Reg Evans Posted July 22, 2017 Author Report Posted July 22, 2017 (edited) 47 minutes ago, Reg Evans said: I haven't formulated one yet,Mack. Still gathering info. My mechanic friend thinks it may be a bent rod. Edited July 22, 2017 by Reg Evans Quote
MackTheFinger Posted July 22, 2017 Report Posted July 22, 2017 (edited) That may be a possibility. I've seen a lot of bent rods in Harley engines but generally they'll spit out a wrist pin circlip while the piston twists around. Thanks for the Christmas wish but obscenity really isn't my thing.. Edited July 22, 2017 by MackTheFinger Quote
JerseyHarold Posted July 22, 2017 Report Posted July 22, 2017 Can a worn intake valve guide or seal allow just that cylinder to suck in more air than it needs, creating a lean condition? Quote
T120 Posted July 22, 2017 Report Posted July 22, 2017 Some light reading..."The Story Behind Cam Ground Pistons" Quote
55 Fargo Posted July 22, 2017 Report Posted July 22, 2017 5 hours ago, MackTheFinger said: I appreciate what you're saying with a few caveats. First, I started playing guitar about 1965 and still don't feel that I really know what I'm doing. I treasure constructive criticism and advice to better inform and make me a better guitarist. The same can be said for my mechanical abilities. I still learn from my own and others mistakes. Second, I've hired more than one person to work for me who had 20-25 years experience but apparently, just as with some of the mistakes I continue to make; they just did the same thing over and over and over. A third caveat is that I've worked on many vehicles that had problems the owner never noticed. I think some of these problems came on gradually and only became evident when either someone else drove the vehicle and noticed the problem or there was a catastrophic event like a collapsed, burnt piston. I get yah, been breathing air since 710 PM CST on 1961-11-21, and still sometime forget how to....LOL I figure you want to help out and see this through with Reg....thanx 1 Quote
55 Fargo Posted July 22, 2017 Report Posted July 22, 2017 4 hours ago, MackTheFinger said: The same fuel mixture is NOT necessarily delivered to all cylinders. There's one intake port per cylinder or there could be a leak between the head and any particular cylinder, neither of which would affect the other cylinders. Since the head had been removed prior to this problem that's where I'd look first. In the absence of any other evidence an overheated, burnt piston with collapsed ring lands supports the theory of a lean fuel mixture. You are correct, especially with #1 cylinder, furthest away from the fuel source, and potentially the leanest, not sure why this wasn't very evident to the poster you quoted. But yes the Siamese ports, being 3 and a stock 1 bbl carb induction with a 1 bbl to 2bbl adapter, could very well have very uneven fuel distribution especially to cyl 1 and 6.... 1 Quote
dpollo Posted July 23, 2017 Report Posted July 23, 2017 You may never know why that piston failed BUT one wise adage is : "Machinery has a LONG memory for abuse ." so this problem may date back many miles. All you can do now is to make sure everything in that bore is on spec. Everything. and don't overlook the possibility that a leaky fuel pump can cause troubles in #s 1 and 2 by washing away lubrication. 4 Quote
thebeebe5 Posted July 23, 2017 Report Posted July 23, 2017 The machinist I work with surmises that the issue started below the rings based on the wear or damage pattern of this piston. The lowest ring land was pushed up into the ring as the piston was pulled downward into the cylider bore. That could support the leaky fuel pump theory I suppose.... Definitely worth checking. 1 Quote
MackTheFinger Posted July 24, 2017 Report Posted July 24, 2017 (edited) I'm fairly comfortable with my lean cylinder idea but came up with a couple of other things to think about. Many years ago I noticed that the connecting rods in some Moto Guzzi motorcycle engines have small holes drilled in the upper bearing area to direct oil spray to the cylinder for cooling. I asked the only Moto Guzzi experts I knew at the time and they said that what I saw was normal, some engines were shipped that way and some weren't. I believe they finally decided that it wasn't necessary. Someone with better knowledge of the oiling system in the Mopar side-valve L6 could tell us if there's a possibility that an oil distribution problem could lead to a lack of piston lubrication in only one cylinder causing it to overheat. At the other end of my lean idea is the possibility that dpollo brought up, an overly rich mix washed the oil out of the cylinder and caused the piston to overheat. It's a little difficult to see how a leaky fuel pump would cause that, though. I'm not comfortable with the bent connecting rod idea because it brings up the need to explain how the rod got bent. The Harley engines I've encountered with bent rods had either been run too hard, worked on by someone with a 12 lb. hammer, or both. It seems unlikely that an engine with the reputation of the Mopar side-valve 6 under normal usage would bend a rod. Unless some other idea comes along I'm still leaning toward additional air somehow getting into the cylinder. Edited July 24, 2017 by MackTheFinger 1 Quote
Don Coatney Posted July 24, 2017 Report Posted July 24, 2017 All Mopar flathead engines have a squirt hole that sprays oil on the camshaft. A bent rod could possibly be caused by too much end play in the rod bearing or in the crankshaft bearings. Piston damage can also occur with a broken ring although this normally happens to a high mileage engine that is over heated. It might be possible that a chunk of the oil ring broke in the piston Reg posted. If this hunk of ring lodged between the piston and cylinder wall it might be possible to do the damage. Quote
Reg Evans Posted July 24, 2017 Author Report Posted July 24, 2017 (edited) )Thanks Don and Mack. Here's another bit of info on this engine. It has been balanced sometime before I bought it. All the rod caps have had material removed but this #1 is missing the most material. There were 3 reasons I took this engine apart. 1) There has been what sounded like a loud tappet noise for years shortly after I installed the engine. 2) A vibration of the engine above 45 mph. 3) And the progressive lowering of the compression reading in #1 cylinder. Despite those symptoms the engine has always run strong with lots of power (more than my other L6's) and has always had a quick throttle response. 30 lbs of oil pressure at warm idle. I've never had to choke it to get it started. Edited July 24, 2017 by Reg Evans Quote
medium_jon Posted July 24, 2017 Report Posted July 24, 2017 19 minutes ago, Don Coatney said: All Mopar flathead engines have a squirt hole that sprays oil on the camshaft. That's a cute little hole Quote
HotRodTractor Posted July 24, 2017 Report Posted July 24, 2017 43 minutes ago, Don Coatney said: It might be possible that a chunk of the oil ring broke in the piston Reg posted. If this hunk of ring lodged between the piston and cylinder wall it might be possible to do the damage. I think this might be the most plausible cause for the damage pictured. Generally if its overheated the damage isn't as localized as this damage is. This could be as simple as a crack that happened when it was first assembled and then over time it broke free, got lodged, and progressively worse with wear. Quote
knuckleharley Posted July 24, 2017 Report Posted July 24, 2017 (edited) 2 hours ago, Don Coatney said: All Mopar flathead engines have a squirt hole that sprays oil on the camshaft. A bent rod could possibly be caused by too much end play in the rod bearing or in the crankshaft bearings. Piston damage can also occur with a broken ring although this normally happens to a high mileage engine that is over heated. It might be possible that a chunk of the oil ring broke in the piston Reg posted. If this hunk of ring lodged between the piston and cylinder wall it might be possible to do the damage. Don,it has got to be said that you post the most informative photos of anyone I have ever seen. Someone should contact you about possibly publishing a book of your photos with text explanations. Seriously. Also,the piston in post 1 doesn't look much like the piston in your photo,so chances are it is an aftermarket piston,and of poor quality,which contributed to the destruction? Edited July 24, 2017 by knuckleharley 2 Quote
medium_jon Posted July 24, 2017 Report Posted July 24, 2017 57 minutes ago, knuckleharley said: Don,it has got to be said that you post the most informative photos of anyone I have ever seen. It is indeed amazing what @Don Coatney has photos of. As someone who takes about 1500-1800 photos a month, what is even more impressive--he can find them. 2 Quote
knuckleharley Posted July 24, 2017 Report Posted July 24, 2017 (edited) 7 minutes ago, medium_jon said: what is even more impressive--he can find them. Yeah,there is a lot to be said about that. I have ONE photo left of me sitting on my 40 Knuckle chopper in 72,and can't find it for the life of me. Edited July 24, 2017 by knuckleharley 1 Quote
medium_jon Posted July 24, 2017 Report Posted July 24, 2017 2 hours ago, knuckleharley said: I have ONE photo left of me sitting on my 40 Knuckle chopper in 72,and can't find it for the life of me. That is a real bummer @knuckleharley . I hope you eventually find it. Quote
knuckleharley Posted July 24, 2017 Report Posted July 24, 2017 23 minutes ago, medium_jon said: That is a real bummer @knuckleharley . I hope you eventually find it. I hope so,too. The bike got stolen in 76,so that one photo is all I have. Been looking for it for a while,and thinking about maybe making it my avatar. Might not,though. I was living kind of wild at the time,and not sure I want anyone from that time being able to recognize and locate me today from that photo. 1 Quote
MackTheFinger Posted July 24, 2017 Report Posted July 24, 2017 7 hours ago, Don Coatney said: All Mopar flathead engines have a squirt hole that sprays oil on the camshaft. A bent rod could possibly be caused by too much end play in the rod bearing or in the crankshaft bearings. Piston damage can also occur with a broken ring although this normally happens to a high mileage engine that is over heated. It might be possible that a chunk of the oil ring broke in the piston Reg posted. If this hunk of ring lodged between the piston and cylinder wall it might be possible to do the damage. Thanks for the pictures. The hole in the Guzzi rods look about like that. I would think a lower end loose enough to bend a rod woulda been hammering hard enough to hear it and cause the oil pressure to be nearly non-existent. Broken ring causing the damage, maybe.. My brain wasn't fully warmed up this morning or I'd have remembered that small block Chevy motors have a notch in the rod to squirt oil at the cam and some of it must be intended for the lower cylinder walls. I've been focused primarily on motorcycles since the late '70's and it's been a while since I paid much attention to automobile engines. Quote
MackTheFinger Posted July 24, 2017 Report Posted July 24, 2017 40 minutes ago, knuckleharley said: I hope so,too. The bike got stolen in 76,so that one photo is all I have. Been looking for it for a while,and thinking about maybe making it my avatar. Might not,though. I was living kind of wild at the time,and not sure I want anyone from that time being able to recognize and locate me today from that photo. I have a picture of me on my old knuck but don't want it public.. I'm still undercover.. 1 Quote
knuckleharley Posted July 24, 2017 Report Posted July 24, 2017 (edited) 5 minutes ago, MackTheFinger said: I have a picture of me on my old knuck but don't want it public.. I'm still undercover.. I was never undercover about or with anything. I was always right out there in the open,and if you didn't like it,you were free to leave. There may have been some people that didn't appreciate that. In 1981 I realized it was time to either quit getting loaded,or turn pro. I quit,and haven't gotten drunk or high since. Edited July 24, 2017 by knuckleharley 1 Quote
Reg Evans Posted August 2, 2017 Author Report Posted August 2, 2017 Okay, back to the subject. I finally got a new piston and rings. I weighed the new and old pistons with rings and pin. The old weighs 646 grams and the new weighs 642. My question is ....will a 4 gram difference be too much and throw the engine out of balance ? Quote
thebeebe5 Posted August 2, 2017 Report Posted August 2, 2017 27 minutes ago, Reg Evans said: Okay, back to the subject. I finally got a new piston and rings. I weighed the new and old pistons with rings and pin. The old weighs 646 grams and the new weighs 642. My question is ....will a 4 gram difference be too much and throw the engine out of balance ? I don't believe 4g would be noticeable in a low reving engine. JMO. I'd run with it. Your other option would be to weight match every other piston. IIRC you arent doing a complete tear-down, correct? 1 Quote
Reg Evans Posted August 2, 2017 Author Report Posted August 2, 2017 That's correct Thebeebe5. Thanks for your O ! I have decided to just replace the one piston. I just dropped off the rod at my local machine shop to just make sure the rod is NOT bent. I'll just install the new piston and hope for the best. The other cylinders had good compression over 100lbs ea. and good oil pressure. If this doesn't work out then I will spend the money to rebuild the original D22 230 that I have stashed in a corner of my garage. 1 Quote
Flatie46 Posted August 2, 2017 Report Posted August 2, 2017 Are you going to hone and re ring the other 5 cylinders? Quote
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