Was looking forward to taking Hanna out to clear our first dump of snow for the year. I let the circulating heat pump warm things up for a couple of hours (it being -18C / 0F). She started without issue. But there was a 'wop/wop/wop' noise coming from something in the control box and it broke the shear pin. I replaced the shear pin and re-started her, with same result. "Hmmm," I wondered... "Could it be related to being cold?" It was -31C / -24F yesterday. But last winter that had not been an issue. Anyway, I let her run with the cab heater on long enough to take the chill out. Then I shut her down and replaced the shear pin and restarted. This time no 'wop/wop/wop" noise. But then I raised the LH side of moldboard. It raised without issue, but when I released the lever back to neutral, there was the wop/wop/wop noise for just a bit, and then it stopped. I then raised the RH side--same thing, but this time wop/wop/wop and silence--the shear pin sheared. I repeated this a few more times, with same results on every control lever. Sometimes the noise would stop. But the next lever would create the noise again and inevitably the pin would shear.

I've got the service manual, but cannot find any trouble shooting description of Hanna's symptoms. I have a sinking feeling that I'm going to need to dissemble the control box. I think the front can be removed to see what might be going on.

Way out of my depth on this, but such is life. Grateful for the wisdom of the ACMOC community. I do wish it had happened in the summer, mind you. Working outdoors this time of year is tedious.  Ah well.

yours is still old enough to have mechanical blade mechs isnt it. cuase that doesnt sound good at all. maybe something happening with the dog clutches or has the shafts or pivots partially seized that could happen in such cold temps metals do shrink in cold temps.

trainzkid88 wrote:

yours is still old enough to have mechanical blade mechs isnt it. cuase that doesnt sound good at all. maybe something happening with the dog clutches or has the shafts or pivots partially seized that could happen in such cold temps metals do shrink in cold temps.
 

Yep. Mechanical blade lift and etc. And yep. Doesn't sound good. Will get her good and warm before trying anything again. But last year I had her out in equally cold weather with no issues.

Make certain the "wop" noise is not coming from some shot "U" joints on the short shaft that come off the engine. Easy to see and check on most models.

D4Jim wrote:

Make certain the "wop" noise is not coming from some shot "U" joints on the short shaft that come off the engine. Easy to see and check on most models.
 
Good advice. But I had checked those this summer (and replaced a couple of u-joints on the control drive shafts. The noise definitely came from the control box. As I note below, I am wondering about the dog clutches being slow to move due to cold, thick, oil.
 

Trainzkid88 got me thinking. The specs for the control housing oil call for 30W. At -18C/0F, 30W can be rather thick, making me wonder if the dog clutches were not disengaging fully because of congealed lube. I am thinking of putting a heater in the cab and getting the control housing good and warm and seeing if the symptoms disappear. If they do, I wonder about switching out to 5W30 synthetic for the control box. That would not have been an option in 1968.

Thoughts?

Good to see you and Hanna again onfoot, I just got my Cat No.12 8T Motor Grader (A.K.A. AT UM) running with the temps dropping to 000*D for Damn Cold. A guy on another forum said to warm up the pony then the diesel and at very low temps the line to the oil gauge (4'-5') gets pressurized but if the oil suddenly drops the oil gauge may take up to several minuets to respond to the drop in pressure. Sounds like he has been there once before. Anyway he suggested to run the diesel oil pressure up and disengage the pinion and watch the pressure drop back down then reengage the pinion to confirm the pressure is accurate. I decided to put an oil gauge in the diesel engine directly into block/head in the starting station area.
I did notice as the temp drops not just the control box in the cab gets cold but also all the lubes in the bull gears, gear boxes and u-joints gets very thick too. (my trany must have 90w in it.LOL). The increasing resistance to the control mechanism puts a lot of pressure on the shear pins. Ice/water can be in the lubes increasing the resistance while decreasing the lubricating properties of the lubricants. I had a bull gear full of ICE on my Adams 311 Motor Grader once. I was lucky I inspected the gears before I had engaged the circle otherwise I would imagine it would have broken shear pins in the control box or broke weak u-joints.
good luck

 
 
 

Who knows what might be in the oil in the control box. Changing to a lighter and clean oil would be a good idea.
It has been so long since I looked at mine that I don't remember if a sheared pin can get into a gear.
Not to belabor a point but if one has taken the short telescoping shaft apart, I believe it is possible that the U joints can get misaligned when put back together.

Clean and lighter oil might just solve the problem. Sure worth a try.

I have been told by more than one Sourdough "with these old rig 10w is you friend in the winter."
Synthetic oil vs.single and multi viscosity oils :
Synthetic oils are made to hold or suspend the dirt (contaminants) in the oil until it is filtered out,
Synthetic oils also have a lot more detergents in them to help clean internal engine parts to send to the filter.
Synthetic oils are very good at cleaning that is what they were made fo r,
However;
single and multi viscosity oils have a long history of additives from lead to zinc to bees wax but the underlining deference, I see, between the oils is the non-Synthetic oil drops the dirt in the sump (oil pan and nooks n crannies) and it settles and what goes through the filter goes through the filter ... until someone comes along and changes oil or pulls the oil pan.
The conundrum:
If one has been using single viscosity/non-Synthetic oils for thirty er sixty years the gunky hardened dirt in the sump is at rest. Sometimes it is best to let sleeping giants lie. To disturb their slumber may prove to be fatal or at least expensive.
There are other reasons such as seals and filters that need to be addressed. 

Conclusion :
If one were to clean and restore the engine, trany or gear box addressing the seal and dirt issues, I see no reason why anyone couldn't use Synthetic oils.


 

yes multi grade oils are much better than monograde. and you could try a synthetic as they cope with harsh conditions a bit better. the old recommendations are based on what was available back then.

and american companies seem to have a love affair with sae 30 oils when much better exists today.

i just had a look online and found out about a product called redline shockproof gear oil its a synthetic and is thin like light engine oil but works like 75w140 gear oil.
made specifically for dog clutch transmission in racing applications. they have 3 grades superlight, light and heavy available in the quart or gallon. from all good performance and racing suppliers. might be just the stuff.