Hi everyone, I'm new to this forum but find the info and advice very useful. Thank you for hosting this forum. I got myself a 1999 CAT 436C-IT Parallel Lift backhoe for a home building project. Over the last year I've been fixing a ton of things but haven't run it for long periods of time or do any hard work with it. Have now changed all fluids and filters and drove it maybe 2 miles in total to get everything warmed up good. Notice now the transmission temperature goes too high, around 110 - 115 C, which is too close for comfort to the red zone on the temp gauge. Note, I did change out the transmission temp sensor and temp gauge and confirmed that it reads temperature close to what is expected. My gut feel is the transmission temp should be around 95 - 100 C. Other posts seem to confirm that. Thoughts? Anyone has any suggestions on where to start unraveling this problem? I haven't removed the radiator and oil coolers yet for cleaning. I just blow temp out with air and pressure washer when I cleaned the machine for painting. This is one thing I derived from another post that I probably need to do. What should the oil pressure be at the oil cooler? I'll have to figure out a test setup to measure the oil pressure. Any suggestions? My biggest fear is that the oil pump may have a problem. But the machine runs fine in all gears so that probably confirms that the pump is doing it's job, agree? Should it turn out being a pump issue it looks like the pump is located in the torque converter housing. How would one go about getting to the pump? It looks doable to remove the transmission but maybe easier said than done. Has anyone done anything like that? Thank you all in advance for your advice.
Welcome to HEF Herman! We have some smart CAT guys around here and hopefully one will jump in with some suggestions for you. I would simply say to check transmission fluid level and if possible use a second temperature measuring device while the temp is up. Certainly possible to be indicating 10% too high. Maybe spray some water on trans cooler/radiator when temp is high to see if it goes down quickly. That might at least verify that you do have cooler flow.
Welcome to HEF, Herman ! Did you paint the radiator ?
Serial Number would help. Unfortunately model years mean nothing with Yellow Iron.
No, that would likely mess up the thermal conductivity and heat exchange. I masked off the radiator for painting.
Thank for responding Nige. I apologize for my slow response, things are a bit hectic right now. The serial number is 2AR01632.
All In the meantime I found document SENR1204-01 published 03/10/1996 and updated 24/10/2013. The number SENR12040005 is also printed on the document. This document covers Testing and Adjusting the transmission. I'm not 100% sure this is the correct document applicable to my machine. If anyone can comment on the correct document for my machine, that would be very helpful. The Serial Number of my machine is 2AR01632. Today I'm going to attach two temperature sensors (RTD's) on the transmission, one on/close to the transmission temperature sensor to confirm whether the temperature gauge indicates the temperature correctly. The other sensor will go on the oil return line from the oil cooler/radiator. That should tell me whether i have flow and heat removal in the cooler. I also figured from the document mentioned above that I need to measure the various pressures in the transmission hydraulic circuit to get a sense of the condition of the transmission. There are 7 ports where the various pressures can be measured. I have 4 pressure gauges ready to hook up to the ports if I can just accurately identify some of the ports. Particularly the pressure tap for the pump and the pressure taps for the Torque Converter inlet and outlet pressures. The quality of the pictures in the document mentioned above are pretty poor so that makes it hard to identify these ports. The other ports I think I have figured out, but confirmation would help. If anyone can help with the correct documentation (in case I have the wrong document), or better pictures showing the location of the pressure ports, it would be highly appreciated.
You have the correct document, and also the latest version of it. I can download a copy from the system if you like but I doubt it will be of any better quality than what you have right now. The illustrations are typical grainy black-and-white for the period and have obviously never been updated since the document was first produced. Maybe the only way (but not guaranteed) to get a better version would be from a paper service manual. The complete manual for the machine is Cat Reference SENR1200. Here's one on eBay. - https://www.ebay.com/itm/324718159977 EDIT: Just in case you question the price, a brand-new manual in paper form is currently $1,430.
Hi All Nige, no need to download a copy of the document. Unlikely that the picture quality would be any better. That is a pretty steep price on eBay for the service manual, let alone a brand new version. Shortly after I got the machine I bought an electronic copy of the service manual, for about $90, from a guy in Israel and that has been very helpful. That's where I got document SENR1204 from. You confirmed that it is the latest version so what I have seems applicable to my machine. This weekend I cleaned off more grime and dirt around the top of the transmission that were hard to reach when I initially cleaned the machine for painting. At that time I did not expect that I would need to look closely at the transmission. I believe I have now positively identified all the pressure taps / pressure test points on the transmission. Now I can start diagnosing my suspected transmission temperature problem. I created a document with better quality color pictures for comparison with the pictures in Caterpillar document SENR1204. Thought I'll share it with this forum in case it can help someone else. If you get a chance, please review the document and let me know whether I've identified the pressure taps correctly. Two of the pressure taps have hydraulic quick connectors fitted. I still need to identify the mating female connectors to hook up pressure gauges. Any advice on that would be appreciated. I have a set of screw in fittings but quick connectors fitted permanently would make things easier for future diagnostics. I consider checking all the pressures in the transmission hydraulic circuit as a health check and also as reference for future comparison. More later.