Attention: TDR Forum Junkies Shortest version. How do you do a hydraulic diagnosis for lockup failure"
of a 47RH transmission, 94 cummins.
Somewhat longer version. I need help diagnosing a sudden no lockup torque converter failure. Transmission shifts through all the gears normally including OD. Electrical has been eliminated, -- I think --- because the solenoid has been replaced, it clicks when you throw the lockup switch. Valve body has been opened up and inspected for broken parts, dirt etc. Pan was clean and the converter gave no symptoms prior to quiting lockup. Below is backgfound for anyone with the time to read.
History: Truck was pulling normal one day, towing with smooth lockups, no slippage etc. Next day no lockup period. Goes into OD OK but no LOCK up. Shifts normally and is drivabe, just no lockup and after awhile a very warm transmission. Took it to a transmission shop. They said Lockup solenoid was bad. I said to my self HMMMM. Continuity was OK and it clicked when I threw the Lockup switch as a test. But I let him replace it because perhaps something else was wrong with it. Still no lockup. He dropped the valve body to make sure there was no broken springs, clogs etc. Checked OK, -- put back together and drove, -- no lockup. The guy is supernice and reputable but he seems to just know how to drop and replace transmissions. I do not want to take advantage of him but I want my truck fixed, but avoid unecessary hi dollar parts swaping if possible.
Before I have this transmission dropped I want to try to get rid of some nagging doubts about my transmission guy. Some comments he made did not seem copesetic
The main source of my doubts comes from Dave Goerend who I called about getting a transmission. He first asked some questions about how we knew the converter was bad. He said there are usually symtoms. Was there any dirt in the pan? Answer: very clean pan. I have been marveling at how clean the pan is since switching to John Deere HyGard. He then asked about some pressure readings, and I said I don't know wheather the trans guy checked any or not. I did not know enough about transmissions to know what to ask. Turns out my trans guy did not put any gauges on the transmission but he is ready to do a rebuild as his next step. Perhaps he knows what he is doing and is through wasting time, that is good.
Dave had mentioned some line pressure readings to watch for as the switch is thrown to engage lockup. I can't remember well what he said. But I believe it was that "line" pressure would drop momentarily and then return to normal. I have no doubt that if I call Dave again he will provide the information cheerfully, --- Heck he offerd to talk to my transmission guy for me. I thought I would post here for benefit of TDR readers and perhaps learn a thing or two so I don't waste the time of hardworking honest people educating me.
I do not have transmission gauges. If this thing can be proven bad with gauge readings, I may buy some gages. If the converter is bad I am going to order a new transmission from Dave and have my trans guy install it.
of a 47RH transmission, 94 cummins.
Somewhat longer version. I need help diagnosing a sudden no lockup torque converter failure. Transmission shifts through all the gears normally including OD. Electrical has been eliminated, -- I think --- because the solenoid has been replaced, it clicks when you throw the lockup switch. Valve body has been opened up and inspected for broken parts, dirt etc. Pan was clean and the converter gave no symptoms prior to quiting lockup. Below is backgfound for anyone with the time to read.
History: Truck was pulling normal one day, towing with smooth lockups, no slippage etc. Next day no lockup period. Goes into OD OK but no LOCK up. Shifts normally and is drivabe, just no lockup and after awhile a very warm transmission. Took it to a transmission shop. They said Lockup solenoid was bad. I said to my self HMMMM. Continuity was OK and it clicked when I threw the Lockup switch as a test. But I let him replace it because perhaps something else was wrong with it. Still no lockup. He dropped the valve body to make sure there was no broken springs, clogs etc. Checked OK, -- put back together and drove, -- no lockup. The guy is supernice and reputable but he seems to just know how to drop and replace transmissions. I do not want to take advantage of him but I want my truck fixed, but avoid unecessary hi dollar parts swaping if possible.
Before I have this transmission dropped I want to try to get rid of some nagging doubts about my transmission guy. Some comments he made did not seem copesetic
The main source of my doubts comes from Dave Goerend who I called about getting a transmission. He first asked some questions about how we knew the converter was bad. He said there are usually symtoms. Was there any dirt in the pan? Answer: very clean pan. I have been marveling at how clean the pan is since switching to John Deere HyGard. He then asked about some pressure readings, and I said I don't know wheather the trans guy checked any or not. I did not know enough about transmissions to know what to ask. Turns out my trans guy did not put any gauges on the transmission but he is ready to do a rebuild as his next step. Perhaps he knows what he is doing and is through wasting time, that is good. Dave had mentioned some line pressure readings to watch for as the switch is thrown to engage lockup. I can't remember well what he said. But I believe it was that "line" pressure would drop momentarily and then return to normal. I have no doubt that if I call Dave again he will provide the information cheerfully, --- Heck he offerd to talk to my transmission guy for me. I thought I would post here for benefit of TDR readers and perhaps learn a thing or two so I don't waste the time of hardworking honest people educating me.
I do not have transmission gauges. If this thing can be proven bad with gauge readings, I may buy some gages. If the converter is bad I am going to order a new transmission from Dave and have my trans guy install it.
