1940plymouth Posted March 17, 2013 Report Share Posted March 17, 2013 The past few years my engine in the Plymouth has been smoking and using lots of oil. The oil was coming out of the breather so I figured it was rings. I ordered the new rings from Egge, (30 over) as I knew that the pistons were 30 over as the engine had been redone before I got the car almost 25 years ago. I also ordered a new headgasket and oil pan gasket. I got the rings from Egge and the gaskets from Andy Bernbaum. Last night after supper( Corned beef, cabbage and carrots with yellow cake and peanut butter frosting, my son and I took the head off, the oil pan was already off, and we removed the pistons and bearings. Five out of six pistons had the top ring broken and I had three out of six connecting rod bearings that were bad. Thankfully no damage to the cylinder walls and crankshaft, I also had one piston that part of the lip was broken right off between the top ring and top of the piston, again, no scoring of the cylinder wall. I am going to order the pistons and connecting rod bearings (10 over) tomorrow from Egge. What is amazing is that this car ran, started good and still got from point A to point B and back to point A. A week ago today I had her out to go to breakfast, the place I went is up in the mountains and a good steep mile and a half climb on the way, I was able to make most of that climb in high gear. Just like the old Timex commercial. "Takes a licken and keeps on ticken" Quote Link to comment Share on other sites More sharing options...
55 Fargo Posted March 17, 2013 Report Share Posted March 17, 2013 Wow Bob, glad you caught this now, before any major damage. Most likely all was still pluggin away, and you don't drive that engine too hard. Once you get things back together, gonna be a much better engine. Might as well have the head shave a bit, get a little more oomph from that, nice for those hills. You will be able to most likely cruise faster now, if you could get a 3.73 set of gears, going 60 mph instead of 45 mph would be much nicer.. Quote Link to comment Share on other sites More sharing options...
DCurrent Posted March 17, 2013 Report Share Posted March 17, 2013 WOW! It's amazing it even ran. Looks like you caught it just in time. Quote Link to comment Share on other sites More sharing options...
TodFitch Posted March 17, 2013 Report Share Posted March 17, 2013 WOW! It's amazing it even ran. Looks like you caught it just in time. I am not amazed. These old L-6 engines can keep soldiering along with all sorts of issues. When I got my '33 the previous owner said everything works except the heater and that it had a rough idle. I drove it about 2,000 mile before I started digging into it. Heater did not work because the water pump impeller had become disconnected from the shaft so it wasn't pumping. And the rough idle was because valves were badly burned on 3 of the 6 cylinders. And all the pistons had broken rings with one missing a piece of the top land. Compression was zero in three cylinders and only about 50 or 60 in the other three. It was hard to start and it lacked power, but it still ran. So it doesn't surprise me when someone else has an engine that runs and is quiet but when opened up has a host of problems. I am not a fan of doing things like shaving the head or doing other mods for more power... The original power is enough for most of my needs and I'd rather keep the loading on the bottom end as low as possible. Seems like it just being nicer to that 80 year old design that way. Quote Link to comment Share on other sites More sharing options...
RobertKB Posted March 17, 2013 Report Share Posted March 17, 2013 Bob, interesting story. Looks like you got it just in time, especially if the engine is original to the car. I always feel if the engine is original to the car, it is nice to keep it that way if possible....................given condition and an owner's financing. You will really be able to enjoy the old girl even more! I agree with Tod also about the engine being tough and running well even when they are hurting. I also agree that there is no need to go looking for a couple more horsepower when what you have is adequate, especially for the easy driving you do on your local roads. Good luck with the rebuild and please keep us updated. Quote Link to comment Share on other sites More sharing options...
1940plymouth Posted March 17, 2013 Author Report Share Posted March 17, 2013 Thanks fellas, there isn't any shaving of heads or other hop up things going to happen. The engine is a 1941 P-12 that was in the car when we got it in Nov of 1988 Quote Link to comment Share on other sites More sharing options...
1941Rick Posted March 17, 2013 Report Share Posted March 17, 2013 If not shaving the head is not in the books, have it checked for true ness. .010 shave would not affect anything but the head gasket. I did the shave, twin carbs, and headers and with out dyno testing I do not think it made a lot of difference. For me it was the cool factor. But thats just me. 2 Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 17, 2013 Report Share Posted March 17, 2013 not that it really matters Robert but his engine is a 1941 model Quote Link to comment Share on other sites More sharing options...
JBNeal Posted March 17, 2013 Report Share Posted March 17, 2013 I don't have the specs memorized, but from what I've read here & there, the last few years they made the flatheads, the compression was increased to 8.0:1 (somebody correct me if I'm wrong) to squeeze about 30hp more out of the same engine, even briefly using a 2bbl carb. Over the decades these flatheads were manufactured, they underwent several design changes to improve performance. I am in agreement about being leery in trying to make power out of a slow-turning flathead 6 that is competitive with a fast-turning V8. But I look at the last years of manufacture to see what kind of modifications that Chrysler sold to the public as something to aim for in possible engine improvements. The only problem is that 'increasing compression ratio' is easier said than done. Were changes made to the engine block casting? crankshaft? connecting rods? bearings? pistons? Some of this can be verified by consulting parts manuals to cross-reference part numbers used from one year to the next, tracking any changes made (i.e. rear main seal changes). But even that doesn't always tell the whole story, as sometimes they would change part numbers on parts with no discernible changes (the Ram hood ornament on '50 & '51 trucks is a good example). I reckon bottom line is that ya do what ya feel safe doing: keeping things original to a certain year model, or making improvements for an older year model to a newer year model Quote Link to comment Share on other sites More sharing options...
TodFitch Posted March 17, 2013 Report Share Posted March 17, 2013 not that it really matters Robert but his engine is a 1941 model Yes, the last year that used the same rod and main bearings as my '33. First version of the Plymouth 218 came out the following year. Quote Link to comment Share on other sites More sharing options...
John Reddie Posted March 17, 2013 Report Share Posted March 17, 2013 Hey Bob, I'm glad that there is no major damage to the engine. Once you get it back together again, you can cruise those gorgeous rural roads that you have. Best of luck to you. John R Quote Link to comment Share on other sites More sharing options...
Daliant. Posted March 17, 2013 Report Share Posted March 17, 2013 (edited) If you haven't done so already you should pull a couple of main bearing caps off and check their condition while you have the pan off, it look like there was a lot of bearing material floating around in the oil, the mains might be wiped out as well. Edited March 17, 2013 by Daliant. 1 Quote Link to comment Share on other sites More sharing options...
1940plymouth Posted March 18, 2013 Author Report Share Posted March 18, 2013 Six new pistons and a set of rod bearings on their way from Egge. Each new piston comes with a new wrist pin and clips. Why were brass cotter pins used to keep the nuts tight on the rod caps and not regular cotter pins? Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted March 18, 2013 Report Share Posted March 18, 2013 Really recommending checking the mains, at least those that provided lube for the bad rod brgs. You're so close at this point, it'd be a shame to put it together without at least looking at them. 1 Quote Link to comment Share on other sites More sharing options...
1940plymouth Posted March 18, 2013 Author Report Share Posted March 18, 2013 Yes, we will check them this weekend Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted March 18, 2013 Report Share Posted March 18, 2013 I ordered the new rings from Egge, (30 over) as I knew that the pistons were 30 over as the engine had been redone before I got the car almost 25 years ago. That is why I recommend disassembly and measurement prior to buying engine parts. Five out of six pistons had the top ring broken and I had three out of six connecting rod bearings that were bad. You will be lucky if your engine does not require any machine work to clean up the bore and crankshaft. I do suggest you take measurements and do more than a visual inspection. The piston damage you found is very common to a high mileage flathead 6 engine. I found the same thig when I disassembled my original engine. 2 Quote Link to comment Share on other sites More sharing options...
greg g Posted March 19, 2013 Report Share Posted March 19, 2013 be sure you pay attention to the offsets on the connecting rods, mark them for which cylinder they come out of and also note the position of the oil spray hole that faces the camshaft. Quote Link to comment Share on other sites More sharing options...
TodFitch Posted March 19, 2013 Report Share Posted March 19, 2013 It was decades ago... But when I ordered pistons for my '33 from Egge I weighed them and they were not within factory spec with regards to relative weight. If you have an accurate scale it would be a good idea to see how close in weight they are. Another reason why an experienced machine shop can be a help as I would hope they would check that type of thing and balance them before installing. Quote Link to comment Share on other sites More sharing options...
pflaming Posted March 19, 2013 Report Share Posted March 19, 2013 (edited) I always thought balancing a engine was only for the performance folk. My local parts store informed me that balanced pistons, ris pins and rods was inexpensive insurance cause balanced they take alot of pressure off the bearings. So I did as was recommended. Ever one who hears the engine comments on how smooth it runs. I'm hard of hearing so any noise is good to me. I wish you well and like my machinist said, wash your hands alot, keep them clean! Edited March 19, 2013 by pflaming Quote Link to comment Share on other sites More sharing options...
TodFitch Posted March 19, 2013 Report Share Posted March 19, 2013 I always thought balancing a engine was only for the performance folk. My local parts store informed me that balanced pistons, ris pins and rods was inexpensive insurance cause balanced they take alot of pressure off the bearings. So I did as was recommended. Ever one who hears the engine comments on how smooth it runs. I'm hard of hearing so any noise is good to me. I wish you well and like my machinist said, wash your hands alot, keep them clean! "Limit of weight variation" for pistons is listed as 1/4 oz (7 gr) in the specifications at the back of the 1933 DeLuxe Plymouth Six Instruction Book. I figure if the engineers thought it was required back then it was probably required. Interestingly, I don't see a specification for that in the 1934 Factory Service Manual, the 1936-41 Factory Service Manual nor in the 1946-54 Factory Service Manual. Also interestingly, the 36-41 manual shows a switch from aluminum alloy pistons in the 41 and earlier (201 and 190) engines to "Light weight cast iron" for the 42 218 engine. Sounds like a step backwards to me. Maybe that is why they changed out the bearings (heavier but cheaper pistons putting heavier load on the bottom end). I don't see mention of the material the pistons are made from in the '46 to 54 manual. Were they aluminum or "light weight cast iron"? Quote Link to comment Share on other sites More sharing options...
ptwothree Posted March 19, 2013 Report Share Posted March 19, 2013 My P23 has alloy pistons...I''ll bet by the time '42 rolled around, aluminum was on the endangered materials list for war time production...back to cast iron. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted March 19, 2013 Report Share Posted March 19, 2013 All the p15 material I've seen says aluminum pistons. I suspect the previous poster is right and it was due to material shortages in 42. Light weight cast iron seems like an oxymoron. Quote Link to comment Share on other sites More sharing options...
Mark D Posted March 19, 2013 Report Share Posted March 19, 2013 Been following your posts on Facebook these past few days Bob. Looks like the snow hitting the ground today will give you plenty of time in the garage over the next week or so. Best of luck with the reassembly. Now that your engine will be in top shape you'll have to plan a run out to Central Mass. Happy to host you for an overnight at our summer camp. Quote Link to comment Share on other sites More sharing options...
1940plymouth Posted March 19, 2013 Author Report Share Posted March 19, 2013 Thanks Mark, time will tell............................Snowing to beat the band here right now, had to stay home, our truck broke down last night just as we were finishing our route Quote Link to comment Share on other sites More sharing options...
Dave72dt Posted March 19, 2013 Report Share Posted March 19, 2013 Also interestingly, the 36-41 manual shows a switch from aluminum alloy pistons in the 41 and earlier (201 and 190) engines to "Light weight cast iron" for the 42 218 engine. Sounds like a step backwards to me. Maybe that is why they changed out the bearings (heavier but cheaper pistons putting heavier load on the bottom end). I suspect as much to do with the war effort at the time more than anything else. Obviously the closer balanced the engine is, the smoother it will run. That's why driveshafts are balanced and why tires are balanced. Quote Link to comment Share on other sites More sharing options...
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