Random Overheating, but Only for a Short Time

[Troymclure]

Hey guys,
Havent been too active here recently, but keep having a recurring problem with my truck overheating.

First happened a few weeks ago, as I was driving home from school. Drove on the freeway for about an hour then pulled off to go get some food at a drive thru. As Im sitting waiting, the temp gauge slowly rises until the needle is pinned in the red. At this point Im freaking out, so I pull out of the drive thru and turn the truck off and get out to. To my surprise, the radiator isn't boiling over, nothing seems extra hot and everything seems fine. I go to start the truck up and the temp is back down in the normal range. I drive the truck around the rest of they day and everything is fine.

My first assumption was the thermostat was stuck closed, and as it heated up, the pressure would build and force the thermostat open, and it would cool down. Fixed that and nothing changed. The next week it did the same thing in the same drive thru.

My next guess was the fan clutch. I thought that since it only happened after long drives on the freeway, then coming to standstill in the drive thru, the thermocouple on the fan clutch was broken, and one the air flow from driving at 70mph would stop, it would take a bit for the fan to kick on to cool it back down. Replaced that, and thought the problem was fixed, since the old one was leaking oil.

Fast forward to the next week, and dammit, it happened again. Temp slowly went up to pinned in the red, then after about 30 seconds, came down to normal. At this point I have no idea what could be the cause. My only other guess would be my gauge is having issues or the temp sensor on the motor.

Anyone have any input? It would be much apprecciated

 

[av8ter]

Headgasket. Buy a coolant funnel, see if you are getting air out of the cooling system.

 

[Utopia]

Another vote for head gasket. V6 or V8?

 

[Ju1cE82]

Headgasket. Buy a coolant funnel, see if you are getting air out of the cooling system.

One better is one of these:

Amazon.com: OEMTOOLS 27145 Block Tester: Home Improvement

Most big box auto parts store can rent it to you, ask for their book chances are they have never heard of one. You will have to buy the liquid but it is cheap. The liquid will change color if exhaust gases are present in the cooling system. I used one starting in the first shop I worked at and at times you would never see the bubbles and it would start to change to urine yellow.

I Hope for your sake it a temp sender or gauge issue.

 

[JB.]

Seems like the quickest, easiest thing to do first is check the gauge.

IR guns are cheap. I'd shoot the main hose and other spots to verify the cluster gauge isn't funky.

 

[Troymclure]

Sketch. I didnt even think it could be a headgasket. I have a V6, but it should only have about 100,000 on it now, since I had it replaced a few years back. My gauges have been having some issues where the whole gauge cluster dies, so Im leaning towards that. Ill grab my temp gun and see if I can get a reading of what the actual temp is on the radiator hoses and block to see if its actually overheating. Might try bleeding the cooling system as well, to see if theres an air pocket in there

 

[av8ter]

Start with checking for air(bubbles) escaping the coolant system first. You've already had one or both headgaskets done?

 

[Troymclure]

Start with checking for air(bubbles) escaping the coolant system first. You've already had one or both headgaskets done?

I had the whole motor replaced. I hydrolocked mine around 124k, and had an engine put in with about 80,000 at the time. Since then have put about 40k on this motor.

Also just tried to get it overheat again by driving on the freeway until it was warm then coming home and letting it idle in my driveway. Took some readings with a temp gauge, and got around 160ºF on the upper hose, 120ºF at the lower, and about 100ºF on the radiator cap. Gauge wasnt pinned in the red though, but was a bit above the halfway point.

Also picked up a block tester. Gotta let it cool down, then Ill test it too. Hopefully it goes well, but if not, might be time for that LS swap Ive been thinking about

 

[fdbyrne]

It could be the head gasket, but that wouldn't be my prime suspect.

Since it stayed cool as long as you were moving fast and heated up only once you slowed down, I would assume that it's something wrong with the cooling system. It sounds like you're not getting enough air moving across your radiator unless you're hauling ass.

 

[dkyleb]

Do you hit a lot of mud or dirt roads? Inspect the area between your rad for dirt and mud build up.

Check that clutch fan is functioning, too.

 

[Troymclure]

Well, just checked with the block tester, fluid came up green after a few minutes of it sitting there. So not sure what that means. I wouldnt think its a headgasket, so maybe its a false positive. It didnt turn bright yellow like the kit said it would but idk. I just replaced the fan clutch, and its working fine, and no mud built up in between the radiator and ac condensor.

I would agree that the fact it only happens after long drives on the freeway, and its weird that it goes all the way up on the gauge and then back to normal within a few minutes.

 

[ghs215]

Replace the Radiator Cap! I had this same problem

 

[Troymclure]

Replace the Radiator Cap! I had this same problem

Hmm, might be worth a try. Cant seem to find any other options at this point.

Did some further research, and a block tester turning green is not really an indication of anything. Not sure where to go from here....

 

[ghs215]

After you drive, check the upper radiator hose. Is it ROCK hard or a bit of squish? It should be rock hard. Mine was a bit squishy, but not after I replaced the cap.

Good luck and let us know what happened.

 

[Troymclure]

After you drive, check the upper radiator hose. Is it ROCK hard or a bit of squish? It should be rock hard. Mine was a bit squishy, but not after I replaced the cap.

Good luck and let us know what happened.

Well, I dont think Ill be so lucky. Decided to smell my radiator when I had the cap off and it smelled like I put my nose straight in my exhaust. That seems to me to be a definite sign of a bad headgasket. :smashputer:

 

[MFreund]

I hate reman engines. They all use shit gaskets.

 

[Troymclure]

I hate reman engines. They all use shit gaskets.

Yeah Im starting to hate them too. Although, not even sure if this engine was even gone through, just swapped in

 

[Troymclure]

Also just realized another important clue that points to headgasket. Have had intermittent rough starts, that I attributed to my dying gauge cluster. Time to order a bunch of parts and get to work pulling my heads

 

[Troymclure]

Well thought Id update this. Gonna go ahead and replace my engine with a remanufactured engine that I found that uses all new oem parts. $2500 when all is said and done, but should last a long time after this, and in the end is the cheapest option that leaves me with a reliable 4runner again.

Toyota Tacoma 4Runner Tundra Engine 1gr 4 0L Zero Miles 2003 2004 2005 | eBay

 

[radlynx]

nobody even suggested to try replacing your ECT sensor. it's located next to the firewall between the cylinder if you have a v6. that's a $50 part. that sensor is what controls the gauge inside the cabin.

Well thought Id update this. Gonna go ahead and replace my engine with a remanufactured engine that I found that uses all new oem parts. $2500 when all is said and done, but should last a long time after this, and in the end is the cheapest option that leaves me with a reliable 4runner again.

Toyota Tacoma 4Runner Tundra Engine 1gr 4 0L Zero Miles 2003 2004 2005 | eBay