benja455

1995 Toyota Pickup (22RE, 170k on the original motor)

Here's the scenario: The GF and I are on the highway...she says "I have to pee." So I pull off the highway to a gas station, she runs to the bathroom and I grab a drink. No more than 5 - 10 minutes later, I start the truck back up and it's 9/10 of the way to the red zone...it never touches the red, but it's close...within moments of the engine being started the gauge comes back down and once we're moving - even under 10 MPH, it's nearly back down to normal.

This happens every time we stop...sometimes it only goes up to 7/10 of the way...but it always goes up.

While this is my first vehicle without an electric fan, I have an idea of how they function...but I'm still wondering - is this normal/okay?

vital22re

iTrader: (2)

Check your fan clutch. How old is the coolant? Do you have a fan shroud?

falcon5nz

Mine does it too. You have ZERO airflow when stopped with a mech. fan so it has no cooling. I believe some electrical fans will stay on for x minutes or when the key is left at ACC.

benja455

How can I "check" the fan clutch? I've read previously of attempting to spin it by hand as a check...but some people didn't seem satisfied with that strategy.

Coolant is new.

Yes, I have a fan shroud.

benja455

This is the answer I expected to get and it makes the most sense...I'm doing highway speed and the almost immediately turn off the engine/fan (gas station right on the side of the road)...there's a lot heat to dump and nowhere for it to go.

With that said, I want to make sure this isn't going to cause any damage if it happens some day that it is outrageously hot (next summer?)

Pat8942

It's just heat soak, all engines do this after being fully warmed up and being shut down, think about it, no coolant flow, no cooling fan, sure it's gonna get hot, but it's normal and it's nothing to worry about. Here is a link that explains heat soak if you're interested. http://cjbfire.com/Heatsoak.pdf

waskillywabbit

iTrader: (-1)

www.ncttora.com/fsm for checking the fan clutch.

:wabbit2:

Terrys87

iTrader: (1)

I had a similar situation and just gave my temps sensor a good cleaning. Also not a bad idea to do the Cold Start Injector Timing Switch and another sensor right next to it ( cant think of name at this time) and try burping the system.


Copied from a post I did............................................... ...................................
Here is a picture of a dirty Temperture Sensor. I have seen worse. I chipped some of the scale build up off so you could see a difference.


The sensor sits just below the Cold Start Injector in the Intake manifold. Uses a 17mm deepwell socket and is a 5 minute job.

abecedarian

Radiator is borderline plugged up.

When stopped, there are some "convection" currents which occur, and this is normal.
Convection currents can even cause the t-stat to open and close.

But "normally", the radiator will radiate heat via the currents I mentioned.
With a marginal radiator, this isn't happening.

Terrys87

iTrader: (1)

Abecedarian has a good point as well. The radiators get plugged and the Prestone kit wont flush them out as need to be. Here in my area, I have to remove the radiator and take it to them to have it power flushed which cost me $25 to have done. It will look like mud coming out and this was after I had flushed it myself. Every truck I work on now I just automatically have it professionally flushed and every time I have done this am amazed at how much grunge is in there. I have seen it drop the heat guage a 1/4 of its normal operating temp.

Just giving your cooling system a good going over wouldnt cost much and probably make a huge difference.

Pat8942

This isn't a problem, it's normal, no point in checking this and that and chasing a problem that doesn't exist. A fan clutch won't cause overheating if the engine is off (How could it) nor will a plugged radiator, (No circulation while not running) and if your temp is normal while running, cleaning the sensors won't do anything but waste your time. This is common sense stuff, if it ain't broke don't fix it, concentrate on the things that really need fixing.

MudHippy

Badger62811

Thank you. I was getting so frustrated reading "this is wrong."



The OP said "No more than 5 - 10 minutes later, I start the truck back up and it's 9/10 of the way to the red zone...it never touches the red, but it's close...within moments of the engine being started the gauge comes back down"

The engine is shut off, not idling at a stop, then restarted. Sometimes my truck hates to restart if I have it off for just a couple seconds, because the temp sensor says it's so hot and tries to lean the fuel even more.

Here's a question. Where is your temp sensor? On top of the engine, right? Heat rises if I'm not mistaken. Common sense stuff going on here. Once some fresh cooler coolant is run through, the SENSOR cools off again and all is well.

benja455- If your truck runs great and doesn't overheat when driving, there is nothing wrong with your coolant system.

Now I'm not trying to diss on YotaTech, but more often than not when someone posts a question, the replies turn into catastrophic failures.
"my truck won't start"
"your engine is toast"
"actually I forgot to turn the key"

I love this place and all of the experience you all have, but sometimes it gets a little crazy.

Thanks, I'm done now lol. Not trying to offend anyone either, so don't take it personal.

benja455

Great replies...I'm glad I posted this. Some of you guys are pretty funny.

- I recently replaced the temp sensor because the gauge was barely moving after starting. Now it runs just below the middle, in the exact middle or slightly above the middle during normal conditions. Once (while in hot, barely moving traffic for 30+ minutes), I saw it creep up to 7/10, but it didn't get much further. Once I got moving, it came right back down to the middle.

- My truck still has the original (or what appears to be the original) radiator. It's been professionally flushed before (not very long ago) but perhaps I should replace it for good measure?

It operates at the normal temp (except for that one time, referenced above)...and while it idles a little rough, I think that has to do with the TPS needing adjustment and throttle body/Auxiliary Air Valve needing cleaned - which are my next projects.

vital22re

iTrader: (2)

Mine doesn't do what the op described. Does yours? How many people have had this happen to them?

I would not throw money at it OP, Just keep an eye on it. Could be the precurser to something, could just be a freak incident.

falcon5nz

I have an after-market temp gauge and the stock yota one. My ute is ex-Tiwai Aluminium Smelter so was constantly operated in a saltwater environ for a few years. As such the radiator, while intact has no horizontal fins. That, coupled with the fact that the cooling system is the only thing on the vehicle that gives me trouble (currently the water pump leaks) made me install a water temp gauge.

The after-market one is plumbed in where the stock one is while the stock one is plumbed in up a bit higher by where the radiator hose comes out.

Now the fact the are not off the same hole may have something to do with this but the stock one gets to "Normal" faster and stays there. Full Stop. No movement unless its really warm or the ute is Air cooled and over heating. The after-market one gets to 60ish and stays there (on a usual day) unless I stop for a short period of time and then it jumps to 80ish. Drive for 2 minutes, back down to 60. Worst I've had was 80/100 on a stinking hot day.

Pat8942

The phenomenon known as heat soak occurs when the engine is turned off. At this time, the combustion process is terminated. This terminates the momentum of the crankshaft, which in turn stops the turning of the water pump. As the coolant is no longer being circulated, the engine block and cylinder temperature increase for a period of approximately 3 to 10 minutes, depending on the engine design and additional components. During this time, the engine block radiates heat to the air surrounding the engine, which slowly cools the engine. However, the cooling process occurs slowly, and as a result, the temperature of the engine block transfers the heat to the coolant. The coolant temperature then increases, which in turn increases the pressure inside the coolant system. This is why the vehicle's coolant temperature gauge increases over a period of time after the engine has been turned off. (Source: Chilton’s Auto Repair Manual,)

ZUK

iTrader: (1)

Hey Ben-
I cut your quote info up to make the point.....you have a future issue coming up with the radiator. You already know that too many overheats and bye-bye head-gasket. When the white smoke starts poring out the exhaust then it's oem headgasket time.

a friend had a recent good experience with http://radiator.com

Also, http://radiatorbarn.com I have been sent 2 radiators....for both of my Runners...Good experience there too.....


Radiatorbarn has a nice simple 1 core with plastic tanks for $100.85 your price. They have an all-metal 2 core for 180 also.



COPY/PASTE--------
4WD, Manual Transmission Only, Gas Engine Only


Specifications
Core Size: 15-3/4 x 20-11/16 x 1-1/4
Inlet Header: 20-1/8 x 1-9/16
Outlet Header: 20-1/8 x 1-9/16
Inlet Connection: 1-3/8 PASSENGERS SIDE
Outlet Connection: 1-3/8 DRIVERS SIDE
Transmission Oil Cooler: YES
Engine Oil Cooler: NONE
Mounting: FRONT FLANGE
Notes: ONE ROW, PLASTIC TANKS ALUMINUM CORE

$90.90 1995 TOYOTA PICKUP radiator
$0.00 FREE Lifetime Warranty
$9.95 Shipping
$100.85 IS YOUR FINAL COST

benja455

ZUK,

Indeed. I certainly see your point.

Those prices aren't bad either. Thanks for the heads up. That will be my next mid-level project.

Terrys87

iTrader: (1)

Hello benja455..Your problem isnt normal. It is not a major problem but is something that is needing looked at. My trucks dont do what yours is doing except when I did have some small issues. Depending on wheter you clean or replace your radiator, all of the checks and cleanings mentioned by the previous posters are cheap or free. If you have another radiator available it should only take an hour or so to do all that has been mentioned.

Your truck is going on 18 years old and am sure its maintance has been lacking as in most cases. From my experience, the heat guage is fairly accurate even after 20 years of use, I dont trust my guages 100%, but I do know that normally when I have my cooling system in great shape, it takes a heavy load or a hot day to get them over the halfway mark. This is just my experience and that is on 2nd and 3rd gen trucks and 1st gen runners and the same even goes for my 3rd gen runner.

Only other suggestions I would have is while in there, I would put in a good quality Thermostat and make sure your Water Pump is flowing good. The way I burp the system is to raise the front end as high as I can get it (hill,jacks,ramps) and with the radiator cap off, I let the engine run and let the thermostat cycle a few times to get the air out. There are some other ways of burping the system, but this is how I do it. Most likely some of your hoses are orginal so would take a look at them as well.

If you do what has been mentioned, I think you will see a nice difference in things. I have paid nearly half for a used radiator what Zuk has for a new radiator so would suggest that. (Thanks Zuk). I wont be on this particular thread, but look forward to your results.