old87yota

That is a good looking truck!

At least you now know what was going on and you are much more familiar with the inner workings of your truck (weather you wanted to be or not )

Neemox

Just gotta say, this has been a super helpful thread on so many levels.

Sucks that you ended up doing a crap ton more work, but at least now you know how to do it, and also, you know exactly the last time your head gasket was changed and that it isn't suspect any longer. Nice work, great attention to detail. This is the stuff YotaTech needs! Also, a great reminder that as "exspensive" as the stealership may be, it's not a bad idea to spend a little extra on these trucks.

raguvian

That's true! I was so frustrated I wanted to get rid of the truck, but as my friend (who diagnosed the issue) said, I've taken apart so much of the truck at this point that I should be able to figure out whatever comes next (and I have this great site!).

Thanks for the kind words! Hopefully this thread does help others in the future.

RAD4Runner

WHEN temp gage shows running hot (very intermittent), I read around 190°F (I'd give the infrared thermometer from Beijing Freight +/- 5°F) at the t-stat housing even when needle points almost up to the upper white line on mine., so I'm also suspecting my sender.

What is the sender and the sensor?
I just called the dealer and was told the sender costs $38. Gotta check with Toyota Parts Deal.
Does anybody have part number for 22R-E?

Neemox

22reperformance has the sender for 30$. I was hoping fr a part number, but no luck. I'm sure that from him it's the right one though. This is for the dash gauge, NOT the ECU
https://22reperformance.com/22re-eng...nder-for-gauge

Jimkola

the sender for the dash gauge should be 83420-20020. That should have a basic spade connection where the wire connects.

Damion812

Hey I just read through all of this . Thanks for the information. Cool truck.

my first Toyota truck:

raguvian

The sender is the one with the single spade that controls the dash gauge. The sensor is the green one on the front of the intake (kind of below the throttle body next to the cold start time switch) that controls the ECU. I paid $26 for the sender and $65 for the sensor from my local Toyota dealership. You might want to check your dealership's website. My dealership has cheaper prices if I buy online and then go pick it up in person vs if I call and order or go in person to order.

old87yota

I should have been looking closer to the picture.

The eBay listing shown earlier in the thread is the temperature sensor for the ECU, not the gauge, and 22RE Performance has the ECU sensor (1984-1988) for $92.88.

The sender for the gauge is more affordable at $30.99 Toyota MSRP.

RAD4Runner

Oh I see. Thanks the for tip. Those are good prices!.

raguvian

Sure! Hopefully your dealership offers similar online prices.

BTW I took a short drive and left the truck running to measure under hood temps. Maybe I didn't drive long enough, but the thermostat housing was 170 degrees, upper radiator hose was 140 degrees and lower hose was 90 degrees. Probably didn't get much airflow since this was all around town so I didn't expect the radiator to be able to do a ton of cooling but I saw about 50 degree drop through the radiator. Hope that helps.

RAD4Runner

Tnx again. I'm getting about same on my radiator. It would be nice to know what others get. It would help future troibleshooting. Good indicator of radiator function and coolant flow.

raguvian

It's a little hard to get an accurate reading IMO because even if you were to drive it on the highway, by the time you pull over (hopefully off the highway and not on the shoulder), grab the thermometer, pop the hood and start pointing it at things, the truck has had a bit of time to start heat soaking again and the drop across the radiator will be less than what it really is, unless you get fancy and wire up some sensors in the upper and lower radiator hoses or something.

Also, FWIW, I replaced the Autozone temp sender with the OEM one from the dealership and my gauge reads a little lower than the Autozone one when it's up to temp. It'll go a little past halfway and then start coming back down and be somewhere between 1/3 and 1/2. I'm still finding it's using a little bit of coolant from the overflow bottle, but I'm hoping it's just air working itself out since I haven't driven it too much since putting the coolant in last week. I don't see any coolant leaks anywhere but I'll keep an eye on it.

2ToyGuy

Perfectly normal. Working correctly, as designed, as we used to put on the forms in the military.

Again, perfectly normal. Especially after replacing the coolant. Air likes to hide all over the system, and work it's way out over time, no matter how well you burp the system. Sneaky stuff, air.
Watch it as you drive it. Don't need to hawk it, just watch it during your normal instrument scan. There may well come a time soon when the gauge goes up, just like you're seeing now, then drops down and stays locked there, when the truck is warmed up completely. Alot depends on the different components in the system, the sender, the actual gauge, wiring, and so on, as to exactly where it locks in when all the air is out.
Also, once it gets to that point, you should not see it use any more coolant out of the recovery tank. When it's warmed up, the recovery tank will show one level, and once it cools down, that level will drop. That's why you only fill it to the lines on the recovery tank. If you put too much in, right after you shut down the engine, it will overflow, as the system gets much hotter right after you shut down. Heat soaking, I believe it's called.
Without the coolant circulating, all the heat retained by the metal parts of the engine, like the block, release that heat into the cooling system. The metal expands some more, too. The level in the recovery tank will thus rise quite a bit, and then, as the heat is released into the atmosphere, the level drops back down, since the water is drawn back into the cooling system as the metal contracts when it cools.
As a quick check, you can squeeze the top radiator hose a bit when the truck is nice and cold. If it squishes down easily by hand, you might have some air still in the system. Just where isn't certain, since only air is compressible, not water. Thus, when you squeeze the hose, it will compress the air, if any, in the system, wherever it might be.

Good luck. I hope you've got this all squared away now!
Pat☺

raguvian

I've been driving the truck for close to 1k miles, and am curious about the temp gauge (still). Sometimes, even on hot days, the temp gauge will sit at below halfway and I'll think nothing of it, but other times, even on cooler evenings, the temp gauge will be just above halfway, like this:



From what I can tell, the coolant level seems to have stopped fluctuating in the overflow bottle and the truck runs fine otherwise. Part of me is wondering if it's a bad fan clutch, but the truck is so noisy while driving that I can't tell if the clutch engages when it's supposed to. The fan clutch is also a new Aisin unit from Rockauto (so hopefully no counterfeits there!).

If I turn the truck on with the hood open and let it idle, will the engine get warm enough to engage the clutch, and will it be obvious if I'm standing right beside it?

Anything else worth checking, or is this all in my head?

Thanks for any (more) help!

Jimkola

There’s a audible difference when the fan clutch locks, but just letting the vehicle run at idle probably won’t generate the heat needed. You’ll need to raise the rpms.
The clutch usually works in city, stop-n-go type driving where the engine is working the hardest and there’s not much air flow.

raguvian

The gauge seems to go down a bit once I get off the highway. I haven't had any issues in stop and go traffic (though due to shelter in place there hasn't been a whole lot of stop and go traffic).

I think I'll keep driving it and see if the gauge ever creeps past that level. It does seem happier cruising at 65 mph than 70+. Maybe the radiator is the limitation, in which case I'll probably get a CSF 3 row radiator for it next year (along with new hoses).

Jimkola

If it’s not losing coolant and has a fairly new OEM thermostat than the radiator starts falling under suspicion.

Make sure you do both lower radiator hoses. Everyone sees the one going to the bottom tank, but it’s the second one under the alternator that tends to soak up any leaking oil and burst. Not the most fun to replace, either. But essential.

raguvian

Interestingly, last night while it was fairly cool out, the temp gauge was reading pretty warm again on the highway, so on a highway interchange I decided to floor it in 3rd and 4th gear. The temp gauge went back down to between the 1/3 and 1/2 mark. I'll take it I guess.

As for the lower hose that curves and goes back to the timing chain cover, that was was fairly simple for me to remove. It was just two bolts to get the metal pipe off. I had to pull that off to get the oil pan off. Thankfully I have no P/S or A/C so the engine bay is quite open.

raguvian

Well, I'm back, and again I don't know if I have issues or not so I was hoping I could ask you very helpful folks for some pointers.

The truck has been fine for the past 2-3k miles, with the temp gauge pointing at about halfway or just below halfway at all times. However, yesterday the weather was in the high '90's/low 100's when I was driving the truck, and it didn't seem to be too happy:



Even on the highway it was running pretty warm:



I still haven't been able to confirm if my fan clutch (which is a new Aisin unit I bought from Rockauto) kicks on. I don't see any moisture or leaking coming from it, but I also can't tell when/if it turns on.

I did get the truck up to about halfway temp yesterday just sitting in the parking lot and the fan still wasn't engaged, but again I'm not sure if it was actually hot enough to engage the fan.


My guess (which probably is 99% wrong) is that the truck wasn't hot enough in the parking lot to engage the fan, because usually upon startup, the truck will warm up and go till past halfway on the temp gauge before the thermostat pops and goes back down to a little under halfway, so I'm guessing ~190 degrees (when the thermostat opens) is just above halfway on the temp gauge. The fan should kick on at 200+ degrees, so it shouldn't have been on when the temp gauge was under the thermostat opening point (if any of that makes sense). I'll grab my infrared thermometer and point it at the thermostat again when I drive it today (another hot day!), but this time I could feel the heat coming off the engine and the upper radiator hose was very hot, so I know the thermostat is working.

My other thought was even though it was running at over the halfway mark, it never went past that for my 15+ mile drive home, so maybe that's the thermostat + fans working at full tilt and my radiator is just not very good? I didn't replace the radiator or hoses when I replaced everything else. I was hoping to do that next spring, but if the consensus is a crappy radiator I'll go ahead and order new hoses and a CSF radiator now. Also, is the fan supposed to be working when on the highway? I would have figured the 70+ mph wind was doing more for cooling than the fan.

Thanks in advance for the help! Sorry for the long post!