# truck rumbles at rpms above 2500



## NelsonCnty (Jan 7, 2008)

hi folks. my truck has developed a very noticeable rumble at the top of most gears. it seems to be worst in the higher rpm range of 2nd, 3rd, and 5th. it goes away completely when I let off the gas. power seems to be suffering in those ranges as well.

any thoughts on where to start looking/testing?

thank you!


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## zanegrey (Dec 5, 2005)

what truck do you have?.. check the fan clutch..


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## NelsonCnty (Jan 7, 2008)

Sorry..it's a 95 HB, 2WD, 4cyl, KA24E.

I replaced the fan clutch a year ago, so I'm hoping that's not it...


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## GeoBMX4Life (Mar 25, 2010)

How is 4th gear, if its all gears but fourth, your tranny might be going.


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## NelsonCnty (Jan 7, 2008)

hmm...4th is notably smoother.

in the past several months, it's been getting harder to get a good smooth shift without a clunk. I can do it, I just need to be extra smooth with the clutch. not sure if that has anything to do with it though.


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## GeoBMX4Life (Mar 25, 2010)

Fourth is a straight spline from your tranny, no gears, if its clean and noiseless, its probly your tranny. I had to replace mine a few years ago and this is what was happening. The clunk wasn't happening to mine tho, but I did replace the uni-joint 2 years previous.


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## NelsonCnty (Jan 7, 2008)

I checked the gear oil last night and it was a 1/2 quart low so I added. As you'd assume, hasn't made much difference. Does the rear take the same gear oil? 

Is there anything else I can try or is there anything else it can be? Can you hear the desperation in my voice?

How much do you think a trans would cost, and is it a pain in the arse job or not too bad?


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## dvdswanson (Nov 6, 2005)

check your u-joints


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## NelsonCnty (Jan 7, 2008)

will do, thanks for the suggestion Dave.


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## NelsonCnty (Jan 7, 2008)

there is play in the drive shaft (truck in neutral), I can roll it back and forth and hear a clunk when it hits in either direction. there is little-to-no play if I shake the shaft up and down and no visible give at the u-joints. there is give in the center bearing/mount, as if the rubber is soft. 

what does this tell me?


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## GeoBMX4Life (Mar 25, 2010)

Check the hanger/center bearings, these wearing out can give some noise too, I redid mine about 10 years ago....and it was the clunk, and or grinding that pointed me to it...keep us posted.


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## NelsonCnty (Jan 7, 2008)

what does the rotary play in the drive shaft tell me?


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## NelsonCnty (Jan 7, 2008)

b'dump bump


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## GeoBMX4Life (Mar 25, 2010)

Do you mean side to side play in your drive shaft? Explain rotary play please.


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## NelsonCnty (Jan 7, 2008)

by "rotary" I mean the play is in its turning. radial? there is play in the way it spins (around). if I grab it in my hand and roll my wrist as if I'm the output of the transmission, it clunks in both directions. definitely play.

another clue: I may be crazy, but I'm pretty sure that the other day when I had 10 cinder blocks in the bed, the rumble was much much better.


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## NelsonCnty (Jan 7, 2008)

one last bump for help...


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## GeoBMX4Life (Mar 25, 2010)

I still think its your hanger bearing, if there is play in the center, it should be looked at.


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## GordonW (Jun 25, 2010)

Some rotary play within the gearbox is normal. These things are not zero-lash on the gears, especially after a hundred thousand miles or so. As long as it's not more than a couple of degrees of free rotation, it's probably not directly indicating a problem.

Try this- is the lash (play) noticeably less when the transmission is sitting in fourth gear, than in second, third or fifth? That might indicate a problem with the slave shaft bearings within the gearbox. That would be a cause for concern, most likely...

I still have a suspicion, however, that they guys who are suggesting checking the U-joints and driveshaft hanger bearings might be on the right track. I've had that happen with other RWD cars and trucks, and it was oftentimes the U-joints, or a slightly bent driveshaft...

Regards,
Gordon.


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## NelsonCnty (Jan 7, 2008)

thanks for those responses. I'll check into all of this and let you know how it goes!


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## lumbee (Mar 20, 2005)

...def sounds like trans to me. I've got the same model. I did a bunch of hauling in 5th gear, and blew out the 5th gear. Smooth in 4th, but herky jerkies in 5th. Try this...with the truck idling, put your ear on the stick shift. Do you hear knocking?

I had the same symptoms are yours. I let it go for about 18 months, finally, the knocking got so bad, I knew something had to be done. I took it to a trans shop, and they did their "diagnostic" for free and all they could tell me is it would anywhere from 800-1800 bucks. Said they would not know what the problem was til they cracked it open. Well, the truck is barley worth that. So I took this as a good opportunity to "get to know" my truck. I pulled the trans myself, and sure enough I had blown out the 5th gear. There's a woodruff key that holds the 5th gear on the end of its shaft, and it was pretty beat up...that gear is normally pressed on the shaft, it just fell off when I took the trans apart. Heres a thread I did on it...you can see the pics...

http://www.nissanforums.com/hb-truck/138899-95-pickup-tranny-rebuild-thread.html

I did the rebuild myself with mixed results...I'm a software engineer not a mechanic. I ended up buying a rebuit tranny, and old girl is still kicking 2 years later. Good luck!


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## NelsonCnty (Jan 7, 2008)

hey Lumbee - that's a really solid write-up, I actually read it a couple of weeks ago  I'm a hobby mechanic (or, a mechanic out of necessity). But I'm a stats/data guy by day.

I'll put my ear to the stick today and report back. And I've done a lot of hauling (firewood) in 5th gear...didn't realize that was a no-no. 

Another thing it does is buck a lot more easily. It's easy to get a clunk when shifting, and in most gears it's pretty easy to get that bucking motion that you get when you goose the gas. 

I dunno. At this point, it needs to make the 30 mile commute just a few more times and then we'll have the family wagon on the road and can give the truck a rest while I figure out what to do. Although, it's just about that time of the season to haul a few cords of wood home.


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## lumbee (Mar 20, 2005)

...yeah, if you'r hauling more that a few hundred pounds you want to keep it in 4th. After I put the rebuilt trans in, I never let it lug in 5th...aways shift to 4th.

The good news is you have some time. It will get worse, but its not gonna just blow up one day. I drove mine around like that for a couple years. I just wouldn't use 5th gear anymore.


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## NelsonCnty (Jan 7, 2008)

lumbee said:


> I just wouldn't use 5th gear anymore.


I use 5th a lot less nowadays, that's for sure. But it rumbles/vibrates in all of the gears (except for 4th).


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## GeoBMX4Life (Mar 25, 2010)

*Bad news if every gear but 4th *



NelsonCnty said:


> I use 5th a lot less nowadays, that's for sure. But it rumbles/vibrates in all of the gears (except for 4th).


 I had to replace my tranny 5 years ago...same symptoms. It won't rumble in 4th because its the only gear that can't be damaged in the same way as the others were. See if you can get a free estimaye at a tranny shop...I ended up ordering one off of Car-Parts.com for 400$ Canadian. Good luck!


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## lumbee (Mar 20, 2005)

...yeah, I found mine on Ebay, and I paid around 400 for it shipped, which was a good price.


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## NelsonCnty (Jan 7, 2008)

I noticed something else yesterday: when idling, I hear a rhythmic knocking outside the truck..if I rev, it gets faster. this goes away when I depress the clutch pedal... related?


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## GeoBMX4Life (Mar 25, 2010)

NelsonCnty said:


> I noticed something else yesterday: when idling, I hear a rhythmic knocking outside the truck..if I rev, it gets faster. this goes away when I depress the clutch pedal... related?


 That could be your throwout/release bearing, when I replaced my tranny, I did clutch and pressure plate, as well as the throwout/release bearing.


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## NelsonCnty (Jan 7, 2008)

had my clutch replaced last year. I'll be pissed if it's the throwout bearing already...


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## lilfoo22 (Mar 22, 2010)

[email protected] clutch!


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## NelsonCnty (Jan 7, 2008)

I'm going to see if any scrap yards in my state have a transmission for sale.

what years/models are compatible with my '95 hardbody (5spd)?

bummer. thanks.


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## GeoBMX4Life (Mar 25, 2010)

*Car-Parts.com*



NelsonCnty said:


> I'm going to see if any scrap yards in my state have a transmission for sale.
> 
> what years/models are compatible with my '95 hardbody (5spd)?
> 
> bummer. thanks.


 87.5-1995 trannys from the same truck will work. Try looking at Car-Parts.com, thats where I sourced mine out.


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## NelsonCnty (Jan 7, 2008)

excellent, thank you.

I've never done this job before but it doesn't seem too bad. I'll be doing it in my driveway, with the truck on jack stands. how many hours do you suppose it'll take me? 

thanks. I'm kinda looking forward to doing this, in some sick way


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## NelsonCnty (Jan 7, 2008)

so I've located a used transmission. is there anyway to "check" it before I buy and install it? or am I pretty much going on faith?

thanks!


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## GeoBMX4Life (Mar 25, 2010)

Not that I know of, but if you're getting it from a wrecker, they should know the mileage on it, and give you at least a 30 day warranty.


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## NelsonCnty (Jan 7, 2008)

thanks. looks like it's got about 120k on it. that's about 160k younger than mine 

what do you make of this: yesterday I hauled home a full load of logs. the truck was loaded to capacity. there was no transmission rumbling! what do you think this means about what is wrong with my transmission? if I can locate the problem in the tranny, I might consider trying my hand at a rebuild instead of replacing it...


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## NelsonCnty (Jan 7, 2008)

probably a related issue, but I'm wondering about:

there is a rattle at idle and the rattle goes away when I push the clutch pedal in. 

input shaft bearing? pilot bearing? think it'll be okay to drive this another 1,500 miles this weekend?


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