I’m not doubting the gearing you mentioned, I’m just wondering if something is wrong with the transmission. Could something be wrong with it throwing the rpm’s higher? I have a m998, I know this has a turbo but I’m well aquatinted with the top speed and the noise this engine produces, I’m almost positive I’m right at redline. It’s essentially the same 6.5.
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M1152 Low Top Speed
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Action
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Take it to AAMCO.
I could throw a wrench at it and fix it better than Aamco.
GuntherRommel
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AAMCO is a rip off and does not stand by their work in my experience years ago, I am surprised they are still in business.
Action
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Take it to any trans shop and ask them to look at it. We cant be of much help without seeing it.
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I suppose it could be the the transmission slipping somehow, but if it's really slipping that much it's probably already toast, and the smell of burnt transmission fluid should be pretty obvious when you pull out the dipstick.
Once you hit lockup on the transmission there shouldn't be any slipping anywhere. that's the entire point of lockup.
At this point though, it's definitely not a bad idea to have someone else's eyes on it.
Getting the RPMs on a diesel is a lot harder than a gasoline engine, but tinytach does make one with a transducer that you clamp to an injection line to get the RPMs.
I don't know what size our injector lines are, but they have multiple sizes of transducers
Diesel Tiny-Tach | Design Technology, Inc., Home of Tiny-Tach
Diesel Tiny-Tach. An hour-meter for diesel engines.
www.tinytach.com
Coonass77
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What does your tach show at idle?
Here's the issue I was having with my m1165. See post #5 for RWH's explanation of why I was seeing what I was seeing.
Also, here's a cheap way to confirm actual engine speed:
Here's the issue I was having with my m1165. See post #5 for RWH's explanation of why I was seeing what I was seeing.
Tachometer Inaccurate?
I have a 2006 M1165, 6.5 turbo, 60mph speedo and a tachometer. My problem is that the tach rpm reading is wrong. The tach shows idle at 950rpm, but my handheld rpm meter shows 700rpm. And with the engine speed set and showing as 2000rpm on the tach, my handheld meter is reading 1500rpm. I...
steelsoldiers.com
Also, here's a cheap way to confirm actual engine speed:
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The 3.08 diffs have a much lower top end…I own 6 or 7 ECV’s, they all tach extremely higher than my M1123’s with 2.73’s.
This assumes 37in tires, TC locking and unlocking as it should.
This assumes 37in tires, TC locking and unlocking as it should.
What do you consider a lower top end?
950rpms. Does that work on diesels though? Normally diesels are harder, normal tachs don’t work on them.
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the one he linked there just requires a shiny spot on a moving object in order to get it's RPMs.
It comes with a strip of shiny tape. You put a piece of tape on one side of the rotating object, and every time it goes past a light from the tach gets reflected back at it.
You'll likely have to do it from underneath the truck to be on the harmonic balancer. Not sure what the furthest distance away it will read.
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just to verify, what generator do you have in your truck? As the other thread said, if it's the 400 amp then it has a smaller pulley and will change what the tach reads.
Where would you put that if you were trying to use it to determine rpm’s? I was thinking it would, just wasn’t sure where you’d put it to get an accurate reading.
I do have the 400a.
I missed the first part of his post. Do you know what pulley they’re talking about? I’d definitely like to have an accurate tach.
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The tach is a handheld unit. You just point the end at the moving object to see how many times per minute the shiny tape you put on it goes past. In this case you'd want something on the crankshaft, as that's the speed you are trying to determine.
However, the added information that you have the 400A generator explains the issues you are having.
The 400a has a smaller pulley, and therefore makes the tach read higher than it would if you had the 200 amp.
The idle on your engine should be about 700. If you are reading 950, then you are about 36% higher than actual.
your 3300 rpm reading at 65mph is actually about 2400 rpms.
I'm not sure the details, but you might want to contact RetiredWarHorses (Steven Kavanaugh) about what pulley and nut you require in order to change your setup. I think what is being said in the other thread is that the over running pulley on the 200 amp generator for trucks after serial number 196900 is the pulley you want, but there is something different about what nut is used to secure it.
As I said, I don't know the details.
You can either contact him here, or through his website which also has a phone number.
He's here on the west coast, so don't forget the time zone change when trying to contact him.
However, the added information that you have the 400A generator explains the issues you are having.
The 400a has a smaller pulley, and therefore makes the tach read higher than it would if you had the 200 amp.
The idle on your engine should be about 700. If you are reading 950, then you are about 36% higher than actual.
your 3300 rpm reading at 65mph is actually about 2400 rpms.
The pulley on the generator. In order for the 400 amp generator to put out the power it is supposed to, it spins faster than the 200 amp generator.
I'm not sure the details, but you might want to contact RetiredWarHorses (Steven Kavanaugh) about what pulley and nut you require in order to change your setup. I think what is being said in the other thread is that the over running pulley on the 200 amp generator for trucks after serial number 196900 is the pulley you want, but there is something different about what nut is used to secure it.
As I said, I don't know the details.
You can either contact him here, or through his website which also has a phone number.
He's here on the west coast, so don't forget the time zone change when trying to contact him.
Gotcha. Thanks. I would have thought that wouldn’t affect the tach but these might be set up differently than other ones I’ve used.
I probably don’t need the 400a but it might be cheaper to get a tinytach. Either way I pray this is my issue. If so, I’m way ahead ata $20k m1152….kind of, actually more like a soft top m1165 since it came with everything for a 4 man setup.
Now I won’t need my spare 4l85e.
Might want to swap gearing for a higher top speed.- 2,975
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pulley size definitely affect it.Gotcha. Thanks. I would have thought that wouldn’t affect the tach but these might be set up differently than other ones I’ve used.
I probably don’t need the 400a but it might be cheaper to get a tinytach. Either way I pray this is my issue. If so, I’m way ahead ata $20k m1152….kind of, actually more like a soft top m1165 since it came with everything for a 4 man setup.
Now I won’t need my spare 4l85e.
The earlier trucks used a drive off the oil pump for the tach.
With the turbo on there there is no room for that drive, so instead it takes a signal from the generator, and since that's belt drive, changing the pulley size affects how fast the generator spins and screws up the tach signal.
Not something you really think about until you're affected. I'm just glad Coonass77 chimed in with the answer you were looking for.
As for top speed, they aren't really made to go fast. As it is, once you get the tach straightened out, you're talking a top speed over 70mph easy, and reports have doing over 80 no problems.
Action
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But he knows his engine is screaming, just because. A different pulley wont change the screaming of his engine.
Action
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There is already an Engine Speed Sensor on the left side / front of this engine. You can make a simple obd jumper for the extra port on the TCM and use a tech2 to read live rpm of the engine.
Anyone know how many revolutions the engine makes per 1 revolution of the serpentine belt? You can see each time the part number goes by on the belt. Count it for a given amount of time and do the math. Or compare your count to that of a 200 amp truck.
Anyone know how many revolutions the engine makes per 1 revolution of the serpentine belt? You can see each time the part number goes by on the belt. Count it for a given amount of time and do the math. Or compare your count to that of a 200 amp truck.
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Dude, no reason to be like that. Seriously, don’t be that guy. I have a m998, I already have a 6.5.