I parked the 720D half-way through the summer when I thought the engine sounded too loud, like maybe a rod was getting ready to go. Seemed like the crankcase oil would slowly build up, and it smelled like fuel in the oil. I figured the oil may have been cut by the fuel and maybe a bearing was fixin to go. Last week I pulled an oil sample and sent it to a mail-order lab (ISO 9001), and to my surprise they found no negative parameters ("component & lubricant conditions are acceptable/oil is suitable for continued use"). Fuel <1.0%, LEM%soot<.01%, water vol <.10%, VIS CS 100C=13.6, SAE Grade 40 (Rotella T 15w40), glycol neg, TBN 12.63. Other results (all ppm by weight): iron 5, chromium<1, nickel <1, aluminum 1, lead 2, copper 2, tin <1, silver <1, titanium <1, silicone 5, boron 10, sodium 9, potassium <10, molyboenum (?) 7, phosphorus 1881, zinc 1503, calcium 2426, barium <10, magnesium 66, antimony <30, and vanacium <1.

So, I'm happy (especially that there's no fuel getting into the oil, since the transfer pump seal was already fixed and the injection pumps were rebuilt, so I was running out of things to worry about for a source of fuel leaks), but still uncertain whether I ought to tear into this engine "just to be sure." If I had a badly knocking rod, wouldn't I expect some evidence of unusual metals in the oil?? Any feedback on the possible meaning of these numbers, one way or the other, would be appreciated. I am prepared to conclude this was the best $32 I could have spent on this engine project.

To further belabor a well-flogged subject on here, check your flywheel & clutch drive disk before you tear into the engine...generations of 2-cyl diesel owners have thought they had a rod out when the flywheel was loose...I have always been amazed by the amount of fuel these engines can tolerate in the oil w/o damage.

Steve

If it runs good and sounds fine now, I would force my little brain to forget about those noises and just enjoy the heck out of that tractor.

I am still working on that with my lawnmower when the oil cap vibrated off the Kaw motor last summer and it barfed all the oil out before I discovered the mess

Steve;
No idea on your numbers, but if we have a metalurgist on board he might know the components in babbit, which is the first to go in a bearing. Like you, if i suspect a rod bearing, i'm not going to chance busting a block. I've seen too many blocks with a chunk busted out the side when it shoulden't have happened.
M-MAN

The sheet they sent says that typical bearing metals are lead, copper, titanium and tin. The tin is specifically mentioned for "babbit overlays." Interestingly, I sent two oil samples for testing, the other one from my F250 diesel with 35,000 miles on a Jasper total rebuild. The 7.3 Ford has been carefully maintained with Rotella T oil changes every 4000 miles. Most of the 720D numbers were smaller than the Ford engine: Ford/720 comparisons for example on iron 48/5 ppm; chromium 2/<1; aluminum 3/1; lead 6/2; copper 4/2; silicon 8/5; sodium 4/9; molybdenum 8/7; phosphorus 1786/1881; zinc 1549/1503; calcium 2183/2426; magnesium 376/66; and TBN 11.45/12.63. All except TBN (total base number, apparently the single most accurate predictor of the remaining life of the oil) are in ppm parts per million. Everything else was equal between the two engines, including tin at <1 ppm. Assuming the 7.3 is a decent standard to compare to, the 720 engine looks to be in good shape. Both engines were declared in good shape by the testing lab. My only hesitation is the 720 oil sample was 6 months old between the time I last ran it and when I sent the sample. So, I suppose the fuel could have volatilized in that time, although the oil I used for sample was taken from the crankcase 2 months after it ran and the sample (a gallon of it, which I shook before sending the small sample to the lab) was kept in a capped container. So much for Jr. Scientist report. Are there any professors present??

No prof here, or metallurgist either, but the one 720D I remember that had a rod bearing out, the engine wouldn't run more than a few seconds before it almost seized, & the smoke started rolling out the breather. The crank was over .100" flat, & the bearing was LONG gone. (South of the border operators)-I guess my idea on what to look for in the analysis would be excessive copper, usually a bearing will get well into the copper layer before it starts giving notice of trouble...

Take the oil filter out and let it drain. Cut the filter paper loose from the housing and look for metal embeded in the pleating. If you have a rod brg. or a piston scuffing it will show up in the filter. flathead

Steve,
Very interesting comparison between the 720 and 7.3L.....

Your knocking sound.... I assume it does NOT go away when the clutch is engaged, which might be why you lean towards a bad rod bearing? If that's the case, I'd pull the flywheel cover, and check the flywheel. When my flywheel got loose, I also suspected a bad rod. I had both inspection covers off, and both rods were TIGHT. It was while I was using the flywheel to turn the engine over that I noticed that the flywheel could be turned just a hair before the crank would begin to move. If you find the same thing, I feel for you.... Some will suggest new bolts for your flywheel, and that's worth a shot.....

Rodney

Rodney - I checked the flywheel out - it seems totally tight with no evidence of slop, visual or otherwise. Don't know about the clutch, altho the noise is definitely there when the clutch is engaged. Have to check that out. Based on the oil results, I think I'll dare to start it up again and look at these other ends of the crankshaft a bit more closely.

flathead's thoughts brought me back to the ole Bell helo days. The motors had wafer oil filters. On a service you inventoried what kind of chunks you had on the wafers and what kind to determine the prognosis on engine health.

FIT - I shut it down back in June because it was knocking heavily under a medium load (mower conditioner). I started tearing it down, but figured I would check the oil first. Since reporting the oil numbers on this post I've rechecked my records, and the oil only had a couple of hours on it when I shut it down. So, I'm still uncertain whether to keep tearing into it, and I haven't had time to put it back together to listen to it. Wouldn't a bad rod knock start showing me tin from babbits even with just a couple of hours? Tin reads <1 ppm. It was not as heavy a knock with clutch disengaged, e.g. not under load. I can't get any slop in either the clutch or the flywheel just by horsing the pulley or the flywheel. It would be great if we could post a short sound recording on the site!

Before going any farther. Pop that flywheel off, look for any wear or fretting. Then do the grade eight bolt, nut and hardened washer thing along with using a real torque wrench set to 275 lb ft on oiled threads.

It came up suddenly, which is to say, over the course of a couple hours of operation (kind of hard to say, since I tend to wear hearing protection when I'm working for extended periods). Let's just say, it was alarmingly loud all of a sudden one day, and I parked it.

Will definitely check out the flywheel as suggested, and I appreciate the tip on how to use the clutch to move the crank to check endplay. It's actually warmed up a bit here today, above freezing, so it's possible to get out there and do a few things. Had a slow fall doing much of anything after a torn and then a detached retina. Doc didn't want me lifting much after that surgery - better now, altho I still won't be lifting the flywheel by myself.

The flywheel bolts are square-headed, as are the nuts. Stock?

Frank-
You say you are using fine thread (SAE) bolts in your flywheel . Are you using the same torque spec of 275 ftlbs? Wouldn't the fine threads change the torque value?

QUOTE (SteveBemis @ Dec 25 2005, 12:44 AM)

It would be great if we could post a short sound recording on the site!

My (ex)-brother-in-law used to call me from H*ll & gone out in the oil field somewhere & hold the mobile phone mike out the window of his truck for me to diagnose a noise in the engine-used to p*ss me off royally, cause it was often as not in the middle of the night...my sister finally wised up & I don't have that problem any more...I can tell you there's so much echo & white noise it's impossible to tell anything ...esp. a 720D-they are not quiet when they're running right, & a mike will pick up every tick & pop that your ear would tune out in person.
Sorry about the family baggage-but it did relate to the subject???
I still bet your flywheel's loose...

If this works, attached is a picture of the flywheel fastening. Bolts appear to be stock (based on the parts book), and I'll soon report the crank endplay and torque value on unfastening the bolts. I assume that once I loosen the bolts, that I should use new to reinstall due to stretching?? The lock nut is itself locked to one of the splines with a couple of punches (not sure if it can be seen - center top), and there seems to be no external evidence of looseness. We shall see.

Crank endplay is .009" using the clutch method described by FIT, so that seems to be OK. There seems to be a rust bond between the locknut and the flywheel, so if there's no movement there, and there's no evidence of movement on the punches which lock the big nut to the crankshaft spline, then it would seem unlikely that the flywheel is loose on the splines. On the other hand, whoever put the bolts in the flywheel obviously put one of them in backwards, which may have compromised their ability to torque it. Have to get a bigger torque wrench than what I have before I start loosening things up.

Once purchased a B that had a knock. Man I bought it from had just put new bearing in it and it still sounded like the rod bearings was knocking. I tore it down and found a loose wrist pin bearing that was free to move. I replaced it and the noise went away

Well, this is the clutch side. Also looks solid to me. Guess I'll double-check the torque on the flywheel bolts and then check the timing before pulling off the pony and checking the rods.

I may even understand this clutch before I'm through. I looks like the 3 clutch drive pins serve as the basic power transmission device, once the clutch package is compressed, to spin the pulley? How, then, does the pulley (or the 3 drive pins??)(or the single drive pin, key #6??) drive the operating disc? The operating disc has to slide somehow with relation to the pulley gear (which cannot move laterally) - does it slide on the "key" #2?

Sorry to chew up your holiday - thanks, and Season's Best.

Yep, had to press it off.

On the clutch workings, I see the pulley move outboard something like 1/8 - 1/4" when it engages. I figure this results from the operating disc moving the pulley and the driving disc into contact via the toggles, operating bolts, etc. Since the driving disc is bolted to the crankshaft and cannot move laterally, the pulley must move in order to make the sandwich. If so, the first reduction gear must be enough wider so that the pulley's gear does not disengage?

If timing doesn't fix this, I hope my journey inward does not require any work on this crankshaft. Rods, wrist pins and pistons are fine. A 720 crankshaft is not my idea of fun.

Will keep you posted.

my 720d sounded like it had motor issues too, got real bangy while driveing it, im sitting hear looking at that driveing disk and how loose it sits on the gear. thats what mine looked like. installed a new driveing disk, and my bangying noises went away!!! for around a 100.00 greens it made my day!!
you havent said any thing about your oil presure?



Merry Cristmas every one!!!!!!!!

70020jd: The oil pressure is OK - in mid-high range when cold, runs mid-medium range under heavy load in summer heat, altho I've not calibrated the gauge with a master gauge.
The driving disk picture was after taking out the retaining bolt, but before I removed it the disk. The end of the disk sits a little bit out beyond the end of the crankshaft, but other pictures show it that way too. I think if the disk were any further onto the crank, it would bind the inner clutch disk when the clutch is disengaged. I did have to take the driving disk off with 1/2" bolts, so it was on there pretty tight with no signs of slopping around. The 3/4" retaining bolt is less than 1-1/4" long, though, instead of the 1-1/2" that the parts book calls for, and those threads are flattened with wear. I think I'll replace it with a grade 8 to be sure I'm getting a full bite when it's tightened down.
FIT: thanks for the extra hints. I'll do most anything that makes sense before pulling that pony off. Good luck with the GPS. I think being lost would be the only occasion when I would have enough time to figure one of those things out.

OK, the timing is a bit off - It has Bosch pumps, and #1 is early by about the width of the line in the pump window; #2 looks to be right on the money. The exact symptom which caused me to shut it down last summer was a heavy bog in the mo-co which resulted in loud knocking and several gushes of heavy black exhaust. Would slightly early timing on one cylinder result in these sympoms?

Happy New Year!

Slightly early timing can jam the pump plunger too far down it's bore and smash everything when she stacks solid.
The early injection event is also building too much combustion chamber pressure before the piston passes TDC. That will make a knocking sound.
Franks single cylinder check would be the next step before re-timing the pump.
As you have the flywheel cover off? This is a good time to check if the flywheel markings are accurate, some are not.

Boy, B&D, a line's width off....not sure that that would even be noticable on a well worn engine. I mean I'd move it to where it needs to be, but man, that's literally splitting hairs.

Just to clarify what I said about "early' - when the flywheel mark for #1 inj is in register with its line, the line which moves with the pump plunger is not quite yet up to its line. I will double-check the flywheel registration to be sure it's mounted correctly, and then run it again and "pull a plug wire." Thanks.

Steve:

f course you know that there are two marks on the flywheel, well actually four, #1 INJ, then #1 TDC, then #2 INJ, then #2 TDC. You have to be sure you look at the correct mark, but seeing that you are this close, I'm sure you are.

Steve...........see you've received alot of suggestions or where to look for the knock. My 720D broke the ten inch by 3/4 inch bolt that holds the counter weight on the crankshaft. Made alot of noise and eventually wiped out all the internal oil lines when the bolt dropped down to the bottom of the crankcase. Could your counter weight be loose. Does it make a clunking noise when you shut the fuel off and let the engine stop under full compression?

FIT: yep, got the right marks.
Blksmoke: I don't think that is the pattern - the noise is under load, not as you describe altho I will check for it when I start it back up.

Thanks.

Steve my 730 did the same thing several years ago was a cracked flywheel, If memory serves me right it started when Iwas doing PTO work, ended up with putting on a new taperlock flywheel no problems since, just my 2 cents..

QUOTE (Blksmok @ Jan 3 2006, 04:07 PM)

My 720D broke the ten inch by 3/4 inch bolt that holds the counter weight on the crankshaft.

Holy Poo-that's one I've never heard of before-lucky it didn't do more damage than it did-

Hate to beat on an old horse, but it's good news (I think) and perhaps instructive. I started this thread when I was worried about possible rod knock, loss of power, etc. With help from this site, I verified no problem with loose flywheel or clutch driving disk, and since the oil analysis was clean, I took the advice of some, and put it back together. Started up fine, but then I realized the clutch was shot. Took the clutch back apart and followed the good advice on old clutch threads: replace the toggles and dogs. Clutch now is tight, and I realize the "loss of power" was a severely slipping clutch.

Has anyone had the experience of a slipping clutch (toggles worn, I believe, since that is what fixed it) so that the clutch bangs in and out and sounds like a rod knock?

Right now, I'm thinking the clutch was my whole problem, since the knocking and the clutch finally wearing out (="power loss") all happened at the same time. Still haven't taken it out for a sixth-gear-up-a-hill load test (closest I can get to a dynamometer), so I still may have a knock, but I'm curious about whether the clutch could produce such a sound with worn toggles & dogs.

Thanks.

Hate to say it, but I don't think so...you said the problem involved heavy black smoke, & that's not consistent w/a slipping clutch, which can't put a load on the engine to the point of smoking. I can't imagine a slipping clutch knocking like a rod either, but I suppose stranger things have happened. Loose clutch parts will hammer when the clutch is disengaged, not engaged. Sorry to be so negative, but the symptoms just don't quite match up. That said, diagnosis over the puter is dicier than the phone, & that's not sayin' much...
HTH-Guest

Thanks.

Good News! Rechecked the clutch, tightened it up a bit more and adjusted the pulley brake, and it's now a solid "snap" on engagement and disengagement. Better than that, the rattling must have been the clutch, because she's silky smooth under load - the smoking must have been my imagination in the semi-darkness last June, or more likely, smoking simply from the surging of a clutch that was shot. Anyway, no tear-down and the 720 is back in the starting lineup. Thanks for all the moral, technical and other support (as well as a well-deserved poke now and then).

Also enclosed is a snap of a neighbor's slightly worn D from last summer :-).

Steve.

Moved here at the request of Steve Bemis. Great info here!

Brandon