Just bought a mudbuddy mini with a 23 vanguard motor(35 hrs). It is in warranty until this December. Only mods is a BPS exhuast system installed 3 months ago. I ran the motor about 3 hours on a straight run with no problems. Motor turned about 3950 rpms, no missing, no smoke, did 26mph on my boat by myself. A little after 3 hours, the motor started missing and backfiring.
It would get up on a plane, but only turn 3400 rpm and still missing/backfiring. Heres what happened since I got the motor home.

!.) I checked the compression and got 70 psi on one and 110 on the other cylinder. These little motors usually have about 150 in each cylinder.

2.) Took it to Joe's mechanic shop in Kenner, La and told them what happened. The mechanic didnt get the message about the low compression and just cleaned the carb, adjusted a loose exhuast valve, and a tight intake valve.

3.) Went to run it again and it ran better at idle, but shitty under a load. turned 3300 rpm and only did about ten miles per hour, missing and backfiring the whole time.

4.) called the shop and asked if they checked the compression before giving it back to me. The mechanic said he didnt know about low compression(secretary didnt tell him) and to bring it back. Both cylinders checked out low in compression to him as well. He did a leak down test and could hear air coming from the crankcase. They said that the valves were gummed up a little, but there may be issues with the cylinder, so they took the heads off. Both cylinders showed hot spots and moderate amount of scarring, not horrible, but still some. The cylinders seem to not be as true as they should as you can slightly see some of the ring on parts of the pistons. There is a little play with each piston at TDC. One mechanic said that he had seen motors way more scarred than that and they still didn't backfire/miss. They asked if it blew any smoke and I told them that it didn't.

They are going to call briggs and strat to ask for any advice, as they don't feel like things are adding up. He said worse case senario, I would probably be cheaper to put a new shortblock on than to hone it, put new rings, etc etc.

I guess my question is if they are unsure of the cause, what determines what Briggs and Strat will warranty on this thing. I tried to ask them multiple times about warranty, but feel like the question was avoided. Its not even two years old and doesnt have 40 hours on it. Yes, the carb appeared to have a little evidence of old gas in the bowl, but should that cause complete engine failure or overheating. Any advice from the experienced crowd? If the cylinder needs to be honed, new rings put in, etc, is it generally advisable or cheaper to just put a new shortblock on?? I have a friend that hones outboard cylinders, so I'm sure I could get him to do it for a reasonable price. I should hear back from them tomorrow, but just wanted to see if anyone had suggestions. Thanks.

Take it to a different mechanic.

It sounds like they are pushing you around. And like you said they didnt tell you about the compression, and they were avoiding your questions.

Go to a different mechanic.


I feel your pain, the mastery service shop in Tulsa is full of a bunch of damned goons.

Briggs mechs seem to give plenty of run around on warranty work if it comes to opening a motor up. They will replace a bolt-on pretty quick but scoff at anything complicated it seems. You just better hope that Briggs doesn't request to see the motor for themselves cause if it comes to that it could be next year before you get something back.

take it to the Boat Dr.,he fools with mud buddy and does mods.He may be able to answer some of your questions over the phone.I have never dealt with him but alot of people around NOLA do.Good luck

These guys have already taken the motor apart, so bringing it to someone else may mean that I pay them for labor to pull it apart, and then pay then next guy to run all the tests again.

I dont mean to sound negative but it sounds like they are gonna dick you. A real mechanic thats knows anything would throw a compression check for symtoms like that.

1. check fuel
2. check spark
3. check compression

If you dont have air god help you.

If compression is low make sure valves are ok then pull the head to check the cylinder /piston and rings.

Bring it to me, Illfix it and test it out all hunting season for ya to make sure its good.