Typical Ford issues...

[jb451]

Working on my aunts 2.0spi focus, the original motor grenaded itself about a month ago due to a broken valve seat. Found a junk yard motor friday and while the lower end appears to be good, as i turn it over on the engine stand with my compression tester in, i hear air hissing out of every single intake port. (as you can imagine, i am getting a big fat 0 reading on my tester) I would think this is because the valve seats are worn, correct? I just want to make sure i have an educated guess before i go into the machine shop and risk them telling me some outlandish reason. Thanks y'all.

Dirtiest cylinder (no.3 i believe)-


Whole block


Cylinders 1 and 2-


Cylinders 3 and 4-



Also, how should i clean the cylinders? Simple brake cleaner?

 

[KEVS79]

If you have zero compression on all the cylinders wouldn't that indicate a timing issue? Maybe the timing belt has slipped and valves are opening at the wrong time. Just seems weird that it would be all cylinders.

 

[jb451]

If you have zero compression on all the cylinders wouldn't that indicate a timing issue? Maybe the timing belt has slipped and valves are opening at the wrong time. Just seems weird that it would be all cylinders.

Yeah, i thought the same exact thing, and the timing was off 1.5 teeth, so i readjusted it and still zero on all of them.

 

[KEVS79]

Yeah, i thought the same exact thing, and the timing was off 1.5 teeth, so i readjusted it and still zero on all of them.

Maybe the valves hit the pistons and bent the valves? Not sure if it is an interference type engine or not.

 

[jb451]

Maybe the valves hit the pistons and bent the valves? Not sure if it is an interference type engine or not.

Anything is possible i suppose…. I believe it is an interference motor. Guess a machine shop should be able to tell me. I hope its just the valve seats though.

 

[KEVS79]

Anything is possible i suppose…. I believe it is an interference motor. Guess a machine shop should be able to tell me. I hope its just the valve seats though.

Normally if that happened you would see a spot on the pistons where the valves "kissed" them. You may take a close look and see.

 

[jb451]

Not so much as a scratch..

 

[jb451]

Alright, got everything cleaned up the best i can, the valve seat most definitely did fall out on this cylinder… My question is, with the gouges that are in this piston, will it kill the motor? They are pretty small, and i can see no visible damage to the cylinder wall. I'm trying to weigh my options, i feel like if i try to have the piston replaced, i might risk more damage than just leaving it in there (i've only disassembled an engine shortblock once before, not a whole lot of experience.)

I know its pretty hard to see, but its the left piston in question, just to the right of the dome.

 

[KEVS79]

So are you saying you think the valves hit the pistons due to the timing belt slipping? One way you can check for bent valves is to turn the head over with the combustion chambers facing up and the cam(s) removed. This way all the valves are shut. Then take some washer fluid and fill the combustion chambers with the fluid. Let is set over night and see which ones are low/empty and if the washer fluid is in the intake or exhaust on those valves. Then you know which valves are bent. I have replaced the bent valves, hand lapped them in and reassembled and drove like a champ.
As far as the piston goes. I can't really see the damage, but if it is just on the top I would think you could just smooth it to prevent any hot spots and move on.

 

[jb451]

So are you saying you think the valves hit the pistons due to the timing belt slipping? One way you can check for bent valves is to turn the head over with the combustion chambers facing up and the cam(s) removed. This way all the valves are shut. Then take some washer fluid and fill the combustion chambers with the fluid. Let is set over night and see which ones are low/empty and if the washer fluid is in the intake or exhaust on those valves. Then you know which valves are bent. I have replaced the bent valves, hand lapped them in and reassembled and drove like a champ.
As far as the piston goes. I can't really see the damage, but if it is just on the top I would think you could just smooth it to prevent any hot spots and move on.

No, there was no contact between valve and piston, bits of the valve seat actually fell into the chamber, and got caught between the piston and the head, causing the gouges in the piston. Ford used valve seats in the aluminum heads that were originally for iron heads, and over time they would crack and pieces fell into the CC. I took the heads to a head shop today and the guy confirmed for me that there weren't any bent valves, just the busted seats. So should i just take some emory cloth to it to clean it up?