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Fascinating thread, Irving. Thanks for posting.

You are correct about the SR5 instrument cluster being plug and play except for the oil pressure sender change out. I installed a 4-Runner cluster in my '92 Itasca ('91 chassis V-6) and all the connectors plugged right into the 'new' cluster. I get by just fine without a gear shift indicator.

I use the old vacuum gauge method of watching for shift points while using cruise control lockup, but you have me convinced to try out an MPGuino. I'm getting 16.5MPG out here in the West with lots of mountains to climb.Like you I live at 48-53MPH on secondary roads.

I might also mention I swapped out the 4.10:1 differential for a 4.56:1. That helped immensely to keep the transmission locked up at lower speeds.

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Fascinating thread, Irving. Thanks for posting.

You are correct about the SR5 instrument cluster being plug and play except for the oil pressure sender change out. I installed a 4-Runner cluster in my '92 Itasca ('91 chassis V-6) and all the connectors plugged right into the 'new' cluster. I get by just fine without a gear shift indicator.

I use the old vacuum gauge method of watching for shift points while using cruise control lockup, but you have me convinced to try out an MPGuino. I'm getting 16.5MPG out here in the West with lots of mountains to climb.Like you I live at 48-53MPH on secondary roads.

I might also mention I swapped out the 4.10:1 differential for a 4.56:1. That helped immensely to keep the transmission locked up at lower speeds.

Thanks for the info on the cluster, twoblocked. I think I'll make the cluster swap my next project.

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Look for a dash from a t100 w automatic 2wd. It will have the PRNDL built in. The 5 speed manual does not have the lights.

Here ya go http://toyotamotorhome.org/forums/index.php?showtopic=2725&page=2

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Have you looked for an SR5 instrument panel? I imagine by now they are going to be in the hens teeth category, but might give you something more to do during your wanderings

If you're talking to me, I don't think it would help. So far as I can tell, pre-79 trucks did not come with tachs, SR5 or no. I swapped to an SR5 cluster in my 83 to get the tach. But I have yet to see a photo of a 78 or earlier pickup with a cluster that looks any different than mine. Maybe I should look into it more, though.

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If you're talking to me, I don't think it would help. So far as I can tell, pre-79 trucks did not come with tachs, SR5 or no. I swapped to an SR5 cluster in my 83 to get the tach. But I have yet to see a photo of a 78 or earlier pickup with a cluster that looks any different than mine. Maybe I should look into it more, though.

Did you ever see these pics from Dudevato on the Chinook site of how he incorporated a tach and other gauges into his existing dash. Really cool work.

https://groups.yahoo.com/neo/groups/toyotachinook/photos/albums/442504520

Linda S

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Wow!

No I never saw that. That level of work is out of my reach without someone like him guiding me the first time, but I could probably do something halfway decent...

I actually really like the way that looks.

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Hi Irving,

I did the same thing, with another type of fuel monitor, on a 1956 Chevy 2 ton! previous owner never got more than 14 mpg, I got 20 mpg. It was a fun thing to do but also saved a ton of gas, since we went from Canada down to Arizona and then pulled a 35 ft trailer back. Thanks for your link I will go to it in a minute and take a look.

On another topic and for all V6 equipped RVs, I would like to spread the word that Toyota has a secret warranty, to rebuild the V6 engines, due to a faulty head gasket. There are conditions, but to keep the story short, take your rig to a Toyota dealer, and ask if you qualify. My first Toy was exactly like yours and the engine blew when on holidays, 3400 dollars later, we were on our way, but while waiting for this rebuild, I found out about the warranty. Back home, we approached Toyota, showed them our invoice and they gave us a cheque. My second Toy (bought a few weeks ago) also qualified, they took it in and rebuilt it for us, no charge. So check it out before the heads let go.

Brian

By the way, I get the same mileage (approximately) as you do. One thing I don't understand is that this motor has an altilmeter sensor built into it, and the higher up in elevation, at some point the overdrive cuts out, and stay disconnected until you descend, you notice that.

So your telling me I can still get the headgasket replaced now? I bought a 1990 last year and would love to have that done. It runs kinda hot, so I'm worried. Who would I talk to at the dealer, go to the service dept, or the guys in the showroom. I didn't think they would honor it anymore, but looks like I'm gonna be headed to the dealership. Anything I should mention if they say they don't honor it anymore?

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So your telling me I can still get the headgasket replaced now? I bought a 1990 last year and would love to have that done. It runs kinda hot, so I'm worried. Who would I talk to at the dealer, go to the service dept, or the guys in the showroom. I didn't think they would honor it anymore, but looks like I'm gonna be headed to the dealership. Anything I should mention if they say they don't honor it anymore?

Look here.

http://toyotamotorhome.org/forums/index.php?showtopic=6305&page=1

Click on the link then scroll down to page 65 and see if you vin is listed. Last numbers only and your looking for cab and chassis long wheel base. If local dealer won't help call toyota corporate and have them open a case for you and find a dealer that will do the work. It is not technically a recall. So Tell them it's a Special Service Campaign. They need your vin to check and see if it's already been done but you can ask the dealer to check that. It's supposed to be in their computers

Linda S

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Maineah,

Thanks for this info on the solar panels as a stand-in for the alternator. I do plan to leave the truck battery in the circuit, and to shut off the alternator through the field coils. The thing that concerns me now is, when I switch the solar panels out and the alternator back into the circuit, you mentioned that the alternator will take off at full tilt, thus overcharging. Will the alternator quickly recognize the full state of charge of the battery and back right down to a trickle, or will it be somehow stuck on full charge?

Why do you want to shut off field current to the alternator? Not nit-picking. Just reading the post and trying to figure out what's being discussed. A 60 amp alternator when making max current only draws around 6 amps @ 14 volts. What does this have to do with installing solar? A typical RV has two battery systems. "Cranking" and "house." In a ideal setup the alternator is only hooked to the "cranking" battery in default mode and both (cranking and house) when the "cranking" battery has reached around 13.5 volts. The solar is usually hooked to the "house" system. If you isolate the batteries with a relay controlled by a voltage sensor (cranking battery voltage) - the alternator charges that cranking battery first. Then moves on to the "house" batteries. Both the alternator and the solar panel regulator work by voltage sensing. So even when the isolation relay is closed and all systems are tied together - voltage control is fine. Only exception is - if you want a different charge rate front and back.

I'm a little lost here. Are you discussing hooking solar to the front "crank" battery system? If so, my first question is WHY? Is there something wired to the cranking battery you wish to use while camping? Or are you trying to drive the truck down the road with the main electrical system running on solar? If the latter -what is the anticipated gain? Are you trying to gain MPGs by having solar do the job of the alternator and want it all tied together? During normal daytime running (no lights on) that alternator is running with around 2 amps of field current. If you were to eliminate that small load - I'd doubt you could perceive any difference in MPGs. You be apt to see more gain by removing the alternator and having less fan and bearing drag. Can't imagine that ever working well though.

If you DO want the solar tied into the front . . and your trying to "hypermile" -seems you'd want an electric clutch on the alternator so you could complete remove it from the belt drive and eliminate fan and bearing drag. That drag probably exceeds the engine power used as compared to what is used making power at normal running. Can't say I've tried it or ever gave it serious thought. Putting "hypermile" and "Toyota RV" in the same sentence is an oxymoron to me.

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Hello Jdemaris,

I have severed the link between the truck charging system and the motorhome electrical system, so the alternator never charges the MH batteries. What I'm looking for is to be able to shut the alternator off (or turn it back on) at will and then tie in the solar panels to the truck electrical and charging system to maintain all the functions of the truck while driving it. This is intended to eliminate the load placed on the engine by the alternator that is caused by the demand for electricity from it by the truck's electrical system. (It wouldn't eliminate the load from the alternator bearings simply due to the fact that it is turning unless, as you suggested I put an electric clutch on the alternator like an a/c compressor has). Clearly this could only be done during the day (no headlights) when the sun is out, but that's when I do almost all of my driving. This type of mod (simply shutting off the alternator) has been discussed on Ecomodder and does produce results I would consider significant. I think that rather than just running down the truck battery I could use my solar panels to keep it charged, since they are there producing electricity anyway. Through some checking I have found that between the fuel pump and the ECU it will take 7 to 10 amps to keep the engine running, and I may be able to produce that with my panels. Taking the load off the alternator will give me more engine capacity to power the MH and I won't have to use as much fuel to turn the alternator under load. Hope this clarifies my earlier posts.

Edited by Irving Renewal
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I agree with J hypermile and Toyota Rv don't belong in the same sentence. Get a Prius and a tent.

If hypermile is your hobby or something then enjoy, but your payback will be a long time coming, and resale will tank.

Slowing down a bit will save more mpg that anything you could do with your charging system

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Hi
Sure this has been mentioned before the biggest change for me was connecting battery negative to inlet manifold via a battery lead. gained 3-4 imperial mpg. also helped to improve starting. my electric wires must be breaking down. this would be part of the big three mentioned on net.

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Hi

derek found this baffling as well but done over 100 miles on 1/2 a tank normally get 75miles. power is up as well. anyone who can explain this please chime in.

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Hi

derek do you want to handle sales stateside after i make my ad. Lol :-) :-) :-)

montana just added another lead to battery -ve post then to inlet manifold.

Vanman i think you are right as i cannot find an engine earthing lead. after 25 years and stored for 2 years with bodged repairs anything is possiable.

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Hello Jdemaris,

I have severed the link between the truck charging system and the motorhome electrical system, so the alternator never charges the MH batteries. What I'm looking for is to be able to shut the alternator off (or turn it back on) at will and then tie in the solar panels to the truck electrical and charging system to maintain all the functions of the truck while driving it. This is intended to eliminate the load placed on the engine by the alternator that is caused by the demand for electricity from it by the truck's electrical system. (It wouldn't eliminate the load from the alternator bearings simply due to the fact that it is turning unless, as you suggested I put an electric clutch on the alternator like an a/c compressor has). Clearly this could only be done during the day (no headlights) when the sun is out, but that's when I do almost all of my driving. This type of mod (simply shutting off the alternator) has been discussed on Ecomodder and does produce results I would consider significant. I think that rather than just running down the truck battery I could use my solar panels to keep it charged, since they are there producing electricity anyway. Through some checking I have found that between the fuel pump and the ECU it will take 7 to 10 amps to keep the engine running, and I may be able to produce that with my panels. Taking the load off the alternator will give me more engine capacity to power the MH and I won't have to use as much fuel to turn the alternator under load. Hope this clarifies my earlier posts.

That sounds fine except when you cross a passing cloud and you come to a stop in the middle of the highway. Your load figures would require solar output in the 85 to 120 watt range just to break even better hope for a nice sunny day. A clutch rig on your alternator will cost far more than you'll ever recover in mileage if you are going to try this just cut the power to the field the only loss then would be rotating mass.The max load of your alternator charging a mostly dead battery is going to be slightly more than one horse power as it recharges the battery the output goes down and the required horse power drops. The electrical load running the engine is only around .1 horse power lifting your right foot a 1/8" will save far more fuel. Again clicking the alternator back on will spike the electrical system most of the stuff can stand it some may not it's a chance you may not want to take.

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Hello Jdemaris,

I have severed the link between the truck charging system and the motorhome electrical system, so the alternator never charges the MH batteries. What I'm looking for is to be able to shut the alternator off (or turn it back on) at will and then tie in the solar panels to the truck electrical and charging system to maintain all the functions of the truck while driving it.

OK, now I understand. I guess I should of read all the posts but there is a lot of reading to do. I find it hard to believe that just turning off the field current to the alternator is going to save anything meaningful (and using solar instead). The alternator has a demand on the engine just to mechanically spin it even with zero field current. Now if you had an electric clutch on it like AC compressor have - it would cut down a lot of that mechanical drag. This is why the belt-driven power steering pumps on many new cars are now eliminated. Just adding solar to the roof adds some wind resistance and takes extra energy -unless you've got glue-on flexible panels. Solar on the roof pointing straight up is very inefficient. But yes -so far sunlight is free.

I kind of look at it like this; First - is this thing you are working on still an RV? If so - then I assume it has lights, water, heat, etc. If I am correct so far - you want this thing to have the utilitarian features of a motorhome but want the best fuel mileage possible? My point being your goal is not an ultimate MPG truck. It 's more about an ultimate MPG motorhome with all the usual features. I've been experimenting with fuel mileage for over 40 years. I've built the so-called "secret" Pogue carburetors that run on gas vapor. I've built a truck that runs on firewood gas. Etc. &c. But all of my projects involve vehicles that are useful and driven at normal speeds. When it comes to RVs - the biggest factor is wind drag. Thus if it was my project - I'd start with a pop-up roof. Like my diesel Blazer Chalet of gas Toyota Chinook. Then it comes to matching engine power to the load. Any internal engine gives the best MPGs when run within it's peak torque curve and matched to the load. That is a huge issue with cars and trucks since the loads vary all the time. If you were trying to break MPG records with a motorhome -you'd want to pick one load goal and match the engine to it. A 3 liter V6 is too much if we're talking about flat-land driving at 45 MPH. The optimal setup would be a smaller engine and/or a variable displacement engine. And note that with variable displacement - you can break that into two categories. True "variable" via cylinders that can be disconnected when not needed (like Honda vans have). Or a "virtual" setup using a small engine and a high boost turbocharger. High boost can make an engine behave like one twice as big when needed. Sort of like what Ford is doing now with EcoBoost.

There is also the issue of short term specific efficiency versus long-term overall efficiency. You say you run your tires at 64 PSI. That will offer maybe a 2% gain in MPGs as compared to running them at 45 PSI but will also wear out the tires faster. How much overall energy is wasted by shortening the life span of tires?

You mentioned using "synthetic" oil. Where is the gain with that? In the USA and Canada any oil can be sold as "full synthetic" and not have ANY synthetic content. Besides that - there are many petro oils that offer the same engine efficiency as true sythetics. What makes you think something labeled as "synthetic" has intrinsic qualities that make it more "slippery?" I am well aware of all the advertising hype but I am talking about real proven facts. The main gain with true synthetic oil is the higher flash point that makes it ideal for jet engines and race cars. A less gain is that it has a more stable viscosity range without the use of polymers that can cause piston ring sticking. You might be using lubricants that have given you gains - but if so - I doubt it has anything to do with them being truly synthetic or not. Regardless - the word "synthetic" in the USA and Canada has little legal meaning. In Europe - yes.

Well I'm getting verbose. Good luck on your project. Have you ever read the specs on the Road Trek ETek with solar? Not a hypermiler. Just an RV with efficiency in mind. Has a lot of solar on it and a huge alternator driven by a diesel engine.

http://roadtreking.com/new-etrek-class-b-motorhome/

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That sounds fine except when you cross a passing cloud and you come to a stop in the middle of the highway. Your load figures would require solar output in the 85 to 120 watt range just to break even better hope for a nice sunny day. A clutch rig on your alternator will cost far more than you'll ever recover in mileage if you are going to try this just cut the power to the field the only loss then would be rotating mass.The max load of your alternator charging a mostly dead battery is going to be slightly more than one horse power as it recharges the battery the output goes down and the required horse power drops. The electrical load running the engine is only around .1 horse power lifting your right foot a 1/8" will save far more fuel. Again clicking the alternator back on will spike the electrical system most of the stuff can stand it some may not it's a chance you may not want to take.

Hi Maineah,

Since the truck battery would remain in the truck electrical system, I would think that it would pick up the electrical load when the solar panels weren't producing enough to run the engine. The load on the alt (or the solar panels) would include all accessories that were on, the fuel pump and the ECU, in addition to maintaining the battery. My solar panels add up to around 150 watts (in full sun). The reason I would want this setup to be easily switchable is for such a situation as you describe, where the solar could not maintain the amount of charge necessary for a period of time that would cause the battery to discharge to a level at which it could not maintain all the functions of the truck. I agree that without some creative gathering of parts (junkyard air conditioner compressor clutch) and DIY, the clutch idea could get expensive. I do most all of my own work. Still, for the small gain, it would be way down on my to-do list...

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OK, now I understand. I guess I should of read all the posts but there is a lot of reading to do. I find it hard to believe that just turning off the field current to the alternator is going to save anything meaningful (and using solar instead). The alternator has a demand on the engine just to mechanically spin it even with zero field current. Now if you had an electric clutch on it like AC compressor have - it would cut down a lot of that mechanical drag. This is why the belt-driven power steering pumps on many new cars are now eliminated. Just adding solar to the roof adds some wind resistance and takes extra energy -unless you've got glue-on flexible panels. Solar on the roof pointing straight up is very inefficient. But yes -so far sunlight is free.

I kind of look at it like this; First - is this thing you are working on still an RV? If so - then I assume it has lights, water, heat, etc. If I am correct so far - you want this thing to have the utilitarian features of a motorhome but want the best fuel mileage possible? My point being your goal is not an ultimate MPG truck. It 's more about an ultimate MPG motorhome with all the usual features. I've been experimenting with fuel mileage for over 40 years. I've built the so-called "secret" Pogue carburetors that run on gas vapor. I've built a truck that runs on firewood gas. Etc. &c. But all of my projects involve vehicles that are useful and driven at normal speeds. When it comes to RVs - the biggest factor is wind drag. Thus if it was my project - I'd start with a pop-up roof. Like my diesel Blazer Chalet of gas Toyota Chinook. Then it comes to matching engine power to the load. Any internal engine gives the best MPGs when run within it's peak torque curve and matched to the load. That is a huge issue with cars and trucks since the loads vary all the time. If you were trying to break MPG records with a motorhome -you'd want to pick one load goal and match the engine to it. A 3 liter V6 is too much if we're talking about flat-land driving at 45 MPH. The optimal setup would be a smaller engine and/or a variable displacement engine. And note that with variable displacement - you can break that into two categories. True "variable" via cylinders that can be disconnected when not needed (like Honda vans have). Or a "virtual" setup using a small engine and a high boost turbocharger. High boost can make an engine behave like one twice as big when needed. Sort of like what Ford is doing now with EcoBoost.

There is also the issue of short term specific efficiency versus long-term overall efficiency. You say you run your tires at 64 PSI. That will offer maybe a 2% gain in MPGs as compared to running them at 45 PSI but will also wear out the tires faster. How much overall energy is wasted by shortening the life span of tires?

You mentioned using "synthetic" oil. Where is the gain with that? In the USA and Canada any oil can be sold as "full synthetic" and not have ANY synthetic content. Besides that - there are many petro oils that offer the same engine efficiency as true sythetics. What makes you think something labeled as "synthetic" has intrinsic qualities that make it more "slippery?" I am well aware of all the advertising hype but I am talking about real proven facts. The main gain with true synthetic oil is the higher flash point that makes it ideal for jet engines and race cars. A less gain is that it has a more stable viscosity range without the use of polymers that can cause piston ring sticking. You might be using lubricants that have given you gains - but if so - I doubt it has anything to do with them being truly synthetic or not. Regardless - the word "synthetic" in the USA and Canada has little legal meaning. In Europe - yes.

Well I'm getting verbose. Good luck on your project. Have you ever read the specs on the Road Trek ETek with solar? Not a hypermiler. Just an RV with efficiency in mind. Has a lot of solar on it and a huge alternator driven by a diesel engine.

http://roadtreking.com/new-etrek-class-b-motorhome/

Jdemaris,

Thanks for the thoughtful post. I do try for mileage as a hobby (I also have a Geo Metro that routinely gets 50+ mpg) and I do, as you suggest, use the MH as a motorhome, retaining the usual functions. I got the Toy because it is capable of better mileage than most other motorhomes in my price range, and we do quite a little traveling in it. Of course I got it to use, not to resell, so any effect on the resale value is not that important to me. I also like the fact that the cabover is tall enough to use as a bed, unlike many other MH's. The Mobil I is used in the hope of less friction, but also because I know that it creates fewer deposits in the engine and thus helps with longevity. The solar keeps my MH batteries charged and I usually have surplus capacity from them for at least part of the day, as they top off my MH batteries fairly quickly once the sun is up in the morning.

Your comments about torque curves and efficiency has me thinking about where the torque peak is for the V6 (RPM). I would like to have a tach. I have heard that the 22RE models can get better mileage than the V6, so that may have been a better choice purely for economy. But I do like the fact that the V6 can climb most hills well, and at nearly my normal cruising speed.

I haven't noticed any abnormal wear on my tires yet, but I will keep an eye on them. You are right of course that if I'm eating up tires to gain mileage that my net savings in both money and energy are an illusion.

Thanks for the good wishes.

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If you wanted to use solar here in the northeast - to make, on average, 10 amps @ 14 volts for 12 hours - with roof mounted panels . . . you'd likely need around 1000 watts of solar panels. Useful solar energy lasts 4-5 hours on good days IF the solar panels are pointed at the sun. So if we're talking a 12 hour day - that doubles or triples the solar need right there. And if a fixed mount points straight up - another 50% loss that means you'd need double again. A single 120 watt panel in the brightest light of the day here in MI or NY makes around 5 amps @ 14 volts. and more like 3 amps per hour for an average of the best 6 hours of light. So I'd need three 120 watt panels just to make 10 amps per hour just during the best 6 hours. And that's when pointed correctly for best solarization. A single 120 watt panel in the NE will make make an average of 1.75 amps per hour for a 12 hour day and less then 1 amp per hour for a 24 hour day. Obviously if you are in a sunnier part of the country you can do better. Also the roof mount pointing up works better in regions where the sun is actually overhead at noon. I have three places that have been run 100% on solar energy for 5 years now. One in Otsego County NY with 5400 watts of solar panels. Another in Hamilton County, NY with 1200 watts in solar panels. The other is in Presque Isle County Michigan with 2400 watts in solar. I've kept close records of actual production of all the panels. All are with a two season "fixed" mount. That means their positions get changed twice a year for the best exposure to the sun. I've got many 120 watt Kyocera, Evergeen and Sharp panels. I've tested them all pointing directly at the brightest sun here and I've never had one make more then 5 amps @ 14 volts even though they are rated at over 7 amps. My 5400 watt array made an averaqe of 300 KWh per month this year. It has 27 panels, 200 watts each and wired at 48 volts. Thats 5400 watts of panels that, on average for the year - make 400 watts per hour. That means each 200 watt panel makes, on average . . 27 watts an hour (if my math is correct). If on a truck roof-top that would be more like an average of 14 watts per hour for a yearly average.

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