Have got a 1974 cat D4D dozer power shift have been working it with no problems until last week when it started to play up as follows it will work ok until it starts to get a little bit hot then it starts to make a noise as though its hunting for trans fluid and will start to stop moving leave it a few minuets and it will move again,oil is topped up to full mark.Now it has also started to push some oil out of the breather when it gets to the stage of stopped moving but if you let it cool down it will be fine again for about a hours worth of use when it starts to get warm again. I have not had time to investigate yet but my next course of action will be to drain trans oil out clean screen filter and replace main trans filter refill with fresh oil and also jet wash water rad out as it has been pushing wood chip about as i thought thats what might be the cause of it getting hot the water temp does go up as well. Any thoughts or advice on it would be greatly appreciated. Thanks.
How are you checking the transmission oil level..? Oil at operating temperature with engine idling & transmission in neutral I hope. You say the engine oil temp goes up, does the converter temperature go up as well..? If it's starting to blow oil out of the breather a possibility could be that the torque converter housing is not being scavenged properly, thus dropping the oil level in the tranny. Have you checked the oil level when you have the problem to see how it compares..?
Hi Nige oil is checked as you have said all correct,i have dropped the oil today and the screen filter was clean also the drain plug had no metal bits on the magnet part of it so all good,took the main trans filter out it looked OK and have yet to replace it with a new one i got today then i will fill with fresh oil and see what that does but i must say everything looked OK. I did check the oil when it was playing up and it was down slightly on the stick from the full mark. What is the scavenged thing you are on about Nige.
To identify if the scavenging is working correctly try checking the transmission oil level when it starts "play up". Has the level fallen from what it was when you initially checked it..?
May be sucking air somewhere, foaming the oil?
That should show on the dipstick too ..........
Any likely places for it to suck air from or is it needle in a haystack job to find it don't know if it is that yet but nice to know before hand what to look for. Should the oil on the dipstick when checked while its doing this stop starting thing be like as though you have just checked it first thing or should it have a little bit of froth at the top of the stick as the oil has been getting a hammering in the trans.
I was more suggesting to look at the oil level on the dipstick to see if it's fallen a long way from the level you had at startup. Also if the oil is frothing due to sucking air somewhere then it ought to be easy to see it on the dipstick by the froth and the fact that the oil on the stick will be lighter coloured and cloudy because it's been stirred up so much. Back to the scavenging. The power train oil feeds both the transmission and the torque converter. All torque converters leak internally and the oil that accumulates in the converter housing has to be scavenged back to the transmission. If you either have a major internal converter leak that is in excess of the capability of the scavenge pump to get it back to the transmission, or if there is a problem with the pump itself, then the transmission oil level will fall during operation. If it falls too far it may compromise transmission operation. By stopping the machine you give the scavenge a chance to catch up and therefore the machine will work again.
Nige, D4D's you might want to re-think the scavenge pump thing as the converter and planet case is common, the trans pump bolts in under your right foot in front of the pressure filter, there is a gasket and 1 O'ring on the trans pump bolt up face, under the filter lid is the large filter O'ring and 2 other O'Rings with oil feed under pressure into and out of the filter, the oil control valve work is all in the spool block under the trans' lid, the oil is cooled via the water heat exchanger next to the oil filter, the back end is a dry deck so no steering pump, this man needs an oil cooler gasket kit and an afternoon to tackle it, the trans pump is also possibly a bit of a knacker, this needs a bit of work to remove, the rubber blocks and drive flange need to be removed to pop the pump off its perch its a fiddle. tctractors
Update on whats happening,i have been down to dozer today and put new (main) trans filter (already cleaned screen filter) in it with fresh oil also jet washed the rad out as it was being used for pushing around 120 ton wood chip about.I then worked it for 1 1/2 hours pushing/leveling dirt around a motocross track with no problems water/trans temp both fine no noises or pushing oil out of breather so fingers crossed.Next is working it for 5-6 hours to further test it. Thanks to everyone for the advice everything helps more minds are better than one.