hey guys am new to the truck business but i have some mechanical experience and an inquisitive mind. I recently bought an international 4700 with 7.3 liter engine and the allison AT545 Transmission, am not certain of the mileage on it because the cluster was broken hence it shows an inaccurate reading of 54000 miles. it has two problems. the torque converter keeps going bad, i mean i replaced it twice in 2 weeks. i have an 18ft refrigerated box on it. i am wondering if am exceeding the towing capacity. At times i have 10,000-14000 lbs of meat on it and some times the terrain does get a little steep. I realize that the radiator and transmission condenser was painted, wondering if that has any thing to do with it. even if am on flat road and i rev the engine past 200 rpm constant constant driving the temperature gauge goes up. Out here in Jamaica there are very few ppl that fixes transmissions of that size., besides the overwhelming majority of persons believes in Standard Transmission/Gear Box when it comes to trucks. i now feel pressured to do a conversion. should I? If so which gearbox should i use? what could be causing the over heating problem?
Did you do a "good" flush of the transmission cooler and lines before installing the converter? What goes bad in the converter, is it a mechanical failure or excessive leakage? Is the trans cooler original or an add on and are the fins straight and tight. If the fins are loose on the core very little heat will be transferred. How have you determined that the converter is bad and not something in the transmission? Have you changed the transmission filter and is it an external spin on type or internal.
The first torque converter was entirely ruined, the gears were dislocated inside, the bearings fell out, the fluid was so very highly sedimented, seem like the clutch in torque converter burned out. I did use an air hose to blow out the lines and the cooler and replaced the internal filter. I dont know if the cooler is original. the second Troque converter started making noises and caused the transmission to vibrate excessive, it drove ok except for the noises and vibration, unlike the first one, the truck could barely move neither did it changed gear. I did changed both the internal and external filters. Am wondering about the paint on the cooler and the radiator because i kno that the heat will not be conducted away optimally. i checked the clutch fan by revving the engine and see if the fan responds accordingly and to my mind it does respond. One thing to note when the truck starts in the mornings it drives like a dream machine but as soon as it gets a bit heated it seems to be loosing power. the second torque converter doesnt smell burnt.
It is a possibility that the replacement converter was poorly rebuilt, it wouldn't be the first that I have seen. Was the converter rebuilt or just a repainted take out? Also air pressure is not a good method of cleaning a cooler. There are deposits and sludge that can build up on the insides of the tubes, use a good flushing chemical and pay attention to the volume that is being pumped in and returned. Any pressure drop indicates a possible obstruction or kink in the tube. If the paint is a real concern take off the cooler and put it in paint remover, this will ease your concern.
The torque converter was replaced, i dont know of any place that rebuild the torque converter in jamaica, so it possibly an original, bought it from a guy with a similar transmission. now that the trann is out again, i will flush the system properly. i noticed that the transmission fluid was only slightly discolored neither does it smell burnt or sedimented. Do you think it blew the cylinder head gasket why the temperature gauge is going up. someone said the coolant cover probably needs replacing.
Is it your engine temperature gauge that is reading hot or the transmission gauge?
The engine gauge is going up when under normal driving conditions over 200 rpm, as mentioned in my earlier post. I dont see a temp gauge for the transmission.
Jamaica is a relatively warm climate year 'round, no? In an area like that all parts of a cooling system would have to be working proper, if just one component of cooling system wasn't proper you would most certainly see increased engine and tranny temp. Just because it seems fan responds when revving engine doesn't necessarily make it so. Can't say for certain about your truck, but generally speaking, by the time 2000 year model machine were made most manufacturers were using high output fans, you should hear an audible "roar" when the fan clutch locks in and engages the fan. If you don't hear that, I'd consider replacing the fan clutch. If it were not working properly it would overheat both engine and tranny oil.
I believe if the fan clutch fails on that unit, it fails in the engaged position. As far as the head gasket goes does your antifreeze "disapear" ? meaning if filled to proper level when cold, does it remain there? if it doesnt you need to figur where its going. for example head gasket, oil cooler, leaky overflow tank, etc.
Willie59, I think i am slowly arriving at the same conclusion about the fan clutch. It grabbed my attention one day while i was going over this hill and i stopped to allow the temperature gauge to return to normal. when i restarted the engine i heard what seamed to me at the time to be a higher than normal roar of the engine, but at i drove off it became scarcely audible. bar tl, i presume you are making reference to the coolant, we are a very tropical island, so the term "antifreeze" is a bit alien to our vernacular, i dont really see that disappearing except that it boils if i allow the gauge to climb too far up. I also removed the thermostat because i dont think its needed here in a place as warm as this. Question, if the fan clutch is faulty could it be the cause of the Torque converter going bad so frequently along with the over heating problem?
I don't know if that's the case or not on his truck, I'm only saying, generally speaking, by the time 2000 year models were being built that most manufacturers were using high output fans and when they're engaged by the fan clutch they make an audible roar. If that roar is not heard at high engine temps, I'd suspect a problem with fan clutch. In your climate, I would wager a guess of most definitely, especially if you're going up and down grades. As I stated previously, in climates like yours, all parts of cooling system must work properly, that includes engine as well as tranny. And I'll add this, if you have a truck that was built for the North America market, you might consider either adding an additional transmission cooler, or installing a larger single transmission cooler. To put it simply, in your climate, to have more than necessary tranny oil cooling capacity is far better than not enough cooling capacity. BTW, concerning "anti-freeze", it's not only useful (necessary) to keep coolant from freezing, it also contains rust and corrosion inhibitors. Additionally, the additives in typical anti-freeze helps prevent electrolysis and helps prevent pitting of cylinder liners. I would not recommend using just water in a cooling system if you plan on getting years of service from the engine. A good anti-freeze/coolant is necessary for a healthy cooling system and engine life.