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Re-ring an engine
Posted by: brocklanders ()
Date: February 19, 2012 10:09PM

So on top of a pinging issue, my car was (Burning?/Leaking?) oil at the tail end of last year. The rear main seal was for sure leaking, I have the new seal and will do that soon. After sitting for a few months, I took a peek down #1 cylinder to see what kind of carbon I was dealing with, and saw a small pool of oil. My limited experience tell me oil getting past the rings isn't good, so I'm wondering what exactly I'm getting into here. I have to find a way to do a leak down test this upcoming week, but my last compression numbers were:
1: 165
2: 155
3: 180
4: 150
5: 170
6: 165

These haven't changed much since my last check a few years ago, but lets assume that the rings are worn. Can I simply pop out the pistons, hone, re-ring and go for it? I'd be checking out of round and taper at the same time, but I'm just wondering what to expect IF it even is rings.
FYI: I'm planning on removing the heads soon to deal with another issue, hence why I'm just trying to research this now.


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: brentc ()
Date: February 19, 2012 10:31PM

Oil in the combustion chambers would certainly ping- doesnt take much either....

Judging from your compression numbers, the rings oughta be fine but if theres a lot of oil, its coming from somewhere, I think it may be possible the engine had been reringed and the oil control rings havent seated properly maybe- a common rering issue. Your commets regarding the rusty head nuts suggests this isnt especially likely, or was done a VERY long time ago.

Might be worth pulling the rocker covers and seeing how loose the valves are in the guides, you might find that the oils coming past the guides or from a defective or modified top cover baffle via the PCV system as well- both are easy to deal with usually, guide seals or a different baffle are easy repairs.

IS there much oil in the air cleaner and PCV tube?

Reringing is in my opinion a last resort repair because usually they break rings shortly after. This shouldnt happen but seems to for a lot of people under 20k post rering.

I will be following your progress with interest!

Brent

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Re: Re-ring an engine
Posted by: Johnniespeed ()
Date: February 19, 2012 10:51PM

Click the easy button.[www.vairshop.com]

John

1962 Rampside
Powered by Injected Vortec 4.3

Sunny Suburban Sparta Michigan.

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Re: Re-ring an engine
Posted by: Spectre ()
Date: February 19, 2012 10:52PM

Why does a re-ring job cause broken rings? Only thing I can think of is 1) carbon not removed from ring grooves and 2) ridge not removed from top of jug.

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Warner Robins, GA (15 miles south of Macon)

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Re: Re-ring an engine
Posted by: Frank DuVal ()
Date: February 19, 2012 11:14PM

I'm with David. Clean the pistons, remove the ring ridge and hone. I have re-ringed many engines (including Corvairs) and never had a ring breaking issue.

That was the poor man's rebuild back in the 60s and 70s.

Not removing the ring ridge will break the top ring.

The compression rings appear to be good in your compression readings. But, the oil control rings may be stuck or worn out (why, I don't know!). But a cleaning and honing should fix it.

The proper way would be to measure the cylinders with a bore gauge once they are off the engine, and measure the pistons. But we never had that equipment back in the day. Just measured ring end gap!

BTW, you can do this with the engine in the car (yes, I done it that way on Corvairs) , but it is way easier to do it on the bench. You do not pop the pistons out of the cylinders (unless you want to replace the rod bearings), pop the cylinders off the pistons, leaving pistons attached to crank. You will need a "take apart" ring compressor.

Don't forget the cylinder baffles on re-installation!

Frank DuVal

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Re: Re-ring an engine
Posted by: Richard ()
Date: February 19, 2012 11:15PM

Both pistons are short of their travel to TDC. Notice the top edge of the ring on the left piston. As the cylinder wears, the radius under the ridge is matched by the wear on the top of the ring. The new ring on the piston at the right has a sharp new edge. When the piston reaches its full height, the ring will bind and either bend, break or the piston land can break.

The ridge should always be cut off, but no one ever does. If the cylinder taper is low and the ridge is small, sometimes, some people get lucky.

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Re: Re-ring an engine
Posted by: brocklanders ()
Date: February 20, 2012 12:19AM

OK. so the consensus so far is what?
Determine Via a leak down test if the rings are in fact bad, Then remove the cylinders and re-ring the pistons, making sure to properly hone them, doing some measurements at the same time AND removing the ridge ring on the top oil control ring?

Brent: No oil whatsoever out the pcv, the heads are coming off, and Very likely going to the machine shop. would the head issues mentioned be taken care of then?

I'm mostly trying to determine if the issues are from simply bad heads, or bad rings (my luck: both!)


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: Brizo ()
Date: February 20, 2012 05:13AM

Brocklanders, The most common cause of broken rings in a "recently rebuilt" Corvair engine is worn ring lands,commonly caused by --long term detonation. The excessive ring groove clearance lets the new rings slap up and down, cracking from the impact. Especially if detonation is still occuring. When the engine was torn down several of the old rings most likely were broken.

Dan Brizendine,
'64 8door Greenbrier 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"

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Re: Re-ring an engine
Posted by: MattNall ()
Date: February 20, 2012 05:26AM

He'll find out when he pulls the barrels!

No visual signs of problems

No broken rings

New rings show a decent "side clearance"


Good to go!





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Re-ring an engine
Posted by: Ratt643 ()
Date: February 20, 2012 02:45PM

Oil possably coming from worn valve guides and bad intake seal?

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Re: Re-ring an engine
Posted by: Andrew ()
Date: February 20, 2012 02:51PM

You can use thicker base gaskets instead of a ridge reamer. That'll prevent the rings from contacting the step.

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Re: Re-ring an engine
Posted by: brocklanders ()
Date: February 20, 2012 03:15PM

I replaced the intake valve stem seals about 3 years ago when I did new pushrod tube o-rings (which are leaking again!)

So, parts wise: Can I safely order new std piston rings, new head gaskets (1 set or 2 to lower CR re: pinging issues?) and thicker barrel base gaskets (what thickness?) to prevent the top ring issue.
also: Would a thicker base gasket achieve the same things as doubling the head gaskets to lower CR?

Great info here...thanks...

Also: Any quick test to determine WHERE the oil is coming from before I get ahead of my self for a re-ring when the heads need re-done?


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: Gregory_Miller ()
Date: February 20, 2012 05:30PM

Wow, did you put Viton O-rings in? They shouldn't be leaking already if so. If you have "spare" money lying around, Ray Sedman can re-design the head quench area of your heads for better ping control. Corvair Performance page of American-Pi.com with head machine services

Greg Miller
Eugene, Oregon

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Re: Re-ring an engine
Posted by: brocklanders ()
Date: February 20, 2012 05:52PM

I'm pretty tapped as far as cash and corvairs are concerned. I'm already stretching it here. Yeah, they started leaking again last year, I'm not completely sold on Viton stuff so far!

P.S: I did search for this: but are the heads the only thing preventing the jugs from being removed? AS in just a rubber mallet and tap them out?


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: B-Vair ()
Date: February 20, 2012 06:15PM

Here's a pic on one of my spare barrels hopefully showing the ridge...I need a new point and shoot smiling smiley)...



Edited 1 time(s). Last edit at 02/20/2012 06:15PM by B-Vair.

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Re: Re-ring an engine
Posted by: MrChips ()
Date: February 20, 2012 06:33PM

Once the heads are off, you shouldn't have to 'tap' the cylinders out.
They should pull almost all the way off (carefully).

Make sure, though, that you measure the bore of the cylinder at the bottom - you can break the rings trying to put them back 'on engine'. Also, the LM cylinder notches can cause ring trouble, too. Whatever your choice, just be careful, and get as much diagnostic data as you can before dismantling.


Where Santiago and Live Oak Canyon intersect in Orange County, Ca

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Re: Re-ring an engine
Posted by: brocklanders ()
Date: February 20, 2012 08:25PM

cool, thats a great shot, thanks!
Yeah I wonder though would a leakdown test verify I have heads or ring issues? I'd like to have a plan BEFORE the heads even come off..


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: MattNall ()
Date: February 20, 2012 08:37PM

Leakdown test would verify Compression ring leakage... or Valve seat / face leakage...

1 Do all the cylinders have oil puddle in them?

2 Does the engine ever smoke bluish smoke?

3 Are the plugs clean or carboned up?





MODERATOR
Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
.............................PG...................................Turbo

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Re: Re-ring an engine
Posted by: brocklanders ()
Date: February 21, 2012 12:36AM

#1: Will check all tomorrow
#2: I've been told yes it does smoke blue
#3: Again, tomorrow

Question: I found an old rig I made up that is basically a spark plug cored out and sealed so I can thread in a hose to the cylinder and release compressed air. I realize this isn't a proper leak down tester, but would this accomplish my goal?
ie: finding out if there is leakage past either the valves or the rings.


1968 500 coupe 110 pg
1967 Fitch Sprint 4 door
Bowmanville, Ontario, Canada

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Re: Re-ring an engine
Posted by: Gregory_Miller ()
Date: February 21, 2012 01:35AM

That should do the trick, just make sure both valves are closed and when you pressurize cylinder if it's at TDC it will try to move down, so maybe rotate it to BDC of each cylinder under test... IE end of power stroke.

Greg Miller
Eugene, Oregon

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