IH 674 Diesel noise

ClarkR

Member
Started to bush hog yesterday and when I engaged the PTO it sheared the bolt in the driveshaft. When I idled down and got off I noticed the knocking. It?s coming from right behind the engine below the steering wheel. I can feel it a very little through the clutch pedal. Clutching and driving doesn?t change the noise. Kind of disappears (or you can?t really hear it at higher rpms). It?s changed by the rear differential lock lever. Moving the lever will make the knock louder at times and there?s chatter when you try to engage (FYI I?ve never used the lock). Tractor operates fine but has the knocking.

Any help with diagnosing would be appreciated. Also if it?s safe to use as is and how to fix.

Thanks
 
Numbers 37,38, and 16 and its mate might have a tooth off. Not simple, not cheap, not advisable to keep running the IPTO at least. WIll it fail completely, probably. The tooth is also "lost" and can cause major scrap metal. Jim
IH parts manual
 
Thanks. Are you saying it may be ok to use without using the PTO? I?d rather just get it fixed, but just asking. Thanks
 
I think it is a constant mesh sets of gears. It may drive the hydraulics (I think it does) if so use may directly cause a very major failure. I also think it is a major teardown to get at those parts, or even see them to find a broken tooth. Pete 23 or the Vet may be needed here, I have not been in there, just looked at the supplied diagrams. Jim
 
Hi Clark, a few questions:
1) Dose your Bush Hog have a PTO over running clutch?
2) Is the knock or rattle by the clutch housing?
3) Does it only occur when PTO is engaged on bush hog? If you remove PTO from Bush hog and run PTO is the noise still there?
You said Clutching doesn't change the noise but to be sure do the following:
4) Does the 674 have a T/A? Does it do the same noise in HI and LO T/A?
5) Is the noise still there when you put the Range transmission in Neutral (REV/LO/HI) and let out the clutch?
6) Put the Speed transmission in Neutral by putting lever half way between 2nd and 3rd gear and let out the clutch?
 
Hi Jim,

Yes the noise is near the clutch housing. It makes it whether the PTO is engaged or not. I tried it in low 4Th and High 1st and the noise continued. I believe it also did it in reverse. It doesn?t have an overrunning clutch. The sound is a knock. It gets louder and changes if try to engage the differential lock pedal up or down. The tractor is on my property about 50 miles from where I am during the week or I?d try some more tests. I?m not sure I tried it in low high neutral but definitely tried in gear neutral and with clutch in and out. Sound never went away. May get a little faster but no louder at higher rpms.

Hope this helps your diagnosis. Thanks
 
Hi Clark, my first guess would be the PTO shaft drive splines on the pressure plate.
I don't know your mechanical ability, so I will explain with reference to a couple of photos that I uploaded.

The first photo below shows the clutch housing with #1 being the throwout bearing, Red arrow is the outer shaft that is the PTO shaft that goes into the splines on the pressure plate in the second photo.
The PTO shaft turns all the time the engine is running and it also drives the hydraulic pump farther back about under the seat in the rear of the tractor is the hydraulically activated PTO clutch/brake, this clutch connects the rear PTO shaft to the internal constant running PTO shaft.
Blue arrow is pointing to the transmission shaft that runs inside the PTO shaft. The transmission shaft STOPS when the clutch is depressed.
The RED circle in the bottom is the inspection plate that can be removed from the bottom of the clutch housing and you can check the condition of the Pressure plate fingers, Throwout bearing and try to get a look at the splines on the Pressure plate that drive the PTO shaft.

cvphoto29627.jpg


The photo below I have a Red circle around the splines in the Pressure plate that drive the PTO shaft.
The reason for asking about an overrunning clutch on the Bush Hog as every time you slow the engine down the splines on the Pressure plate have to attempt to slow the PTO shaft and the reverse when you speed the engine up. Problem is the splines on the Pressure plate are made of a softer steel than the PTO drive shaft and they will ware and start to chatter anytime there is a load on the PTO.

cvphoto29628.jpg



Hope this helps
JimB
 
Thanks Jim. This is very helpful and makes sense giving when it occurred (when the PTO shaft was engaged). How complicated of a job is it? Obviously the tractor has to be split at that point (which I have never done). I removed, rebuilt and reinstalled the PTO clutch pack with a friend's help a few years ago and have replaced the hydraulic pump. However, my overall mechanical skills are somewhat limited. Never really attempted something too complicated. Just wondering if it's something I could handle.

It looks like the tractor needs to be parked until I can get it repaired to avoid more serious damage. Just hard to find folks to work on older tractors around here.

Thanks, Clark
 
I am seeking understanding, not questioning your European knowledge. What would make a spline drive make a repetitious clicking in this case? Many IHC tractors have the drive you show, when they fail, the noise is often described as a nasty grinding vibration, not a clicking. With respect, Jim
 
Hi Jim, my brother has 5 of these IH/CIH 54/74/84/95/32XX series tractors. Many years ago the 454 was used on the manure spreader and when you came to the end of the field and slowed the engine RPM down but the beaters on the manure spreader wanted to continue running at the same speed we would hear a clicking noise from the clutch housing area. Other PTO implements had an overrunning clutch and you would never hear anything. When we had to replace the clutch on the 454 there was only about 1/16" inch tooth left on the pressure plate splines. The PTO input shaft was still good and the clicking noise disappeared when using the manure spreader. We have changed the clutch on the 684 twice and the 495 once. The 495 had no spline ware as the PTO is not used that much. The 684 had some spline wear but not significant.
PS, maybe my description of the sound is not accurate but I can appreciate if the 454 clutch hadn't been replaced eventually the spline teeth would have stripped and the noise would have changed to a grinding noise.

JimB
 
Ah Hah! The splines were worn like the one in the video. While the PTO was in gear, the U joints caused deceleration and acceleration to the IPTO system. This hammering (and if I do say so a poorly designed method of driving the "live" systems in the entire IH lineup of Live PTO/hydraulics with that clutch cover spline drive) is at fault on yours. The videos sure show a broken tooth in the constant mesh drives in the trans. My thinking is in that area as it happens all the time after the shock incident. Jim
 
I?ve had tore a lot of them down and found a tooth off the PTO gear caused by a rotary mower because it shocked it somehow and the teeth out wide but I?ve seen them broke off Take the bottom plate off the transmission and look at the gears
 
Clark, I am not saying 100% sure that is the problem but it is something to investigate. There could be also a broken tooth on the input PTO shaft gear or on the PTO shaft driven gear.
The PTO shaft is the only shaft that runs constantly when the transmission clutch is depressed. I have no idea why the noise is worse when the diff lock is depressed.
I would do more diagnostics before tearing into the 674. If you remove the pin out of the clutch adjustment clevis, you can reach up through the inspection hole and push the throwout bearing and carrier rearward and you can have a good look at the pressure plate and fingers, throwout bearing and wiggle the PTO input shaft to see if it is loose in the splines.
 
Clark, I also like timmyih's recommendation of draining transmission and remove the bottom cover closest to clutch housing and look at PTO shaft gear.

Re splitting, if no loader or cab very easy split. Being a 674 the oil cooler lines maybe be hydraulic hoses with enough length to split the tractor with out disconnecting them.
The newer model 684 has steel hydraulic lines and you have to disconnect them down by the right side cover by brake pedals and up under battery box.
Also 674 may have an electrical connector connector under left side of battery box that will allow to disconnect front electrical from rear and large battery cables, remove ground side first and starter solenoid wires. Maybe oil pressure gauge line.
There are the fuel lines from the tank to first fuel filter and the return line up by front of batter box.
Throttle under battery box, STOP/START/RUN cable.
 
Jim
Your message above says there could be a broken tooth on the input PTO shaft gear or on the PTO shaft driven gear. Being these are substantially further back, could they cause the noise all the way up at the clutch/throw out bearing area?
Thanks
 
The teeth are right behind the throwout bearing guide tube flange. In the videos there was a tooth broken off!! Jim
 
Hi Timmy can you change the gear on the PTO shaft without a tractor split by reaching in through the inspection plate and removing the bearing cover and the C-clip on the PTO shaft and then removing PTO clutch sliding PTO shaft to the rear and then change gear by removing bottom off transmission?

Thanks
JimB
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top