Dresser 540 transmission overheating.

[RocksnRoses]

The transmission on our Dresser 540 has suddenly started to run really hot. It has been working fine up until recently, but now in about 45 minutes to an hour of average work, the temperature goes up to about 240 degrees F, where the buzzer starts. When it first got hot, the oil level dropped quite dramatically and I topped it up, but I could not work out where the oil went, because it does not leak that bad. I am wondering if the seal on the torque convertor has let go, filling the fly wheel cavity with oil, because it is very wet around the starter motor and a couple of other spots on the fly wheel housing and I do not think that there should be oil there, but I am not 100% sure. When the machine is operating, there is no sign of any slippage anywhere, it all works quite normally, but just gets hot. We have cleaned the radiator and oil coolers and the engine is running a little under 180 degrees F at the time. I am wondering if some of you fellers that have operated these machines over the years, might have any ideas.

Rn'R.

 

[RocksnRoses]

Obviously no-one here has had a problem similar to this. I have never experienced a transmission, or it could be the torque converter, overheat so quickly. I can only assume that something might be having a major haemorrhage. If anyone has any thoughts on this, I would certainly appreciate your replies.

Rn'R.

 

[Chris5500]

Are you checking the temperature with the transmission temperature gauge or are you using an infrared thermometer? The reason I'm asking is to verify that it is the transmission that is overheating and that the sensor is working correctly or if it's the torque convertor that is overheating.

Does the temperature rise when you stall it and fall when you come off stall?

Obviously having too low an oil level in the transmission will cause over heating issues both in the transmission and torque convertor. Check the transmission filters for contamination causing a restriction of oil flow.

Have you noticed if the RPM at high idle and low idle whilst the transmission is overheating are lower than they should be?

Are there any abnormal noises of late?

In the mean time, get a gauge on there and check some pressures! You’ll have to find some specs to compare them to though, no good otherwise!
Check the transmission modulating pressure and the inlet pressure of the torque converter.

 

[RocksnRoses]

Thanks for the reply, Chris.

Are you checking the temperature with the transmission temperature gauge or are you using an infrared thermometer? The reason I'm asking is to verify that it is the transmission that is overheating and that the sensor is working correctly or if it's the torque convertor that is overheating.

With the guage, I have not got a thermometer at the moment, but the transmission is extremely hot, much hotter than normal and you can smell that it is hot. This is what I am trying to work out, whether it is the the transmission or the torque converter ,causing the problem.

Obviously having too low an oil level in the transmission will cause over heating issues both in the transmission and torque convertor. Check the transmission filters for contamination causing a restriction of oil flow.

The oil level is normal, but I will check the filters, we have never had any contamination problems, unless there is something happening inside, to cause it.

Have you noticed if the RPM at high idle and low idle whilst the transmission is overheating are lower than they should be?

No, they are the same as always.

Are there any abnormal noises of late?

Not really.

In the mean time, get a gauge on there and check some pressures! You’ll have to find some specs to compare them to though, no good otherwise!
Check the transmission modulating pressure and the inlet pressure of the torque converter.

The transmission pressure gauge is still reading pretty much the same as it always has and everthing else is operating fine, it just gets hot. I thought perhaps there might be some slippage or the drive just slowing down, but there is none of that. The pressure checks are the next thing and we will take it from there, but obviously, something is not right. I just thought that someone here on the forum may have had a similar problem and might know what could be causing it.

Thanks once again.

Rn'R.

 

[Chris5500]

My apologies, I misunderstood what you said, I thought you wanted step by step advice on how to troubleshoot this problem, but instead you just wanted to know if anyone has had this same problem with the same machine so you could fast forward to the part where you fix the problem?

 

[John C.]

Power shift transmissions really can't heat up the oil temperature. If they are slipping the machine quits moving or at least slows down and sometimes starts making a lot of noise. Also the oil for the torque and the transmission is the same so if one component is shot, you need to go through both.

I haven't worked on one of those in a lot of years so I'm working with a failing memory. The bell housing as I recall on those machines is wet. Usually heat is caused by one of the elements in the torque going bad and oil leaks out between the clearances and causes the heat. If you have a bearing in the torque that fails you will usually have silver colored oil in a hurry. The elements will be rubbing together. As I recall the stator is not cast in those. I've seen stators go bad and let the vanes turn to the wrong angle and the oil hits the impellor vanes wrong making the heat. This issue usually doesn't create a loss of power. An oil sample might give you a better idea of what it might be.

I have seen transmission oil coolers plug up on the water side. The bottom liner rings in the engine erode over time and the pieces always seem to end up plugging the cooler core. You haven't stated how many hours are on this machine or the components.

As mentioned before, an infrared thermometer would help a lot.

 

[Chris5500]

Firstly, has the operating conditions changed such as new operator (incorrect speed, incorrect transmission gear selection to match load, stalling for extended periods, using the service brakes instead of the transmission cut-off/impeller clutch etc) Different type of material which the machine is digging for example tougher, heavier specific gravity material etc

An oil sample would be the best option before doing anything major.

Even though you’re not experiencing high engine temperatures check the coolant level and fan belt tension, even the water pump.

Check the torque converter regulator valve or relief valve for out of adjustment, or contaminated causing abnormal operation.

As John mentioned, check for a blocked torque converter or transmission cooler core (check the temperature and temperature differential)

Check the torque converter charging pump or transmission pump for any abnormalities such as vibration, noise, air admittance etc

Lastly, there could be a possibility of heavy leakage of oil inside the torque converter (seal ring nuked), plug loose, pump (turbine) cracked causing excessive oil friction and generating abnormal temperatures.

 

[RocksnRoses]

My apologies, I misunderstood what you said, I thought you wanted step by step advice on how to troubleshoot this problem, but instead you just wanted to know if anyone has had this same problem with the same machine so you could fast forward to the part where you fix the problem?

It's all relevant, Chris, we are just trying to work out what could be causing the problem, so that we can fix it.

The bell housing as I recall on those machines is wet.
I have seen transmission oil coolers plug up on the water side. The bottom liner rings in the engine erode over time and the pieces always seem to end up plugging the cooler core. You haven't stated how many hours are on this machine or the components.

As mentioned before, an infrared thermometer would help a lot.

You have answered one query that I had, John, that explains the oil around the starter. As soon as I get time, I will check the filter and have a closer look at the cooler. The machine has done about 12,500 hours that we know about, but there could be more that we don't know about and before we go much further, I will get hold of an infrared thermometer, just in case the guage is out.

Firstly, has the operating conditions changed such as new operator (incorrect speed, incorrect transmission gear selection to match load, stalling for extended periods, using the service brakes instead of the transmission cut-off/impeller clutch etc) Different type of material which the machine is digging for example tougher, heavier specific gravity material etc.
Even though you’re not experiencing high engine temperatures check the coolant level and fan belt tension, even the water pump.

No, nothing has changed, Chris, the coolant is right up, we have only recently fitted a new fan belt and as far as I can tell, the water pump is fine, because usually the engine temperature hangs around 180F all day.

I will check these few things first and if nothing shows up, we will have to delve deeper.

Once again, thank you for the replies, they have been most helpful.

Rn'R.

 

[RocksnRoses]

Just an update on our overheating problem.
I took the filter out and cut it open and while there was a little bit of brass filings or really it was more of a brass paste on one end, there was no great heaps of metal or other material in there. We checked the temperature with an infrared gun and the guage is spot on, it goes up to 240F in about 45 minutes. The cooler appears to be working OK, the oil leaving is about 30F cooler, than the oil entering. Another suggestion was that the relief valve on the pump sometimes plays up, causing the oil to heat up. This morning, the pressure built up in the bell housing and blew a plug and a lot of oil, out of the back of the bell housing. It appears that this plug may be there for that very reason. Would that mean that pressure is coming through seals from the torque converter, pressurising the bell housing. There is a large hydraulic line coming from the bottom of the bell housing, feeding back to the bottom of the transmission, so technically the pressure should not be able to build up, because the transmision has a reasonably large breather, which I have checked. There is also a small line going from the top of the bell housing, to the transmission. We are fairly busy, so we do not have a lot of time at the moment to spend on this problem and we are still using the loader to load trucks, as it is not running long enough to get too hot. We are just trying work out what the problem may be, before we start pulling it apart. We also have to do a pressure check, but I need to find out the operating pressures for this machine. Does anybody have any ideas where I might be able to find them, because I do not have a workshop manual for it and being an older machine, I doubt that the dealers here, would have that information, anymore. Aside from this, the loader operates perfectly normal, the same as it always has.

Here is a pic of the plug, that blew out.

Rn'R.

 

[John C.]

That plug is for a jacking screw used to turn the engine over by hand.

 

[RocksnRoses]

That plug is for a jacking screw used to turn the engine over by hand.

Thanks John. Do you have any thoughts on why the pressure built up enough to blow the plug out?

Rn'R.

 

[John C.]

Your torque converter is shot. Probably the internal clearances between the turbine, stator and impeller are letting oil go out. There are some hook ring seals inside there. In any case if the cooler has the proper drop and your oil is around 240 going in then the converter is making the heat.

You might check torque converter out pressure. As a general rule it runs around 12 PSI or more. I've seen them run at 5 PSI and not get hot.

 

[RocksnRoses]

Your torque converter is shot. Probably the internal clearances between the turbine, stator and impeller are letting oil go out. There are some hook ring seals inside there. In any case if the cooler has the proper drop and your oil is around 240 going in then the converter is making the heat.

You might check torque converter out pressure. As a general rule it runs around 12 PSI or more. I've seen them run at 5 PSI and not get hot.

Well, it looks like we have some work to do, at least we now know which end the problem is. Thanks very much for your input, John.

Rn'R.

 

[RocksnRoses]

Out it comes.

Your torque converter is shot.

You are right, John. We parked the machine up until a Dresser mechanic could get out our way and he arrived today. A pressure test showed up the problem, the pressure was only half what it is supposed to be. He explained, as you did, that the oil passes through impeller into the bell housing and churns around because it can not drain away fast enough and this creates the heat. At the same time, most of this oil does not get pumped through the cooler, which compounds the problem, so out it came and has gone to be rebuilt.

RnR.

 

[John C.]

I'm sorry to maybe be right about the problem and that it wasn't something easy. That looks like some tight spots to swing a wrench in.

If you get the chance could you take some photos of the internals when they get it apart?

Thanks for these photos.

 

[RocksnRoses]

That looks like some tight spots to swing a wrench in.

There wasn't much room to move, John, the three hydraulic pumps are mounted to the front of the torque converter, with all of the associated hydraulic hoses. The chap helping us is one of the 'old school', he has been working on Houghs and Dressers most of his life and he and the boys had it out in a bit over four hours.
It is all back together now, ready for the trial run tomorrow. The main problem was that the the brass bush and the center piece were worn, which in turn allows the oil to pass through the impeller. You will probably have a better understanding of it, than I have. He replaced the bush and center piece, as well as all of the bearings and seals, but he said the impeller was fine and there was no need to replace that.

RnR.

 

[John C.]

Thanks for posting the photos.

Let us know how it works.

 

[RocksnRoses]

Let us know how it works.

It works really well, John. The loader is much more responsive in the drive, pushes better and the temperature of the oil holds around 180F. With hindsight, the torque converter has been heating up up for quite a long time. This machine is our yard loader, so it is not working all the time, but when we did use it, after a while the torque converter and transmission always seemed hotter than normal to me and they smelt hot. I have never had a torque converter fail before, so I didn't pick it, but I know now.
Well, I guess that's the end of this thread, thanks to you and Chris for the help.

RnR.

 

[KennyT]

At the end of the day..

what was the total cost of this repair ?

 

[RocksnRoses]

what was the total cost of this repair ?

The whole job cost around A$5,400. Parts came to A$1,570 and the rest was labour and travelling etc. The mechanic lives 300 km away, but he has worked on Dressers for years and he worked our job in with another one in our area.

RnR.