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I think I will go get the Winnie from the dealership today. I will take a look at it and maybe do some of these easier fix's, like the fuel filter and the washing of the AC condenser. I will check the air flow around and through the radiator. I keep thinking there is something contributing to the overheating only uphill with the AC on. I would think this wold be the most extreme stress on this engine- it would be working the hardest under these conditions, and under these conditions the engine heats to a temperature that the existing cooling system is not capable of handling. I have to wonder why the excess engine temp? Why is it working so hard? Is this normal? Or is something not functioning correctly and it evident under this extreme condition.

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Having too small a radiator is plausible. But - how did they determine your's IS too small? Ratings like 1, 2, or 3 tube are sometimes meaningless. Some one tube radiators have more cooling capacity then three-tube. It's all about how deep the tube area is and NOT how many tubes there are.

I don't get the electric fan thing. That is unless you totally removed the mechanical fan. But yes - proper fan operation is important when stopped a long red lights or on very slow-moving hill climbs. In normal highway conditions - you don't need any fan.

I think you are asking for more headaches going to the suggested forums. Yes a few people there really know there stuff and many more are clueless "know it alls." It can be tough trying to sift through it all and deciding what info is actually useful. You are likely to get a lot more bad info then good.

The dealership does not know that the radiator installed is too small, they only know that it is not OM. Same with the electric fan and shroud. They don't know that they are "the problem" they only know that they are not OM and therefore could be the problem.

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I think I will go get the Winnie from the dealership today. I will take a look at it and maybe do some of these easier fix's, like the fuel filter and the washing of the AC condenser. I will check the air flow around and through the radiator. I keep thinking there is something contributing to the overheating only uphill with the AC on. I would think th is wold be the most extreme stress on this engine- it would be working the hardest under these conditions, and under these conditions the engine heats to a temperature that the existing cooling system is not capable of handling. I have to wonder why the excess engine temp? Why is it working so hard? Is this normal? Or is something not functioning correctly and it evident under this extreme condition.

I had pretty much the exact same symptoms recently with my 2001 Kia Sportage. Ran fine and cool with normal highway driving but got pretty "warm" when climbing long steep hills. If I put the AC on it got dangerously hot. In that case - it was the radiator and nothing else. It was somewhat plugged internally. A new $120 radiator fixed the problem. Any gas engine (or diesel) wastes most of the fuel it burns by turning it into waste-heat that has to go out the tailpipe or dispensed by the radiator. The harder you work it the more waste heat. If you turn on the AC then there is even MORE waste heat. A restricted exhaust and/or an inadequate cooling system can cause engine overheating.

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The dealership does not know that the radiator installed is too small, they only know that it is not OM. Same with the electric fan and shroud. They don't know that they are "the problem" they only know that they are not OM and therefore could be the problem.

I am usually the last person to defend people in repair shops but in this case - I can see their point. That does not mean I think they are correct. When you bring a rig there - in theory - you pay for every minute they are even thinking about your repair. I don't think they want to take the time to figure out the square-inches of actual cooling area you have and if it is correct. I doubt they even now what it is supposed to be. Their easy way of insuring correct parts is just to order those approved by Toyota. Toyota makes almost none of these parts so all are, in a way, "aftermarket." I worked in many repair shops and if you came to my place with the problems as described thus far - I would not guarantee a fix. I'd talk more like a medical doctor and suggest various approaches with non-guaranteed outcomes. I am surprised they were willing to do the head-gasket change, knowing your problems and give some sort of disclaimer. Or did they?

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I am usually the last person to defend people in repair shops but in this case - I can see their point. That does not mean I think they are correct. When you bring a rig there - in theory - you pay for every minute they are even thinking about your repair. I don't think they want to take the time to figure out the square-inches of actual cooling area you have and if it is correct. I doubt they even now what it is supposed to be. Their easy way of insuring correct parts is just to order those approved by Toyota. Toyota makes almost none of these parts so all are, in a way, "aftermarket." I worked in many repair shops and if you came to my place with the problems as described thus far - I would not guarantee a fix. I'd talk more like a medical doctor and suggest various approaches with non-guaranteed outcomes. I am surprised they were willing to do the head-gasket change, knowing your problems and give some sort of disclaimer. Or did they?

I totally agree with your thoughts on this and the approach the dealership is suggesting. I think there approach is get it back to "stock" and then if the problem still exists then look at other issues. But my gut says going back to "stock" won't solve my problem. The fact that the truck stays cool in stop and go traffic with the air on- seems to indicate the fan is sufficient to cool the radiator. The fact that the truck cools so quickly when not going uphill, seems to indicate the radiator cooling capacity is adequate. Also runs cool at 60 mph on the freeway with air on. I like the idea of the exhaust system maybe being an issue. I have been told by one of the mechanics that he thinks there might be a exhaust leak. (i mentioned this is a past post). I think there is something going on with the muffler -exhaust pipe.

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I am usually the last person to defend people in repair shops but in this case - I can see their point. That does not mean I think they are correct. When you bring a rig there - in theory - you pay for every minute they are even thinking about your repair. I don't think they want to take the time to figure out the square-inches of actual cooling area you have and if it is correct. I doubt they even now what it is supposed to be. Their easy way of insuring correct parts is just to order those approved by Toyota. Toyota makes almost none of these parts so all are, in a way, "aftermarket." I worked in many repair shops and if you came to my place with the problems as described thus far - I would not guarantee a fix. I'd talk more like a medical doctor and suggest various approaches with non-guaranteed outcomes. I am surprised they were willing to do the head-gasket change, knowing your problems and give some sort of disclaimer. Or did they?

They knew nothing! It was covered under the recall so they did the work. I did not think it was the HG but since it was a free fix I had it done as another issue that could be checked off. We now know it was not the HG as the same problem still exists. All though all this work has taken a good running truck into a GREAT running truck - oh yeah except for that pesky overheating problem.

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Keep this in mind. Your RV was NOT designed by Toyota. Ergo overheating is something that cannot necessarily be blamed on Toyota. It is likely heavier than Toyota allows and also has the Toyota-intended air-flow changed by sticking an RV coach on it. I don't think Toyota has had anything to do with RV designs in the USA since the early 70s Chinooks. A hot engine happens when it makes more heat that is being removed. More heat is made to make more power, like done when climbing hills. Even more heat is made to "upset the apple-cart" when you turn the AC on. If this was an OEM Toyota truck - it would be tested to make sure it had the cooling system and air-flow needed to work in such extreme situations. In your case - with a Winnebago RV - it kind of falls on them but not if the RV is over its GVWR which it likely is.

There have been so many posts I lost track of some of the facts. Does your RV overheat when climbing a hill if the AC is off? That was the determinate factor on our Kia. Using AC was the "straw that broke the camel's back" and made it get too hot when the radiator was inadequate.

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Bozo again. We are grasping at some pretty thin straws here, so heres another one.

The AC adds to much heat too the cooling system when going up a hill, this is a known fact.

SO REDUCE the AC heat load.

Take a cheap shower curtain and hang it from the cabover bed all the way to the floor sealing off the cab from the house. This will keep the AC from trying to cool the whole house. Instead it will have to cool just the cab which is what it was designed to do. This will reduce the amount of heat that the AC system dumps in front of the radiator. Use air reculate too.

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I believe it was said in an earlier post that it did NOT overheat while climbing with the A/C off because I very nearly posted suggesting to switch it off while climbing. But that seemed to me to be too obvious a solution and perhaps not acceptable to some in warmer climates than mine. :)

I believe some vehicles were fitted with vacuum switches that would disable the A/C under high load conditions (accelerating or climbing).

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I think you are asking for more headaches going to the suggested forums. Yes a few people there really know there stuff and many more are clueless "know it alls." It can be tough trying to sift through it all and deciding what info is actually useful. You are likely to get a lot more bad info then good.

For those of us without mechanical backgrounds we can forum hop a bit, not take any one answer as gospel, ask on one forum and then bounce it off another forum, hopefully the wheat can be separated from the chaff. Particularly in a situation such as this where all the usual fix's have not worked!

Jim SW FL

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Another 'bandaid' solution:-

The misting systems were common in the bus conversion community. Even with massive radiators and huge fans some of the Detroit Diesel's were really hard to keep cool. Certainly an option, but I would do it as a last resort.

Jim

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Keep this in mind. Your RV was NOT designed by Toyota. Ergo overheating is something that cannot necessarily be blamed on Toyota. It is likely heavier than Toyota allows and also has the Toyota-intended air-flow changed by sticking an RV coach on it. I don't think Toyota has had anything to do with RV designs in the USA since the early 70s Chinooks. A hot engine happens when it makes more heat that is being removed. More heat is made to make more power, like done when climbing hills. Even more heat is made to "upset the apple-cart" when you turn the AC on. If this was an OEM Toyota truck - it would be tested to make sure it had the cooling system and air-flow needed to work in such extreme situations. In your case - with a Winnebago RV - it kind of falls on them but not if the RV is over its GVWR which it likely is.

There have been so many posts I lost track of some of the facts. Does your RV overheat when climbing a hill if the AC is off? That was the determinate factor on our Kia. Using AC was the "straw that broke the camel's back" and made it get too hot when the radiator was inadequate.

Just picked up the Winnie and the answer is yes it does overheat when going up a hill with the AC off, it just takes a little longer to get to the red line.

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The misting systems were common in the bus conversion community. Even with massive radiators and huge fans some of the Detroit Diesel's were really hard to keep cool. Certainly an option, but I would do it as a last resort.

Jim

Ha Ha! Living in Las Vegas I have a portable misting system, I tried to rig it on to the front of the Radiator, but it did not work long enough. I also remember the canvas radiator bag that my dad used to hang in front of our car when I was a little girl. I would do something like this in a minute, I just wonder if my engine getting hot is not a symptom of something other than the cooling system not handling the heat. I don't want to hurt my engine.

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Bozo again. We are grasping at some pretty thin straws here, so heres another one.

The AC adds to much heat too the cooling system when going up a hill, this is a known fact.

SO REDUCE the AC heat load.

Take a cheap shower curtain and hang it from the cabover bed all the way to the floor sealing off the cab from the house. This will keep the AC from trying to cool the whole house. Instead it will have to cool just the cab which is what it was designed to do. This will reduce the amount of heat that the AC system dumps in front of the radiator. Use air reculate too.

We have a Curtain that blocks the cab from the rest of the camper. The AC works so well that we usually only need it on low. But I just did my up hill test drive without the air conditioning on and it still overheats it just takes longer to get to the red line. I would gladly drive up hill with out the AC if that would eliminate the problem. I have to wonder why us? I think I read that other people drive around in their Toyota Campers with the AC on and go up hill!

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We have a Curtain that blocks the cab from the rest of the camper. The AC works so well that we usually only need it on low. But I just did my up hill test drive without the air conditioning on and it still overheats it just takes longer to get to the red line. I would gladly drive up hill with out the AC if that would eliminate the problem. I have to wonder why us? I think I read that other people drive around in their Toyota Campers with the AC on and go up hill!

I can't. Not if it's a hot summer day and I've driving over 55 MPH. Well - I've never overheated doing it but that gauge shows it's close. I never considered it an issue since when going that fast - opening a window works well enough for ventilation. And remember - I'm in northern Michigan. So I'm talking maybe high 80s outside. I suspect it gets warmer where you are.

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Here is the Youtube video of my last test drive https://youtu.be/zJgICYoJlTQ

I guess my question is - After doing all this work- do I assume the engine is working properly and I need to retrofit it so that it does not overheat in the hot temperatures here in Las Vegas? It was around 85% F when I did this test drive. To me this is rather cool, but not to my Camper. I could get a bigger radiator, add more fans, add a mister system? or all three? Do I just do what ever is necessary to keep the temp down - regardless of why it is happening?

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You are showing your age with the canvas bag! If you can find one hang it on the grille and use one of these for cooling the Toy instead of the AC. Problem solved!

attachicon.giftoy.JPG

You can still buy the canvas bags http://kool-water.com/

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another old trick for over heating was to roll a ll windows down and turn the heater to max heat and fan on high . gets hot on the people but can drop the engine temp to safe limits.

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Your sure makin this fun/hard/interesting. 85 deg in LV is not hot. Been there too many times

Clean AC condenser and check to see if the fins are OK (straight)

Looking at the pictures of the radiator it has mounting tabs on the sides that bolt it to the radiator support so air leaking past the radiator is out.

Have you talked to the original radiator shop?

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I guess my question is - After doing all this work- do I assume the engine is working properly and I need to retrofit it so that it does not overheat in the hot temperatures here in Las Vegas? It was around 85% F when I did this test drive. To me this is rather cool, but not to my Camper. I could get a bigger radiator, add more fans, add a mister system? or all three? Do I just do what ever is necessary to keep the temp down - regardless of why it is happening?

Unless I missed it - you never posted your radiator core size - did you? That is one of the most essential factors here. A four-cylinder radiator has a core around 15 3/4" high X 20 3/4" wide X 1 1/4 thick and that comes to 408 cubic inches of coolant capacity and 327 square inches of frontal cooling surface. A V6 radiator has a core that measures 18" high X 19" wide X 1 1/4 thick and has 427 cubic inches of coolant and 427 square inches of frontal cooling area. There are places that make custom radiators (for V8 swaps into your Toyota) with 1728 cubic inches of coolant and 576 square inches of frontal cooling surface area. My point being - make sure you have at least the minimum correct size radiator core. If not - get the OEM correct one. Better yet-get one custom made that is even bigger. Many places make them. Do NOT be fooled by all the 3 or 4 tube claims. It, in itself means nothing. Some one-tube radiators cool better then some four-tube. You NEED TO MEASURE your radiator core (just the part that holds coolant and not the tanks or frame).

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another old trick for over heating was to roll a ll windows down and turn the heater to max heat and fan on high . gets hot on the people but can drop the engine temp to safe limits.

Been there done that ;)

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Unless I missed it - you never posted your radiator core size - did you? That is one of the most essential factors here. A four-cylinder radiator has a core around 15 3/4" high X 20 3/4" wide X 1 1/4 thick and that comes to 408 cubic inches of coolant capacity and 327 square inches of frontal cooling surface. A V6 radiator has a core that measures 18" high X 19" wide X 1 1/4 thick and has 427 cubic inches of coolant and 427 square inches of frontal cooling area. There are places that make custom radiators (for V8 swaps into your Toyota) with 1728 cubic inches of coolant and 576 square inches of frontal cooling surface area. My point being - make sure you have at least the minimum correct size radiator core. If not - get the OEM correct one. Better yet-get one custom made that is even bigger. Many places make them. Do NOT be fooled by all the 3 or 4 tube claims. It, in itself means nothing. Some one-tube radiators cool better then some four-tube. You NEED TO MEASURE your radiator core (just the part that holds coolant and not the tanks or frame).

Spectra Premium - Radiator
Line: GT | Part # CU1190
  • Construction: Plastic Tank/Aluminum Core
  • Core Width (In): 19 Inch
  • Core Height (In): 17-13/16 Inch
  • Core Depth (In): 1-1/4 Inch
  • Number Of Rows: 1
  • Inlet Hose Diameter (In): 1-3/8 Inch
  • Outlet Hose Diameter (In): 1-3/8 Inch
  • Inlet Hose Diameter (mm): 34.93mm
  • Engine Oil Cooler Included: No
  • Transmission Oil Cooler Included: Yes
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Been there done that ;)

My dad had a brand new 1959 Ford with the "Mileage Maker Six." It was the absolute cheapest car Ford sold and had no options and power-nothing. Manual steering, manual choke, three speed on the column with no synchros in 1st gear. I went with him to pick it up by the Mahwah Ford plant in New Jersey. First trip we took was on the New Jersey Turnpike in August. Got stuck in bumper-to-bumper traffic and sat there, not moving, with the heater on full blast. Note - we still overheated. The car and us. Unlike your Toyota - the Ford only got hot when it wasn't moving.

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Your sure makin this fun/hard/interesting. 85 deg in LV is not hot. Been there too many times

Clean AC condenser and check to see if the fins are OK (straight)

Looking at the pictures of the radiator it has mounting tabs on the sides that bolt it to the radiator support so air leaking past the radiator is out.

Have you talked to the original radiator shop?

They know nothing, offer to make a custom copper and brass radiator approx $600.00

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They know nothing, offer to make a custom copper and brass radiator approx $600.00

Advance Adapters sells copper Toyota radiators for V8 swaps in the $400-$500 price ranges. I'd call and ask if one can be had with the correct connections for an OEM V6. Since the tanks are metal and not plastic - seems changing one over would not be very difficult. Note - I have never owned nor driven a V6 Toyota RV. All mine are four-cylinder powered. I've read that V6 cooling is "marginal" in Toyota RVs but have no first-hand experience. Advance Adapters sells the custom copper radiators but also sells a bolt-in replacement for your Toyota. All aluminum and plastic but it might be worth having. You'd have to call and ask them for specs.They have none posted for it. Nothing wrong with aluminum and plastic when it comes to cooling. Just not something you can solder, take apart, or make changes to. I replaced the copper radiator in my 94 Ford diesel truck years ago with a new aluminum and plastic one and it's been fine. If anything, it cools better then the original.

post-6578-0-67884100-1444572646_thumb.jp

post-6578-0-15992600-1444572648_thumb.jp

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I have had excellent results with my CFS radiator. All metal and they do have a 3 row. It's much larger than the one you have and after all the work you've had done what's another 200 bucks

http://www.ebay.com/itm/CSF-88-95-Toyota-4Runner-88-95-Toyota-Pickup-Radiator-3-ROW-AMR-2057-/231681919091?fits=Year%3A1992%7CMake%3AToyota%7CModel%3APickup%7CSubmodel%3ABase%7CEngine+-+Liter_Display%3A3.0L&hash=item35f1518873&vxp=mtr

Linda S

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Might be a great upgrade. Just keep in mind that "three row" means nothing. What counts is how deep, in total, the coolant tube area is. Three 1/2" tubes are not as effective as one 2" tube. I'd ask for actual specs. With one of my Chevy diesels - the HD upgrade uses a single tube and the OEM lighter duty three tube.

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I have had excellent results with my CFS radiator. All metal and they do have a 3 row. It's much larger than the one you have and after all the work you've had done what's another 200 bucks

http://www.ebay.com/itm/CSF-88-95-Toyota-4Runner-88-95-Toyota-Pickup-Radiator-3-ROW-AMR-2057-/231681919091?fits=Year%3A1992%7CMake%3AToyota%7CModel%3APickup%7CSubmodel%3ABase%7CEngine+-+Liter_Display%3A3.0L&hash=item35f1518873&vxp=mtr

Linda S

Linda do you have a V6 3.0 ?

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Linda do you have a V6 3.0 ?

I have a 4 but I only have a 2 row, the 3 row was back ordered then, and my rig runs almost too cool. This is the model for the V6 radiator and it's larger anyway and this one is larger than the size you posted on yours. I just think you've gone through so many repairs this is a fairly low cost thing to try. No one seems to have any real answers for you.

Linda s

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Question for the forum, could a restricted exhaust system be causing the problem?? Jim

Yes, but it would also result in a loss of power. Such restriction is easy to verify with a vacuum gauge.

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Yes, but it would also result in a loss of power. Such restriction is easy to verify with a vacuum gauge.

what is this vacuum gauge and how do i verify? I did pass a state required smog test in late June.

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