Temp gauge fluctuates frequently at higher rpms

So i have a 04 tacoma 2.7L, shes got 267,000 miles, and nothing has ever been changed on it (besides oil, brakes, minor things). And recently i noticed that when my engine is at moderatly high rpms (not very high) the temp gauge will go all the way to the top (overheating side), and if i let off the gas and let it sit in neautral then it will slowly go back down to normal. Just driving at normal rpms it starts to rise on me.

However i dont notice any difference while driving it, and i put my heater on full to see if it would help, and it barely made a difference if any. Also the air coming out of the vents was like luke warm.

Any ideas what to do?

 

Is the radiator full?

I'd check / replace the thermostat, and take a good look at the water pump and radiator to make sure everything is flowing properly.

 

If your coolant level is good, then it sounds like a bad thermostat that's not opening completely and letting it flow. I have no idea about whether or not that's a pain to swap on a 2.7, but that's where I'd start.

 

Checked the radiator and it was pretty much empty, im not sure how full it was supposed to be but i guessing thats my problem. Would it be necessary to do a full flush of my system? i looked online and it seems that mixing coolants can be a bad idea and im not 100 percent sure what or when was the last time the coolant was changed

 

A full flush / refill wouldn't be a bad plan - especially with 267k on the odometer.

If you're in a hurry, a quick refill probably won't hurt anything for a few weeks - until you can get around to it.

 

The radiator should be full to the top, and then fill the recovery / overflow tank to the appropriate level (hot vs. cold mark).

Check it after a day or two (engine cold), and top off as needed. If you are losing fluid over time, then you have either a leak or a head gasket issue.

 

Ok so im going to flush the system, but after looking online im still confused on where the drain plugs are. I found a little plug on the lower passenger side of the radiator, and im assuming thats it. But do i need to drain it from the engine also? or will I be ok to just drain it from the radiator

 

Yes, that's most likely the plug you want (considering I can't see it)......

I'm not sure if there is a drain on the block, but maybe someone else will chime in. If there isn't then just fill the system with water and run it for a while until it gets hot enough to open the t-stat with the heater on. Then drain the radiator again and refill with antifreeze (it's OK to repeat again with water, if you want).

I don't know how much fluid the block will hold, so you may need to do some research to figure out the blend needed to get to 50/50 once it mixes with the water in the block.

 

Honestly sounds like the belt could be slipping and not providing enough spin on the water pump at higher RPMs.

 

i just flushed the radiator out, except when i ran water through it i didnt let hte engine run. is that a problem?

 

You won't get all of the old coolant out if you don't.

 

how much of a problem is that? do i need to flush it out again right away? or am i ok for awhile. i used the prestone coolant that says it mixes with all kinds

 

You're in better shape now than you we're before, but the old coolant will mix with the new and potentially reduce it's effectiveness. Not saying it will hurt anything though.

Your call.

 

ok ill just flush it out again in awhile. thanks for your help man! i really apreciate it

 

Sorry that I missed this thread. Looks like you are on track with what you need to do. If you pull the thermostat, then you will drain out most of the coolant. You will typically have no more than 1 quart of fluid left in the block. A small percentage of coolant mixing of the old with the new is not that much of an issue, so you can do a single drain and refill without any issues. Once you are done with this of course you will want to keep an eye on your coolant level in the radiator for several weeks. (Remember do not remove the radiator cap while hot!) Loss of coolant should be addressed at that point. Some parts places will sell a dye that can be added to your coolant to help locate a leak. The dye is harmless, and will REALLY help if you have a small leak. Good luck.

 

thanks man, i changed the coolant and it fixed the issue. im gonna let it run as is for awhile, and then later ill do a flush again but do it the right way. Time to start taking care of my baby more haha

 

Hey guys. I see it's been awhile since some of y'all have been on here, but please chime in if u are a experienced toy guy! I have a 98 taco w/ 3.4. It has about 225000 miles on it. Got it 7 months ago. The prev. owner (2nd owner) said all he ever did was replace the timing belt and water pump and rebuild alt. And general mait. So, I've been doing my best to take care of it. Changed all fliulds, and flush radiator cause it was bad rusty looking, when I first got it. Anyway a couple days ago while driving home from work (210 miles round-trip). the temp shot straight up all the sudden. I shut it down and let it cool a little. It was about 45 degrees and raining. I pulled the radiator cap off and watched it spray all the water out , there was plenty of cold water in the ditch, so I poured it full and cranked it up and it cooled down pretty fast. Needle was halfway , almost normal, so I drove it the 60 miles left,on home. And it never overheated again. But I did have the heater on high also. I did turn it to halfway about 20 mins before I noticed it overheated. After I got home I felt of the top hose(hot ) and bottom hose(cold) so I thought therm. So I went and got one and put it in and filled back up with water and drove it with the heat off,on cold for a few hours all over and let it sit and idle for a while. Didn't overheat. So I had to drive to work today and took it easy and my temp needle is right in the middle ( little higher than what it usally is) but I can see it move just a little, but it's doing it almost constantly. ( Do u think that means anything). I did the plugs and wires about three weeks ago cause the two weeks ago I did the valve cover gaskets with all the normal things that we are supposed to do. So the past week I've had a higher then normal idle(1100) that I've been trying to fix, and this past weekend I replaced the IAC gasket cause I stretched it when I took it apart. So the idle got back to normal after about the 4th start up. But it's crazy cause now it's back up to 1100 and then sometimes it's at 700. I can deal with the idle, I just telling you cause I don't know if that tells you something about being related to the overheat, that one time. I had a bunch of brown dirt stuff from the eruption of coolant when I took the cap off that one time and it looks like that stuff (tablets) u use for a radiator leak. And I put my old therm in some boiling water and it opened. And I pulled my timing cover and looked at the weep hole and it was dry. So now I'm nervous as hell. I'm hoping I don't have a bad head gasket. And is the irratic idle a sign? It ran fine on the way over here this morning, but the needle constantly moving a little has me worried that it's getting hotter than it should. I check the oil, like 3times a day and it's great. Pulled a plug last night and it's good. I know when I drained the water out before I put coolant back in and burped it. The water was way brown. Hey also I was having a heater issue after I did the valve gasket job. I thought I had air in the system so I tried to brup it. It would get hot when I put it all the way over on red and fan on low, but when I turned the fan on high ,it would start to cool down like it couldn't produce enough heat. And after burping it a week ago it was a little better but still did the same. Now after I replaced the therm.yesterday morning, it is back to normal and working just fine, if that tells you anything? So if you're experienced like bammatoy, please chime in and give me ur thoughts. If I make it back home without any problems then I'll probably try to do the gas test in the coolant, if my local store has one? This is my only driver and have no way of getting anywhere without it, so I'm nervous as hell. And since I only got a part time job that's far away , and owe for everything a guy can put off, I sure can't afford for it to be anything major!!! I'm not a mechanic but being broke has turned me into one. I just don't have the money for a tow truck if I was to break down and have so save a couple weeks to get a hundred dollar part. And have to be able to drive to the store to get it. So any extra money I have I spend on pm for my truck, trying to avoid being broke down. So if you put all of these little things together and they sound familiar to you then let me know what you think it could be? God I hope u tell me I just had a stuck thermostat!!!!

 

OMG, break up your post a little. Kinda hard to follow... didn't read the whole thing...

So wait, you dumped some ditch water in there? Is that STILL in there? Flush all that crap out and add COOLANT, not pond water! That could easily be why you're seeing rusty brown water in your radiator.

Does the coolant level fluctuate? As in, is the coolant escaping somewhere? I assume it is since you needed to add ditch water to it. Coolant only has 2 places to go: the ground or the tailpipe. If you don't see any external leaks, you have a problem with coolant getting into your combustion chamber which can mean a few things, namely a blown head gasket.

What does your oil look like? You say it's "great" but just looking at what's smeared on the dipstick doesn't tell you a whole lot besides how much there is. Have you changed it since you've been having this over heating problem? Is it foamy or milky looking?

 

Sorry. I'm at work. 30 mins of writing with a five minute break. I'll rewrite it tonight when I get home. In short. Did valve cover gaskets three weeks ago and only problem I've had is been a high idle. We'll deal with that later. But as far as overheating. Yesterday I was on the interstate and all of the sudden my heat gauge needle went to red. I pulled over and shut it down. I tried to wait as long as I could but was about to get ran over from everyone as there was only a small shoulder to pull over on. So I put rags on the cap and took it off and of course it all came shooting out. As expected. As for pond water. It was raining and the water I used was clear rain water from the ditch that I made sure it didn't have anything in it. And yes I drained it out when I got home. It didn't overheat on the way home. I changed out the thermostat the next morning. Filled it up with water and drove it around ,and drove the shit out of it. And also let it set and idle. Never overheated. Got home and flushed it and filled up with coolant. There is no coolant leaks or ever has been and the only coolant I lost was from taking the cap off when I overheated. My old thermostat opened when I put it in hot water, so it has me concerned. I know it doesn't mean that it was working properly. No coolant in combustion camber as far as I call tell but I'm thinking the only way to know for sure is to air test it. Truck runs fine now but I am concerned. If it don't overheat on the way home I'll feel better . I'll explain more when I get time. I'm hoping it was just a stuck thermostat, or maybe my radiator has not got good flow. Ill post tonight.

 

Yeah, it's possible you have a blockage in the radiator that was cleared when you flushed it.

I hate those "you never really found THE problem, but now it seems to work" things.