Lmackattack Posted December 30, 2010 Share Posted December 30, 2010 Been working on the old Superliner and need to replace the tach drive. I have not washed the engine so its kinda oily down near the tach drive. Looking down there I cant see how it is held in place. I can see one nut on top but not sure if thats all that holds it on ? Hope its as simple as one nut and it pulss out? is it that simple???????? also this truck is 24V, equipped with a mechinal water temp gauge. Would I need a special "24v" water temp gauge and sending unit if I converted it to electrical? right now the mechinal gauge is installed with the probe in the water housing / probe lead runs back to the dash gauge. Its not working and would like to replace it with a electric unit as you can just run wires instad of the thicker mechincal probe lead...Trent Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/ Share on other sites More sharing options...
bobo Posted December 30, 2010 Share Posted December 30, 2010 Hey T. You sure the truck is 24 volt? Not 24v start and 12v truck? Bobo Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69395 Share on other sites More sharing options...
bad1989gt1 Posted December 30, 2010 Share Posted December 30, 2010 Been working on the old Superliner and need to replace the tach drive. I have not washed the engine so its kinda oily down near the tach drive. Looking down there I cant see how it is held in place. I can see one nut on top but not sure if thats all that holds it on ? Hope its as simple as one nut and it pulss out? is it that simple???????? also this truck is 24V, equipped with a mechinal water temp gauge. Would I need a special "24v" water temp gauge and sending unit if I converted it to electrical? right now the mechinal gauge is installed with the probe in the water housing / probe lead runs back to the dash gauge. Its not working and would like to replace it with a electric unit as you can just run wires instad of the thicker mechincal probe lead...Trent Not sure what V8 you have , but i just replaced one on my ENDT866b, and it was held in by a crows foot / fork with one bolt then just pop it out and up "very tight on my truck". The one I received from Watts mack I had to take apart and use the very short drive shaft from the original, old tach drive, the one that came with the new tach drive was too long there for not allowing the tach cable to screw into the top of the drive . hope this helps Brian Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69397 Share on other sites More sharing options...
Lmackattack Posted December 30, 2010 Author Share Posted December 30, 2010 I got the presser washer ready for tomorrow so I will be able to see better if it has a crows foot. that sure will make life easy if it does!!!!The truck has four 12V batterys but the dash gauge range shows a 20V-28V range, I assume its a 24v truck? with the lights only running off 12V?Vin number is 1M2AY12Y7MM005499BUILT 5-90 DELIVERED 6-90Finished by R.G. smith Desplaines IL450HP V8 with a mack 13 speed 38K camelbacks. Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69399 Share on other sites More sharing options...
rhasler Posted December 30, 2010 Share Posted December 30, 2010 I got the presser washer ready for tomorrow so I will be able to see better if it has a crows foot. that sure will make life easy if it does!!!!The truck has four 12V batterys but the dash gauge range shows a 20V-28V range, I assume its a 24v truck? with the lights only running off 12V?Vin number is 1M2AY12Y7MM005499BUILT 5-90 DELIVERED 6-90Finished by R.G. smith Desplaines IL450HP V8 with a mack 13 speed 38K camelbacks.It shows a 12 volt alternator and 24 volt starter. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69406 Share on other sites More sharing options...
Lmackattack Posted December 30, 2010 Author Share Posted December 30, 2010 hmmm...dont know how its wired up..all I know is the gauge shows 24v. all the other macks I have been in had the standard 12V gauge and 12v start? thanks for looking into it tho. Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69409 Share on other sites More sharing options...
bobo Posted December 30, 2010 Share Posted December 30, 2010 My guess is that some one put the gauge inline with the starter, to check voltage drop during cranking? Just use an old bulb to check for the 12v from another gauge while you have dash panel off. You are doing your self a favor, go with the wired sending unit over the cap. Tube. They don't like vibration and seem to break the tube quickly. I just changed over mine on the E9. Bob0 Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69410 Share on other sites More sharing options...
Lmackattack Posted December 30, 2010 Author Share Posted December 30, 2010 I have a volt meter so I will check the cab system volts tomorrow. My mack dealer said the truck came factory with a Electric temp gauge. At some point it was replaced with a PAI mechanical?. Time to go back stock! Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69414 Share on other sites More sharing options...
rhasler Posted December 30, 2010 Share Posted December 30, 2010 You might be able to just install the electric guage, the chassis shows that it had what I assume is an electric gauge (part number 3MT323AP2) when built. There should be a harness branch going to the "A" panel of the dash that connects to the main cab harness with a large black 8 pin connector. If it's there, wires 18 B/G, 18 W/R, 18 B/W, and 18 B connect to the water temperature gauge (plus the wires/socket for the gauge lamp). Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69415 Share on other sites More sharing options...
Lmackattack Posted December 30, 2010 Author Share Posted December 30, 2010 > I saw some louse wires behind the gauge but near the sending unit/prob port the wires were missing. I will have to dig vor them tomorrow. I think this truck had a kisor alarm unit also so I will have to figure that out as well... Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69416 Share on other sites More sharing options...
David Posted December 30, 2010 Share Posted December 30, 2010 Trent, The 18 B-W runs from the gauge to the number 2 post (second down from the top) on the firewall block. Then 16B-W runs from the same post to the water temp. sending unit. Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69417 Share on other sites More sharing options...
Lmackattack Posted December 30, 2010 Author Share Posted December 30, 2010 thanks for that info David..I hope this truck has not been hacked into much!!! Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69418 Share on other sites More sharing options...
Lmackattack Posted January 5, 2011 Author Share Posted January 5, 2011 Alright I got the tach drive installed today.. pretty easy with a magnet tool to get the crows foot in. I noticed they had the crows foot in backwards so im sure that helped it wear out faster. Got it for around $90 at my local mack dealer. Next issue. I think this engine is running a little under powered? this is a 1991 E9 450Hp gov @1900 RPM. The Tach only reads 1800 at full throttle (no load). I dont recall if they should spin faster than the advertised governed RPM with no load? I know the 6 cyl macks would spin to around 2250-2300 RPM with no load.Whats the boost range on this engine. I cant get more than 15 psi out of it and it seams as soon as the boost comes on at 1500 it falls off at 1700. This truck has that air throttle so im not sure if the pump is getting full fuel. I also think it has a torque limiter device.Any thoughts. Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69798 Share on other sites More sharing options...
rhasler Posted January 5, 2011 Share Posted January 5, 2011 Alright I got the tach drive installed today.. pretty easy with a magnet tool to get the crows foot in. I noticed they had the crows foot in backwards so im sure that helped it wear out faster. Got it for around $90 at my local mack dealer. Next issue. I think this engine is running a little under powered? this is a 1991 E9 450Hp gov @1900 RPM. The Tach only reads 1800 at full throttle (no load). I dont recall if they should spin faster than the advertised governed RPM with no load? I know the 6 cyl macks would spin to around 2250-2300 RPM with no load.Whats the boost range on this engine. I cant get more than 15 psi out of it and it seams as soon as the boost comes on at 1500 it falls off at 1700. This truck has that air throttle so im not sure if the pump is getting full fuel. I also think it has a torque limiter device.Any thoughts.The 1991 tuneup specs say operating range 1300-1900 rpm. Boost is quoted at 18-26 psi. Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69801 Share on other sites More sharing options...
Lmackattack Posted January 8, 2011 Author Share Posted January 8, 2011 Thanks Rahsler Sounds like its turning a little slow then... throttle is wide open so Will have to mess with it to get the RPM back....Ok nother problem ...im on a string of bad luck... the new tach drive just went out. Have to pull it tomorrow to see why. Last tach drive had the a cracked shaft that incerts into the block. What is it driven off of? Im thinking what ever turns the tach drive has too much slop and is braking the shaft? any thoughts? Quote Link to comment https://www.bigmacktrucks.com/topic/17056-v8-tach-drive-and-water-temp-gauge/#findComment-69987 Share on other sites More sharing options...
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