Hi Steve from Australia, got a 73A D6C, engine & tranny temp has slowly been rising over last 18months up to 100 degrees Celsius. So I have rebuilt engine, new head, thermostat, new belts & pulleys, new copper radiator. Have checked oil & transmission coolers. I have no metal in the converter plugs, or magnetic strainer or filter. Have done stall test on coverter, about 4 litres of oil. Once engine is at 100 degrees celcius can stop for 10 minute and engine temp drops to 80 degrees celcius but tranny temp doesn't drop. Have also replaced all gauges. Once back working engine temp rises back too 100 within a short period of time. Am at a dead end any ideas or suggestions appreciated, thanks.
When the temp rises and you "stop" do you mean stop working with the engine still running or shut the engine down..? If it's the latter you really don't want to be doing that, run the engine at High Idle with the transmission in neutral to reduce both coolant and transmission oil temperatures. How did you test when you measured the "4 litres of oil" - is that what came out of the converter housing drain plug while stalled in 3rd speed for 1 minute..?
i had some same problems in some equipments i fixed before in hot waether countries, as i can see you are from australia, wich is your average temperature ( outside) because in hot weather i usually trow away the thermostat, because even i change them a lot them always got stoked again, the thing you can do before take thermostat is cheking when machine overheat the hoses from radiator if the 1 in top is hot and the 1 down is cold your thernmostat doesnt work
If the trans will not cool down when idling in neutral you have a torque outlet or cooler flow problem. Check your torque outlet pressure. Removing the thermostat is not a good idea. When the thermostat opens it also closes the internal coolant bypass.
I agree. IMHO removing the thermostat is NEVER a good idea. If a thermostat is failing then there is probably another underlying reason why it is failing. That reason could be anything from a poor quality non-OEM thermostat to a much more serious cooling system problem. I work in a tropical climate (temps around 35-40DegC) and we have had no thermostat failing issues whatsoever, all we do is replace them when called for at the specified maintenance intervals.
When you rebuilt the engine, did you have the fuel system rebuilt also? If the engine is running lean it will cause heat also. Did you recheck timing recently? I'm not saying it can't be the transmission slipping causing the heat, but sometimes it is the engine and since the trans cools on the engine coolant, it will be affected. Just something to check. Good luck.
How about the baffels around the rad core? Later Bob
Fairly certain that a diesel will run quite happily lean, but over fuelling is what kills them. Opposite to a petrol engine.
Just a couple thoughts. First agree that removing t-stat is not good. If it is working all it should be doing is shortening the time till engine is up to operating temp and setting the minimum while running. I'd be wondering about the fuel system, but not rich or lean, but the timing. Sounds like your problem may be more in the transmission than the engine, so just guessing could the converter housing getting over full causing drag? Not on a Cat but have seen Allison converters get cracks in the bolt flange around the outside of the converter that would flood the housing with oil causing drag and heat. Have you checked the trans. pump and lines to be sure the scavenging section is in good condition? Also I'm thinking there are two screens in the transmission system, one in the lines to the pump and one on the bottom of converter housing, are both clean? Does this machine have a fan with reversible blades? Make sure one or more are not positioned wrong, had that cause a problem on a 3306 (966C) where one blade was facing the wrong way, just enough loss of air flow to cause a problem.
Hence my question of exactly how the OP came up with the figure of "4 litres" of oil in a converter stall test. That doesn't make sense to me.
Reversible fans even with all the blades facing the right way are about 20% less efficient than a fixed blade fan due to the the large centre hub creating a dead air space.
Yep Nige, stall test was done like you said, dropped the bung out of the converter and measured 4 litres. Have checked both screens and tranny filter, all are clean. Im not sure if this is too much oil in the converter, I had a deisel fitter tell me it should only be 1 to 1.5 litres?
Thanks to everyone for their input, I have got a solid fan, thermostat is fine, just wondering how you think the timing should be done?
Will check a few ideas you guys threw out there thanks. Will check tranny & convertor pressures to start with.
Like others have said, if your engine is cooling down but the tranny isn't I'd sure bet on the issue being there. It could be an engine issue but I'd lean heavily toward a torque converter issue. The torque/tranny is what's heating up your engine IMO
I've always been told removing the thermostat will cause overheating because the coolant will move too fast thru the system; it will not have enough time for the radiator to do its job. If the machine cools better without the thermostat, I would guess the radiator is probably due for replacement.
I guess I've never seen or heard of an engine running hotter with the thermostat completely out....... but I can still hear some so I will be listening.
Cat uses a bypass type thermostat. Here is a link to a good description of how it works. http://www.are.com.au/feat/techt/thermostat.htm
Good explanation about the by-pass type t-stat, but the D6C has a 3306, so if it is set up like the 3306's I have worked on in 966C and other applications it has what I would call a Blocking style t-stat, I'll check in SIS and see if I find a good picture.
This is the best picture I can find online: With this style there is no lip type seal as used in the by-pass type. I seem to recall that when open it does kind of "get in the way" of flow to the by-pass port but not as positive as the types with the seal that are probably much more positive on the shutting off of the flow to the by-pass port. On the overheat problem, I seem to recall a large genset either a D398 or D399 we had that was having an over heat problem and what I found with that one is the pressure cap was not sealing. At that time my theory was that with no pressure on the coolant at the top of radiator the water pump was cavitating and not getting full flow to the engine. All I can be sure of is once I installed a new pressure cap the problem was gone. This could have also been contributed by a partially restricted radiator core, all I know problem was gone and engine ran good for the rest of the time we were using it.
well guys in this kind of old engines i have been working w/o Tstat many years and never have a problem, i have 1 that have been running more than 30 years, i know its very important have tstat but in hot waether usually i never use them. but well Stephen already told us about his fan, radiator and tstat are ok, so let think what else can be the problem with his d6 and not make this a discussion about Tstat's LOL
According to my info the Aussie 73A is equivalent to the US 76A which is a 4-1/2" bore D333A and uses the old style thermostat.
On the 980B loaders with 3306's there's a large bypass line. When cold the thermostat directs water thru the bypass line back into the engine when hot it directs it through the radiator. If the thermostat is removed the water will go through both never getting the full cooling of the radiator.
Is the same as a 76A. Checked the water pump steve ? impeller could be loose. for timing; things do wear over time and because they have a non adjustable drive only way to compensate for wear is on engine lifter settings. dealers probably don't even have the gear for older engines like this; as is a slow job and a lot of accuracy is needed. A new copper radiator should solve any heating problems; did for me on my D6D. But im thinking a lack of water circulating is causing her to get hot quick. Be careful they crack heads easy these old D333.
Merv everything is band new, new copper radiator,belts and pulleys,water pump,thermostat ,new head, injector pump tested by cat and all of this has made very little differents
Any bubbles in the coolant noted at fill neck? Are you loosing coolant?
I spent quite a while yesterday looking for some figures for internal converter leakage but failed to find anything. 4 litres in a minute does not sound right to me.
I have never seen it published but have heard 2 gpm under stall with warm oil. Later Bob
The actual scavenge pump is rated at 5-6 gpm @500 rpm and 120 psi. I'd guess something on the order of half that capacity or less would seem to be normal leakage.
Have you checked the inlet and outlet of the trans cooler with a infrared? Should do that after checking if pressures are in spec. This all sounds way to familiar to the prob I had on a D7H. It had some gunk in the torque outlet pressure spool, oil was coming in at about 200+, out at like 125. It didn't have the flow it needed to cool and would heat the engine up.
if outlet relief valve spool has been fitted wrong way round it will get hot fast. This is soon verified by a pressure test as inlet relief valve will be dumping oil because it cant flow through outlet rv. Figures for oil drain out of t/c after stall test is 5-10 litres from memory from a cat service magazine.
Just in case nobody has asked this before,when the temps start climbing, is is possible to determine which one starts to climb first - converter outlet or engine coolant..? That may be another clue into determining where to start looking, but my money goes on the converter system somewhere.
What are you doing with the tractor,how is it being operated? What was oil coolers checked mean? Bob
Is the crankshaft pully new? When the grooves wear enough that that the belts bottom out thay will slip no matter how tight you make them, new belts only make the problem worse.
thanks to everyone, have got some good ideas to chase up will be few weeks, will keep you's posted Merry Christmas