Lower Radiator Hose Cold ? ? ?

[ARCHINSTL]

I replaced the thermostat with a genyewine Toyota one a couple of months ago, and renewed the AF as well (Prestone and distilled water, just as before). The radiator cap was replaced about six months or so ago
Now - I never noticed this before, so don't laugh...
After the MO safety inspection this morning, I opened the hood this AM after driving 6-7 miles, to confirm that the recently installed fuel pressure gauge stopped leaking (I hadn't tightened it enough). It had, and I just happened to drop my glove on the lower hose - and then noticed that it was cold. The upper one was appropriately hot. The temp gauge never went beyond the middle and no funny smells, noises, or steam were emanating. The hose was also firm and not spongy (3 1/2 years old).
Hmmm...so I waited until it cooled down and then went out for another 5-6 miles. Same thing - gauge OK, heat OK from heater (not HOT, but never has been), nothing awry in the engine bay, upper hose hot and lower hose cold.
I called the tech at the local garage and he said the thermostat was acting properly (he is the same age as Goldie).
Online queries made me feel less comfortable - not dramatically so, but a bit uneasy.

So - is this normal? I must confess that I've never thought to check it before.
It is cold for STL this early in December - 18F this AM, but that shouldn't make a difference - should it?
Am I making my usual mountain out of a molehill?

I even thought of installing one of the FailSafe or perhaps a Stant SuperStat (mixed findings on the latter).
I'm embarrassed to say that I do not recall if the Toy OE 'stat came with a jiggle valve or even a little hole.
Thanks,
Tom M.

[Highlander]

Tom- The toy thermostats that I've removed all had a jiggle valve as you call it- there should be some transmission of coolant through even when the tstat is closed. IIRC, the lower hose should be hot if the tstat is open with the engine hot. I've got my own questions about what they did different from '83 to '85 that makes the '85 not heat the passenger compartment, my '83s both cooked me out, where the '85s freeze me out. I don't have any advice for you, but I'm waiting to see what Petros says with baited breath (here kitty, kitty, kitty).

[Petros]

Yes, this is the way it is supposed to work. The hot water goes out the front of the head into the top of the rad, and it is cooled in the rad, and is sucked into the engine from the lower hose after it is cooled. So the lower hose always has to be cooler than the top one (water is always taken from the bottom of rad so it will not suck air if you are low on water).

If it real cold out, the t-stat would be almost closed and all the engine cooling needs are supplied by the heater. The heater coolant is circulating from the back of the head, through the heater core, and back into the back side of the water pump behind the t-stat. So heater core coolant is circulated so it totally bypasses the radiator if it is cold out, meaning the lower rad hose will not even have any water circulating through it. the upper hose will always be hot even when the water is not circulating by thermal siphon.

Your system is working just fine.

[SynthDesign]

Thx, Petros for putting it in laymans terms...

So if the lower hose is above warm you have cooling issues. I don't know why I didn't think of that before but it seems so simple.

I was wonder the same thing a while back and figured if it was working fine, that's the way it supposed to be.



Again Petros, Thx for your wealth of knowledge.

[ARCHINSTL]

Petros -
Again, I bow in your direction. THANK YOU!
I did read what you wrote just a few weeks or so ago, but still thought...
When one drives a 22-year old car, car is attuned to (perceived) anomalies. Periodically paranoia pals around with the "attuning"...
My paranoia partially proceeds from having had the head of my '83 cracked by my Beloved Sister by her ignoring the temp gauge and billowing steam back in '86, so I always pay close attention to the temp gauge. The other part proceeds from advancing decrepitude, I fear.
After initiating this topic, I did take the '88 Dodge/Mitsu out for a drive; upon return, the top hose was hot and the bottom one was warmish, so I figured... Of course, after reading your advice, I did a Homer on my forever-flattening forehead, uttered a "D'oh," and looked at the Mitsu FSM. Shore enough - it has a great explanation (with drawings!) of exactly what you describe.
Incidentally, I really don't think that the Toy stat had a jiggle valve; I recall thinking that it should, but since it was a genuine Toy stat, maybe it changed.
Also incidentally, the FSM I have and the one on our site shows the "spring" part of the stat being inserted into the housing inlet, whereas it just won't fit, and appropriately so - wonder why?
Again - thanks for the confirmation - and for finding us!
Tom M.

P.S. With apologies to others - after initiating the thread, I fervently hoped that Petros or keith or splatterdog or GTSSportCoupe would assuage my angst.
P.P.S. To Highlander: Yeah, my '83 would really get toasty, too - even allowing that I was coming from a Frigidaire of a VW Bus - whereas the '86 just "gets warm," whether with the '04 tstat installed when I got it, the '05 AZ stat, or the '08 Toy thermostat.

[keith]

Well just for the heck of it, I concur with petros. Its winter out there so the radiator is working much more efficiently. In the summer, you will probably notice the lower hose getting quite hot, not as hot as the upper hose, but hot enough. After the engine is shut down, you could run your hand down the inside surface of the radiator and you should feel the gradients going from warm at top to cold at the bottom. The bottom tank should be cold so the fan should not start up.

[ARCHINSTL]

"Yup" to your last two sentences. I did notice this.
Tom M.

[takza]

If you've ever tried to warm one of these cars up by idling in the driveway...you'll see how long it takes to get it to the center of the gauge.

[Petros]

If it makes you feel any better, I will suffer the same angst over cooling issues whenever something goes amiss with any of the old cars I drive. Driving something as old as these cars there is something always about to fail, so you have to be vigillent to make sure it does not cost a lot more to fix because you did not notice.

I recently replace my head gasket on my Tercel, and while I was at it I replaced the t-stat, the heater hoses, coolent, spark plugs, and a few other items for the winter. When I got it running again I drove it for the first few days with my eyes glued to the temp gage and noticed how it would rise to just above mid way, and then drop to just below it every 4 to 10 min. Everytime it was on the way up I would get all worried, turn on the heater, slowed down, etc. and then it would come down again. After a few days of this I decided this was just the normal operation of the T-stat, and that I do not normally watch it that close and I just notice this behavior now.

That occured the day after I just blew the head gasket in the Corolla all-trac because for some reason I lost all the water out of it and pegged the temp gauge. So now I have to redo the head gasket on that car too, but if I noticed the temp gauge was climbing, I might have saved all that work (and for some reason an almost identical head gasket for the 4AFE is about $50, vs. the $25 for the 3a). The all-trac has 290k miles on it and otherwise runs great. So I am going to have to find the sourse of the water loss too.

So you bet I am sensative to temp issues, but it is important to make sure you know what is a real problem, and what is normal operation. I have to always keep reminding my self of these kind issues too.

[takza]

After having this happen at least once...you start to wonder why they don't typically have an overheating light like they do an oil pressure light. All it takes is one time when you aren't looking.

[ARCHINSTL]

I recall wondering that at the time my B.S. fried the '83. It probably would have saved me over 1100 1986 dollars...
But then, I grew up with so many BritMobiles that never even had a gauge.
I think I would have rather had that than the inclinometer...
Tom M.

[keith]

IF I were designing cars, lol, I would leave the temp gauge in, but add a light for temp AND wire this light and the oil pressure light into the warning chime. They wire the headlight switch into the warning chime so you won't damage a $50 battery, but no chime for a multi thousand $ engine? Doesn't make sense to me.

[Neu]

Yeh, it wouldn't be hard at all to add a chime. A simple "Ding" or just wire it to that ANNOYING buzzer that runs when you dont have your seatbelt on.

[Petros]

Now that is the best use for that obnoxious seat belt buzzer yet. I disabled mine because when it is cold I always start the engine first, and then put on the seat belt. I really hate that stupid buzzer, and the sh*t-for-brains federal bureaucrat that thought this was a good safety feature that all cars should have.

I agree though, all cars should have both temp and oil pressure gauges, and idiot light back-ups to go with the gauges. They serve different purposes, the gauge tells you what the engine is doing when you look at it. It can tell you information you want to know when going up hills, towing, etc. But you do not watch them all the time, a light, or better yet a buzzer, would protect the engine all the time it is running.

[golden_glory]

Since we are on the topic of buzzers... Where is that thing in the T4WD? I have been meaning to locate mine and terminate it with extreme prejudice. Anyone know? Thanks in advance...