piston OK?

[rebuildit]

2000 Ford Escort, 2.0L DOHC 80,000miles
Want to know if my one piston is useable as is. The background is the car had coolant line leak, overheated, and stalled. Found blown head gasket and damaged head because of blow by, but may be able to repair/replace the head. The issue is one piston has three 'dents' about 1/8" wide by 1/32" deep around the top outside edge of the piston. The metal is rolled over almost like a screwdriver got jammed down between the cylinder wall and the piston. I cant feel any scratches on the cylinder wall where the dents are and dont see any pieces of debris. There are no marks on top of the piston. I'm working from my garage and dont have equipment to take the block out (and really dont want to). My question is if the damage on the piston looks bad enough that I should scrap the whole engine.


Thks![:/][:/]

Untitled

• rebuildit
• 17 Jun 2012
• 1

 

[Burnerman]

I think if you were to pop that piston out you'd see ring damage mate....the mark on the right side of the pic looks like there's a bit of aluminium picked up on the cylinder.
I would imagine with the sump off you could release that big end and bring it out of the top?
John

 

[Peter.N.]

You can test the piston for leakage by pouring some thin oil on the top and seeing how long it takes to drain away then comparing that time with the other cylinders. If there is no sign of damage on the bore it will likely be OK.

I have seen engines where the rings have broken up and worked their way up the side of the piston and eventually got onto the top and been hammered between the piston and cylinder head, I have also seen damage caused by a valve seat dropping out but yours doesn't look anything lake as serious. Could be someone dropped something down the plughole.

Peter

 

[Peter.N.]

Ooops - done it again

 

[Burnerman]

I would think there would be a chunk of ring missing in there - wouldn't you Peter?
Hence my comment about the debris top right......its really clean in there! Maybe thats the pot that had the head gasket failure.
John

 

[Peter.N.]

No actual hole in the edge of the piston but as you say, ideally the piston needs to come out, don't know what its like to get the sump off. When I have had this happen with diesels you can see a piston ring width sized hole at the edge of the piston and usually bits of ring embedded in the piston/head, but of course there is more room in it being petrol.

Peter

 

[Burnerman]

The sump comes off easily enough but I can't remember if there are baffles in the way.....if it was mine I'd want the piston out - or trade the car
John

 

[Mursal]

Yes ring broke and looks to be a bit of wear on the cylinder. Which cylinder is it?

Just be careful when you put the new rings on, that you grind the top edge a little to stop it breaking on the wear edge. Especially if its No1 or No4 as they tend tp wear the most.

Ensure all the piston is taken from the cylinder wall, emery paper and diesel probably best. Put a rag over the crankshaft journal to keep the wash off the shaft.

Clip-on boring bars are available to re-bore in the car, but need a skilled operator.

Nothings easy when you are in so deep. You have to spend time/money to ensure you dont have to do it all again

 

[rebuildit]

You can test the piston for leakage by pouring some thin oil on the top and seeing how long it takes to drain away then comparing that time with the other cylinders. If there is no sign of damage on the bore it will likely be OK.

I have seen engines where the rings have broken up and worked their way up the side of the piston and eventually got onto the top and been hammered between the piston and cylinder head, I have also seen damage caused by a valve seat dropping out but yours doesn't look anything lake as serious. Could be someone dropped something down the plughole.

Peter

I like the thin oil drain test. Simple and if it drains fast, that's a sign of ring damage.

 

[rebuildit]

I'll probably try to take the piston out to see if there is more damage. Thanks for the advice.