My Tractor Forum banner
1 - 4 of 4 Posts

· Registered
4 Posts
Discussion Starter · #1 ·

I recently acquired a Lawnboy walk behind mower and know very little about it other than it looks identical to the one I used to mow with as a kid at home helping mom and dad in the yard. The only problem is that the engine is seized up, not solid, but to where pulling the rope is very difficult. The tag on the engine says D400, I'm not sure if that is the model number of the engine or the mower itself.

I hopped online thinking that finding an engine overhaul kit would be a snap. I was clearly wrong. I did some searching on this site and found that my best bet would be eBay or NOS from an old dealer. Like I said, I have very little knowledge on this mower. That being said, I am looking for some guidance on the rebuild process on a seized up engine as well as suggestions as to where I should search for the parts.

I would love to get this mower running, and MTF definitely seems like the place to come for the right information to help me do that.

Thanks everybody!

· Super Moderator and over 6K Posts!
6,791 Posts
Hi and welcome to the forum! There is a vast amount of knowledge here and I am sure you will have all of your questions answered. I have not had the pleasure of a complete rebuild so I am sure someone else will be able to give you a better idea of what you need to do. It sounds like it may have been straight gassed so you will more than likely need to remove the cylinder and inspect for any damage. If there is aluminum transfer from the piston to the cylinder that can be removed with Muratic acid. Then the cylinder bore can be checked for any significant damage. If there are any scratches that you can catch a fingernail on that would be considered a problem. Small imperfections will be removed when the cylinder in honed in preparation of receiving a new or good used piston with new rings.

One of the best sources of information is the Lawnboy Service Manual. You can access it online here.
When you have time read through any and all sections that pertain to a tear down and rebuild as there are some important specifics when it comes to rebuilding these engines. You can also buy the paper copy of the manual through any Toro dealer or check eBay.
As you have already found there is no rebuild kit for these. Here is another source for information regarding parts look up for your mower. Just enter in the model number and select the year and your off and running.
Make a list of any and all gaskets, needle and seat, float, etc., that you think you may need to complete a rebuild. Many items can be sourced through your local Toro dealer but check eBay as well for bargains.
Proceed slowly and carefully, ask a lot of questions, and read the manual, and in no time you will have that mower up and running.
Be sure to provide us with the model and serial number so we can be of additional help.
Also it is mandatory on this forum that you post pictures of your new acquisition because we like pictures!!! :sidelaugh Just kidding of course but we do like pictures.
Again welcome to the forum and enjoy your stay. Bill


· Premium Member
482 Posts
[/B][/B] hello there
there is a tag on the housing that has the size of cut and model number
that is on back of the mower it is a metal plate also if you need parts i can
help you out i am a lawn-boy expert with 35 yrs exp you can give a call at
707-498-0329 be glad to help you have a great day Scott

· Registered
3,025 Posts
That is one of my favorite engines, simple and lightweight. First of all ensure the crank is not bent. If ok remove the blade and stiffener plus the muffler. There are three small holes in the port they may need to be cleaned out with a wood or plastic probe. Don't use a screwdriver. Take a peek, if the piston is galled it's tear down time.
1 - 4 of 4 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.