Outdoor Power Equipment and Small Engines - Troy-bilt lawn tractor won't start

My battery had died, so I was jump starting it. Had opened up the seat switch. It started fine. I connected the switch terminals with the motor running. When I connected the second terminal, there was a loud sound and the motor died. Could you guys tell me what did I break? Now when the motor cranks, but will not engage to start up.

Thanks for your help.

Remove the spark plug and check for spark while cranking.

Is the engine full of oil?

What kind of loud noise? (backfire bang? Something clanking? etc...)

What kind of engine?

Why did you have the seat switch "opened up"?

The engine is an MTD, do you need the model no.

The tractor is in the shed and its too cold out there, I will try the spark plug when it gets warmer. I had it in the garage yesterday. I had looked at the spark plug and it looked ok. But I did not try to see if it was generating the spark.

Well, as far as the sound is concerned, I think it was a clanking sound, can't be sure, was a few days ago.

I had disconnected the seat switch because the battery is under the seat, and with the seat lifted I could not start the engine.

It was completely functional before, so I don't think its engine oil problem

When I try to start, with the battery terminals paralleled to my car battery, it does crank, but just makes a whirring sound and does not engage.

I am not sure if this is sufficient info. I will try one of these days when the weather is warmer.

Thanks for your help.

MTD doesn't make engines. It has an engine of some brand and model on it. If we don't know what engine you have, it's hard to give instructions that pertain specifically to your engine. We have to be general.

A clanking sound could be entirely related to the level of the oil, and the condition. If it is low, or hasn't been changed in years, the engine could have blown (broken a rod, etc...). An engine was always completely functional before it messed up.

You can crank the engine with the seat up...just lock the park brake on.

My Troy-Bilt has a compression problem that keeps it from starting. ...it cranks like it's going to turn over, but never does. I'm told it's common with them. I bought the parts and a manual, I just haven't gotten down to doing the adjustment yet. I keep getting through it by making sure the battery is on full charge and the plugs are shiny clean. This gives it enough juice to start, but it can't be healthy for the machine.

Don't know what engine you have, but if it's a single cylinder briggs OHV engine, you need to adjust your valves. This should be done yearly.