I have finally got back onto the mower rebuild!

I purchased a small sand blasting cabinet and dust extractor from the Hare and Forbes Machinery House 3-day sale a few weeks ago. Now I can start sandblasting the old paint and built-up rubbish from the outside of the engine casting, this should get things done a lot faster!

Sand blasting cabinet

It’s a small sand blasting cabinet, but should be fine for these small parts.

Using a 25Kg bag of Garnet that I also bought from the sale, I have sandblasted the head of the Briggs & Stratton after plugging up the spark plug hole with an old sparkplug, it’s cleaning up quite nicely :)

Sand blasting briggs and stratton head Sand blasted briggs & stratton head

I need to go over it a few more times to remove some little bits I missed, however I am quite happy with the results. I just hope I can find time to do the rest of it soon.

Briggs & Stratton Cover - RustedBriggs & Stratton Cover - Rust Removed

Preparing the metal cover has been quite a bit of work, I had already prepared the top side of the cover by removing the paint, rust and dents using elbow grease, however I decided that I should also remove the rust from the underside of the cover too before I respray – If a job’s worth doing, it’s worth doing well!

Recently I have been looking into ways to restore old rusted tools and I have been very intrigued in the method of using electrolysis to remove rust. During the past week I had been doing a bit of research online on the subject and I tested it on an old rusted ring spanner which cleaned up quite well. I decided it was a good way to remove rust off parts of the mower without much effort (don’t work harder, work smarter) and the result above speaks for itself! I wont go into the specifics of the rust removal in this post, I’ll dedicate another post to it shortly as I didn’t take enough pictures of my set-up, however in the meantime if you are interested this site has great information on rust removal by electrolysis, there are also many tutorials on youtube.

Briggs & Stratton Compression Test

My compression test kit arrived, so I bolted the head back on to do some testing. The kit came with quite a few adapters to suit different engines / spark plug holes so it should be a handy kit to have around. To perform the test, I simply pulled out the spark plug and connected the compression tester in its place. I pulled the pull-start cord a few times and checked what pressure was reading. I never seemed to get a reading higher than 50psi which I thought was extremely low and not only that, but the pressure would drop away very fast! I need to confirm if it is the engine or the test kit itself, the Nitto style air fittings that the test kit uses seem too loose to me so I will hook it up to an air compressor with a regulator to verify none of the fittings are leaking.

Even though my compression test seemed unsuccessful I decided to go ahead and continue with pulling apart the engine, I took the head off again, then removed the valve spring cover and proceeded to remove the valve springs. The valve spring retainers are buggers to get off, the intake valve spring came out easier than the exhaust valve spring, but once I got both of the springs out I noticed that I could not pull the exhaust valve out of the case whereas I could pull out the intake valve fine. On closer inspection it appears that the base of the valve where the valve spring retainer pushes against has been put under a lot of force and expanded the diameter of the valve stem and now it wont fit back through the hole. I am not sure exactly how this could happen unless the valve was somehow obstructed and could not be push all the way open, but if that had happened then I would have expected the valve to be bent. I noticed when the valve is fully closed it is not seating very well due to all the crud build up underneath it, this could be a reason for the low compression (I hope). I have a new exhaust valve on its way so I think I will replace it. To get the exhaust valve out I had to use a sanding wheel on my Dremel to grind the diameter of the base of the stem back to size.

Next I need to remove the top and bottom flywheels (bottom flywheel has the blades attached), unfortunately I never seem to have the right tools around. I really could use an air impact wrench / rattle gun to remove them… Till next time…

Carbon Crud

I have a bit of an update to my Briggs rebuild, I pulled off the head and inspected the carbon build-up on the piston and valves, as you can see from the image above its quite a lot! and a large piece actually fell out as I was taking the head off. I have since cleaned this up with a wire brush and it’s looking much better now. I will be putting the head back on shortly to test the compression before I replace the piston rings and lap the valves.

Below is an image of most of the peripheral parts laid out on a shelf ready for cleaning (more thoroughly). After pulling the carby off the fuel tank, it looks like ill be needing a new diaphragm.

Briggs & Bits

I have also striped back the paint off the steel cover using some thinner and sanded back most of the rust with 100grit sandpaper, some of the deeper stuff I had to use a sanding wheel on my Dremel, there were quite a few dents in the front and I have managed to ‘panel beat’ most of them out and clean the rust out of the pits, a few smaller dents remain which I will fill before respraying. Hopefully I will get a chance to respray it tomorrow before it starts to form rust. I purchased some red engine enamel and my new Briggs & Stratton decal sticker has arrived, so it should come up a treat!

Briggs & Stratton Cover

Briggs & Stratton

While mowing the lawn the other week, looking down at my aging Briggs & Stratton, I thought it would be time to give it a little TLC, perhaps even a new paint job. The engine originally came from my great-step-grandfather who owned a little mower shop, he had given the mower to my father many years ago, I remember my father mowing the lawn with it when I was very young, and now it is in my hands.

The engine’s muffler had fallen to bits years ago and had been patched up with bits of metal and rivets by my grandfather who possibly at the time thought that replacement parts could not be obtained for the old engine, needless to say the muffler did not muffle much. I had decided to have a quick look to see if I could find a replacement muffler for the engine, after all even though the engine is old, the design probably doesn’t change much over the years and I should be able to find something. After searching online (mainly ebay) I was pleasantly surprised to find many suitable mufflers for my engine. After ordering a muffler I decided that an oil change is well overdue, then I was thinking that the engine is pretty old, It probably has a lot of carbon build-up inside the head, perhaps I should do a more thorough maintenance job on it.

I had never really been interested in mower’s, unlike my grandfather who loves working on them. However recently I found myself wanting to do more and more on the engine. I decided that it would be a good learning opportunity for me, as I have never worked on an engine before. After quite a bit of research online I decided that I would go ahead and clean out the carbon deposits, then decided to do valve lapping, then after discussing it with my grandfather, he recommended that if i’m going that far I should change the rings too, he also handed me a crank shaft for the engine that he has had for years in new condition, the list just grew and grew…

My to do list so far:

  • Degrease and clean the engine case.
  • Clean carbon deposits in the head.
  • Valve lapping.
  • Replace the piston rings.
  • Hone the cylinder.
  • Replace the crank shaft if required.
  • Replace all gaskets.
  • Strip the old paint off the engine and cover.
  • Prepare the surface for painting.
  • Re-spray the engine and cover.
  • Replace the muffler.
  • Oil change.

After reading a lot about these engines, I found out that my particular engine was manufactured in 1977, so it is 33 years old (older than me! I want it to last at least another 30 years). The Briggs and Stratton model/type/code number which is located on every engine can tell you when the engine was made, my engine is: 110908-0214-03-77012004, the first two digits of the last section is the year code (see model type code), using this code I managed to find the illustrated parts list for my engine, listing every part and its Briggs and Stratton part number for ordering replacement parts. A quick search on ebay, and most of the parts I would want to replace are readily available.

Before I start I will do a compression test, then compare it to after I finish all the work, see if anything I do actually makes a difference. I have ordered a compression test kit, new exhaust valve, new intake valve, new piston rings and new muffler.

I have pulled the head off and the carbon build-up is quite a lot, I gave it a quick clean with a metal brush but I can not do much else until all the new bits arrive.

I amĀ  now awaiting the arrival of the compression test kit before I go any further.