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Thread: Possible thermostat issues.

  1. #41
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    Overheating issues on 1988 Toyota van.

    Hello,

    This is my first post on this forum. I have been here a bit though ever since purchasing our van a year a go.

    Its a 1988 4wd Auto Tarago (thats what they are called here in Australia).

    I know there have been lots of threads here addressing overheating. However, I have read most of them and performed all the recommended cures without avail. Any advice would be really appreciated. I'll lay out the details.

    Issue: Overheating. Specifically under load at low speeds. Eg: labouring the engine up a steep hill with A/C on. No overheating on the freeway or at idle or if its a cool day. When I say overheating I mean the temp gauge going over half way into the 3/4 region. It definitely tends to overheat more readily when its hot outside. Its summer here so that doesn't help!

    Background: I have had the van for 1 year. I love it- it does everything I want all in one car. It has never had overheating problems until recently. And I have worked it hard since having it: towing, carting heavy batteries, paddock work, etc. The problem first became evident when I was towing a trailer with some sheep to a customer (I live on a farm). It was a warm day with the ambient temp about 30 degrees celcius, I was towing approx 800kg combined weight and had the family in the car (wife and 4 children). The temperature gauge was hovering just over halfway for the outgoing trip but on the way home, when the trailer was empty, it climbed up close to the red as I slowed down from the freeway and came back into town. It never went into the red. I pulled over and the coolant boiled over. Ended up letting it cool down and refilling with water to get home. No issues getting home later that night when it was cooler. Since then it has had a tendency to overheat when the conditions are right.

    What I have done:
    - Replaced thermostat with a Tridon brand (from local auto store). Checked that it opens.
    - Checked water pump. It is only 2 years old and spins freely and does not leak.
    - Flushed and refilled coolant multiple times. The van has not really used any significant quantity of coolant during all this. Maybe 1/2 cup every 500kms or so. I find it hard to check as it seems to move in and out of the overflow bottle.
    - Cleaned out radiator both inside and outside. It was clean and did not leak. Outside was grotty with grass seeds and dead locusts but is good now.
    - Checked the thermofan. I wasn't sure it was working as it should so purchased a new clutch. It performed exactly the same as my old clutch (aisin) so I put the old one back in. I can kind of hear it blowing when I open the throttle at idle but I'm not totally convinced about it. I used to have a Volvo 240 and I could hear that fan come on and off really clearly from the cabin.
    - I did a compression check thinking it must be a blown head gasket. 3 cyl were reading 160 psi and the 4th was 120 psi. I concluded it must be a blown head gasket causing all the trouble. I changed the headgasket and got the injectors cleaned as well. The engine runs well and the car has power but it still overheats!
    - Checked Ohms resistance at the temperature sensor. It was not reading anything across the two pins and the workshop manual says it should be. However, the temperature gauge on the dash appears to be working. As in, its readings are consistent with the driving conditions and the times when it overheats. So not sure what to make of that...

    I feel like I have done everything I can think of and everything recommended here by you all. I am at a bit of a loss. Any advice would be great.

    I am inclined to think it is the thermostat. That is what it feels like when I am driving. It feels like maybe it should be opening earlier than it is or more completely open. It does not appear to open at all when starting the car and letting it idle. That is, the bottom radiator hose stays cold. Even when the engine is hot after a hill and I pull over and check things, the bottom hose is still never as hot as the top one.

    Anyway, let me know what you think.

    Many thanks in advance.

  2. #42
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    Re: Overheating issues on 1988 Toyota van.

    yes i've read the OEM toyota thermostat is the way to go as it's specifically made to keep the cooling system running optimally. my van's was stuck open when i first purchased and i replaced with OEM and all has been well

    i've also read other posts saying their stock temp gauge was running high (3/4) which worried the owner enough to install an after market very accurate temp gauge which showed things were running at a good temperature (lower than the existing dash gauge was reading). people have said the stock temp gauge is more of an approximation

    i've seen my temp gauge crawl slightly above the middle on hot days lugging up hills with the AC on but that's as far as it's gotten. hope that helps maybe others with more experience will chime in

  3. #43
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    Re: Overheating issues on 1988 Toyota van.

    Thanks for the reply.

    I know OEM thermostats are recommended. However, its pretty involved here in Oz to get one. There are not many of these vans around anymore and the only place I could find was a Toyota service centre who said they would have to order it from Japan! It was going to take some time to get here so I decided to get aftermarket.

    If the consensus is that that is the problem I guess I could still order it while Im doing other things.

    I don't think the gauge is the problem as it is not "stable". It hunts around everywhere. Going down a hill or on the flat it will be where it should (3/8ths) and then uphill it will quickly climb to 5/8ths and then back again at the top. If it was just reading a little high and everything else was good then it would climb to its spot at 5/8ths and stay there.

    Thanks anyway for your thoughts.

  4. #44
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    Re: Overheating issues on 1988 Toyota van.

    Given all the work you have done and the fact that A/M stats are notorious for causing the exact problem you're describing, changing out the stat is the first order of business.

  5. #45
    Van Addict boogieman's Avatar
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    Re: Overheating issues on 1988 Toyota van.

    since its summer, you could try removing the tstat for testing purposes..

  6. #46
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    Re: Possible thermostat issues.

    The stock TOYOTA t-stat opens at 82 degrees Celsius, and it's been refined by Toyota to work efficiently with these vans. You need to use that one... from all my research and endeavors only the OEM t-stat runs perfect.

    This one: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 (I am guessing you might not have the AMAZON option???)

    Holy mother of GAWD!!! LOL Just looked at the Amazon Au site and the T-stat you need list for like $114.00!!! Here:https://www.amazon.com.au/s/ref=nb_s...29+Thermostat+ WOW. No wonder you went after market. The cheaper aftermarket one list for $71??? What the heck is going on with the exchange rate there man? Ha.

    Also, the factory gauge is notorious for not reading true. It's a fairly weak design to basically act as an idiot light at best... Lot's of peeps here have added an aftermarket digital gauge to better monitor the temp. Theres quite a few threads on it actually. The KOSO brand seems to be the go to.


    Their is also the option of ADDING a piece of additional cooling equipment that I am kind of fond of, and it is outlined HERE: http://www.toyotavantech.com/forum/s...ng-system-Mods

    Hope that helped a bit MATE!

  7. #47
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    Re: Possible thermostat issues.

    Ok. It seems everyone is in agreement to just get a OEM thermostat. I will contact the dealer today.

    Yep, they are expensive and take a while to get here (from Japan). I will compare dealer price with amazon. Thanks for looking that up for me.
    I think I paid about $30 for my A/M thermostat.

    I hear what you're saying about the gauge. Funny thing is it used to be really stable before all these shenanigans. It would slowly climb up to 3/8ths and stay there no matter what the driving conditions or outside temp. So I have been going on the assumption that the gauge is fine.



    I'll let you know how it goes.

  8. #48
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    Re: Possible thermostat issues.

    Quote Originally Posted by petedemol View Post
    Ok. It seems everyone is in agreement to just get a OEM thermostat. I will contact the dealer today.

    Yep, they are expensive and take a while to get here (from Japan). I will compare dealer price with amazon. Thanks for looking that up for me.
    I think I paid about $30 for my A/M thermostat.

    I hear what you're saying about the gauge. Funny thing is it used to be really stable before all these shenanigans. It would slowly climb up to 3/8ths and stay there no matter what the driving conditions or outside temp. So I have been going on the assumption that the gauge is fine.



    I'll let you know how it goes.

    Yah, my van when I first got it ran pretty cool... never went past the quarter mark of the gauge, and upon removal I found it had failed open like most do. After I replaced it with a new Toyota one I found my gauge reading dead center and maybe slightly over at times. Kind of the normal resting spot for the temp... Heater works great (I live in snow country, just under 8,000 feet). These vans run high just due to the design of the cooling system. The Radiator doesn't exactly get the best air flow and the engine compartment heats up because it's pretty much just a closed coffin for the block/ head, all the electrical, A/C and etc... I am definitely going to have to add the remote heater core assembly up front for the summer months. Although where I live in Az, it stays around 75-80 for the bulk of the summer.

    I have been to Perth and Darwin for work, I know what your guys summers are like! Ha... stay cool man!

  9. #49
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    Re: Possible thermostat issues.

    Ok thats good to know. I just read about the heater core mod. Sounds like a worthwhile improvement.

    Yeah, it can get hot here (Im near Canberra) though not as hot as Darwin! Had a few successive days of 38 degrees here. Thats your 100 degrees F.

    Thank goodness for aircon!

  10. #50
    Administrator JDM VANMAN's Avatar
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    Re: Possible thermostat issues.

    petedemol,

    Is your 88í Tarago diesel or petrol?

    Iím asking because if itís diesel 2C series motor would it use the same T-Stat as the petrol 4Y motor?

    JDM

  11. #51
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  12. #52
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    Re: Possible thermostat issues.

    Hi vanman,

    My Tarago is petrol. 4YE motor. Not sure if its the same thermostat or not but I doubt it.


    Update on my overheating issues.

    I have ordered an OEM thermostat as you all recommended. I ordered it from the Toyota dealer. The first guy I talked to told me $100 plus and ordering from Japan. That was when all the issues first started. When I rang again the other day I got someone else who said $35 and 2 days delivery! Very strange. Needless to say I ordered it. Coming tomorrow.

    Secondly, I pulled the guts out of my old thermostat yesterday just to see how it went. I was driving around today in 42 degrees without any overheating! Awesome. Think I have finally nailed the problem. It was the thermostat all along. You guys were right. Anyway final confirmation will be when I put the OEM one in tomorrow. Will let you know how it goes.

    If that ends up being the solution I will have wasted a whole lot of time and money. Very annoying. I guess not totally wasted. Learnt a lot more about the motor internals in the process.

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