really find any negative feedback for the Mountfield HP185 lawn mower. Most owners have found it very reliable, solidly built and great value for money. There were comments about rubbish assembly instructions and difficulties constructing the grass box but once the mower is built, the comments are hugely favourable. Lots of love for the automatic choke and easy height adjustment. 

How does the Mountfield HP185 lawn mower compare?

Retailing at around £219.99-£249.99, the Mountfield HP185 lawn mower is, undeniably, excellent value for money. 

The closest competitor from an equally well-respected brand would probably be the Cobra M46SPC lawn mower (available at Amazon) (opens in new tab), which also has a 46cm cutting width, but it is self-propelled and costs a little more at around £279.99. 

The Cobra offers a few more cutting heights (10, ranging from 25mm to 75mm) but it’s a little heavier (33kg) so could be harder to manoeuvre when the engine isn’t running. The Cobra does seem like a good option if you are seeking a self-propelled alternative to the hand-propelled Mountfield.

Should you buy the Mountfield HP185 lawn mower?

Mountfield HP185 139cc lawnmower in garden

(Image credit: Linda Clayton)

It’s really hard to find fault with the Mountfield HP185 lawn mower, which is a strong recommendation in itself. Comfortable to use, not excessive on the vibration front, nor painfully loud, the grass box is easy to empty and the generous 20cm wheels are easy enough to push along. The powder-coated steel chassis looks and feels ruggedly robust, and fuel economy was also decent, which is important given today’s petrol prices. 

While the Mountfield HP185 is lightweight and not hard to push, personally I prefer the extra assistance you get from self-propelled mowers, especially when tackling our main lawn, which can get a bit laborious after a while. I also suspect those with steep lawns in a sloping garden might struggle to push the Mountfield HP185 back up slopes.

In short, if you are looking for a low cost, hand-propelled petrol mower, then the Mountfield HP185 should be at the very top of your hit list.

About this review, and the reviewer

woman mowing a lawn with petrol lawn mower

Quiet enough to allow a good Podcast session while I mow

(Image credit: Linda Clayton)

Linda Clayton is a freelance journalist living in the wilds of mid-Devon with her husband, their two daughters and three dogs. Her fairly large south-facing garden is mostly laid to lawn, which gently slopes away with views towards Dartmoor. The smaller front garden is also mostly lawn – primarily because she hasn’t quite got the hang of weeding flowerbeds without weeding out the flowers! 

She tested the Mountfield HP185 over several weeks in the early-to-mid cutting season, focusing on ease of use, emptying and also had her eyes peeled for any issues or red flags that potential buyers might find helpful. We are not paid to review this product, but Mountfield did supply it without charge for testing and are invited to collect it afterwards. 

For more information on how we test products at Gardeningetc, see our guide.