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Thread: Replacing your van's thermostat

  1. #1
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    Replacing your van's thermostat

    See THIS Library Article for step-by-step instructions on replacing your van's thermostat!

    Gwen
    1985 5-speed window cargo van set up for llama haulin'; 345K ("Trustyvan")
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    Re: Replacing your van's thermostat

    DISCLOSURE: I just replaced my thermostat today. I also bagged my alternator and disconnected the power steering pressure line (the curved one) to make things a little easier!! I also found it a little odd that i have a 4WD pump on my '88 2WD...

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    Re: Replacing your van's thermostat

    I watched a mechanic install a thermostat on a friends van and ripped out the "jiggly-valve". I was told that it improves function of our thermostats to remove. Something about it only allows trapped air to go back and forth sometimes..verses with removed jiggly valve, air can pass freely at any time? does this sound right? BS?

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    Re: Replacing your van's thermostat

    I'm sure that mechanic has more knowledge and is better educated than the Toyota engineers who designed it to be there. After all, he has risen to the lofty position of "mechanic" rather than waste his time as a lowly engineer . Just my $.02

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    Re: Replacing your van's thermostat

    Quote Originally Posted by timsrv View Post
    I'm sure that mechanic has more knowledge and is better educated than the Toyota engineers who designed it to be there. After all, he has risen to the lofty position of "mechanic" rather than waste his time as a lowly engineer . Just my $.02
    "Eh, you don't need that part. Let's also drill some holes in your shocks to reduce weight and increase performance. Also, if you paint this van red, it'll go faster."
    "What? Me, worry?" *nervously looks at temp gauge*

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    Re: Replacing your van's thermostat

    Get what you guys are saying thanks. I am interested though in the this jiggle valve and purpose behind it.. The van this work was done on is still getting hot, only on inclines. (well above half way mark) then goes back down. Even after new radiator, fan clutch, hoses...head gasket was replaced after blown.. flushed..etc. This is an 89 automatic camper conversion. I recently (2,000 miles ago) did a cooling system overhaul on my 88 4wd manual, and did not remove the jiggle valve, and I haven't seen the temp needle go above 1/4 even on steep terrain (I love hearing that fan roar when it does get warm...) ....I wonder if the valve really does make the difference?...

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    Re: Replacing your van's thermostat

    Jiggle valve probably doesn't do a whole lot, and I do believe it's there to help purge air from the system. The manual is specific on it's placement & since it's easy to install @ 11 O'Clock, I figure why not? I'll be the 1st to admit there's a whole lot I don't know, so why not rely on the judgement of the engineers? Just seems arrogant to dismiss their judgement and disable functions of expensive OEM parts. Tim

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    Re: Replacing your van's thermostat

    Where are the Preston Gen-2 t'stats sold? Anyone know the part #?

    If this part can't be found, is OEM the next best thing?

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    Re: Replacing your van's thermostat

    IMO, OEM is the best, but the Prestone one didn't create any adverse effects (like some do), so it was acceptable. As far as I know, Prestone stopped making those about 6 or 7 years ago. The correct part number for the van was 761-180. There's probably still some hanging around in a warehouse somewhere, but I'm thinking they'd be hard to find. Toyota part number for this is 90916-03069. Don't forget the gasket/seal, it's Toyota part #16325-63010. Tim

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    Re: Replacing your van's thermostat

    Thanks, Tim.

    Do you happen to know if the OEM gasket is interchangeable with any of the aftermarket gaskets?

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    Re: Replacing your van's thermostat

    Yes, I've used Stant #27280. I'm sure there are others. Tim

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    Re: Replacing your van's thermostat

    I'll be damned if I didn't read this thread AFTER I installed my thermostat. My factory service manual showed up on the mail yesterday but I didn't bother to consult it either. I am such a failure. I have never heard of a "jiggle valve" so I went to the manual and lo and behold, there it is. So at 7pm in the rain, in the dark, in my pajamas, there I was tonight pulling my van onto the ramps and removing the thermostat housing to check the new thermostat. One hour later I was done and taking it on a test drive. I felt like the dad in A Christmas Story when he gets a flat tire and tells the mom to time him. Pretty quick for a radiator drain, t-stat remove and replace, and radiator refill if you ask me. After all that...this thermostat didn't have a jiggle valve. Oh well, I can sleep tonight without that keeping me awake.

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    Re: Replacing your van's thermostat

    Quote Originally Posted by Rufus View Post
    After all that...this thermostat didn't have a jiggle valve. Oh well, I can sleep tonight without that keeping me awake.
    Are you saying you didn't use an OEM Toyota T-stat? Me and a few others here have spent countless hrs chasing down hot running issues, only to find out the new T-stats we installed actually were the issue. For some reason not all T-stats work well in the van. I know it sounds odd, and I refused to believe it when others claimed it, but I got burned on this one too. Since then I will only use OEM Toyota T-stats on the van. Hopefully you lucked out and got a good one. The one that burned me was what Napa gave me after I asked for their "Premium quality" T-Stat. It was a Tama Enterprises Co. Part #154-2403 "made in Japan" & even had a jiggle valve. Tim

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    Re: Replacing your van's thermostat

    I did not use an OEM thermostat. Unfortunately I currently live in Podunk Skunkpatch, California and the nearest dealer is 40 miles away. If this thermostat gives me issues I will go with OEM.

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    Re: Replacing your van's thermostat

    That was similar to my issue. I actually had a new OEM one here (someplace) but had recent moved & couldn't find it . Of course I didn't start looking until I had the old T-stat out. You'd think that it wouldn't matter, and in most cases it wouldn't. In my case it was sort of "okay", but at times my temperature would get very close to the danger zone. It was like my radiator was clogged or the fan clutch wasn't working at full efficiency. Eventually I went full circle and replaced the T-stat (again) with OEM. It actually surprised me when that remedied my problem. It's weird how these things can be so quirky sometimes. All things considered, I would say odds are in your favor that the t-stat you installed is fine. After my experience I tend to be a little superstitious about T-stats. Tim

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    Re: Replacing your van's thermostat

    Well I plan on replacing the power steering pump in the next couple of weeks and that will be the prime time to swap the thermostat. I will be putting an OEM T-Stat in at that time.

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    Re: Replacing your van's thermostat

    Quote Originally Posted by Rufus View Post
    Well I plan on replacing the power steering pump in the next couple of weeks and that will be the prime time to swap the thermostat. I will be putting an OEM T-Stat in at that time.

    From how it was explained to me, the Toyota OEM for our vans are designed to work with horizontal flow, while most others are designed for vertical flow. Having changed thermostats in other vehicles, but not thinking about the flow while doing so, and now thinking back, they were all used vertically. My '89 4x4 was running hot and I know it doesn't have the OEM t-stat because I helped with the motor swap 5 years ago - I did n't own the van back then nor know about using OEM t-stats, just got her in March. I also have the water pump and fan clutch just in case. It got close but I was able to baby her with the idle carrying my at that speed. Didn't go far and had to keep letting her cool down, but I made it to where I got a u-haul car hauler and a buddy met me with his truck.
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    Last edited by K0ZLU; 04-29-2016 at 02:54 AM.

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    Re: Replacing your van's thermostat

    these t-stats are also on the suction side of the water pump. Most other vehicles have the thermostat on the output side of the pump. Not sure how much difference that makes, but there it is. BTW, that doesn't look like a good spot for overheating . Tim

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    Re: Replacing your van's thermostat

    Quote Originally Posted by timsrv View Post
    these t-stats are also on the suction side of the water pump. Most other vehicles have the thermostat on the output side of the pump. Not sure how much difference that makes, but there it is. BTW, that doesn't look like a good spot for overheating . Tim
    Tim, I recently was replacing the lower rad hose (that connects to the T-stat housing) and ending up spilled some (not TOO much) coolant on the alternator....from what I've read online in other forums its not the worst thing in the world. However, I noticed you mentioned earlier in this thread that this caused someone to replace the alternator. I was wondering if there was anything that could be done to ameliorate the issue without having to replace the alt....i have already rinsed it with a liberal amount of water and dried what I can with towels....let me know your thoughts.

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    Re: Replacing your van's thermostat

    It's not the worst thing. Our alternators are sensitive, that is certainly true. They are however built to put up with occasional water intrusion. They don't like prolonged exposure to power steering fluid (ATF) as that gums up the brushes. I would think antifreeze is not as bad as ATF, but probably worse than water. If I got antifreeze in mine I would rinse with water (like you did), then forget about it. Nothing more you can do anyhow, so no use worrying about it. I'm guessing there will be no long term ill effects. Tim

    PS: Next time put some plastic over/around your alternator to avoid exposure.

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