Make your old lawnmower like new with this guide.
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Step 1: Teardown Part 1
The first thing to do is to completely tear the lawn mower apart. Make pictures of everything you take off and keep everything organised for when you're putting it back together.
Step 2: Teardown Part 2 Electronics
With a lawn mower there are wires everywhere. If you look at the scheme it is a very simple concept. But the damn wires are everywhere. Make sure you make pictures of how the relais is connected, where the mass is connected, and what wire goes too the start engine. Everything else is almost impossible to connect wrong due the connector, but it is still smart to make a picture just to be safe and multiple components use the same connectors. You don't want the mowing on button connected to the clutch.
Step 3: The Engine
After you have torn the whole lawn mower apart we begin by revising the engine. As you can see my engine was a bit damaged but mostly dirty and rusty. Before you take the engine apart clean it roughly with air (compressor) or if you have a high pressure water cleaner (even better if it has heating) clean it with that one. Though make sure you do not point it on slots or holes.
Step 4: Open Engine
After the engine is roughly clean disconnect the bougie from the alternator. Then disassemble the carburetor from the engine (make sure to make pictures of certain presets like the throttle lever). When you have it apart fill the holes in the engine with some kitchen paper or tape. Now you can clean the carburetor, this is in most of the engines the problem why it doesn't run good or doesn't run at all. The carburetor is the place where gasoline is mixed with air. All carburetors work roughly the same but there are a lot of differents between them so if you don't know how to do it here you can find a example Carburetor cleaning in 8 steps or search your carburetor by your engine model on google. As you can see there you have all kind of special carburetor cleaning sprays but i always clean them with simple breakcleaner.
After the carburetor is cleaned, open the cyllinder and clean that with some kitchen paper(make sure you return the bolts at the same place). When you have the cyllinder opened watch if all the rubbers are still good and if necessary replace them.
Then you can clean the oil. First let all the old oil out with the special tap somewhere underneath or bottomside. After its empty fill it up with new oil prefererably 10W40. If you really want too clean your engine you can open it and clean all the oil away but this is only necessary in extreme cases.
Then put all this back together, clean the flywheel and test the alternator(multimeter) and bougie(spin flywheel and film bougie because sometimes you cannot see it with the eye). Important is too put the alternator at a good distance from the flywheel, this is described in the instruction manual of the mower. If everything is okay put it also back together, clean the airfilter and you can test your engine. Also don't forget to check/change your fuel filter and check the valves.
By testing i found out that my start engine was broken, the brushes were completely destroyed. After some research i found that i could buy them new for 200 euro locally and secondhand for 100 euro. This was way too much and by luck a mate told me he could get them for 5 euro from the US with 13 euro shipping cost. This was a hell of a lot better.
I also had the bad luck that the oil seal leaked(see picture), so I had to replace that one too.
Step 5: Starting the Sanding: Frame
Because many parts of the mower had rust on it, I decided to repaint the whole mower. This was by far the most time intensive work. After you're sure your engine works, you can start by sanding the frame because that is were everything is connected.
First remove all the dust an sand from the frame. This can be done by compressed air or with high pressure water. The sanding can be done on different ways: sanding paper, sanding machine, steel brush, steel brush on accu drill or with a grinder. I advice not to use sanding paper and a sanding machine, it takes way too much time for too little result. I am also against the grinder however I did use it something on hard spots or difficult spots. It leaves the steel brush and the steel brush on the accu drill. Well everything is easier with a accu drill so I did almost everything with that (I included a picture of the steel brush accu drill). Also make sure you use safety glasses and if you can't handle the use a mouth cap.
Now the sanding can begin. First sand all the places where rust is. Sand it all away till you see the steel beneath. On places where the paint is starting to get loose make sure you sand them too. The places where the paint looks like it is in perfect shape don't have to be sanded. On the frame mostly the edges are rusty/letting loose.
Yet to be finished