My ZZ4 burns alot of oil. It did it before and I changed the rings which were broken. But after I redid the engine it still burns, if I drive it a little hard it burns a quart every 50 miles. Now I did a compression check on the rings and they were all like 180-170psi, and the ones with the worst carbon were the best. When I port matched the heads and manifold I nicked the surface a little bit in some places would the smallest nick near the ports cause an oil leak that big? It only seems to smoke really bad when I put a load on the motor. Thanks.

 

maybe the oil control rings haven't broke in all the way??

 

This may be a stupid question but did you rehone the cylinders before you put new rings in? I know someone that didn't do that and then wondered why his engine was still smoking after he rebuilt it. And just because it has good compression does not mean the oil rings are working.

 

if you have a leaking intake gasket of the lifter valley side it'll burn oil, pvc system will cause oil burning too.

 

No I did not hone the cylinder, the cylinders still had the cross hatch in them. After I reringed the motor it has about 3000 miles on it so they should be broken in. IF it has good compression which it does, doens't that mean the rings are working properly? They are gapless so should seal a little better anyways.

 

since you never rehoned it i'd guess you trashed the rings, very often you can see cross hatch on high mile engines. leak it down and see what you come up with.

 

You should ALWAYS re-hone when putting new rings in, even if you only ran the engine for 5 min., the rings need the rough surface of a fresh hone to run against so they will round up and seal properly. A new ring may look round but it's really only touching the bore in a couple spots until it seats.

 

You may be able to save it by changing to a SAE 10W NON-detergent or plain ISO 32 mineral oil. If you cannot find a non-detergent engine oil, visit you local industrial lubricant suppler for a gallon + of ISO 32 lubricating oil (no sulfur, and no additives other than rust and oxidation inhibitors). They likely don't sell by the quart, and may not even want to break into a 55 gallon drum, but you should be able to find it somewhere.

Run the engine through the normal new ring break-in procedure, give the oil about 100 miles / two hours of break-in driving, and hope that the bearings don't see too much loading.

The normal ring break-in procedure requires starting the engine, allowing it to reach operating temnperature, then drive the vehicle with varying speeds and loads on the engine for the first 30 miles. Drive at light to moderate loads, avoiding a lot of throttle or high RPM.

With the engine still warm, drive the car in a lower gear in a few medium- to moderately heavy acceleration runs to about 55-60 MPH (4,500-5,000 RPM), then releasing the throttle and allowing the engine braking to slow the car to 10 mph or so (no brakes, please). This action produces combustion gas pressure behind the rings to force them outward on acceleration (ring seating phase), then creates a high vacuum on deceleration to draw oil past the rings into the chambers (cooling/flushing phase). Repeat this cycle about 5-6 times.

Drive the car normally for about 5-10 minutes, not exceeding 50 MPH/2,500 RPM to allow the oil to cool and flow normally and flush any metals away from the rings and ring grooves.

Then, perform a 2-3 full-throttle accelerations up to about 5000 RPM (55 to 60 MPH), then letting
off in gear and coasting back down to 10 MPH for further pressure on the rings against the cylinder walls, and the subsequent flushing/cooling.

Run the vehicle back to your shop, and drain the oil while it is still warm. Watch for metal particles that will likely drain with the oil.

Refill with your favorite detergent mineral oil of appropriate viscosity (don't exceed 10W30) and a good clean filter. Avoid wide-range viscosity oils due to their excessive polymer content. Also, avoid any oil filter with orange paint on it. Plan on another 500 mile oil change, then check your oil consumption again.

Aside from that, your option is to disassemble the engine and glaze-break the cylinders. You'll have to decide if you want to potentially save a tear-down or not.

 

I'm not recommending this but I remember reading about something Chevrolet did back in the mid-50's when they had a problem of not putting a proper cylinder finish on there small blocks and the rings would not seat, they told the dealers that if a customer came in complaining of excessive oil consumption that the fix was to pour some mildly abrasive Bon-Ami cleaner down the carb and that would get the rings to seat. Anyone else ever hear of this?

 

Nope, but that doesn't mean it hasn't been done. I had an old acquaintance (now deceased) that swore the best way to decarbon an engine was with uncooked rìce through the intake at nearly full throttle. He said he had cleaned up several flatheads that way, back in the day.

I would think that an abrasive such as that would accelerate wear, but maybe in the wrong direction. It would be difficult to make circumferential scuffs in cylinder walls with the piston moving only longitudally, and I'd think the oil wouldn't be much good after that kind of contamination.

EDIT: Goofy board filter. I can't even use the word "rìce" in the proper context...

 

Vader why do you say to stay away from anything over 10W-30. Since I live in florida wouldn't it be better to use a good 20W-50?

 

Because that that 20w50 is too thick for anything with close bearing tolerance...I live in Florida also and run 10w30 Mobil1.

Another thing when that cranks is spinning hitting that thick oil it cause all kinds of affects, one being a loss of HP.

 

Tim,

Mineral oils have a nasty tendency to lose viscosity when heated. Something about a poor VI that just doesn't cut the muster in an engine (or anything else, for that matter). In order to combat this, oil blenders mix in polymers that are effectively long chain molecules that are temperature sensitive. These molecules curl and uncurl as temperature changes, taking up less or more space (to effectively "thicken" the soup). Unfortunately, their temperature sensitivity also make them prone to burning, which creates sludge and ash. This contaminates the oil (and engine) and reduces the viscosity stability (VI) of the mixture as these molecules burn. At about 3,000 miles of normal driving, there are barely enough polymers left to control viscosity at higher temperatures. And this is only because too many polymers are added, so that enough are available at the end of the drain interval to prevent engine destruction. The rest are all in the filter or packed into the recesses of your engine as sludge and varnish.

The wider the span of viscosity, the more polymers are required to maintain that VI. 10W30 is essentially 10W mineral oil with enough polymer to control the viscosity to 20 basis points (making it act like SAE 30 when hot). 20W50 is basically 20W oil (which is better), but needs more polymers to control the VI for THIRTY basis points, or to SAE 50. This range tends to create even more sludge and varnish, to the point of being a problem. The greater the viscosity index range of a mineral oil, the more chance of premature oil contamination.

Synthetics suffer none of these problems, since the synthesized molecules are less prone to reduction as temperature increases. A 10W synthetic will have a given viscosity at 0°C (32°F), and will have nearly the same viscosity at 40°C (100°F) or 100°C (212°F). Since mineral oils are commonly rated at 0°C, 40°C, and 100°C, the allowable viscosity measurement lowers as temperature increases. An oil with an SSU (Saybolt Seconds, Universal) viscosity of about 150 seconds at 40°C is considered in the range of SAE 10W. That same oil at 100°C will test at about 40 SSU, and is still an SAE 10W. An SAE 40 mineral oil will test at around 700 SSU and 75 SSU, respective to the temperatures. A synthetic (that changes less with temperature) will test at 130 SSU at 40°C and 75-80 SSU at 100°C. By the tests, the synthetic is actually a little less viscous than 10W mineral oil at the low range, and the same as SAE 40 mineral oil at the high range - all without any additives to contaminate the sump. The synthetic is just inherently a "multigrade" lubricant, based on the antiquated presumptions of the S.A.E. Their rating system is 100 years old, and a lot of the rest of the world has changed since then. That's why synthetics can provide better overall protection in both extremes and last longer. They don't contaminate themselves with burned additives, stay cleaner, provide better cold flow and lubrication, and don't lose viscosity anywhere nearly as quickly as mineral oils.

If you're planning to stay with mineral oils, try to use one that has the highest base stock viscosity for your ambient temperatures, and has the least amount of viscosity range rating, so the amount of polymers is as low as possible. A 20W30 would be ideal, if you can find such an oil.