Diesel engine compression question.

[City Farmer]

Hi guys.

Yesterday I went and looked at an engine, 3 cyl Ford. I know it came from a low hour machine. I grabbed the flywheel and turned it by hand clockwise, there was no resistance at all with 2 full turns of the flywheel. I then turned it counterclockwise and there was some resistance but I had no problem turning it over. The injectors were still in and tight but the lines were off, they sold the injection pump.

Now, I'm talking to a guy at work. He's telling me because the lines are off the injectors, it's not going to build any compression. I think it should have compression in both directions, CW & CCW with the injectors in and the lines off. The owner said it's probably just a stuck valve. I passed on the engine because I don't need another project. Is the guy here at work right? I'm thinking he's wrong but I'm not positive.

 

[Leejohn]

I thank he is wrong, it takes something around 2000 psi to open the ejectors.

 

[thepumpguysc]

He is dead wrong.. w/ the injectors IN the engine it should have compression.. just like spinning the top of your riding mower by hand..
It might be easy for a second until the piston comes up and build compression then stops, but if you keep pressure in the turning motion it will slowly keep going as the compr. bleeds off.
Good call on passing it up..
MORE THAN LIKELY what happened was.. all the rings broke on the pistons from using starting fluid & it was to much for the owner to get into so he sold the pump..
The injectors are sealed tight when no fuel is present.. that means NO compression can leak past the injectors..unless they are ALL stuck open, which is virtually impossible.. the guy at work is wrong.. I sure hope he's not the company mechanic.. lol

 

[RickB]

3 votes against your buddy.

 

[TemporaryKubotaOwnerMark]

Four. The injectors aren't exactly two way valves.

They have to hold the pressure of firing diesel, don't they? Does your buddy think the injector pump does that? The pressure would bleed past the injectors and be stopped by the injector pump?

 

[City Farmer]

Thanks guys. It took about 10seconds to figure out something was wrong with that engine. The seller was a nice enough guy. He said he never thought of checking for resistance by turning the flywheel. It was a big place and he was just a salesman so I'd like to believe him. The guy at work was trying to justify the problems like the salesman trying to lower the price to get me to buy it. They were just making up stuff without thinking about what they were saying. I always walk when something doesn't seem right and it paid off this time.

 

[Tx Jim]

3 votes against your buddy.

4 votes against your buddy!

 

[Sawyer Rob]

5 against... Those other 4 votes are right.

SR