| Author | Message | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 78 Registered: 11-2008 Posted From: 70.52.100.49  Rating: N/A |
Concerning an 8V-71, does anybody know at what temp MCI set the sensors to trip the 'high temp' alarm? Same question re: the 'Low Oil' alarm? I found the right wires (thanks to splendid advice in my earlier post) but don't really want to just disconnect the alarms... I'd rather re-set the sensors (if possible) or just get new ones. If I need new ones (hopefully just one), will any old sensor work (if set to the correct temp / pressure) or do I have to order them from DD or MCI? (They look pretty much like any old part 'off the Flying J shelf' but I don't know about the 24V issue). Thanks again. Nellie Wilson | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 902 Registered: 12-2000 Posted From: 71.54.29.215 Rating: |
Hi temp sensors cannot be reset. If you look at the sensors (usually referred to as Alarmstats), they should be stamped on the brass part (probably 210 or 205). that is the temp they go off at. To change this setting you would have to replace with a different rated alarmstat. What is in there is probably what should be, it is very unusual for these to be changed to a different setting. Low oil sender is usually about 3-5 PSI and is also not adjustable. I do not think the 24 volt makes any difference, as they are simply on or off switches that complate the circuit to ground.Jack (Message edited by JackConrad on December 17, 2008) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 670 Registered: 8-2006 Posted From: 207.231.75.253 Rating: |
Nellie, Jack is right, 12 or 24 V doesn't matter. They are two seperate devices, the low oil sender will be low on the curb side, teed in with the oil pressure sender, on a hose bolted to the frame. The water temp alarm will be near the water pump on the upper left side of the eng. I'm still having problems with both low oil and hot alarms flashing at the same time, when the gauges don't show low or hot? As in bare wires touching metal? HTH, George | ||
| James Robinson (Jjrbus)
Registered Member Username: Jjrbus Post Number: 182 Registered: 12-2000 Posted From: 173.102.120.118 Rating: N/A |
I have heard of a busnut that had a problem with an off the shelf fuel pressure switch!! Its just a switch right?? The consensus was the switch was not heavy duty enough for a bus. Personnaly I will stick with the MCI switches for these applications. That is only my opinion, backed by very little evidence. Jim | ||
| james dean boggs (Jd_boggs)
Registered Member Username: Jd_boggs Post Number: 132 Registered: 11-2004 Posted From: 76.83.222.176 Rating: N/A |
I replaced the oil sensor last week from Car Quest. The parts guy told me that these sensors vary 3-5 psi and to get one that fits mechanically (thread size and wire crimp style). I would replace that one first and see if that alarm goes away then replace the other one. There may be a different fault. Seem strange to see 2 alarms trip at once. Good luck. | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 79 Registered: 11-2008 Posted From: 70.52.101.167 Rating: N/A |
George! We must be DD soulmates. We share precisely the same problem. Don't know about you, but it's driving me nuts. I've finally learned (took awhile) that I'm really NOT destroying my engine whan that alarm goes off... but even so, how do you keep driving with that thing blaring? Sounds like a 3-alarm fire! It works on your head to the point you gotta pull off anyway. Then you just HAVE to check everything, dontcha? Ye Gads! What a way to travel... or not. Let me know if you figure it out - and I'll do likewise. And, hey, you guys... thanks for all the info. Thought that 24v-12v thing would matter, since it seems such a big deal concerning eveything else. But WHY doesn't it matter? (Just trying to pick your brains and learn something... I'm SUCH a hopeless rube.) Thanks So Much! Nellie Wilson | ||
| Jim Wilke (Jim Bob) (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 348 Registered: 2-2001 Posted From: 69.77.157.42 Rating: N/A |
Nellie, Though you didn't ask me, I had the same issue of not wanting to listen to (in my case) the low air pressure alarm, a particularly nasty snarling buzzer which would go for 3-5 minutes each morning when I was building air pressure. I did not want to completely disable the alarm system by putting a silence switch in it, so I installed a double throw switch and a big red alarm light installed right in the center of the dash that you can't miss even in the daytime. At night it's kind of like there's a small fire truck in front of you. If I were to do it over I would add a little relay in the circuit so that it would default back to alarm when the "ignition" was turned off though I have never forgotten to switch it back manually. And you can forget about being a "hopeless rube". Not only are you amazingly sharp mechanically, (when you first started posting I was certain you were a guy by your comprehension) but if that's really your picture you are easily the most beautiful motorhead I have ever seen. | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 607 Registered: 10-2006 Posted From: 66.82.162.20 Rating: N/A |
"I've finally learned (took awhile) that I'm really NOT destroying my engine whan that alarm goes off.." You mean yours is happy with under 5 psi oil pressure and head eating 210 temps? Or that you have learned your system generates FALSE ALARMS ? FF | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 81 Registered: 11-2008 Posted From: 70.52.104.242 Rating: N/A |
Not a bad plan, Jim Bob. Even simpler in my case, 'cause I've already got the existing dash lights. My mechanical guru says these sensors (alarmstats, whatever) are just electro / mechanical switches (same thing as Jack says). And - like most anything - they eventually wear out...either fail completely or lose setting and ground out before they're designed to. I don't really know, but sounds logical? Problem is, can't figure much out unless the alarm is already blaring... and, knowing my luck, that'll happen on a busy bridge at night during a raging blizzard. The trouble with trouble-shooting? Can't shoot the trouble if the trouble ain't happening. And no way will my Jessie rise above 180 degrees just sitting. But (SUDDEN REVELATION!!) maybe that in itself eliminates the Low Oil alarm as the culprit? I mean, even sitting, I can bounce the oil pressure all over the place without sounding the alarm [Hey, up there! George! Did you hear that? Waddaya think?] Anyway, if I can't track the problem, I'll try your solution. My humble thanks and a tip of my battered old straw for your kind compliment. To address your lingering (and totally understandable) doubts, I quote from our very own and most profound Bus Nutter, John MC9: "Yup." That's as in, Yup, Jim Bob, that's truly moi. But you can double-check by ambling over to: www.myspace.com/vivianericard, or (same URL) /vivianellie. (If the slideshows don't auto appear, just click 'photos' and click 'Back' to my page). Thanks, Nellie Wilson | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 322 Registered: 8-2004 Posted From: 68.84.6.177  Rating: N/A |
Nellie said "But (SUDDEN REVELATION!!) maybe that in itself eliminates the Low Oil alarm as the culprit? I mean, even sitting, I can bounce the oil pressure all over the place without sounding the alarm [Hey, up there! George! Did you hear that? Waddaya think?]" Nell, do you have an instrument panel oil guage? I just added one to my bus. Although the book says that what seems like microscopically small oil pressures (6-8 psi at idle, warmed up and 18-20 at highway speeds) are OK, it's still a little disconcerting to see those numbers (I'm used to 50-60 pounds on other engines). Still, my alarms have never gone off except once when I didn't "burp" the heater loop correctly and too much antifreeze drained into the heater and out of the radiator/engine. But I had spare antifreeze and water on board so no damage was done. The worst part was sitting on the side of the road waiting for the engine to cool down so I could see if there was any damage. I also added a coolant temp guage. My bus originally had alarms for overheat and low oil and also "idiot" lights for each but I think that the same sensor was used for both so a failure of the sensor disables both (or causes a false alarm on both). | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 82 Registered: 11-2008 Posted From: 70.52.104.242 Rating: N/A |
Sorry Fred - Didn't mean to ignore your question, our posts just crossed (ships in the night). I musn't have made myself very clear... just assumed most had posted on my previous thread -'Revisiting the 'Hard to start 8V-71 Thread' (in which, BTW, I quoted you, Fred). [My gosh, if I don't quit quoting everyone, I'm gonna get sued for plagarism] What I MEANT was (in a nutshell) that my alarm announces a problem that seems not to really exist. Or, in your words, false alarms. Hope that better clarifies? And thanks for asking. Nellie wilson most had read that my previous oo much ' | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 83 Registered: 11-2008 Posted From: 70.52.104.242 Rating: N/A |
Bruce- I hope George reads that: "My bus originally had alarms for overheat and low oil and also "idiot" lights for each but I think that the same sensor was used for both so a failure of the sensor disables both (or causes a false alarm on both". Or maybe George already knows, but it's news to me. But question: How can two entirely different systems shate one sensor? It sure acts like they do, but I can't wrap my head around that. Yes, I installed both an oil pressure and temp gauge in the dash. Also a new rear temp gauge in the engine compartment, to ensure accurate comparisons. In my case, I kept the idiot lights, figuring I could use all the help I can get. I WAS going to install a rear oil pressure gauge as well, but now I'm not so sure. Like yourself, I was worried by my aenemic psi - hoping I had a bad gauge but fearing I had a bad engine. But I learned - from a recent thread on this topic - that these old DDs just don't have the oil pressure I'm used to seeing (in cars and such). But, yeah, it is darn 'disconcerting' to be tooling down the pike at 65 mph and seeing only 20 lbs. (or even less) on your gauge. I'm pretty okay with it now, but I sure wasn't before. Actually, it still bugs me a little but my mechanic guru says it's the best two-stroke DD he's worked on (and he works on a lot of them). Now it's my job to just keep it that way. Thanks for the great input, Nellie Wilson | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 323 Registered: 8-2004 Posted From: 68.84.6.177 Rating: N/A |
Nellie wrote "But question: How can two entirely different systems shate one sensor? It sure acts like they do, but I can't wrap my head around that. " I apologize, I wasn't clear. What I meant was that the alarm for low oil and the oil "idiot" light are both triggered by one sensor. The overheat buzzer and the "temp" idiot light are triggered by another sensor. Thus, the light and alarm *for each system* share a sensor but it's a different sensor for each system. Sorry, I didn't phrase my first post clearly. Nell also wrote "I WAS going to install a rear oil pressure gauge as well, but now I'm not so sure." It's easy to do. And it's an additional check for a highly critical operating parameter. I've done it on my bus and I think it's worthwhile. Nellie also wrote "Like yourself, I was worried by my aenemic psi - hoping I had a bad gauge but fearing I had a bad engine. But I learned - from a recent thread on this topic - that these old DDs just don't have the oil pressure I'm used to seeing (in cars and such)." Yes. My bus is a 6-cylinder 4-stroke diesel but it's the same principle on the oil pressure. And I'm used to being where "pulling over to the side of the road" means finding a nice long field into the wind with no power lines around it so I'm *really* touchy about oil pressure :^) But what would be thought of as low on other engines is OK on these. | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 240 Registered: 10-2003 Posted From: 66.165.176.60  Rating: N/A |
I guess my DD must be pretty fresh as it always runs around 50 psi. Good to know the acceptable range though | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 85 Registered: 11-2008 Posted From: 76.64.243.180 Rating: N/A |
Hi Tim - Speaking from my own EXTREMELY limited personal experience (but much discussion with others), 50 psi (at op temp) is pretty rare. Probably good, mind you, but rare. I see that kind of pressure on my engine, but usually when it's loading before full warm up, or in lower gears and torquing pretty hard... like on long grades while just losing the power curve - usually just before a downshift. That is, unless the summit is near and I try to hang with the gear (an accidental rhyme!) just a little longer (while gritting my teeth and watching the tach fall... and the temp rise). I know, I know... slap my (right) hand. I'm sure FF will sniff this out and be over here in a hot second to scold me out about lugging my old DD. But... a confession. I HATE downshifting... it's so d*** embarrassing to miss and then having to pull over and start again from scratch. But, in the immortal words (well, word) of John MC9: "Yup." As in, Yup, it's true... been there, done that, got the T-shirt. (Now THERE'S a little girly confidence you guys can all yuk-it-up about)  Sorry about just jabbering on here. Just felt the need to 'talk bus' - since I sure ain't driving one. Ordered some used plates today (thanks Ralph) and some bolts and nuts and stuff (thanks, Luke) and reserved my lift for Saturday PM. Had hoped to get the h*** (nicer than the word I'm really thinkin') outta Dodge and down to Arcadia B-4 Christmas, but just learned the parts won't show until next week. (No fault of Ralph or Luke). 'Next week' being Christmas week, in case nobody but me is counting. So here I'm stuck... broke, cold and without resource (as in no way to make a quid). As Janice J. might say, Oh Lord, won't you buy me an MCI Bus, one that's got air and won't make no fuss... Luv ya guys... and don't mind me, I'm just rantin'. Actually, I'm learning to love pea snow and slush. Great with maple surple. Nellie Wilson | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 608 Registered: 10-2006 Posted From: 69.19.14.27 Rating: N/A |
But... a confession. I HATE downshifting... it's so d*** embarrassing to miss MR Long has a very good bit of advice on shifting posted in the archives , for a decade or so. Topping a hill in to high a gear is how/why main and rod bearings need to be changed at at 75,000 to 100,000 miles , to restore SOME semblance of oil pressure. The GM 06 Sportscar "drivers hand book" gives LOW OIL pressure limits , that might be useful to observe , and use as a guide when to refresh the bearings. FF | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 87 Registered: 11-2008 Posted From: 70.52.106.155 Rating: N/A |
Fred, I love ya! I predicted you'd sniff me out and give me a good thrashin' for that. But, seriously, I know you're absolutely right and when I get a bit more shift savvy I won't be so tentative. And I promise I'll do it by DA BOOK. Thanks for the reading tip... I WILL look that up. Re: MR's article. I found that awhile back, even printed it out and stuck it in the bus. Problem is, I don't drive enough to put his advice into practice. Kinda like golf and sex... read all you want, but you gotta APPLY it to really get it. Know what I mean (wink). Thanks, Bud - Nellie Wilson | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 671 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Nellie, It has been said that work is the crabgrass in the lawn of life... Just got back from weeding, so here's a couple of suggestions. One, the alarm sensor, or sender, whichever you prefer, is entirely seperate from the gauge sender, on both the temp and oil pressure. Oil pressure is a function of both temperature and engine rpm. Oil pressure will be higher on startup, and decrease as the engine warms up, and clearances increase. Just a fact of life with all of ours, and everybody elses. My V12 showed nearly 20 at cold idle, and made about 60 at full rpm cool. That dropped to about 50 at full rpm warm, and about 10 at idle warm. Enough of that, a couple of specifics, please. Take a flashlight, shine it at your idiot lights, and tell us if there are seperate low oil and hot eng lights. Just turning on the master with a dead eng should show you a steady low oil light and buzzer, if yours is wired the same as mine. (Mine does have two idiot light panels, with two rows each,) I think yours only has one, maybe with three rows? The simple solution, if you have a manual, which you should have, is to PM me the electrical schematic. Then I can give you a CORRECT answer! (Hunting without a license is illegal.) Detroits have another peculiarity, the fuel injection system is in with the lube oil system. What this means is that when a leak occurs, the leaking fuel dilutes the lube oil, which will cause bearing failures fairly quickly. So, you have to get used to your oil pressure, and your oil level. If the oil pressure starts to go lower than it usually does at the same eng rpm and temp, pull over and take a look fairly quickly. Pull the dipstick, look and smell. If its over full, and smells like diesel, you probably have a jumper line leaking. This requires a fix, followed immediately by an oil and filter change. HTH, George | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 609 Registered: 10-2006 Posted From: 69.19.14.42 Rating: N/A |
AS an old airborne bus driver I still have the scan , and watch the gauges as we roll thru life. Sure the original stuff works too , BUT IF I were doing a bus that did not have alarms I would take a different tack. Murphy Gauges are pure mechanical units (to install back with the engine) that have settable alarm contacts. A few wires up to the dash and when the light lights or the buzzer sounds , its telling YOU that whatever YOU set has triggered the alarm. FF | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 100 Registered: 11-2008 Posted From: 70.52.103.219 Rating: N/A |
Well dog-GONE it, George. Here I'm thinking we share the identical problem and now (your last post) you sound like you BUILT these stupid things. And, by golly, it's nice to hear about that leaky fuel thing. No wonder my oil level never goes down... Seriously, how can they say these things go three million miles (or even one) with all the inherent defects? I mean, even if they could roll that far, the driver would turn into Randle P. McMurphy just from sheer stress. LOL (See, at least I'm picking up the lingo) But I'm gonna follow your advice. Let's see... a flashlight. Gotte find a flashlight... Nellie Wilson | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 214 Registered: 3-2006 Posted From: 209.50.72.2 Rating: N/A |
Nellie If you are concerned about the oil level never going down then you can smell the oil on the dipstick. Like George says if it smells like diesel then you probably have a leaking jumper line. If you aren't sure you can get an oil sample kit from your local DD dealer and send it off to be tested. This will tell you for sure. If you do have a leaking jumper line look for one that has no oil droplets around the nut. The leaking fuel will wash it clean. Do not over tighten the nuts as they will crack or split the flare. 12 - 15 ft lbs torque. I assume you aren't running DDEC. Bill | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1473 Registered: 12-2000 Posted From: 67.181.166.160  Rating: N/A |
Nellie (and others) - Quick "diesel-in-the-oil" check: Pull dipstick & wipe it off. Replace dipstick, let it sit for 10 seconds or so, pull it out. Allow oil to drip off end of stick onto a paper towel. Watch how the oil disperses into the paper - if it's steady all around, it's only oil. If you have an area that spreads much faster around the outer edges, and a second area in the center that disperses more slowly, chances are you've got diesel in the oil. Of course, the smell test works, too! FWIW & HTH. . . | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 102 Registered: 11-2008 Posted From: 70.52.100.238 Rating: N/A |
Well, my comment ("No wonder my oil level never goes down...") was meant to be tongue-in-cheek. But I see it's something I should take more seriously. The oil LOOKS great - still clean and heavy and no water bubbles, etc. but it really doesn't go down much - of course, I hardly drive it either. And, except for a light film around one valve cover, the old DD doesn't leak, I do get some fuel seepage at cold idle, but that's from the exhaust (at the pipe connection, midway across the back (well, front FACING back) of the engine. But it stops when things warm up. Doesn't that seems totally unrelated to fuel seeping into my oil??? BTW, I HATE that exhaust leak. Other than that, I'd have a nice clean motor. Anybody have the same problem? Any quick cures? Anyway, I'm gonna follow your tips before my next startup. Never hurts to be sure. All of which reminds me of another question, but it's probably a topic for a new thread. Thanks for the heads up. Nellie Wilson | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1269 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Don't worry Nellie, you go pounding out a 6 to8 hundred mile trip at full cruise and you'll find leaks you never thought you had. Major Detroit job is to keep up with the big ones and don't get too crazy about the small drips. The 2 cycle engine sound makes up for the oil leaks. | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 105 Registered: 11-2008 Posted From: 76.68.203.142 Rating: N/A |
Amen, Brother John I'm sure you're ab-so-lu-tly co-rrect. And I can't hardly wait to see them little brown spots... be happy to sprinkle 'em up and down all over this ol' country. Be kinda like riding a Harley, only fatter. Nellie Wilson |
