Craftsman T1200 MTD Engine no compression

[Ron_AU]

.I can get 80 thousandths gauge between the piston and cylinder and can push gauge all the way in between the red marks shown on the photo...no hitting the rings... So looks like I inherited a lemon.

That's an 8 thou feeler gauge, not 80.
Maybe pull the piston and check for broken rings, and put new ones in even if not broken?
The rings might just be stuck in the piston grooves.
The engine looks tired, but should still be a runner.

 

[Cusser]

Wow. Maybe there are NO rings at all !!!

 

[ILENGINE]

What I see in the cylinder picture is about .20 thousands or more on the cylinder walls from the ridge at the top of the cylinder. Signs of overheating at the bottom of the cylinder with the discoloring, and patchwork lining up with the cooling fins. Also aluminum transfer on the lower left side of the picture. So the piston rings are jumping and skipping across the cylinder walls.

 

[LeisureSpecialist]

That's an 8 thou feeler gauge, not 80.
Maybe pull the piston and check for broken rings, and put new ones in even if not broken?
The rings might just be stuck in the piston grooves.
The engine looks tired, but should still be a runner.

long day.... 80 Ten thousandths...my fault...

 

[bertsmobile1]

Quick & dirty test for a broken upper ring is to wipe a very thin layer of grease around the bore then move the piston up & down a few times at the very top f the stroke , a broke ring will leave a vertical line as will the end gap

 

[LeisureSpecialist]

I pulled the piston and the rings are barely extending beyond the piston. They are all intact but are hugging the piston pretty closely. I can easily replace the piston back in the cylinder with very light finger pressure on the rings. I'm going to put in a new ring set and see if it runs.

 

[Cusser]

How much for a new piston ?

 

[LeisureSpecialist]

$40 for the piston, close to $100 for the piston, pin and snap rings.

 

[kbowley]

I have had three of those so-called "MTD Engines" come through my shop with identical symptoms; Very hard or no start, very low compression, worn rings with some bore wear. All three were replaced under warranty by Craftsman without questions or hassles. They sent me a new short block and I sent back the old one for their engineers to examine and determine the cause of failure. In two of the three, dirt ingestion was the cause, and the last one, poor oil flow to the bore causing overheating and dirt ingestion. The ingestion causes premature ring wear because of poor metallurgy if the ring manufacturing process by the supplier. I do not know if it has been corrected, both the efficiency of the air filters and the ring alloy quality. I would assume so since I haven't seen any issues with them since the build dates of mid-2018.
In Summary, the failures were caused by poor air filtration and the low alloy piston rings.

 

[StarTech]