Rings never seated: At what point do I tear it down?

[metalmonkey47]

Welp, looks like it might be time to tear the LZ down.

 

 

I'm leaking oil from about every gasket. Compression test shows about 133psi on Cyl 1 and roughly 170 on cylinders 2-4. I've put about 10,000 maybe more miles on the motor and It's not gotten any better. I took my first reading with cyl 2-4 at normal numbers only a week after putting in the motor. Cylinder 1 never picked up. I've got just enough blow-by that It's leaking from the oil pan, and inspection plate on the front of the motor. Both new gaskets, both sealed with black RTV just to be sure. 

 

I've got no PCV since the U67 manifold has the EGR ports welded up, but I'm running a hose from the crankcase vent and valve cover straight to a catch can, that seems to work well. Not well enough to get all of those gasses out of the crankcase I guess.

 

 

It's a Z20 block with an 86mm bore, forged Mahle pistons, and low drag rings. I guess at this point I'm trying to decide if there's really any other explanation to my problem or if it's just shit luck, and the ring will never seat properly and I'll be stuck with low compression as long as I leave it as is. I just REALLY fucking hate leaking oil. It's ruined all of the fresh parts.

 

[wayno]

The catch can is vented, correct?

I would also check the 2 front head bolts, make sure they are still torqued to spec, I lost the threads in the headbolt hole closest to the thermostat housing, no water in the oil, but I was pressurizing the radiator.

I had to put a helicoil in that hole, I used an ARP head stud kit after that, no issues since.

[Stupid_fast]

Silly question ... did you set the valves? Did you try setting them to stock nissan hot spec and re-do the comp test?

 

 

My L20b has a TON of blowby when I'm hammering it, no PCV ATM ... but usually only when its edging over 180deg sideways clutch kicking over 6k rpm ...

 

 

What break-in method did you use?  I ran mine hard and they sealed up fine. 

[metalmonkey47]

The catch can is vented, correct?

I would also check the 2 front head bolts, make sure they are still torqued to spec, I lost the threads in the headbolt hole closest to the thermostat housing, no water in the oil, but I was pressurizing the radiator.

I had to put a helicoil in that hole, I used an ARP head stud kit after that, no issues since.

 

Correct, one hose in that joins in the center with the valve cover, then filtered out. I'll upload pics of the setup tomorrow afternoon. I have an ARP setup currently, but I'll double check torque.

 

Silly question ... did you set the valves? Did you try setting them to stock nissan hot spec and re-do the comp test?

 

 

My L20b has a TON of blowby when I'm hammering it, no PCV ATM ... but usually only when its edging over 180deg sideways clutch kicking over 6k rpm ...

 

 

What break-in method did you use?  I ran mine hard and they sealed up fine. 

 

Nissan spec isn't quite right with the Racer Brown cam. I haven't check them since the head was installed which is probably a major fail. But it's something I need to get on top of. I forgot the specs, but I'll find em. I know the best method is to set the lash measured at the valve.

 

I broke it in by initially running it up to temp @ 3K for 30 minutes. Turned it off, let it cool off and checked the oil/fluids. Ran it again for 30 minuets, same as before. Changed the oil/filter and I've been driving the PISS out of it ever since. It's seen revs as high as 8000, but only once. No power up that far with the tiny carb. I really beat this motor up. Like Datzenmike says, exercise builds muscles. 

 

 

My blow-by is a little much at idle. Not an appropriate amount. The oil cap even has oil residue around it and down the valve cover. And yet it's tight.

 

 

 

 

EDIT: I do enjoy goofing off in dark parking lots. I leave tire marks EVERYWHERE.

 

http://instagram.com/p/gx9_fJTSgp/

[wayno]

I don't know nothing about "low drag rings", but my machinist told me to drive it like normal for a few hundred miles and change the oil and filter, and then I was good to go, he told me that the quality of parts he buys these days is so good, that the rings are broke in when the block is put together.

I personally have never heard of running the engine up to 3000rpms for 30 minutes to break it in, but like I said, I have never heard of them type of rings either.

[EricJB]

Adjust the valves first. Take a comp test on #1. Squirt some oil in the cylinder and do it again. If the comp goes up, It's rings. If not, valves.

[Farmer Joe]

yank it, blow it apart, hone the cylinders to that have some fresh crosshatch and put some new rings on the pistons.

 

did you use cast or chromoly rings before?

 

until it saw boost, id put a set of cast rings in it. thats just me. they set in a lot easier than the chrome rings.

 

the 2 engines i built with chrome rings had compression issues like this too. they never quite set in right.

[metalmonkey47]

I don't know nothing about "low drag rings", but my machinist told me to drive it like normal for a few hundred miles and change the oil and filter, and then I was good to go, he told me that the quality of parts he buys these days is so good, that the rings are broke in when the block is put together.

I personally have never heard of running the engine up to 3000rpms for 30 minutes to break it in, but like I said, I have never heard of them type of rings either.

 

Being in the business of selling these parts, It comes with the understanding that *most* parts these days can be installed, and run. Little to no time spent wearing in, or breaking in. Even Exedy told me there was no necessary break in on their clutches when I called them, although I had always heard quite the opposite. I don't know much about low drag rings except that they exist and I have them.

 

I believe the idea of running for 30 minuets was to get all the oil circulated through the galleys, bearings, etc. Even though it was properly assembled and greased, it made sense to me. Especially after changing the oil before even driving the truck. The mixture of different looking things that came out was just pure nasty. Assembly lube, grease, etc. 

 

Adjust the valves first. Take a comp test on #1. Squirt some oil in the cylinder and do it again. If the comp goes up, It's rings. If not, valves.

 

Good point, didn't even think about that for some reason. Guess maybe I'm just too tired to be mulling this over in my head.

 

yank it, blow it apart, hone the cylinders to that have some fresh crosshatch and put some new rings on the pistons.

 

did you use cast or chromoly rings before?

 

until it saw boost, id put a set of cast rings in it. thats just me. they set in a lot easier than the chrome rings.

 

the 2 engines i built with chrome rings had compression issues like this too. they never quite set in right.

 

To be honest, I'm not sure but I'm confident that they were probably chromoly rings. The engine was built for tons of boost before I bought it and assembled it. It still will see it one day I hope, I'm just pushing it off until I have another car to drive and can afford to. 

 

Big block chevy ARP rod bolts, fully floating wrist pins, etc etc etc. This thing is just BEGGING to be flogged.

[Stupid_fast]

 

 

Nissan spec isn't quite right with the Racer Brown cam. I haven't check them since the head was installed which is probably a major fail. But it's something I need to get on top of. I forgot the specs, but I'll find em. I know the best method is to set the lash measured at the valve.

 

I broke it in by initially running it up to temp @ 3K for 30 minutes. Turned it off, let it cool off and checked the oil/fluids. Ran it again for 30 minuets, same as before. Changed the oil/filter and I've been driving the PISS out of it ever since. It's seen revs as high as 8000, but only once. No power up that far with the tiny carb. I really beat this motor up. Like Datzenmike says, exercise builds muscles. 

 

 

My blow-by is a little much at idle. Not an appropriate amount. The oil cap even has oil residue around it and down the valve cover. And yet it's tight.

 

 

 

 

EDIT: I do enjoy goofing off in dark parking lots. I leave tire marks EVERYWHERE.

 

http://instagram.com/p/gx9_fJTSgp/

 

True ... Just set to what racer brown said to.

 

Set at the valves ???  F* that, just measure with a feeler gauge between the rocker and cam.  CLOSE ENOUGH.  

Valve adjust is finnicky on L series.  I go to 2 skid pad events and less than 1000 miles and two valves are way tight !!!  

I usually set them before an event or after driving hard.  Minimum maintenance should be check the clearance every oil change and adjust as needed.

 

Valve adjust can have a huge effect on comp test!!  Cams, too.  I changed the cam and it dropped comp test pressure by 20psi.

 

 

I've *READ ON THE INTERNET* that running at steady RPM on fresh rings will cause them to seal improperly ... that warm it up to temp and then drive it HARD to about 7/10ths with varying RPM and engine braking ... but then again I read it all on the internet.

[datzenmike]

The 3K for thirty min. is a break in for the cam. All they want is good oiling until seated in. I would ignore that and start driving like breaking in the motor. As long as the revs are kept up there should be no problems with oiling. OR fire up on an old cam and break in a new one later. To seat the rings it should be done as soon as possible after a proper warm up. No not 8K but always increasing and decreasing speeds. Varying loads 2,000 to 4,000 range. Make it work. Lots of long decelerations and hard accelerations in 3rd.

[Stoffregen Motorsports]

My break in procedure ( for cam and bearings and rings and everything) is to rev the motor, gently, from idle to about 2K for about 5 minutes, then up to 3K for another 5 minutes. Do not hold the steady RPM, but rap the throttle during this procedure. Shut it off and let it cool, retorque the head and adjust the valves once it has cooled then fire it up and drive it gently, but at varying RPMs for the first 100 miles. When I say gently, I don't mean to drive it like a granny, you need to get on it a bit to fully seat the rings. And you should never fire it and hold the RPM steady for 30 minutes like you were told. Piston ring contact on the cylinder wall varies in altitude (the height of the bore from bottom to top) as the RPMs change. Harmonics in the RPMs allows the piston ring to be more focused on one area of the bore at a certain RPM and then at another area of the bore at another RPM.

 

I think you need to pull the head and check. Look for scratches too, as low drag rings are easy to crack upon install.

[banzai510(hainz)]

the guy who did my blocks put the rings in dry. He said the seat pretty much instantly but i have the cast rings. Moly ones take a longer time to seat.

as front the leaks in front and oil pan that I think is more or less how one puts on the gaskets and reck if its tight.I think if open vented it should have enough air to volume from the top valve cover and crank case vent to escape.

All mine leak a litle. I retorq them then they good for awhile.

 

Only thing is maybe the rings werent gapped correctly and maybe a ring land broke.

valeve seats noose or something else

[metalmonkey47]

My break in procedure ( for cam and bearings and rings and everything) is to rev the motor, gently, from idle to about 2K for about 5 minutes, then up to 3K for another 5 minutes. Do not hold the steady RPM, but rap the throttle during this procedure. Shut it off and let it cool, retorque the head and adjust the valves once it has cooled then fire it up and drive it gently, but at varying RPMs for the first 100 miles. When I say gently, I don't mean to drive it like a granny, you need to get on it a bit to fully seat the rings. And you should never fire it and hold the RPM steady for 30 minutes like you were told. Piston ring contact on the cylinder wall varies in altitude (the height of the bore from bottom to top) as the RPMs change. Harmonics in the RPMs allows the piston ring to be more focused on one area of the bore at a certain RPM and then at another area of the bore at another RPM.

 

I think you need to pull the head and check. Look for scratches too, as low drag rings are easy to crack upon install.

 

 

The 3K for thirty min. is a break in for the cam. All they want is good oiling until seated in. I would ignore that and start driving like breaking in the motor. As long as the revs are kept up there should be no problems with oiling. OR fire up on an old cam and break in a new one later. To seat the rings it should be done as soon as possible after a proper warm up. No not 8K but always increasing and decreasing speeds. Varying loads 2,000 to 4,000 range. Make it work. Lots of long decelerations and hard accelerations in 3rd.

 

 

the guy who did my blocks put the rings in dry. He said the seat pretty much instantly but i have the cast rings. Moly ones take a longer time to seat.

as front the leaks in front and oil pan that I think is more or less how one puts on the gaskets and reck if its tight.I think if open vented it should have enough air to volume from the top valve cover and crank case vent to escape.

All mine leak a litle. I retorq them then they good for awhile.

 

Only thing is maybe the rings werent gapped correctly and maybe a ring land broke.

valeve seats noose or something else

 

Sorry guys, I might be a little retarded, or I was too tired to be posting on the internet. I didn't hold it steady at 3K, but varied a little bit between idle, 2K, 3K. Not consistent, I was kind goofing off playing with it. I compression tested it after about 1000 miles, and 2-4 were about 160PSI with cyl 1 at about 130 psi.

 

Spoke with Master_o_turbonics (builder) and talked a little bit about valve adjustments that will probably need to be made, also going to get some block test fluid and look for exhaust in the coolant. Returque the head a little tighter, etc. He's convinced it's not bottom end, and to do with valves/seats/head gasket. A leak down/wet compression test will tell for sure. I'd just REALLY hate to tear into the motor right now. Might have some numbers tomorrow for reference.

[620Turbo4X4]

What oil did you use for your break-in?

 

You never want to use a synthetic for break in. Petroleum is the best, but finding it with a adequate amount of zinc for the cam not so easy... I used royal purple break in oil. I think amsoil also makes break in oil with zinc too....

 

My last engine was basically assembled dry with only a light coating of ATF on the bore and piston skirts. Sealed up much better than the slathering the pistons and rings with oil method.

 

Having a PCV valve will also help with break in by providing a slight vacuum on the rings. Helps cut down oil consumption, leaks, and makes your oil last longer.

[metalmonkey47]

What oil did you use for your break-in?

 

You never want to use a synthetic for break in. Petroleum is the best, but finding it with a adequate amount of zinc for the cam not so easy... I used royal purple break in oil. I think amsoil also makes break in oil with zinc too....

 

My last engine was basically assembled dry with only a light coating of ATF on the bore and piston skirts. Sealed up much better than the slathering the pistons and rings with oil method.

 

Having a PCV valve will also help with break in by providing a slight vacuum on the rings. Helps cut down oil consumption, leaks, and makes your oil last longer.

I used Valvoline 30W for the break in, and 10W30 after that. I'm now running Mystik JT8 15W50 that's got a high moly & zinc count. Part synthetic, but conventional throughout the first few thousand miles.

 

The motor/rings etc wasn't soaked, but lightly coated. The cam was broken in previously, it's an old 70's ground Racer Brown so it's seen some light use in the past.

 

My U67 intake has the EGR deleted and welded, so unfortunately there's no way to put a PCV valve on the intake unless you drill/tap a hole.

[datzenmike]

PCV valve won't affect a motor break in. It will affect it long term. No PCV means the motor gets dirty oil sooner and needs changing much more often. By dirty I don't mean dirt but diluted with water and combustion by-products and acids. If you can build a motor you can drill and tap a hole.

[metalmonkey47]

PCV valve won't affect a motor break in. It will affect it long term. No PCV means the motor gets dirty oil sooner and needs changing much more often. By dirty I don't mean dirt but diluted with water and combustion by-products and acids. If you can build a motor you can drill and tap a hole.

 

The U67 intake is only temporary, I'm trying to put $$$ together for Weber 40's that will run a PCV... but in the meantime I get all the water/moisture through the catch can. I emptied about 1/2 quart the other day. Left from about 1.5 oil changes. 

 

Future motor plans are to run a cut down L28 manifold, megasquirt, turbo, etc etc. But that's down the road.

[620Turbo4X4]

I don't agree that a PCV valve will not help with seating the rings, but everyone is entitled to their own opinion. From what I've read, racers/machinists if talked to, and personal experience, having a negative pressure in the crank case aids ring sealing. Anything that helps sealing keeps the rings in contact with the cylinder better which equals less blow by and oil getting by the rings. A simple google search of benefits of a PCV valve confirms this. Even drag racers use crankcase ventilation systems to achieve some negative crankcase pressure (header extractors and or dry sump oiling systems) and it is not so they can get 4000+ miles from their oil.

 

Not saying that a PCV valve is the cure, but every little bit counts. The right oil, course ness of the hone/crosshatch pattern for the rings, and proper break in are key.

 

The low drag rings should be ran hard for break in and are better suited for all out race engines.

 

I like your turbo plan. My next engine for my 620 will be turbocharged. You may want to consider making your own custom intake instead if cutting down a 280 intake. The z car EFI intakes have tiny 1-1/8" ports. I'm cutting one down a N42 myself for my N/A engine so I can shit can my weber. Hogging out the tiny ports to 1-3/8" is challenging and time consuming and going to 1-1/2" ports is out of the question.

[datzenmike]

There could be a negative pressure inside the motor if the valve cover vent were sealed up, but it's about the size of your finger and open to the inside of the air filter. Fresh air is drawn into the crankcase by a small vacuum leak at the PCV valve. If it could even be measured it would be very very small and only at idle or deceleration.

 

 

Dragsters have vented crankcases but not a PCV valve. There is going to be a huge amount of blow by in a 1,000 hp per cylinder dragster motor that has to be vented. The oil is changed too often for it to be contaminated.

[Stoffregen Motorsports]

I really doubt a low tension ring would be affected by a PCV upon break in.

 

I use WD40 for installing the pistons down the bore.

 

I haven't bought it in a while, but we used to use Pennzoil 25/50 GT Performance oil for break in.

[EricJB]

Possibly not the right hone for the rings. I have used the same rings on the same block with way different seat in times. Only difference was the hone.

[datzenmike]

MM if possible try a different head. This will (probably) nail down if upper or lower compression problems.

 

It's a Z20 block with an 86mm bore, forged Mahle pistons, and low drag rings. I guess at this point I'm trying to decide if there's really any other explanation to my problem or if it's just shit luck, and the ring will never seat properly and I'll be stuck with low compression as long as I leave it as is. I just REALLY fucking hate leaking oil. It's ruined all of the fresh parts.

As the Z20 came with an 86mm bore maybe it's worn too far for a hone and new rings? Was the ring end gap checked?

 

If it was not too worn maybe try some softer cast iron rings to get a good quick seal?

[620Turbo4X4]

There could be a negative pressure inside the motor if the valve cover vent were sealed up, but it's about the size of your finger and open to the inside of the air filter. Fresh air is drawn into the crankcase by a small vacuum leak at the PCV valve. If it could even be measured it would be very very small and only at idle or deceleration.

 

 

Dragsters have vented crankcases but not a PCV valve. There is going to be a huge amount of blow by in a 1,000 hp per cylinder dragster motor that has to be vented. The oil is changed too often for it to be contaminated.

I never said "dragsters", nor did I say they use PCV valves. I was using drag racers just as an example. Hell, even my lawnmower has crankcase ventilation. I also said in my first post that it would be a slight amount of negative pressure. Surely nothing that could be measured. The pressures inside the case are always changing with piston movement and blow by. If the valve cover breather were to be plugged as you stated there is no "could be" negative pressure. It would so high at closed throttle that the oil pan would most likely collapse (or implode).

 

I read and was responding to metal monkeys original post about the ring sealing problem and gaskets leaking oil everywhere. Just trying to be helpful to a fellow datsuner and cover some things that had not been previously mentioned. Take it or leave it. No need to make a pissing match over it, or put words in my mouth to try to make look like some sort of dipshit. I may be new to this forum, but I'm not new to building engines etc... I've been a mechanic damn near my whole life. Started with cars, then gantry container cranes, now I'm the lead millwright at the most productive grain terminal on the west coast. So... Believe it or not I do know a thing or two about turning wrenches.

[datzenmike]

...and I've been misunderstood. My mistake for being less than clear. Written words don't always carry the sincerity and meaning clearly. Drag racers or dragsters use crankcase ventilation but only added they don't use a PCV valve for the obvious reason that they are nothing like a car engine. Nothing more than that.   

[Stoffregen Motorsports]

If the valve cover breather were to be plugged as you stated there is no "could be" negative pressure. It would so high at closed throttle that the oil pan would most likely collapse (or implode).

Since we're splitting hairs...

 

If you plug the valve cover breather (and the block breather for that matter) you can still run a vacuum. Race motors get vacuum from the dry sump oil pumps. Not a lot, but some. And even though the breathers are plugged, air comes in around the crank seals. Sometimes you can actually hear it. It kind of sounds like a high pitched fart (pardon my French).

 

And for the record, I am not telling you you are not a good mechanic, I'm just clarifying a common misconception.

 

Now that we've gotten off topic, maybe we can get back to helping the metalmonkey.