How should I go about diagnosing/charging customer?

[Mr Mower Man]

I have an Ingersoll tractor in the shop powered by a 20HP Onan (P220G-I/11457H). The owner bought it for about $200 from a local metal recycling place. The previous owner just wanted to get rid of it, evidently.

It would only spark on one cylinder, so I replaced the ignition coil to fix that problem. Then I discovered that although both sides were getting spark, the engine still ran on just one cylinder. No compression on the dead cylinder. I thought it was probably a valve stuck open or something like that, but when I took the head off and rotated the crankshaft, the piston didn't move. Bummer, probably not worth fixing. The dead cylinder, by the way, is the same one that wasn't getting any spark at first.

It's things like this that make me question my diagnostic practices. When I didn't get spark on the bad cylinder, it never occurred to me to also run a compression check, to see if the engine was worth investing in a new ignition coil. After all, it is highly unlikely that a cylinder will have a broken rod AND no spark. Yet customers are paying me to be the professional who "should've known." So I'm trying to figure out the best way to avoid these situations in the future.

Do any of you just test compression as a routine check? I never have, and if I start making every test I know a routine procedure, I'm going to waste a lot of time. In hindsight, I guess that since the owner wasn't aware of the equipment's history (since he bought it from a scrapyard), it may have been a good idea to check around a little more than if he'd been using it and it suddenly lost spark on one side.

So was this just "one of those things," or do any of you have shop practices which, if I had implemented those same practices here at my shop, would've prevented this situation?

Thanks

[Deere2me]

I have an Ingersoll tractor in the shop powered by a 20HP Onan (P220G-I/11457H). The owner bought it for about $200 from a local metal recycling place. The previous owner just wanted to get rid of it, evidently.

It would only spark on one cylinder, so I replaced the ignition coil to fix that problem. Then I discovered that although both sides were getting spark, the engine still ran on just one cylinder. No compression on the dead cylinder. I thought it was probably a valve stuck open or something like that, but when I took the head off and rotated the crankshaft, the piston didn't move. Bummer, probably not worth fixing. The dead cylinder, by the way, is the same one that wasn't getting any spark at first.

It's things like this that make me question my diagnostic practices. When I didn't get spark on the bad cylinder, it never occurred to me to also run a compression check, to see if the engine was worth investing in a new ignition coil. After all, it is highly unlikely that a cylinder will have a broken rod AND no spark. Yet customers are paying me to be the professional who "should've known." So I'm trying to figure out the best way to avoid these situations in the future.

Do any of you just test compression as a routine check? I never have, and if I start making every test I know a routine procedure, I'm going to waste a lot of time. In hindsight, I guess that since the owner wasn't aware of the equipment's history (since he bought it from a scrapyard), it may have been a good idea to check around a little more than if he'd been using it and it suddenly lost spark on one side.

So was this just "one of those things," or do any of you have shop practices which, if I had implemented those same practices here at my shop, would've prevented this situation?

Thanks

The KEY word here is ROUTINE. I usually don't on a routine basis. But think about it, bud, would you consider that unit a ROUTINE piece of equipment??? Neither would I, especially considering it's history. It really depends on what I'm working on, or against.
A compression test can be quite useful. If a comp. test is warranted, I generally will follow with a cyl. leakdown test. But again, not on a routine basis.
Live and learn.

[bgsengine]

I'm with Deere on that one. However, probably would have noticed lack of compression when rolling engine by hand.. which I usually do while doing Preliminary checks and diagnostics like that, before cranking it over to check spark, normally I'd have been rolling engine by hand to make sure nothing was stuck that might jam or bend or punch a hole in piston.

[bobodu]

From now on, I bet you will always run the basic three. Screwdriver test for spark, thumb over the spark plug hole test for compression and the shot of carb cleaner test for fuel. I will do those for free to see how good the guy's money is.

[Mr Mower Man]

From now on, I bet you will always run the basic three. Screwdriver test for spark, thumb over the spark plug hole test for compression and the shot of carb cleaner test for fuel.

I'm partial to a spark tester for checking spark, but you're spot on for the compression and fuel tests. I guess mistakes can be the best teachers sometimes because you don't forget their lessons very easily.

My customer will no doubt be disappointed by the news about the engine, yet he'll be pleased that I'm owning up to my mistake and not making him pay for my lack of experience.

[bobodu]

STILL.....for $200 he isn't out a whole lot. You could cut him a deal on the labor if he is willing to wait for the work to get done when you feel like messing with it. There always seems to be a slow down after the blowers are all running. December through March is when I rebuild engines.