No compression with old Briggs?!?

[thebetterman88]

Hi,

I'm decently experienced with small engine repair and decided to help my neighbor fix his old MTD push mower. It had been sitting for awhile and I expected the carb to be clogged but we got it to start up for 5 minutes before it died and wouldn't start. I ordered a carb repair kit, new governor spring, and new air filter as those parts were damaged or worn. Installed them all and went to start it up. Nothing....not a sputter, not even a glimpse of life. I clean the spark plug, adjusted the gap, and reinstalled....still nothing. I then pulled the plug and put my thumb over the hole and tried to start it up. There was no compression at all. So then I decided it was probably the valves. I pulled off the head and sure enough there was deposits and pieces of something brittle like carbon that were stuck under the exhaust valve. Pulled both valves and saw some damage on the valve stem of the exhaust valve. Ordered a new valve, lapped both valves, and reinstalled. Checked to make sure that they actually seated. Then I reinstalled everything with new gaskets. Went to fire it up and there was still nothing. It backfired a little bit out of the exhaust but wouldn't start. I checked compression and sure enough it wasn't there. I'm about to pull my hair out....what is going on?

 

[Fish]

You need to check and adjust your valve clearances.

 

[PartStockPile]

Next time order your parts from partstockpile.com and maybe we can give you some kind of deal!

 

[Fish]

Sounds like you are here to sell some stuff!!!!!!!!

 

[Fish]

And not help anyone!!!!!!

 

[Fish]

Just checked out the site.... Dang, your prices are quite high, looks like one could get better prices from his local shop.

 

[reynoldston]

If the valves are adjusted right as Fish told you the other thing would be piston rings and cylinder walls. I have a B&S this spring that had a ring problem and very low compression. One way to test the rings is put oil into the plug hole and see it the compression comes up and if so the rings are bad.

 

[reynoldston]

Next time order your parts from partstockpile.com and maybe we can give you some kind of deal!

Just what do you give for a discount for a small repair shop? I have been using Jacks and they do give a small discount for a repair shops. Jacks has OEM parts with very fast shipping. Jacks had me fill out a form. I also find some very good pricing on E-Bay, but you need to shop.

 

[thebetterman88]

Wow....the thread got hijacked quite quickly haha. So thanks for the tips guys. It turns out the valve clearances were the problem. I completely forgot to check them and sure enough there was pretty much no clearance at TDC on the intake or exhaust valve. I'm going to grind and polish the ends and get this engine going.

 

[Fish]

Yeah, it gets hijacked quickly, but you got a correct response quicker, eh? Just keep me in mind when I am running for "mower dude"... It is a lucrative position... Does not pay anything, but I need all the friends that I can get.......