Matt Wilson Posted August 28, 2017 Report Share Posted August 28, 2017 (edited) My 265 flathead is at the machine shop, and I dropped in the other day to see how the work was progressing, and I saw that the crankshaft rear main seal surface was rather rough-looking, even though the rest of the crankshaft has been re-worked already. I mentioned it to the machinist, and he said it would be difficult to get that surface looking good. He said he will try polishing it a bit, but that it may not get much better. I asked him about taking it back to the shop that welded the damaged thrust flange, and he said welding it would be feasible, but grinding it back smooth would be the hard part because the shop that did the welding and grinding work does not have a grinding wheel that narrow, and he said such narrow grinding wheels are not common. The area between the flywheel flange and the thrust flange is about 1" wide. The seal is a neoprene type, with the upper half fitting into a recessed groove in the block, and the lower half fitting into a recessed groove in the rear main cap, typical of the later flatheads. If necessary, I suppose I could adapt a seal of the type that bolts to the backside of the block, but I've heard those are not as good as the type I have. Anyone here have any other suggestions? One other point: I've read a couple of posts by people saying that it's not critical for the rear seal to be in good condition on these engines, because the thrust flange acts as a slinger, and by slinging the oil outward from the crankshaft, the oil doesn't have much chance to escape out the back of the engine. If so, then it may not be that important for the seal and seal surface to be in excellent condition? Thanks. Edited August 28, 2017 by Matt Wilson 1 Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 28, 2017 Report Share Posted August 28, 2017 I think it needs to be very smooth for the rear main seal ( especially rubber) to do it's job... Surprised the machinist didn't agree. "it's not critical for the rear seal to be in good condition on these engines, because the thrust flange acts as a slinger, and by slinging the oil outward from the crankshaft, the oil doesn't have much chance to escape out the back of the engine." All I can say is WOW Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 29, 2017 Report Share Posted August 29, 2017 I'd find a new machinist........lol..............how rough is the surface?, and how could it become "rough"?..........doesn't make sense............andyd Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 3 hours ago, Dodgeb4ya said: I think it needs to be very smooth for the rear main seal ( especially rubber) to do it's job... Surprised the machinist didn't agree. "it's not critical for the rear seal to be in good condition on these engines, because the thrust flange acts as a slinger, and by slinging the oil outward from the crankshaft, the oil doesn't have much chance to escape out the back of the engine." All I can say is WOW Yeah, I'm surprised the machinist didn't agree, too. By the way, he's not the one who said the thrust flange acts as a slinger. Other folks who have thousands of miles and decades behind these engines are the ones who told me that, so I think it has some credibility, although it's definitely not my first choice to rely on that. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 29, 2017 Report Share Posted August 29, 2017 I wonder if the factory engineers ever considered just a oil slinger on the rear main.? There is a slinger and a front timing cover seal at the front of the later flatheads timing covers. They will leak oil if the seal fails. I know if the rear seal leaks the bell housing gets pretty oily on these flatheads..A good seal surface and seal at the rear main is a must IMO. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 2 hours ago, Andydodge said: I'd find a new machinist........lol..............how rough is the surface?, and how could it become "rough"?..........doesn't make sense............andyd I've been happy with this machinist so far, other than this issue. I've had much worse, believe me. Still, it's hard to think that he can't make a suggestion on how to remedy it. He just says "that's a common problem with old engines" and says that some engines can be fitted with an alternate seal that is a little smaller diameter than original, so that they will fit a shaft that has been ground down a few thousandths undersize, but I doubt anything like that is available for these engines. As for how rough it is, it seems fairly bad, but it's hard to say for sure without attempting to polish the surface. I believe it got roughened by corrosion, after moisture collected between the seal and the shaft and sat that way for a while, repeatedly for years, most likely. I've seen that before on other crankshafts. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 10 minutes ago, Dodgeb4ya said: I wonder if the factory engineers ever considered just a oil slinger on the rear main.? There is a slinger and a front timing cover seal at the front of the later flatheads timing covers. They will leak oil if the seal fails. I know if the rear seal leaks the bell housing gets pretty oily on these flatheads..A good seal surface and seal at the rear main is a must IMO. Ok, thanks for the enlightenment. Sounds like it's pretty crucial to get it right. Vintage Power Wagons suggested it may be ok to take off a couple thousandths (or maybe more?) from the shaft, and still have the seal fit snugly enough to do its job, as the seal is normally pretty tight against the shaft. But if it comes down to it, I'll look into installing one on the backside of the block. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 29, 2017 Report Share Posted August 29, 2017 You sure don't want a rear seal leak after all your time and investment in your 265 project!!! Quote Link to comment Share on other sites More sharing options...
thebeebe5 Posted August 29, 2017 Report Share Posted August 29, 2017 A crankshaft polisher should fit down in a 1" space easily. A shop that polishes crankshafts should have different grits for different purposes, different width polishing belts and ought to be able to give that surface some attention. Whether that will be enough I cannot tell, but having the crank in front of you you ought to be able. Quote Link to comment Share on other sites More sharing options...
ptwothree Posted August 29, 2017 Report Share Posted August 29, 2017 My 218 crank had what looks like poc marks, small depressions, around the circumference of where the main seal would be. These looked like factory markings. This on a standard size crank. My guess is they are there to hold a small amount of lube for the seal, be it rope or neoprene. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 17 hours ago, Dodgeb4ya said: You sure don't want a rear seal leak after all your time and investment in your 265 project!!! I agree with that! Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 15 hours ago, thebeebe5 said: A crankshaft polisher should fit down in a 1" space easily. A shop that polishes crankshafts should have different grits for different purposes, different width polishing belts and ought to be able to give that surface some attention. Whether that will be enough I cannot tell, but having the crank in front of you you ought to be able. I didn't know that the belt devices were called crankshaft polishers, but I thought the same thing - I know those hand-held belt devices will fit right in there. It may take a while to use one of those to knock down a welded area to be smooth and flat with the surrounding metal, but it seems like it should be an option. I'm going to mention that to the machinist. Also seems like a spray-weld operation would be a good candidate for this type of repair, and wouldn't require as much metal removal afterward to smooth it up and bring back into dimension, so I'm going to mention that to the machinist as well. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 9 hours ago, ptwothree said: My 218 crank had what looks like poc marks, small depressions, around the circumference of where the main seal would be. These looked like factory markings. This on a standard size crank. My guess is they are there to hold a small amount of lube for the seal, be it rope or neoprene. That's interesting. I've seen three different cranks from 230's, and a 251 crank and I've never noticed those pock marks. In the area where my 265 crank is rough, it's also brown like rust. It's a 1/8" wide band of rust-looking stuff all the way around the circumference of that area, so that's why I think it was caused by moisture sitting between the seal and the crank surface. 1 Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 29, 2017 Author Report Share Posted August 29, 2017 (edited) My machinist is now saying that the welding process itself is risky because it can warp the crank, which would be a problem because the crankshaft has already been ground to final dimensions everywhere else. I'm thinking spray-welding would be less likely to cause that kind of problem, though. I'd be a little surprised if no one else on this forum has ever run into this problem, so I'm hoping someone will chime in with their solution. Edited August 29, 2017 by Matt Wilson Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 30, 2017 Report Share Posted August 30, 2017 14 hours ago, ptwothree said: My 218 crank had what looks like poc marks, small depressions, around the circumference of where the main seal would be. These looked like factory markings. This on a standard size crank. My guess is they are there to hold a small amount of lube for the seal, be it rope or neoprene. Matt, if I recall my 41 Plymouth 201 had marks on the crank about where PTWO3 mentions them.........from memory they appeared to be as tho' they had been "knurled" onto the crank on purpose..........I'd be trying to find out whether these marks are indeed from wear or a purposeful thing...........andyd Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 30, 2017 Report Share Posted August 30, 2017 Tons of questions about this issue on google. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 30, 2017 Author Report Share Posted August 30, 2017 31 minutes ago, Andydodge said: Matt, if I recall my 41 Plymouth 201 had marks on the crank about where PTWO3 mentions them.........from memory they appeared to be as tho' they had been "knurled" onto the crank on purpose..........I'd be trying to find out whether these marks are indeed from wear or a purposeful thing...........andyd Ok, good point, will do. Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 30, 2017 Author Report Share Posted August 30, 2017 11 minutes ago, Dodgeb4ya said: Tons of questions about this issue on google. I'll start looking around, thanks. The possible good news is that I looked at some photos from when I disassembled the engine, and I ran across some that showed close-up views of the crank and seal installed in the block, and it appears that the brown band might be just a tiny bit to the rear of the seal. It's hard to say for sure, but that's the way it looked. The cleaner, somewhat shiny surface appeared to be where the seal rides, which may make sense. I'm not sure if that crankshaft was the 251 shaft I was taking out of the engine, or if it was the 265 that I was test-fitting in the 251 block. I may take my seal to the machine shop and see if he will do a test fit to see where the seal rides relative to the rough patch. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted August 30, 2017 Report Share Posted August 30, 2017 As you have proven .....Don't jump too quick! Take plenty of time to check out all different avenues and you will get it solved in a good way! Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 30, 2017 Author Report Share Posted August 30, 2017 35 minutes ago, Dodgeb4ya said: As you have proven .....Don't jump too quick! Take plenty of time to check out all different avenues and you will get it solved in a good way! No, I'm not one to jump very quickly. In fact, my wife complains that I get my PhD in everything I do, lol. I did call a couple of other machine shops today, and was surprised when they gave me the same answers my own machinist gave me. I mentioned the possibility of getting the crankshaft spray-welded, as that seems like it would put a thinner layer of weld material on, which could be more easily smoothed, but one of the shops I spoke to getting in there with a grinding wheel would be tough, and using a hand-held polishing belt would only remove a tiny amount and would most likely not result in a surface that's circular. So I'm learning, little by little. 1 Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 30, 2017 Report Share Posted August 30, 2017 (edited) Matt........admittedly this was on a different item to what you are contemplating ..........but..........I had a outer rear axle bearing go bye/bye on the 40 Dodge, ..........when I installed the 318 Poly/torqueflite I also used the complete rear axle, this was the engine/gearbox/diff from an Oz 1962 Chrysler Royal, which was a 1953/54 Plymouth body/chassis with 1955/56 Plymouth front & rear fenders and 1957-61 Plymouth Poly and I think around 1955/56 rear axle.............lol............you following me?..............lol...........anyway I had not played with a rear axle bearing before and didn't realise that the bearing outer race or cup shell had cracked and ever so gently spun in the axle housing to machine the inside of the housing maybe 10-20 thou.........the new outer bearing was a little how do we say?.........floppy?.........in the housing and this was the housing that had my custom rear disc brake setup..........1969-70 Oz Valiant front disc rotors on the Chrysler Royal drum brake axle hub with 1975/76 Ford mega buck vented rear calipers.............so what to do......a mate suggested getting the new outer bearing race metal sprayed.........luckily living in Oz's largest city at the time, Sydney had its benefits as there was a company that did metal spray cranks, etc, only 10 minutes from home..........from memory now, I had to have this done twice, first go wasn't quite enough to restore the bearing to a firm fit in the axle housing so after the second light spray it was a perfect fit, no play, a nice firm tap fit..........lasted from about the late 70's till about 10yrs ago when I decided for unrelated reasons to replace the whole rear end with a complete 1990 Ford Falcon Disc brake rear end...........anyway...........my personal experience with metal spraying is a positive one and worked for me.............admittedly living in the Oz country area means this engineering skill isn't available locally.....but just thought I'd add my Oz 2 cents...........regards, Andy Douglas Edited August 30, 2017 by Andydodge Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 30, 2017 Author Report Share Posted August 30, 2017 10 hours ago, Andydodge said: Matt........admittedly this was on a different item to what you are contemplating ..........but..........I had a outer rear axle bearing go bye/bye on the 40 Dodge, ..........when I installed the 318 Poly/torqueflite I also used the complete rear axle, this was the engine/gearbox/diff from an Oz 1962 Chrysler Royal, which was a 1953/54 Plymouth body/chassis with 1955/56 Plymouth front & rear fenders and 1957-61 Plymouth Poly and I think around 1955/56 rear axle.............lol............you following me?..............lol...........anyway I had not played with a rear axle bearing before and didn't realise that the bearing outer race or cup shell had cracked and ever so gently spun in the axle housing to machine the inside of the housing maybe 10-20 thou.........the new outer bearing was a little how do we say?.........floppy?.........in the housing and this was the housing that had my custom rear disc brake setup..........1969-70 Oz Valiant front disc rotors on the Chrysler Royal drum brake axle hub with 1975/76 Ford mega buck vented rear calipers.............so what to do......a mate suggested getting the new outer bearing race metal sprayed.........luckily living in Oz's largest city at the time, Sydney had its benefits as there was a company that did metal spray cranks, etc, only 10 minutes from home..........from memory now, I had to have this done twice, first go wasn't quite enough to restore the bearing to a firm fit in the axle housing so after the second light spray it was a perfect fit, no play, a nice firm tap fit..........lasted from about the late 70's till about 10yrs ago when I decided for unrelated reasons to replace the whole rear end with a complete 1990 Ford Falcon Disc brake rear end...........anyway...........my personal experience with metal spraying is a positive one and worked for me.............admittedly living in the Oz country area means this engineering skill isn't available locally.....but just thought I'd add my Oz 2 cents...........regards, Andy Douglas Thanks, Andy! So that's +1 for spray-welding. Doing a Google search yesterday, it seems that there are a couple of places that do spray-welding in my area, so I probably will call them today or tomorrow to see what they say. Of course, the best scenario would be if I were to find out that my seal contacts my crank in a smooth area, not in the rust patch like I have been fearing. I hope to get to the machine shop to determine if this is the case in the next couple of days. 1 Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 30, 2017 Report Share Posted August 30, 2017 Matt, is there any chance you can take a clear pic of the area on the crank, I think that rust patch or brown band is actually on the outside of the seal area, I can't imagine how it could be where the seal runs or inside..........a pic would really help............other thing re the metal spraying is that you will need to be able to machine the sprayed area back to a smooth surface, smooth as in equal to the journal surfaces, otherwise the sprayed surface being rough will tear the seal to pieces or at the very least wear it down very quickly...........I didn't have this issue when the bearing race was sprayed as it was on the outside of the bearing and fitted into the housing...............andyd 1 Quote Link to comment Share on other sites More sharing options...
Matt Wilson Posted August 31, 2017 Author Report Share Posted August 31, 2017 5 hours ago, Andydodge said: Matt, is there any chance you can take a clear pic of the area on the crank, I think that rust patch or brown band is actually on the outside of the seal area, I can't imagine how it could be where the seal runs or inside..........a pic would really help............other thing re the metal spraying is that you will need to be able to machine the sprayed area back to a smooth surface, smooth as in equal to the journal surfaces, otherwise the sprayed surface being rough will tear the seal to pieces or at the very least wear it down very quickly...........I didn't have this issue when the bearing race was sprayed as it was on the outside of the bearing and fitted into the housing...............andyd Yep, I have a pic from when I disassembled the engine, and it looks like the rust patch might be behind the seal contact area, but it's hard to say for sure, and I'm not 100% sure if the photo shows the 251 crankshaft or the 265 crankshaft, because I tried out both cranks in the block. And yes, I share your concern about the surface needing to be smoothed after spray-welding. Not sure if you saw my earlier post above, but I spoke to another machinist about this, and he said it would be difficult to get a narrow enough grinding stone in there, and even a hand-held belt polisher would not be very feasible because it can only remove a tiny amount (about a half-thousandth), and won't leave the surface round (consistent diameter) like the seal needs it to be. So while spray-welding might be feasible, it will also have its challenges. In any case, the crankshaft is at the machine shop now (has been for a while), so I plan to head there in the next day or so to do a test fit of the crankshaft and seal in the block, and I'll see if the rusty portion touches the seal. I'll take a pic of that and post it. Quote Link to comment Share on other sites More sharing options...
Andydodge Posted August 31, 2017 Report Share Posted August 31, 2017 O/k..........I'll look forward to the pic & info...........andyd Quote Link to comment Share on other sites More sharing options...
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