seafoam + idiot = blown compression ring

[TheBirdistheWord]

I am the idiot, I have used seafoam in the past with great results and still plan to use it.

 

Looks like I poured a little to heavy and revved a little too much. I heard rattling after 5 minutes on the road, and it got progressively worse for the next 5 minites it took me to get back. It didnt over heat or even stop running, I cut it and rolled it into the driveway. Started and ran it for an additional 10 seconds to verify there was an issue.

 

Pulled the head, nismo oversized carbon head gasket looked rather beat considering it had just under 6k on it. Pulled a chunk of metal out of the #3 cylinder, and it looks like piston took 50 direct bb shots. The dish is still evident, and it look as if I may be able to grind it down and flexhone the cylynders and possibly use it again... does anyone advise against this?

The bore on my l20 is at 86mm. The rest of the cylinders look flawless, less some carbon build up from an improperly tuned carb. My concern is that the #3 cylinder had damage being beyond the capabilities of a flex hone to fix. I'm considering eliminating any guess work and boring it another mm to 87mm and building a long rod stroker since stock z22 and z20 parts seem to be easier to find than dished 86mm l20 pistons. I've considered flat tops but pretty sure I'm going stroked, either way my CR is going to end up just under or around 10:1. I've always used premium, but I'm pretty sure I'm was getting pinging last summer on this build that was at approximately at 9.5:1. Albeit I may not know what pinging sounds like, I just know it sounded like a light metal tapping with the rpms even when it was running great.

Do I have to worry about piston damage with the higher CR in consistent 80+ degree daily driven days? I have a three core radiator which keeps overall temps reasonable at all times. Can I compensate with a heavier fuel mixture like manufacturers do with air cooled motorcycles? To achieve that, does anyone know what ratio am looking for with a wideband?

 

Any help or input it appreciated!

[ggzilla]

Generally, piston marks wont hurt.

 

 

You pulled a chunk of metal out if the cylinder. That could cause the rattle. What evidence do you have that the compression ring is blown?

[datzenmike]

You would have to dump a gallon down a running engine to get enough (maybe) to hydro lock it. Why Seafoam? Was the engine doing something that you felt the need for this?

 

Seafoam itself isn't going to cause marks on a piston, so something fell in while you were pouring or was already in there maybe inside the intake just waiting. In the air force this is known as FOD. Do you have an air filter on your carb?

 

What's wrong with the cylinder? Vertical scores and scratches? Maybe post a picture of it and the chunk of metal you removed.  

 

 

 

 

For the record I wouldn't run any of those 'miracle' engine cleaners through a good running engine. If your valves and combustion chambers are all carbon-ed up, then fix the cause.

[HRH]

Seafoam works great, but it's a detergent like anything else.  The standard Seafoam can, of which I sell a lot, does 10-20 gallons.  That's when mixed in the tank.  If you're dumping it into the carburetor while it's running, it's no different than running through a big puddle and sucking water into the engine.  Sure it's combustible, but not in a 500,000:1 ratio.  And it's a detergent so combustible means it will burn, but I'm betting it won't catch fire if you throw a match at a puddle of it.

 

I think it's quite possible you increased the space too much and the resulting effort was too much for the piston.  As much as it sucks, I'd say it's time to start over and at least bottle brush the cylinders depending on how deep the scratches, or have it bored.  I'd check all the ring lands on ALL the pistons.  Chances are you may have hurt the rest.

[datzenmike]

If a ring is broken, a liquid dumped down the carb wouldn't do this. If the piston top is intact yet marked up 'like BBs' hit it then it's foreign object damage.. FOD, and certainly not a piece of ring. To be a piece of ring or piston there would be a chunk visibly missing. If a loose piece (of something) was recovered, post a picture of it. If there is missing piston say so or post a picture of it also. You mention honing the cylinder, so does this mean bad scoring? Post a picture of it.

[Stoffregen Motorsports]

A pic of the affected area would speak volumes.

 

It sounds like you may be in over your head a bit. No offense, but if you don't know how to listen for pinging, you should probably have another set of eyes look at it before you complete your diagnosis. And then once it's back together, have your distributor checked out and possibly recurved, have your cam timing checked and your ignition timing set (at full advance) and then have your induction checked out for flaws.

 

Rings and pistons break from detonation. One form of detonation is "pinging" but the more deadly type of detonation is the high RPM detonation that you never hear. That is probably what broke your piston.

 

If you're worried about being able to clean the bore, you could use a light sandpaper and WD40 to scrub the area until the foreign material or discoloration is removed, then run your flex hone through it. After this cleaning and honing, if you can fell scrathces with your fingernail, you probably need to have it power honed or overbored.

[TheBirdistheWord]

https://www.dropbox.com/sh/tjoja46c8p6bdfz/AABbwQ6aQcQBoanMdc1nh8jea?dl=0

 

I always seem to have issues with photos on here, so here's a dropbox link to the photos.

 

first one is the piece I pulled out

second is a reference of all the pistons

third and fourth show the scoring and damage to the #3 cylinder and piston

fith is the chunk that is missing from the #4 piston 

and the sixth picture is of the whole car with my new rims!  :rofl:

 

Generally, piston marks wont hurt.


You pulled a chunk of metal out if the cylinder. That could cause the rattle. What evidence do you have that the compression ring is blown?

no other evidence of it being the ring other than the damage to the corresponding piston.

 

You would have to dump a gallon down a running engine to get enough (maybe) to hydro lock it. Why Seafoam? Was the engine doing something that you felt the need for this?

 

Seafoam itself isn't going to cause marks on a piston, so something fell in while you were pouring or was already in there maybe inside the intake just waiting. In the air force this is known as FOD. Do you have an air filter on your carb?

 

What's wrong with the cylinder? Vertical scores and scratches? Maybe post a picture of it and the chunk of metal you removed.  

 

 

 

 

For the record I wouldn't run any of those 'miracle' engine cleaners through a good running engine. If your valves and combustion chambers are all carbon-ed up, then fix the cause.

I dont see seafoam as a "miracle" engine cleaner.  I have used it in the past with astounding results, and in fact you can see in the photos it was working to a certain extent on the other pistons.  I do agree that I needed to fix the cause of the carbon build up to get the car running efficiently.  I believe I over fueled it because I was reading the plugs incorrectly, also, im speculating the rings may have not been seated properly because of a presumed "good," but leaky valved head being used for the break in and a couple thousand miles after that.  I am thinking these two things together are what created the boat loads of carbon, the head has been repaired and 6k put on it with the aforementioned nismo gasket and the result of that many miles is in the photos... I am running a weber dgv with a standard manifold and 1 inch filter 

 

there is definite vertical scoring, despite the cross hatching being readily evident.  I think this will ultimately be a blessing in disguise as I will be able to set the rings properly and tune the carb with a wideband with this rebuild assuming the crank isnt damaged

 

Seafoam works great, but it's a detergent like anything else.  The standard Seafoam can, of which I sell a lot, does 10-20 gallons.  That's when mixed in the tank.  If you're dumping it into the carburetor while it's running, it's no different than running through a big puddle and sucking water into the engine.  Sure it's combustible, but not in a 500,000:1 ratio.  And it's a detergent so combustible means it will burn, but I'm betting it won't catch fire if you throw a match at a puddle of it.

 

I think it's quite possible you increased the space too much and the resulting effort was too much for the piston.  As much as it sucks, I'd say it's time to start over and at least bottle brush the cylinders depending on how deep the scratches, or have it bored.  I'd check all the ring lands on ALL the pistons.  Chances are you may have hurt the rest.

this is exactly what I have been thinking!  looks like I definitely hurt the rest

 

If a ring is broken, a liquid dumped down the carb wouldn't do this. If the piston top is intact yet marked up 'like BBs' hit it then it's foreign object damage.. FOD, and certainly not a piece of ring. To be a piece of ring or piston there would be a chunk visibly missing. If a loose piece (of something) was recovered, post a picture of it. If there is missing piston say so or post a picture of it also. You mention honing the cylinder, so does this mean bad scoring? Post a picture of it.

slight chunck missing from the #4 cylinder which is REALLY strange to me.  doesnt look like enough material to make up the chuck in the photo

 

A pic of the affected area would speak volumes.

 

It sounds like you may be in over your head a bit. No offense, but if you don't know how to listen for pinging, you should probably have another set of eyes look at it before you complete your diagnosis. And then once it's back together, have your distributor checked out and possibly recurved, have your cam timing checked and your ignition timing set (at full advance) and then have your induction checked out for flaws.

 

Rings and pistons break from detonation. One form of detonation is "pinging" but the more deadly type of detonation is the high RPM detonation that you never hear. That is probably what broke your piston.

 

If you're worried about being able to clean the bore, you could use a light sandpaper and WD40 to scrub the area until the foreign material or discoloration is removed, then run your flex hone through it. After this cleaning and honing, if you can fell scrathces with your fingernail, you probably need to have it power honed or overbored.

I dont take any offense to that, I have learned everything I know about the internal workings of a combustion engine on this platform.  I have made a bunch of mistakes that have cost me a lot of time, money, and long trips on public transportation. :blush:   I have corrected or improved upon my mistakes every time so far, that's with a bunch of help from this forum!  I would definitely like to do the same this time!  my mechanical timing was on point, and the ignition timing was set properly and 12BTDC but I havent ruled out the possibility of a lazy vacuum advance or something else with the distributor.  It's a matchbox that I bought it used, and have put almost 15k on it since then.  I feel confident I can work this next build out if I go slower with smaller changes, use a wideband O2 sensor, and dont daily it while I am tuning it and breaking it in, all of those things being the opposite of what I did last time....  :poop:  And these are all things I have the flexibility to do now, so I would like to take advantage of it while I can so I can say later on down the road that its "still running and I am not in over my head"  :thumbup:

[TheBirdistheWord]

also, another thing I find to be a bit strange is the #3 combustion chamber on the head shows equal damage to the piston but the valves themselves look untouched other than some buildup

[Doctor510]

Check the head to see if you broke a valve guide.  From some where the motor sucked a bunch of bad stuff. The vertical scoring MIGHT be from the Seafoam knocking the carbon buildup from the back of the valves. Worst case, you blew a ring land (new pistons, rings etc.)  If you have never rebuilt one of the L series motors, you will soon.

[TheBirdistheWord]

Check the head to see if you broke a valve guide.  From some where the motor sucked a bunch of bad stuff. The vertical scoring MIGHT be from the Seafoam knocking the carbon buildup from the back of the valves. Worst case, you blew a ring land (new pistons, rings etc.)  If you have never rebuilt one of the L series motors, you will soon.

this was actually my first L build.  I touched everything from the crank out, had the head done professionally after It failed the first time.  It doesnt appear there was carbon build up on the back of the valves, just the combustion chamber.  ill look closer for the valve guide.  Doesnt that suggest the rings never seated to begin with?

[ggzilla]

> chunk that is missing from the #4 piston

 

That's bad. Have to replace the piston. Weigh the new piston and if it differs get the engine re-balanced.

 

Rings might still be OK, but a quick hone and new rings won't cost much.

 

 

> Doesnt that suggest the rings never seated to begin with?

 

Naa rings not seated are evidenced by the engine smoking bluish-white smoke.

[TheBirdistheWord]

 

> Doesnt that suggest the rings never seated to begin with?

 

Naa rings not seated are evidenced by the engine smoking bluish-white smoke.

 

which i definitely had progressively more and more the weeks leading up to this.  That would also explain why I had so much carbon build up the last time I pulled the head at 10k.  If I broke the motor in with a head that had leaky valves and wasnt sealing, the compression would have been off and if I understand correctly that would have created a low vacuum issue that could adversely effect the seating of a ring.  once I realized the head needed to be reconditioned it was too late and once I put a fresh properly rebuilt head on there it only exacerbated the weak seated rings symptoms.  I am better understanding how things operate, and just realized I was chasing this issue right from the beginning by breaking in the engine with a leaky head.  Looks like it will spend a decent amount of time at the machine shop between boring and assembly.  If the crank checks out, I am pretty dead set on assembling a stroker and dialing/breaking it in with the weber then seeing how far I can push it with carbs.

[datzenmike]

https://www.dropbox.com/sh/tjoja46c8p6bdfz/AABbwQ6aQcQBoanMdc1nh8jea?dl=0

 

I always seem to have issues with photos on here, so here's a dropbox link to the photos.

 

first one is the piece I pulled out

second is a reference of all the pistons

third and fourth show the scoring and damage to the #3 cylinder and piston

fith is the chunk that is missing from the #4 piston 

and the sixth picture is of the whole car with my new rims!  :rofl:

 

no other evidence of it being the ring other than the damage to the corresponding piston.

 

I dont see seafoam as a "miracle" engine cleaner.  I have used it in the past with astounding results, and in fact you can see in the photos it was working to a certain extent on the other pistons.  I do agree that I needed to fix the cause of the carbon build up to get the car running efficiently.  I believe I over fueled it because I was reading the plugs incorrectly, also, im speculating the rings may have not been seated properly because of a presumed "good," but leaky valved head being used for the break in and a couple thousand miles after that.  I am thinking these two things together are what created the boat loads of carbon, the head has been repaired and 6k put on it with the aforementioned nismo gasket and the result of that many miles is in the photos... I am running a weber dgv with a standard manifold and 1 inch filter 

 

there is definite vertical scoring, despite the cross hatching being readily evident.  I think this will ultimately be a blessing in disguise as I will be able to set the rings properly and tune the carb with a wideband with this rebuild assuming the crank isnt damaged

 

this is exactly what I have been thinking!  looks like I definitely hurt the rest

 

slight chunck missing from the #4 cylinder which is REALLY strange to me.  doesnt look like enough material to make up the chuck in the photo

 

I dont take any offense to that, I have learned everything I know about the internal workings of a combustion engine on this platform.  I have made a bunch of mistakes that have cost me a lot of time, money, and long trips on public transportation. :blush:   I have corrected or improved upon my mistakes every time so far, that's with a bunch of help from this forum!  I would definitely like to do the same this time!  my mechanical timing was on point, and the ignition timing was set properly and 12BTDC but I havent ruled out the possibility of a lazy vacuum advance or something else with the distributor.  It's a matchbox that I bought it used, and have put almost 15k on it since then.  I feel confident I can work this next build out if I go slower with smaller changes, use a wideband O2 sensor, and dont daily it while I am tuning it and breaking it in, all of those things being the opposite of what I did last time....  :poop:  And these are all things I have the flexibility to do now, so I would like to take advantage of it while I can so I can say later on down the road that its "still running and I am not in over my head"  :thumbup:

 

 

Great. Your photo account asks me to join in order to see them, lot of help that is. Try Photobucket or one that allows public viewing.

 

The missing chunk of piston should have been mentioned in the first post and would have eliminated the assumption that something went down the carb and did the damage.

 

Broken ring, and or piston land, can also be from overheating. This could have happened long ago and was pushed over the edge when seafoaming it. Detonation is the next probable cause but the piston will look more melted around the missing piece.

 

A head needing a valve job wouldn't have much to do with the break in. Vacuum isn't a factor. Rings are 'broken in' during the power stroke when they are forcibly thrust against the cylinder walls and rough surfaces are smoothed.  

 

The chunk is likely smaller because pieces were broken off of it while bouncing around in there. Wish I could see the pictures.

[JoeCool]

Seafoam works great, I use it about twice a year on all my cars, heck, it is the ONLY "magic fuel injector cleaner" I have found that actually does anything. But you pour it into the gas tank, not down the carburetor! It is not designed to work that way. I have found it works best when mixed in with 5-10 gallons of fuel, no more. Use that and spray the carb with carb or "intake" cleaner, a few short sprays at a time.

[thisismatt]

Seafoam works great, I use it about twice a year on all my cars, heck, it is the ONLY "magic fuel injector cleaner" I have found that actually does anything. But you pour it into the gas tank, not down the carburetor! It is not designed to work that way. I have found it works best when mixed in with 5-10 gallons of fuel, no more. Use that and spray the carb with carb or "intake" cleaner, a few short sprays at a time.

Actually, it is.  They even have instructions on their site, called the vacuum line method to draw it in through the intake.

[TheBirdistheWord]

It worked for me after I signed out, anyone with that link should be able to see those pictures, anyone else able to see the photos?  photobucket is cumbersome use, ill throw it on imageshack if this doesnt work.  I now think the draw through method is to only be used with injected vehicles that can properly distribute and atomize the mixture which i suppose would make sense.  

[Dolomite]

I'm quite sure seafoam has nothing to do with your problem. When my car sat for a few years it would barely start and ran like shit. I put a fuckton of seafoam in the tank with a few gallons of gas, it started rough but was noticeably better after revving it hard a few times. Knowing the su carbs function better with a load, I took it out on the freeway and redlined it through the gears. By the time I got home the car was idling properly and had quit the backfiring through the carb. Its the only fuel system product I've ever seen that does what the packaging says.

[datzenmike]

 

 

Barely a nick, certainly not enough to be anywhere near the top ring.

 

 

 

Not gouged. You know I would just clean the tops off those other pistons and put it back together with a new head gasket. Run it and then do a compression check. As long as all the cylinders are within 10% of each other, I say good to go.

 

I'm quite sure seafoam has nothing to do with your problem. When my car sat for a few years it would barely start and ran like shit. I put a fuckton of seafoam in the tank with a few gallons of gas, it started rough but was noticeably better after revving it hard a few times. Knowing the su carbs function better with a load, I took it out on the freeway and redlined it through the gears. By the time I got home the car was idling properly and had quit the backfiring through the carb. Its the only fuel system product I've ever seen that does what the packaging says.

 

Driving it regularly like that without seafoam will help keep it clean.

[TheBirdistheWord]

thats good news!  I was hoping for some advice like this.  Since I will have everything apart, is it worth getting it bored another millimeter, balanced and putting the Z20/22 parts in it?  Im curious if the slight displacement gain and increase stroke will be noticeable, or is the emphasis in proper fuel delivery?  For example, im bored to 86mm with two size larger main jets and a peanut head, if I anticpate going with ITBs in the future, would it be worth my while to stroke it? 

 

I am at the very minimum going to disassemble, hone, and re ring it, because I have good reason to believe I didnt break it in properly.  I was way too nice to it because I worried I would break something, even though I was aware that I should rev it all the way to 6 and let it engine break down through the rpm range, I just didnt but I know to do it right this time. 

[Dolomite]

 

 

 

Driving it regularly like that without seafoam will help keep it clean.

I drive it like I stole it nearly every time I'm in it. Datsuns are like women, they say they want a nice guy but in reality, they respond better when you're a bit of a dick to them.

[datzenmike]

What little damage there is looks like something fell into the engine and not detonation. Are you running an air filter?????

 

 

 

A stock L20B with a closed (peanut) head has a compression of only 8.9 and not 9.5. At a stock timing of 12 degrees it will likely ping as this is the setting for an 8.4 compression. Higher compression shortens the burn time so the ignition should be dropped a couple or few degrees and or run higher octane gas.

 

thats good news!  I was hoping for some advice like this.  Since I will have everything apart, is it worth getting it bored another millimeter, balanced and putting the Z20/22 parts in it?  Im curious if the slight displacement gain and increase stroke will be noticeable, or is the emphasis in proper fuel delivery?  For example, im bored to 86mm with two size larger main jets and a peanut head, if I anticpate going with ITBs in the future, would it be worth my while to stroke it? 

 

I am at the very minimum going to disassemble, hone, and re ring it, because I have good reason to believe I didnt break it in properly.  I was way too nice to it because I worried I would break something, even though I was aware that I should rev it all the way to 6 and let it engine break down through the rpm range, I just didnt but I know to do it right this time. 

 

 

The L20B is already at 86mm from the factory. If you 'rebuilt it' it couldn't have been bored if you are still at 86mm and was likely just a hone and re-ring.

 

For $30 you can get a cheap Felpro gasket and get it running.

 

When it's running, get that carb properly jetted, overly rich will carbon it up and carbon will retain heat and can be a cause of pre ignition, set the timing by ear if you have to till you do not hear any pinging, drive a few miles and then do a compression test with the engine hot. 

 

Now with those numbers in hand you have more information to make an informed decision. If the compression is reasonably high and even and all within 10% of each other, put some miles on it and re-test the compression to see if the number came up any.

 

 

Honing it again, which will be the second time at least, isn't advised. The bore is likely well worn by now and can be tapered or oval or both and even harder to seal.  See what compression numbers are first. It will only cost you $30 to find out. .

[TheBirdistheWord]

I had a L20b blocked bored .040 over, if im not mistaken the stock L20B is 85mm.  I bought pistons labeled 86mm .040 over/1mm oversized L20B pistons, a local machinist familiar with L6 motors did the work and installed the pistons.  I know what work I had done as I oversaw most of it.  I am now looking at the plugs that were in it at the time and it looks like the #3 plug is missing the ceramic piece it is supposed to have around the diode, I guess thats my foreign object!  The jetting it pretty close to spot on, as I mention before I didnt read the plugs properly and turned out the mixture screw too much.

[Stoffregen Motorsports]

The "mixture screw" is only for idle, so misadjusting it won't affect anything other than idle. Unless you're talking about the well jet in a pair of SU's.

[TheBirdistheWord]

well, that was an assumption on my part.  The only place the carbon could have came from is burnt oil from the rings if this carb is working properly, which I believe it is..... I was speculating I caused the problem because these motors seem to be very easy to build.  I think i am missing something..

[datzenmike]

Yes 86mm is a 1mm overbore, what was I thinking.

 

Still I say put together and run it. Get the mixture problem solved and continue driving it then do a compression test. This could very well be a good engine as is. There's an old expression... Don't throw the baby out with the bath water.