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Popping Smoke

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
Looking at that end gap I do not think you have any choice but to at least pull that piston / rod out. Typical gap is .016 - .020.
 

gr8scott

Contributor
Bronco Guru
Joined
Jul 1, 2011
Messages
1,823
What would that mark look like? From what I can tell, the engine has never been apart.

You'd have to clean the carbon off of one, but it would look something like this:
 

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Lawndart

Lawndart

Sr. Member
Joined
Nov 23, 2014
Messages
836
Loc.
66030
Took time to drop the pan and punch #8 out this afternoon.
Top ring gap at 2 o'clock
Second ring at 12 o'clock
Oil ring at 12:30

Top ring would not rotate in groove, nor would second. It wasn't a solid-hard stick, but I could see some issue at the stuck region (approx 8 o'clock).
42818173014_e2d2921be7_c.jpg


I was able to work the ring out without much trouble. Note the darkened area on the ring at the stuck region.
29663965748_4bee142a4a_c.jpg


The debris fell out with a touch of the pick...
41727050000_18a9a75427_c.jpg


Looks like head gasket material to me %)

So... headgasket fails and some of the gasket material gets jammed in the compression rings, causing the rings to stick. This reduces compression and causes blow-by and burning of whatever the gasket failure allowed into the chamber.

Clean and reassemble with old rings or new rings for this piston? Remember, rebuild in the winter, but probably 3-4 thousand miles down the road (if all goes well).
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Whats the ring gap with the ring in the cylinder without the piston. It looks like the ring is no longer symmetrical. The ring is no longer the same width all the way around. What did the rod bearings look like?
 

Powerbyford

New Member
Joined
Jun 8, 2018
Messages
34
Loc.
Garden City, MO
Clean up the piston and ring well and put it back on the piston. See how easy it moves then. You can probably get by for a few miles until the winter if it no longer hangs up and has normal spring back. You are risking scoring the cylinder wall which could make that block into scrap metal, so get new rings on it if in doubt. Unless you plan to swap that block out during the upcoming rebuild and don’t care.
 
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Lawndart

Lawndart

Sr. Member
Joined
Nov 23, 2014
Messages
836
Loc.
66030
Things are soaking tonight. I plan on cleaning, inspecting and measuring tomorrow. I ordered rings and gaskets. Certainly don't want to bugger the block. BTW, bore looks good.
 

gr8scott

Contributor
Bronco Guru
Joined
Jul 1, 2011
Messages
1,823
You plan on de-carbonizing the piston tops?

[youtube]ZlGgkJQJM90[/youtube]
 

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
I'm confused how the end gap was so large when in the bore photo but it is not damaged. Like Rusty said square up that ring in the bore without a piston and measure the gap.

You can't just put new rings you need to break the glaze in the bore using a ball hone. The new rings won't seat without a textured finish.
 
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Lawndart

Lawndart

Sr. Member
Joined
Nov 23, 2014
Messages
836
Loc.
66030
Update -
- New rings placed in cylinder - proper end gaps noted (.016 would fit between top ring and 0.020 between second).
- New rings installed.
- Cylinder lightly honed.
- Installed piston and head last night.

Did a leakdown since I did not have the push rods installed. Measure about the same as the others (rings not seated).

I cannot explain the large end gap that was noted. Cylinder looked fine. The rings were certainly stuck from that gasket material.

I plan on removing other head, clean, lap, install new valve stem seals and of course new gasket :)
Hoping to be completed this coming weekend.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Glad your moving forward. this should buy you some time to put together your future engine on your time and pay check.
 

tirewater

Contributor
Sr. Member
Joined
Jan 28, 2011
Messages
1,040
Loc.
San Francisco Bay Area
Heh, hopefully 'lightly hone' meant didn't really hone. :) I wouldn't want a bunch of slurry falling on my crankshaft.

Update -
- New rings placed in cylinder - proper end gaps noted (.016 would fit between top ring and 0.020 between second).
- New rings installed.
- Cylinder lightly honed.
- Installed piston and head last night.

Did a leakdown since I did not have the push rods installed. Measure about the same as the others (rings not seated).

I cannot explain the large end gap that was noted. Cylinder looked fine. The rings were certainly stuck from that gasket material.

I plan on removing other head, clean, lap, install new valve stem seals and of course new gasket :)
Hoping to be completed this coming weekend.
 
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Lawndart

Lawndart

Sr. Member
Joined
Nov 23, 2014
Messages
836
Loc.
66030
Cranked - popped. Re-stabbed the diff.
Fired up.
Little smoke.
Several heat cycles.
No smoke.
Sacrificial oil drained.
Should be ready to drive tomorrow.
Thanks everyone!!
 
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