Case 621b

Hello, I am new to the forums but I read them religiously. I figured why not join maybe talk out a few issues I have with you guys before spending the big bucks on case mechanics to come out.
I have a small fleet of loaders what we use for snow plowing only. We do not use them for anything else. I have a few case 621b machines, one I recently have an issue with. We acquired this machine in the spring, I’ve driven it all around town threw the summer to different shops to have new tires put on and other service work and back to our facility. No issues. Soon as the snow season started and this machine was brought to site I started to have transmission issues.... It says it’s getting hot. Now I’ve been in this business since I was a kid in high school. I know my stuff..... but this is strange. The machine doesn’t miss a beat. Runs great pushes hard. No issues except now it says it’s getting hot under load after a while. *Could the temp sensor be no good?
Could the pump be failing?
Tomorrow I am going to run some tests I have an thermal run I will run the machine until the alarm goes off and I will check temp with the gun.
Anyone ever have this happen to them? We don’t use this machine to it’s full capacity currently because of this issue. We only really use it to fill salt trucks at this point because it’s already on site with 7 other machines backing it up but we have a break in the weather I’d like to try to figure out what’s happening. It also doesn’t powershift I noticed. But I’m not worried about that quit yet......love some feedback.

Hello, I'm not sure the Case 621B got which kind of transmission. ZF 4 WG 150 or 180? Or other brand?
Anyway: Transmission cooler is oil-water or oil-air? Equipped with thermo valve for short oil circuit? Check function or bypass completely. Clean cooler. Is a cooler fan installed? Does it work?
I do not fully understand: "Does not powershift"? Will not change gears?

Hey Bigbert,
thanks for responding! I don't have the answer for you right now on what zf transmission is in it but I will get some info back to you tonight. it is a ZF though...as far as the other questions about the cooler or bypass the machine is fully stock. Id have to ask our mechanic these details Monday. as far as the powershift. these machine basically have an automatic transmission. you can leave it in 3rd or even 4th gear on the lever and as long as the power shift button is on it will shift 1-4 automatically. like a car. the machine runs threw the gears just fine changing them manually by twisting the lever but the autmatic shift doesn't engage. Even when the switch is on. but thats the least of my concerns. I just want to mow why all the sudden it says its running hot on the gauge. The weather isn't good here today so I never went down to preform the tests I stated in my first post. cold and rainy today....I did pull the transmission temp sensor yesterday it looked like ****. we ordered a new one. I noticed im not the first person to pull it it had signs on others before us pulling it out.

Hello Plowking,
for no auto up and downshift please check output speed sensor and its plug plus wiring. See picture (WG200, but 150 pretty much similar).
Good luck.

Hi There, I may be able to help you out. It's been a good 15 years since I worked on a 621B so if I am a little fuzzy on details please forgive me. If it seems to function correctly(nice crisp shifting) I think there was a service bulletin on repositioning the temp sensor, if it's at an elbow, the oil piles up and throws a overheat signal. Beyond that i would change the oil and split the filter (use a ZF filter, I have seen aftermarket filters fail and mess with the pump) The weak point I saw on high hour machines was the torque, they are rebuildable.
With the autoshift there are 2 (two) speed sensors, one on the right hand side high in the case (input) and the other left hand side lower (output) Spent many a service call changing the plugs and sensors. It is usually the lower one that get hit with debris.
Hope this helps.

yes thats exactly whats happening and yes its at an elbow. very interesting. this machine just cracked 4000 hours its actually a beautiful machine.

old timer,
what did they do about the sensor in the elbow? step it back a ways? and yes it manually shifts great. I highly doubt anything is wrong mechanically.....

Yep... that is familiar. But for the life of me i can't recall that bulletin as to where to reposition it. Check with you're local Case dealer about that bulletin, got to be 20 years old. If not, you could try drilling and tapping the flat of that fitting, puts the business end of the sensor in the oil flow, don't tap too deep, might restrict the oil flow. I think you have a great plan in direct testing the heat!
4000 hours is not high if the service intervals were kept up. I have seen them recently with 10000 hours plus on original engine and trans.
I am positive i can find my manuals tomorrow if you need anything more.
Good luck!

Thanks a lot guys! keep you posted on things later this week. (old timer) if you remember how the sensor gets repositioned please let me know! Thanks again

I'm back, just ran down to the machines to check the sensor locations. The picture I sent of the temp sensor from earlier you can see the lower speed sensor. which is cool, its easy to get to. the upper one was on the other side by the transmission fill half way up the transmission roughly. The one in the picture (Lower) does appear to be damaged. the boot was just dangling on the line.I couldn't inspect it much because its dark and raining "funny I got it in that picture earlier on accident"

Case Dealer didn't have much to say about the service bulletin. They said they would get back to me and have never heard of this happening before. Pretty frustrating

I hear that..... I remember that bulletin came from their tech department, before Case was bought by Fiat. Just out of curiosity....
does the engine warm up when the transmission overheats?

the service manager did comment on how back in the day case moved to a new software and the B models were not included in there system as far as bulletins so even if it was there then its not now. which was disappointing to hear.
no the motor is fine, why do you ask? weather is still terrible here. most likely tonight ill go out with someone to test machine get temp readings

I asked about the engine because if the transmission is actually overheating the engine will get a lot hotter, the transmission cooler is in the bottom of the rad. ZF's run about 100F above ambient, and I think the alarms in a Case come on around 250F give or take.

There was a bulletin on moving the trans oil cooler from the radiator and installing an external cooler above engine on hood.
Also the engine temp sender there was a one way diode added to the sending unit and grounded to the engine head.

Coy Lancaster you are the man,
Thats correct. the sensor doesn't move they called for the external cooler to be installed. I was doing the testings when you wrote that. my transmission got up to 215 last night, so it was getting hot. and as soon as I read your post I drove over to another 621b we have a few miles away and sure enough it has the external cooler setup. Called back case, they agree thats the bulletin, so thats what ill do. Thanks guys I really appreciate the help!

Hello all I am a couple years late to the party, and not tech savy. I recently purchased a used Case 621B. Seems to be a very strong machine, with the only issue is that the transmission temperature sensor goes off sporadically while it is working. Fluid level is fine, I am going to replace the filter, but I called my Case dealer and they couldn't locate the transmission temperature sensor, only the transmission speed sensor. Does anyone have a part number for it or where it is located? I would greatly appreciate any wisdom.

Hi Brian,
Yes I can tell you exactly what to do But at the moment I’m dealing with a snow storm. I’ll be in touch later

What’s your phone number I’ll just call you and explain

Plowkingroc84 said:

What’s your phone number I’ll just call you and explain

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5082458821 Thanks