LOL How major is major? It wont move is a good hint. I'm sorry, my second wife made me say that (B#$%ch). Yes, we are lucky the crank is not busted. And it happens. Glad you didn't meet my second wife. Broken cranks were easy for her. ,rc
The Leading cause of Divorce is? You guessed it Marriage. And if you want to make 1 millions dollars in the boating industry, just start off with 2 million. Getting back to whats important. From the looks of the bolts it doesn't seem like they were all sheared because some broke well inside the Camshaft threads. Was this do to improper installation? I read today that you must use copaslip, the original never seaze. I wonder if they were installed without that, there was certainly no size of it when we removed the bolts.
Back to important things; Never thought Flywheel threads should be greased or never-size applied. Always built with clean (real clean) threads, clean (real clean) surfaces of crank/flywheel, CORRECT GRADE BOLTS and PROPERLY TORQUED BOLT HEADS. Nothing beats a correctly built flywheel assembly. Somebody screwed up here (past wife)... Despite my course humor here, I am so glad it's not your crank AND 71's rule... ,rc
Neither Did I, but this site says so: Detroit Diesel 12V 71 engine specs at Barrington Diesel Club. We provide technical data, specs and bolt torques for the 12V 71 Detroit Diesel engine. At Barrington Diesel Club specs for many diesel engines may be found. Im with you.. 71's are a solid engine.
"Lubricate with 'International Compound No 2, or Copper-Slip' or equivalent." I have had discussions about lubricated or dry torque procedures before. 35+ years later, my thoughts have never failed. Very (very) clean and dry have never failed me. Disclaimer; on those open threads into a water jacket, yep, ya do have to put a couple drops of dope on da threads. Hate it when that happens. ,rc
Hi, The two that broke last 1st from left and 3rd from left look like they have broken in the area I would expect for a bolt that had been stretched or over torqued. I would suggest that it would be prudent to get a Tap Wrench (Plug Type for use in blind holes) that suits the thread and run it through the holes in the crankshaft boss by hand to make sure they are all clean and burr free. You should be able to wind the bolts in all the way by hand before you start. Use Copper Slip as recommended in the manual, many manufacturers recommend similar practices. A lubricated thread is far more likely to enable you to reach the full torque, it is the tension under the flange of the bolt head where it contacts the flywheel face that provides the resistance to turning. If the holes in the flywheel have been welded and re drilled make sure they are smooth and the mating faces level on both sides.
K1W1, Thanks for the tip. Will let my mechanic know! Today a machinist is coming out to remove the other broken bolts. He recommends welding a piece of stock to each one and then welding on a bolt head to turn them out. Then we will replace the crankseal and put on the fly wheel. The Torque spec for fly wheel bolts from that website says 184 ft-lbs. That sound kind of low I would think. Its the same number for 6-71, 8-71, 16-71. Any one know of another website?
Hi, The only book I can get my hands on right now is for 53 Series Engines. It calls for 180 to 190 ft lbs Torque on 9/16" x 18 Bolts on the 8V Engines This seems to be pretty close to what you found.
Lubricated threads (with the proper lubrication) always give a more consistent and accurate, torque. 180-194lbs on 9/16" threads is a considerable amount of torque on that bolt size and I wouldn't expect a torque reading to be any higher than that.
Capt J, The new methodology call for a 50lb torque across all bolts and then another 90 to 120 degree turn to clam them down. We are going with copaslip type lube on all bolts. As for the progress tonight, all the remaining bolts were removed and the rear seal too to boot. Bolts did not arrive today even though the overnight freight was paid. That's Detroit for you I guess. Will post pics a little later.
Great news ... Way to dig into that project yourself, identify the issues and solve the problem without getting broke.
Not too much progress tonight. We got remainder of the screws out, but bolts didn't arrive from Detroit. Must of been an Obama cost reduction thing. Anyways, looks like we have some work to do with the crank and cleaning it up. Threads and all, before we set the new bolts in due to arrive tomorrow. Would love to be cutting water by the weekend. Again, thanks for everyone's input.
Be carefull,the mating surface between crank flange and flywheel is close tolerance, if any galling is present on either surface expect failure even if you replace all the bolts. Keffer
Another day with out the most important parts to do this repair. I ordered the 6 new bolt from RPM Diesel in Ft. Lauderdale on Tuesday. I paid $40 to over night them. The bolts only cost $1.31. Yesterday they claimed there was a problem with shipping, which is true. Today the said the same thing. I called the Parts Manager at Florida Detroit Diesel in Ft. Lauderdale and he gave me a 10 minute explanation of what happened in Detroit, Michigan plant. On Monday afternoon the conveyor belt system went down and It was not fixed till Wednesday. So Monday's overnight orders went out yesterday and Tuesday's will go out today. Im hoping I get them tomorrow. Stay Tuned...
I have been holding back a small piece of evidence regarding this crankshaft - flywheel detachment issue. Back in the summer of 2009 on my way to Treasure Cay in the Abacos, I was cruising on the bank east to Little Sail Cay from West End when I told my Dad to watch the Helm so I can go down below to the boys room. As I was walking down the ladder, I began to feel and see a vibration like I had never seen. I quickly ran back up the ladder and brought both mains to idle speed. The vibration was coming from the right side. It was more like a shake or earthquake than a vibration. I reached for a mask and fins and went below. Sure enough I found the problem. Somehow, a 6" diameter poly rope had tangled on my starboard. It took me a while to cut all the strands off. I never thought much of it after other than I needed to get that shaft straightned out. But now, after finding those rusted bolts in the bell housing, I am starting to think if that caused the begining of this problem... The good news is that the rope did not touch the port side.
A trama like that could definately have cracked a few of the flywheel bolts. Especially if it was enough to bend a shaft.
Well, It was Friday and finally bolts came in from Michigan on a special overnight freight price of $40 only that it took 3 nights to get here. I guess it was Friday night so the crew of OZENA scattered. They all must of been drinking a few at the favorite watering hole. Greg and I on the other had proceeded with the issue at hand. We were able to reattached the flywheel to the crank properly with new rear crank seal to boot. Then came the moment of truth. I spun the engine with ease with fuel rack off. And then, just a couple of turn with fuel and fire and all of sudden there was exhaust fumes everywhere. There seem to be absolutely nothing wrong with the motor. Now comes the tough part, putting on the tranny and re-alignment. Stay Tuned!
Here are some pics.. For the record we torqued the flywheel bolts to about 50lbs with torque wrench then we marked off 90 degrees on each bolt and attempted to torque to that angle. We had to break out the 3/4 inch torque bar for this job. The readings went well above the 184 in the spec. It was more like 220. However we only went 90 degrees not the max mentioned in the manual which is 120.