pulattie58

I've got a 1994 toyota pickup, 22re, and its been running good except I noticed that after I've driven it a while and turned it off, then started back up the temp gauge is creeping up. When I get it going again, it cools back down. I'm in texas and its hot, so I've assumed the engine just isnt cooling back down after its stopped cause of the heat and the temp goes back down once the water pump gets coolant flowing. However, I want to make sure I'm not on the verge of my water pump or radiator going out. Any help or input is appreciated!

Other possibly important info: I replaced the radiator a year or two ago, but the replacement was a light cheap looking plastic. I topped off the coolant when this started a week or two ago. I believe the thermostat is new-ish, at least not super old. No idea how old the water pump is.


Thanks
Josh

Kingjerd

Id say check your coolant hoses to make sure they are soft and flexable. The water pump could be failing but usually there is a leak to go with it. Have you bled the coolant system? Also, what coolant mixture are you using?

abecedarian

Okay... ambient air temp isn't anywhere near the 185-195F the cooling system works at... even in Texas.

You 'could' get a spike in coolant temp with a hot start, as in shut of, wait a minute (literally), and restart... but you shouldn't- the coolant temp sensor is between the #2 & #3 cylinders on the intake manifold, so it should basically be as hot as it will be when you shut the engine off, and can only cool of from there.

The water pump is able to fully circluate coolant a few times per second, at least. So a spike in temps suggests some restriction, maybe near the sensor, or possibly in the hoses near the water pump inlet: bad hoses can restrict flow and may "relax" when the pressure on one side is near the pressure on the other side.

fierohink

@abe, yes and no. Yes ambient temp wouldn't affect the coolant temp since, even in Texas, air temp is lower than engine operating temps. However as you mentioned the water pump circulates water through the system in short order which is part of the reading from the temp sender. It reads 185* on cool and moving water. Once the motor stops, the water pump stops, and the coolant left in the block becomes stagnant and absorbs much more heat than 185*.

What we all need from the OP is a more accurate time frame that this occurs over. If the restart is in the 2-10 minute realm, I'd blame stagnant water as a result of the water pump no longer turning.

Rerunn

Put a clutch fan on it drain the coolant and add new and a thermostat. If it persists the radiator is clogged.

Terrys87

iTrader: (1)

Dont think this will solve your problem completely, but do feel it needs addressed as I have had it to affect the temp guage. The temp sensor gets hard water deposits and just needs a good cleaning.


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

That is called "heat soak" and it is normal for most vehicles in most quick stop/start situations.
There are also convection currents which will circulate coolant without the aid of the water pump however those stop at the point where the thermostat is no longer opening.

The situation where the temp gauge shoots up, then lowers fairly quickly is known on the 22RE, and is mostly a function of where the gauge temp sending unit is located- between #2 & #3 cylinders and not directly exposed to flow through the thermostat.


I would argue "heat soak" as opposed to stagnant water.
On the other hand, we could be talking about the same thing from different view points.

Punchy

Did you reinstall the fan shroud with the radiator.

Fanclutch bad?

abecedarian

Just to add....
When you turn the engine off the coolant temp sensor (for the gauge) sees the average temp of the water moving through the engine, even though the engine itself may be hotter.
After setting a little bit, the heat from the engine (which was actually hotter than the coolant) can cause the coolant contained within the engine, and maybe even some in the radiator, to rise above the temp the gauge was showing when the engine was stopped. This is due to both convection and conduction: convection will cause the coolant to circulate without the water pump and conduction will elevate the temperature of anything physically connected to the engine.

If the temperature gauge moves up when restarting after a short stop, I wouldn't be concerned AS LONG AS the temperature gauge moves down within a few seconds after starting the engine.

wyoming9

iTrader: (1)

I have this happen all the time till I don`t even notice.

If the temperature goes up when your driving that is another thing.

The fact it goes back into normal range as soon as you start to drive means your good to go.

Although it never hurts to change the hoses when it is time.

TNRabbit

Inaccurate advice.

A clogged radiator will tend to overheat more at speed than sitting as the engine generates MUCH more heat pushing a 4,000 lb truck shaped like a brick through the air~

Rerunn

Yes that is true as well but if the rad is packed with stuff internally or externally it can cause the same symptom. Granted the truck is under load more heat shall generate but vehicles over heat sitting still quicker because there is not as much air flow to remove the heat. Thanks for pointing that out. I'll be sure make sure every statement of advice i give is completely accurate from now on lol