Possible Over Heating Transmission?

[Odyssey 4x4]

Sorry for the long explanation, I'm trying to be thorough here.

I am currently in Pendleton, Oregon and have been traveling non stop since I left Florida about 3 months ago. Before leaving for this trip the motor of my truck was completely rebuilt. This includes every part of the motor including pistons, head job, cam, water pump, oil pump, timing chain, fan clutch, etc.

When I got to Texas and started getting into some long uphills on the interstate the motor was getting hot. Also sitting in hot Texas traffic it was getting hotter than it should have. I replaced the cheap 1 row plastic radiator with an all metal CSF HD 3 row radiator when in Wyoming. The significantly helped cooling when sitting in traffic and around town driving.

Well now that I am in Pendleton, Oregon and have been driving even steeper long hills, I am still getting higher temperatures than I think I should be. The only time the temp is rising is when going up long steep hills on the interstate. My gauge has the normal white section of temperature, and then above the white section there is a small area which is the "red" section of the gauge. When I drive in normal traffic my gauge is at above 40% of the normal white area. When I am going up the long hills here in Oregon driving I85 West, my temperature gauge is reaching about 75-80% of the normal white gauge, never going about the top white line into the "red area".

Is this normal for driving steep hills in the over loaded Toyotas? It should be noted I am also hauling 400 pounds of motorcycle on my rear bumper but this hasn't been a problem yet and the truck drives 70 mph without a problem on flat roads. When I am going up the steeper hills I have the pedal to the floor and it moves at about 50 mph. The temperature steadily rises and when I reach the top of the hill and start on my down hill the truck cools back down to around 40-50% of the temperature gauge within about 2-5 minutes.

It should be noted that in the past with this truck I had the transmission overheat and my rear tail house extension bushing was leaking fluid heavily. I replaced the bushing and have not had any other problems with leaking fluid. I do not smell burning transmission fluid and transmission fluid looks alright. It should also be noted that when I was doing my motor rebuild I discovered the radiator had a crimped line on the transmission cooler part of the radiator, the truck also has an external transmission cooler.

My "crimped" transmission cooler line before I fixed it by un-crimping...

My motor build can be seen here...

http://toyotamotorhome.org/forums/index.php?showtopic=6823

I was thinking the first thing I should try is adding some Lucas Transmission fix and seeing what that does for it as it has high reviews. I cannot think of any reason my motor should be overheating with all new parts including heavy duty radiator. It has a small dual electric fan on it as well. A friend of mine said it sounds like my transmission may be slipping, but it shifts without a problem and has never had a problem shifting and my overdrive works perfect.

Once again sorry for the long type, thanks for any help and advice.

[linda s]

I think your just pushing it too hard with all that extra weight. I never try to get faster than 35 to 40 on steep hills when I'm in the mountains. Pedal to the metal probably isn't doing you any good. Downshift and drive it easy. Lucas is great for slipping trannies but it won't do you any good on engine temp. Doesn't sound like your tranny is giving you any problems. At 70 mph I'm thinking your not getting any better mileage than a V10 would have. If only we could tour the country and have it all be downhill

Linda S

[Vanman]

When I am going up the steeper hills I have the' pedal to the floor' and it moves at about 50 mph.

No matter what you're driving this is a prescription for disaster. Go down to a gear where you can maintain between 1/2 and 3/4 throttle. Your new motor will last and run cooler to boot. I live on a hill I can only take in first gear up one side and barely get up in second gear and only then with a good run at it, that's just the way it is. If you want to go fast up hill you will have to get a very much larger motor for those 6,000 PLUS pounds.

vanman

[Odyssey 4x4]

Got it, I'll down shift and take her easy on the hills. Flashers on and roll with the big wheelers.

[kgibson4]

This discussion begs the question: What is the optimal temperature for the transmission to maintain? At what temperature is it suffering damage?

I have a transmission temp gauge (which I just replaced) and on the "maiden voyage" we went up a mountain, gaining 6000 ft in about 25 mi. At 30 - 35 mph it reached 190 degrees. Is that too high? It does have a Toyota branded trans cooler in front of the A/C condenser.

Anybody have a gauge in their rig that can offer some comparisons?

Thanks,

Ken

[linda s]

190 going up a hill sounds like your cooler is working fine. Here's a chart showing failure rates at high temps

http://www.txchange.com/heatchrt.htm

You Odyssey is one of the bigger toy homes so just remember don't use the overdrive unless on very flat or slight downhill terrain. Preferably with a tail wind

[Donnie]

It is good that you have a trans. temp gauge..But the temp fluid varies quite a lot relative to where you have your sending unit.

Contrary to what most people think, 90 % of your trans fluid temp is generated in the torque converter & not by slipping clutches.

I have opened MANY purple converters in my day & they are not that color when new...Takes a lot of heat to discolor steel.

If you are reading the fluid in the pan after it has been thru the cooler.......190 is pretty hot......if you are reading it as it leaves the converter to go to the cooler 190 is good...Again, I'm not sure where your sender is located or what fluid you are using...Synthetic fluid can withstand a higher temp than organic before breaking down...I'm not telling you what to use.. Just making a statement. Synthetic won't run any cooler, it will just withstand more heat.

Others have given you good advice.....gear down & stay out of overdrive as Linda says "unless you are on a flat or down hill.".

Remember you are fully loaded at ALL times & lugging it will increase the fluid shear in the converter causing heat & lugging it also causes xtra strain on the gear train....Think of it like this: In 3rd gear your input shaft & output shaft in your trans are connected together...Sort of like direct drive.

There is no multiplication of gears in 3rd. In 4th the overdrive planetary gear set is working & mostly under some strain in these heavy units.

Even though Asian Warner has increased the gear size in some of their transmissions....3rd gear is the best gear to use for the trans to enjoy a long & easy life...Remember these Toyota's are overloaded & under powered from the git go..Not owning one, I can't say how much fuel mileage that you will gain by using overdrive..I can only tell you what I have seen in many years of building both converters & transmissions..thanks for reading..Donnie

[Derek up North]

This discussion begs the question: What is the optimal temperature for the transmission to maintain? At what temperature is it suffering damage?

I have a transmission temp gauge (which I just replaced) and on the "maiden voyage" we went up a mountain, gaining 6000 ft in about 25 mi. At 30 - 35 mph it reached 190 degrees. Is that too high? It does have a Toyota branded trans cooler in front of the A/C condenser.

Anybody have a gauge in their rig that can offer some comparisons?

Thanks,

Ken

190 degrees sounds fine here too.

Not too many have a temperature gauge, so you're in a good position to carry out a few tests , with and without o/d. If you choose to do so, of course. Please report back any observations. Lots of people say "Don't ever use o/d, it'll overheat your transmission." The trouble is, none ever seem to have a gauge installed and can report any hard numbers!

[linda s]

This is a quote from Don Ferguson a long time member of the toyota-campers group. He learned the hard way after spending a week in Arizona while his tranny was being rebuilt. He mentioned a chart like I posted above so I'm pretty sure he knew what was too hot

"After the tranny replacement and reading discussions on the group, I installed transmission temperature gauge. It always showed the transmission temps headed to dangerous levels when in overdrive."

Linda S

[Vanman]

I have a 91 Toyota pick-up Dolphin V-6 automatic with OD. Is it possable to engage the torque conveter lock-up in the lower gears, or does that only work in 3rd or overdrive???

vanman

[zero]

When I got to Texas and started getting into some long uphills on the interstate the motor was getting hot. Also sitting in hot Texas traffic it was getting hotter than it should have.

I was thinking the first thing I should try is adding some Lucas Transmission fix and seeing what that does for it as it has high reviews.

I cannot think of any reason my motor should be overheating with all new parts including heavy duty radiator.

A friend of mine said it sounds like my transmission may be slipping, but it shifts without a problem and has never had a problem shifting and my overdrive works perfect.

I assume you are talking about engine temp and your engine coolant gauge? Or do you have a trans-temp gauge installed? I read your post twice and I'm still not sure. At 70 MPH on a flat road or going slower climbing hills - the torque converter will be constantly slipping and making heat. 15% - 30 % slippage. That is normal. If I had to guess - going by what you've said - I blame the engine rebuild. You no longer have a 2.4 liter engine. You've gone from 2361 ccs, up to 2426 ccs. With an .050" overbore - heat transfers through the thinner cylinder walls into the coolant chambers more quickly. I've seen it happen on several vehicles - gas and diesel - with severe overbores. Also on farm tractors. We put all rebuilds on a dyno for 4-6 hours and the overbores always heat up more. .010" or .020" rarely bothers much. .050" is a lot. If it had been mine - I'd searched for a good used engine with standard bore rather then punch one out all the way to .050". I'm not trying to put down your engine job. Just telling you what I've personally experienced with overbores on gas and diesel engines. I've got a diesel V8 in a truck right now with a large overbore and the same exact heating problems as you report. Also has a new radiator, rebuilt lock-up trans, etc. Truck can run 190 F engine temp all day long until a hill climb. Then the extra heat transfer in the cylinder walls along with the trans no longer in lockup and lots of torque converter heat - make it climb to 220-230F real quick. When GM increased their 6.2 liter diesel engine to a slightly larger bore to make it a 6.5- they had to upgrade the cooling system twice to combat the excess heat problems. My suggestion for you now would be take it easy. Your RV is probably less capable now of long hill climbs then it was before with an OEM bore 2.4 engine. Having a slipping torque converter just adds heat to the problem. If you were able to convert to stick shift - it would likely climb the hills cooler. With my diesel overbore RV with the lockup trans - originally lockup only was allowed in 3rd and 4th. I put in a manual override that forces lockup even in 2nd gear. So now I can climb hills in a lower gear with no torque converter slippage.

In regard to Lucas treatment for the trans? I'm not a believer in "snake oils." I've rebuilt many automatic transmissions and when seals are blown, bearing worn, and/or clutches burnt- no treatment is going to fix the issues. Maybe if you've got a sticking hydraulic control valve somewhere a different oil might help a bit.

[darrel]

Have a question for Donnie. How would I install a temp gauge and sensor to pick up the temp after it leaves the torque converter? Also a mechanic, I trust, told me he likes Valvoline MAX life full synthetic for our transmissions. What would your take be on this oil? I have a 93 truck toyhome.

[Odyssey 4x4]

I assume you are talking about engine temp and your engine coolant gauge? Or do you have a trans-temp gauge installed? I read your post twice and I'm still not sure. At 70 MPH on a flat road or going slower climbing hills - the torque converter will be constantly slipping and making heat. 15% - 30 % slippage. That is normal. If I had to guess - going by what you've said - I blame the engine rebuild. You no longer have a 2.4 liter engine. You've gone from 2361 ccs, up to 2426 ccs. With an .050" overbore - heat transfers through the thinner cylinder walls into the coolant chambers more quickly. I've seen it happen on several vehicles - gas and diesel - with severe overbores. Also on farm tractors. We put all rebuilds on a dyno for 4-6 hours and the overbores always heat up more. .010" or .020" rarely bothers much. .050" is a lot. If it had been mine - I'd searched for a good used engine with standard bore rather then punch one out all the way to .050". I'm not trying to put down your engine job. Just telling you what I've personally experienced with overbores on gas and diesel engines. I've got a diesel V8 in a truck right now with a large overbore and the same exact heating problems as you report. Also has a new radiator, rebuilt lock-up trans, etc. Truck can run 190 F engine temp all day long until a hill climb. Then the extra heat transfer in the cylinder walls along with the trans no longer in lockup and lots of torque converter heat - make it climb to 220-230F real quick. When GM increased their 6.2 liter diesel engine to a slightly larger bore to make it a 6.5- they had to upgrade the cooling system twice to combat the excess heat problems. My suggestion for you now would be take it easy. Your RV is probably less capable now of long hill climbs then it was before with an OEM bore 2.4 engine. Having a slipping torque converter just adds heat to the problem. If you were able to convert to stick shift - it would likely climb the hills cooler. With my diesel overbore RV with the lockup trans - originally lockup only was allowed in 3rd and 4th. I put in a manual override that forces lockup even in 2nd gear. So now I can climb hills in a lower gear with no torque converter slippage.

In regard to Lucas treatment for the trans? I'm not a believer in "snake oils." I've rebuilt many automatic transmissions and when seals are blown, bearing worn, and/or clutches burnt- no treatment is going to fix the issues. Maybe if you've got a sticking hydraulic control valve somewhere a different oil might help a bit.

This is the engine temp gauge I should have mentioned. I'm thinking maybe it was not bored .50 over as that does sound excessive but I do not have the paperwork in front of me and do not remember. Should I look into putting on a couple high performance radiator fans on the back of the radiator. The one on it now is a small dual fan that only covers a bit less than half of the radiator. If I could fit two high performance 10" fans on the back it seems that should make a decent difference. The new radiator definitely took care of the engine running hot in high temps and in traffic. The old radiator was not stock and was a cheap 1-row piece. The only time I have any temp over 45% of the gauge now is on long up hills.

[linda s]

Sorry but your engine rebuild thread does say you had it bored .50 over. Nice for more power on the road but your just going to have to watch those hills. Bigger fans might help

Linda S

[WME]

I think your OK. Just practice downshifting and slow down a bit.

One thought the stock Toyota cooling fan is a very good system IF the clutch works and the full fan shroud is intact.

[Maineah]

Doubt any one bored it 50 over maybe .5 MM. 190 isn't overly hot don't forget it is indeed bolted to the engine and the heat will follow. Using lower gears does help it makes the converter slip less. If the sensor is any where in the return that will be what the trans is going to use before it is heated again the pan is really the best place for a temp gauge. The factory extra cooler is OK bigger is better though. There are a lot of Toy homes out there with well over 150K so these things are a lot tougher that one might think. I agree with WME the stock clutch fans move plenty of air if they are working properly.

[kgibson4]

Escaper, thanks for initiating this topic. I'm getting some valuable pointers here.

And thanks for the responses to my questions. I will be taking another trip in the hot southwest soon. I will try to get some transmission temperature data under the different traveling conditions and will report back.

Ken in Tucson

[Odyssey 4x4]

Thread update, I just arrived in Pasco, Washington. There were some long uphills on the interstate here, probably about 10 minutes of continuous uphill driving, only somewhat steep in a few parts. I tucked in behind a semi and cruised with overdrive off and by the time we reached the top of the hill the semi was down to 35 mph in a 55mph semi zone and I just cruised a few car lengths behind him. My temp obviously rises with the uphill driving in comparison to flat land driving, but went to about the same temp as any other hill driving. Just not as quickly as it would have with me trying to move with the flow of traffic rather than being the slow guy in the right lane with his flashers on.

To give an idea of my temperature I took a couple pics.

This is my gauge during normal in town driving here in Pasco with a temp of 95 degrees F.

And here is my temp gauge during the interstate drives uphill, this is about the highest it ever goes, maybe a hair higher.

Is this a temperature not worth worrying about? I'm used to having my newer vehicles where the temperature gauge never really fluctuates in any condition so maybe I am just being overly cautious with this.

Thanks for the active thread and everyone giving their 2 cents, this is what makes this forum great.

[Maineah]

No that's fine.

[linda s]

Looks just right to me. Actually considering the weight your carrying it looks fantastic

Linda

[WME]

At 35 mph you should be in 2nd gear. I would recommend a tach installed asap. The redline with a 22r is 5750rpm, it will climb all day at 4-4500 rpm

[Odyssey 4x4]

Excellent, thanks folks.

[zero]

Doubt any one bored it 50 over maybe .5 MM.

His pistons are clearly marked .050" over.

[Odyssey 4x4]

His pistons are clearly marked .050" over.

Nice work, I forgot that was shown on the pistons, thanks!

[darrel]

That's what my temp looks like, 94 Warrior. Don't worry , just go slower. I don't even drive my 04 Tacoma at 70.

[Odyssey 4x4]

Sounds like I'm in better shape than I thought for being on the other side of the country from home. At least there was plenty of good info shared in the thread.

[Donnie]

I'm with Maris on this one---.050 is excessive on the overbore. Remember Toyota is concerned about weight, they do not make anything any heavier than needed........If the bores were sonic tested I think you would be amazed at how thin your cyl walls are.....In the bad old daze, .050 was OK...

just remember this is not your grand dads Buick......Also I am not a fan of the factory gauges, not just on Toyota, on anything...

You can't beat a gauge with numbers on if want to be more sure....not looking for a rebuttal, just stating my opinion...........Donnie

[Donnie]

To address the query by Darrel.......Maineah is correct in telling you that the pan is a good place to put the sender as IT IS the temp of the fluid that the trans is going to use as it has been cooled. But if you want to see how much heat is generated by the converter........install a T fitting in the front line going to the cooler.. Install it as close to the trans as you can...This will require some fabrication as the tip of the sender must be in the stream of the fluid & constructed in such a way as not to impede the rate of flow...I think that this will qualify my statement of how much heat is generated by the converter.

If you are tech minded, you can install a sender in both places & connect them to one gauge using a double throw toggle switch....this will test the efficiency of your cooler.........There are easier ways to to do this, but if you decide to undertake this project, I'm sure the members would like to know the results........As far as recommending a fluid........I am gonna take a pass on that one.....All I will say is on my 93 Previa at 100,000 miles I changed the fluid.

I have always used Castrol products on my gas engines & Rotella in my diesels.. The Previa has just flipped over 200,000 rounds & shows no signs of distress...engine or trans...One thing to consider, the 93 Previa was made in Japan BEFORE their economy hit the crapper..At that time they were pretty flush & destined to show Detroit how to build a machine......it is the same engine, just laying on its side .all the above is just my opinion...........thanks for reading.Donnie

[Maineah]

His pistons are clearly marked .050" over.

I don't see" just as well could be .5MM or 10 thousands The piston is from CES a supplier of import pistons my money is on ,5MM

[Derek up North]

Well, to my old eyes squinting at a computer monitor, I pretty clearly see 0.50 marked on the piston. So, is it 0.50"? Somehow I doubt it.

[WME]

.5mm=.020

[zero]

Well, to my old eyes squinting at a computer monitor, I pretty clearly see 0.50 marked on the piston. So, is it 0.50"? Somehow I doubt it.

Yes, .5" would not be possible. The largest pistons I've seen for a 2.4 Toyota are .080". They are sold for racing purposes. It's the curse of the metric system when used in the USA. Especially with people brought up with US standards when turning wrenches. The poster says in his blog (the text) that the engine was bored "50 over" and had deep gouges in the cylinder walls. Looking closer now at that text with my glasses on - he wrote ".50 over." If accurate that would have to be mms and not inches. That would amount to an .015" overbore which would not remove what I would describe as "deep gouges." But that means different things to different people. When I first worked in an auto machine shop - the term "50 over" was the spoken word for what was actually "0-50-over." Verbal shorthand.

I still curse the metric system. I was told in high school in the 60 s that in 20 years the US would be all metric. Never happened. We still have a confusing mix of USS, SAE, and metric - with a little Whitworth thrown in. I remember when Ford announced their first US made car to use metric hardware. The Pinto. Ford took the trouble to color code the bolt heads. Metric had blue heads and all else was SAE. Now with new cars? I'm still finding a mix.

[zero]

By the way, Toyota does sell .046" oversize pistons for the 22R and 22RE. They would be marked 1 mm if from Toyota or some other foreign supplier.