My 1995 3.0L V6 4Runners is overheating and I can't figure out why. I have replaced the thermostat, and the radiator cap and had the radiator checked at a shop to make sure it was okay. The temperature gauge on the dash reads normal but when I get out I can hear the water boiling in the reservoir. Should I start with checking sensors like the engine coolant temperature sensor or what?

 

Pressure test the cooling system. It will allow you to see where it is leaking. If no noticeable leaks, then I would look at your head gaskets. Do a compression test; if you have 2 consecutive low cylinders, then you know where it blew out.

Do you have a lot of white smoke coming out the back end? Look at your spark plugs and see if one of them is really clean, like coolant leaking into the calendars and steam cleaning the plug.

Overheating is the worst thing you can do on a 3.0 motor. Tell us more once you test things a bit more. Good luck and welcome to Yotatech.

 

Thanks, I will check these items and let you know...Tracy

 

The only visible leak I can see is that it has developed quite an oil leak. I haven't noticed a lot of white smoke...but will definitely pay more attention to that. Also, I checked the oil and there is no water in it.

 

I'm not an expert, but you probably still have air in the cooling system... If it is definitely is holding the pressure, try burping the rad. I'm not sure on the exact procedure, but you can lift the front end into the air and run it for a few minutes. Do a search for burping/removing air from the system and hopefully that helps.

 

Do you have the stock fan setup? Check to see if the fan clutch is working properly.

I have electric fan in mine and mine was overheating because the electric fan thermostat went out.

 

I just replaced the thermostat on my 89 v6 3.0 pick up and the thermostat I pulled out had a bleeder valve of some sort on it. The guy at the parts store said he didnt think it mattered but thought it was strange that there were a few different part numbers for it Needless to say it didnt work. Anyone know if that valve is nessasary or do i have a deeper seeded problem

 

Not sure I've never replaced my thermostat but you could run it without a thermostat to see if the thermostat is the problem. Only downside to that is that it will take longer for the motor to warm up

 

I personally havent had to replace my tstats, so Im no expert, but.... I do recall many a thread here on yotatech, about that little valve, and these 3.0's being finicky about them, IRRC the solution was to pony up the extra few bux, and get oem from the dealer....

 

I have the same problem with my '92, so I deceided to change the Thermostat. When I removed the Thermostat I found that there wasn't any coolant, just dirty water. I flushed the system and added new coolant and still have the same problem. I have a fan clutch and fan as well as an electric fan that doesn't work. Where is the switch for it located?

 

What temperature range is the 3.0L susposed to opperate in?

 

I commited the cardinal sin of removing a hot radiator cap and used my fluke to test the temp and it read 208 degrees Fahrenheit. That seems a little hot to me. Any ideas, or comments besides the cap removal?

 

I am thinking that you are talking about the electric fan that is in the front on the passenger side? If that is it, it only comes on with the AC, if it does not come on with the AC, check the fuses in the engine compartment fuse box.

 

Ok, the mechanic is telling me he thinks it's probably a head gasket. Not what I wanted to hear!! Why would the truck only run hot sometimes. It's really strange...there is no oil in the water, water in the oil, white smoke, it doesn't leak any fluid, and the heat works. Is there any other way to test this head gasket without tearing the engine apart.

 

comp check the cylinders, if the hgs are blown anywhere it pumps air into the cooling system, which is prolly what u hear bublin out

 

I have the EXACT problem in my 92 3.0. No smoke, not wet plugs - nothing.

I guess the next step would be a comp test... grrrr

 

any updates? im having the same issues. I did a compression test and had 135 across the board

 

I had something like that. Has anyone thought to have the oil cooler on the driver side of the block flow tested whike the coolant was drained? I replaced mine and always kept getti g bad thermostats. I stay away from the O'Reilly ones now. I did pull my thermostat out and hollowed the middle so the seal would stay intact and replaced my water pump. Still have the same issue before I replace the thermostat with a "mock" one. No more overheating and it still warms uo decently fast

 

I went through three bad veezy thermostats before getting one that works. They open at 180 iirc (its been a few years since i had one) but take it out, suspend it in a pot of water on the stove so it doesn't touch the sides, and make sure it works. I spent over a hundred bucks on coolant learning that lesson, now i check them all. Also, the jiggle valve is supposed to let any air bubbles pass through the thermostat and make it easier to bleed the system. I was told to clock it to the 12:00 position.

getting the coolant checked for exhaust gases is the quickest/cheapest thing to do and where I would start.

 

that little electric fan comes on with the a/c as a aux