Welcome! Please use the navigational links to explore our website.
PartsASAP LogoCompany Logo Auction Link (800) 853-2651

Shop Now

   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver

Crawlers, Dozers, Loaders & Backhoes Discussion Forum

Help!!! Cat D7G Weird drive problem

Welcome Guest, Log in or Register
Author 
Rick Routliffe

08-31-2003 13:09:45




Report to Moderator

The machine has a powershift transmission and runs fine all day so long as it is at high idle. Once it is idled down, after a few minutes (2-15) it will dump a bunch of oil on the ground and will not drive. The torque divider will be extremely hot, apparently indicating it is too full of oil. The oil level in the transmission will be low enough to not show on the dipstick.The machine must sit a while, usually overnight, then drive returns (assume oil has returned to the transmission). The dumped oil appears to come out of the torque divider housing via the starter (we think). The following components have been replaced without solving this problem, transmission, torque divider,scavage pump, oil cooler, engine. This is an older early seventies machine in very good shape. This condition has existed for seven years and baffled many mechanics, including the dealer. Anyone seen something like this before or have some ideas? Thanks

[Log in to Reply]   [No Email]
CAT FIXER

09-07-2004 17:57:34




Report to Moderator
 Re: Help!!! Cat D7G Weird drive problem in reply to Rick Routliffe, 08-31-2003 13:09:45  
I HAD THE SAME PROBLEM I work at a CAT dealership rebuilt lots of Army D7G dozers check to see if the O ring that goes between the stator part of your torque converter is there or if it is cut also there are a couple of sealing rings there that could be cut



[Log in to Reply]  [No Email]
Bob/Ont

09-01-2003 09:14:02




Report to Moderator
 Re: Help!!! Cat D7G Weird drive problem in reply to Rick Routliffe, 08-31-2003 13:09:45  
Rick,I am not sure if you meant that you have changed the Torque Converter or not but if you have and still have this problem maybe the Converter inlet relief valve is jammed shut and you have split the new convertor with cold oil in winter. If the convertor housing is flooding as you say it is then there is too much leakage or the scavenge pump is not taking it out fast enough, EI it floods when left idling and the pump is turning slow. To check convertor leakage try this. Drain the torque housing, place an empty 5 gal pail under the drain hole. You might want to put this 5 gal pail in a larger tub incase you find what I think you might. Thern start the tractor and stall the converter for 1 minute exactly. Shut down and see how much oil you got out of it. The pail should be about 1/2 full. If the pail is 1/2 full the problem is scavenge pump related if you get a pail full the convertor is leaking too much, may be cracked. Also I am not sure if the converter inlet relief is mounted on the converter case or in the trans. If it's on the converter case, check it is not stuck open first. Later Bob

[Log in to Reply]  [No Email]
Rick Routliffe

09-01-2003 10:02:14




Report to Moderator
 Re: Re: Help!!! Cat D7G Weird drive problem in reply to Bob/Ont, 09-01-2003 09:14:02  
Bob, a couple of questions on that leak test for the torque converter. I assume it should be done with the transmission oil at operating temperature. Is this correct? Engine at high idle? Can we damage the scavenge pump running it foor 1 minute without oil? It would be easy enough to remove it during the test if necessary. Thanks



[Log in to Reply]  [No Email]
Rick Routliffe

09-01-2003 09:41:37




Report to Moderator
 Re: Re: Help!!! Cat D7G Weird drive problem in reply to Bob/Ont, 09-01-2003 09:14:02  
Bob, both converter inlet and outlet reliefs are mounted on the bell housing. I posted a response to brokenwrench's reply with some additional info that you may want to read. Thanks for the torque converter leak test information, we will check that. This dozer belongs to a friend and I got involved in it a few days ago. Seems like the previous "technicians" mostly replaced expensive parts. I am a service rep. for a forestry equipment manufacturer, but am not familiar with Cat equipment, although the circuits involved here are fairly straight forward. Where in Ontario are you, we are in Brantford. Once again, thanks for the help. Will keep you guys posted.

[Log in to Reply]  [No Email]
Bob/Ont

09-01-2003 10:51:51




Report to Moderator
 Re: Re: Re: Help!!! Cat D7G Weird drive problem in reply to Rick Routliffe, 09-01-2003 09:41:37  
Rick, I'm about an hr. north east of you.If your scavange pump will move 4GPM at idle that's twice what the torque should leak at stall. If you have the torque inlet and main relief valve on one housing, I would check it. You can only get the spec. pressure of the TC inlet relief for a few min with cold oil, then the oil thins out and goes throught the torque and cooler easy. The inlet relief is to protect the converter from blowing up in winter from high pressure caused by cold oil. The inlet should not open when the oil is warm. I would check that valve first, if it's on the convertor housing it dumps into it and could cause your problem if it's not closing tight. If its' jammed and not opening the new convertor could have been cracked in winter too. Email me and I can get you a trans test sheet if you give me the serial#. Later Bob

[Log in to Reply]  [No Email]
Brokenwrench

08-31-2003 16:29:44




Report to Moderator
 Re: Help!!! Cat D7G Weird drive problem in reply to Rick Routliffe, 08-31-2003 13:09:45  
The torque converter is possibly leaking more oil than the scavenger pump can return to the trans.If you are sure the scavenger pump is good and the screen isn't clogged, check the converter base and cover very carefully for a crack. I had one where the converter cover had a crack that was not visible to the naked eye, but would open up as the converter heated up. Found it after I pulled the converter the third time and had it magnafluxed. Also check the trans. pressure to make sure it is within spec.

[Log in to Reply]  [No Email]
Rick Routliffe

09-01-2003 09:25:58




Report to Moderator
 Re: Re: Help!!! Cat D7G Weird drive problem in reply to Brokenwrench, 08-31-2003 16:29:44  
Thanks for the reply. Torque converter leakage is a good potential for this problem, however, it has been replaced three times. I realize this may not rule it out completely, but it is unlikely that all had the same problem. Scavenge pump has also been replaced at least once. I assume the screen you mention is in the scavenge pump outlet at the tramsmission end. The transmission is also brand new. That's the only screen in that circuit isn't it? Flow checked scavenge pump (using bucket and watch method) and it looked like about 4 gallons in a minute at low idle. Checked pressures (at low idle, cold oil) for convertor inlet, convertor outlet, and transmission pump. All were OK, in fact convertor inlet pressure was lower than the 135 psi spec. but that shouldn't cause this problem, although maybe it is a clue. Transmission pump has not been replaced, but was taken apart and inspected. It was noticed that the lip on the shaft seal is toward the bell housing, not inward toward the interior of the pump. The manual seems to show it as being correct and the dealer says that's the way it should be, but this seems odd to me. Do you have any experience with the seal? Did the crack in your torque converter present the same problem? Thanks again, Rick

[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:


TRACTOR PARTS TRACTOR MANUALS
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. [ About Us ]

Home  |  Forums


Copyright © 1997-2023 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters

Website Accessibility Policy