Oil Smoke

[jimbrandberg]

I've got a 65 110 where the guy is unhappy with oil consumption and my test results are not clear.
Compression Test:
6 - 155 5 - 140
4 - 150 3 - 95
2 - 70 1 - 110
#2 Leakdown Test with 90# pressure only holds 10#. The loss is pretty much in the Intake and loosening the rocker arm didn't help. With a straight edge comparing the two it seems like Intake spring may be high or Exhaust spring may be low, I would like to think the Intake valve is down in the seat but when I compare it to others it almost seems like Exhaust valve spring is low. A bit confusing.
#3 Leakdown Test only holds 15#. Can't hear anything in Intake or Exhaust, maybe a little in the crankcase and maybe more from the head gasket but I'm not sure since it's hidden.
No oil on any of the plugs. Some carbon down in #6 between the ceramic and the outer shell which came out easily and dry not oily. I imagine the higher compression in that cylinder could be from carbon build up.
When I take it out for a drive I'm not seeing smoke even when coasting down a hill. I don't see any smoke out of the breather to the air cleaner or any oil. It doesn't smoke when I blip the throttle. If I hold the RPMs up to say 2500 at a steady speed then it begins to blow a lot of smoke out of the exhaust.
I'm trying to make a hypothesis. It is clear to pull the left head to see about the Intake loss in #2.
It's a little less clear to pull the right head to see about #3 losses. I should be able to hear the air better with at least the carburetor and top shroud removed.
I was thinking smoke at a steady speed would indicate a bad ring or rings but I would think oil would be showing up on a spark plug or there would be some sign of cylinder pressure in the crankcase. Perhaps it's because there's a difference between an oil control ring and a compression control ring.
If there's trouble with #2 Intake perhaps it's drawing oil past the guide but I can't help but think that would be the worst at a high vacuum time like at idle, not at a steady 2500, although I suppose vacuum at a steady speed is high as well since that's what vacuum advance is for.
This guy complained about oil consumption and no visible leaks before an event where he lost the fan belt and drove home 10 miles. It would be easy to just blame that event but it does not explain the lack of clarity and what conclusions would I be drawing if I didn't know of the event.
I suppose I should be thinking along the lines that the rings got hot and lost their temper but I sure wish I had some more symptoms to back that up. Perhaps if I fixed the valve losses I'd be seeing more crankcase pressure.
Thanks for helping me reason through.

[Dennis66]

To use that old saying "I feel your pain". From reading, I see a major concern with the having driven it 10 miles with no fan. Did he say if it was consming oil before the incident? Personally, with a situation like this, if I had to pull one head (pull engine), I'd pull both. Because of the overheating, oil consumpption, and crankcase pressure issues, while the heads were off, it isn't all that much more to pull th ecylinders and check the pistons / cylinders / rings to make sure everything's right.
I had the same issue with the Greenbrier I rebuilt several years ago. Started with pulling heads, to be cautious, I pulled the cylinders, and at that point wasn't happy with the way the rod bearings felt. Ended up with complete rebuild, crank from Clark's, rings, bearings, one cylinder I didn't like, valve job. Again, it all boiled down to the owner who did something they shouldn't have.

[Frank DuVal]

As I read it:
1. Customer complained about oil consumption being high. How much? I guess Jim does not know, and people have different ideas on what is high. 50 miles to the quart is usually considered high by most... *

2. Customer drove 10 miles w/o fan belt. This is never a good sign....

3. Jim gets car to diagnose. Now smokes visibly at 2500 rpm going down road ~ 50 MPH.

I'm in the rings and valve guides bad group. And who know what size the cylinders are, and now we do not re-use factory 164 cu in pistons due to cracking. Back in the 70s and 80s we still did re-rings on 164 but the occasional broken piston later cured us of doing that anymore... I would still re-ring a 140/145 cu in today!

* back in 1976 I drove a 50 Studebaker Champion 170 cu in with umpteen miles on it (hey, it was a $25 car!) and I used ND 40 because it got 50 miles to the quart. A little sluggish for that 6 volt battery system in the winter!

[66vairguy]

10 miles with no cooling ----- Agree the engine is damaged.

A person in our club bought a 140HP engine cheap that had been driven without a fan belt. When he pulled the heads the gasket was 1/4" into the lower side and 1/8" into the higher side past the original gasket surface (and deeper than the combustion area!! Yup CROAKED --- the head got so hot it literally melted and twisted on the cylinder !!!!!!!!!!

I would not have believed it if I had not seen it --- heads were junk.

So - pull the heads to look for overheating damage. That engine might literally be TOAST.

NOW I always tell folks -- when the FAN/GEN light comes on TURN THE ENGINE OFF NOW and coast off the road.

[Dennis66]

Rereading original post shows (I missed it) that the oil consumption was BEFORE the missingbelt incident. This bring us ot the unknown previous history of the car. While a borescope might tell a little more, IMHO it's time to tell the customer to get the wallet out.
This brings up an interesting question: One has to wonder - with no fan cooling, how is heat buildup / dissipation on a Corvair engine? Do the center cylinders heat up worse? Would make an interesting experiment with a digital temperature meter and a running engine with the belt and shroud removed.

[66vairguy]

Rereading original post shows (I missed it) that the oil consumption was BEFORE the missingbelt incident. This bring us ot the unknown previous history of the car. While a borescope might tell a little more, IMHO it's time to tell the customer to get the wallet out.
This brings up an interesting question: One has to wonder - with no fan cooling, how is heat buildup / dissipation on a Corvair engine? Do the center cylinders heat up worse? Would make an interesting experiment with a digital temperature meter and a running engine with the belt and shroud removed.

Probably the old GM SAE engine papers might provide the answer, EXCEPT that was the basic 1960 engine.

While the cylinders will heat up, the heads will heat up faster. When the fan stops you not only loose airflow, but the heads and cylinders are in an enclosure with the exhaust manifolds!! Hard to say how long you have at idle without a belt, but under load the heads heat up quickly.

[jimbrandberg]

Years ago my wife felt a bump on the gas pedal but didn't see the light and kept driving a 66 110 until it wouldn't go any more. It seemed to be okay but I didn't use it more than a few months after that or pull the engine when a guy bought it mainly for the Title I think.

[Frank DuVal]

Probably the old GM SAE engine papers might provide the answer, EXCEPT that was the basic 1960 engine.

Back in the early 80s a shop had a 60 parts car and back then no one wanted the 1960 80 HP engine parts. So at a Corvair gathering they towed the car in and had people guess how long the engine would run at full throttle with the fan belt off. Engine was still in the car.

So, how long did the 80 HP engine run at full throttle with no belt?

BTW, I thought this was the stupidest idea at the time, as I like to save all the Corvairs...

[Dennis66]

Just to clarify my statement, when I say "cylinder", I'm refering to th entire cylinder meaning Barrel, piston / rings / head and valves. Yes, the majority of heat is in the head, and particularly around the exhaust valve.

[jimbrandberg]

I used to be a snob about 80 horses but now I like them. My '60 80 HP PG does everything I need on 87 octane gas. The cute little cam bumps and valve springs are adorable. You gotta love full fin cylinders. It's running pretty good and the shift points are easily tailored with the foot which helps a lot.
Some would say a '60 4-door 80 HP PG is the original and still the best.
If someone wanted to blow it up I would fight them.

I've got a few '61 80 HP engines and a few pairs of '62 80 HP heads. Maybe a 80 horse with automatic chokes will come together one of these days.

I'm still mulling over the 110 smoky. The guy is not adverse to spending some money and we're not married to this particular engine.
I just picked up 4 .020 cylinders and I have 2 others. I might buy a set of cast pistons and if those cylinders don't pan out I have a lot of STDs...

I asked a while back whether people prefer Grant or Hastings cast iron rings but never got a clear consensus. A while back someone didn't like one or the other. You could PM me if you don't want to publicly besmirch anything.

It's not like I don't have other stuff to do but I should get going on Machine Shop services if I need them.

[66vairguy]

I asked a while back whether people prefer Grant or Hastings cast iron rings but never got a clear consensus. A while back someone didn't like one or the other. You could PM me if you don't want to publicly besmirch anything.

It's not like I don't have other stuff to do but I should get going on Machine Shop services if I need them.

First most piston rings are cast iron, plain or plated with chrome, moly, etc.

Over the years the most complaints I've read were about the DEEVES piston rings. Out of round in cylinder bore and other quality issues reported. I've never used them.

I used the Clark's chromed HASTING piston rings on one engine and they took awhile to seat - some oil burning until break-in

My Corvair machinist said the plain GRANTS piston rings were a high quality cast iron piston ring that seats FAST and he's used them in a few engines built for racing with no issues. Will they run as long as plated rings, no, but if they go 80,000 instead of 120,000 that is FINE with me.

Just my Jim.

[Tramp61]

Still waiting to hear from Frank about how long the 80 hp with no fan belt lasted before self destruction. Inquiring minds want to know.

[Wittsend]

Still waiting to hear from Frank about how long the 80 hp with no fan belt lasted before self destruction. Inquiring minds want to know.

Me too. Hey..., Maybe it's still running! Not only how long it ran..., but what was the failed part.

[Frank DuVal]

Well.... No one tried guessing.

The climactic end was the seals, assumed push rod tubes, since low on the engine, gave up and oil started pouring out at about the 28 minute mark IIRC. I was trying not to pay attention to the debacle. Then the fire started with the oil, so they had to extinguish the still running engine. The shop, who towed it away after this, said it still started so they could move it around their lot!

Heck, it's only been ~ 40 years, maybe it is still in their lot....