Overheating question for the gods!!!

77'911 said:
What type of rad did you use? The 3vze needs to have a pretty serious unit in there(ie 3 core). The factory has even upgraded the unit from the original that was in our 1990.
regards
Click to expand...

I just bought the best one Napa could sell me. I asked if they made a higher capacity unit but they said that the one they sold me was the best one out there.
 
I would look at ur tstat and rad cap. Do you get really hot air from the vents when the heat is on or does it get cold if the fan is on high speed
 
Naked sure there is nothing in between the radiator and condensor. There could be leaves, plastic bag, etc wedged in there causing the over heat.
 
I would be willing to bet that you have a water pump issue. I could be wrong though. It seems like the system is bled right and you have a bunch of new parts. But, your issue is only at lower rpm's when the water pump isn't moving as fast. Just my guess but it's really hard to give good advice on your position without being there in person.

Good luck!
 
Thanks SV_Dude! I'm thinking I may need get a good OEM rad cap and tstat which would be a pretty small investment and then if that doesn't work, go in and have a look-see at the water pump like you say.
 
Thinking more about it. Is your water pump belt tight enough? That would explain a low flow at low rpm and good flow at high rpm
 
calinaki said:
The rad cap I used was one of those that had the lever on top to manually release pressure into the expansion tank so you can remove it while it's hot. When I would park and turn off the engine after it got hot, I would often hear bubbles into the expansion tank. I assumed it was water boiling out of the 50/50 mix that was stagnant next to the engine block. Granted, I wouldn't have bubbles unless I had some water boiling off but maybe the radiator cap isn't holding enough pressure in the system?? Anyone have a link to a good OEM cap I can buy online?
Click to expand...

Could be the cap not holding pressure..get a napa one to test with
 
Iknow nobody wants to say it here. But I'm betting head gasket. before you do much else run that chemical test on both your exhaust and on the coolant. Thay will indicate for sure if you have a BHG issue, or a head issue.

No sence in continueing to chase this, unless you can eliminate that 100%.

ask me how i know!
 
calinaki said:
Doesn't the water pump run off the timing belt?
Click to expand...

I'm not sure with ur engine. If it does than that's probly easily ruled out. If just a regular belt than may be a possibility that the belt is old and has some shine on the inside.

He said he wasn't seeing oil in coolant or vice Versa. So hg is hopefully okay
 
calinaki said:
Alright,

Hat's off to anyone that can properly diagnose this one. Haven't found any solutions on this site for what ails my 1995 4Runner.

So I know the 3.0 V6 (3VZE) sucks and has lot's of cooling issues but here we go.

As I pull up to a stop light after driving on the hwy, the temp rises just up to the red. If I rev the engine, it get's the fan and water pump moving faster and brings the temp back down. Here's what I've done in my quest to solve this issue:

Flushed the cooling system, New Radiator and cap, new thermostat, new fan clutch, and when I bought the rig last year, it had a new head gasket (exhaust/driver side only), timing belt, and water pump. I've had the front end extremely high in the air and have tried over and over to get any air out of it and believe that it's all out. I don't blow white smoke, there's no oil in the antifreeze, no gunk under the oil fill cap, and I'm not using any antifreeze except for some water that slowly boils off after it gets hot and I shut the thing off.

So,... why the overheating when I roll to a stop?

Oh, and the fan blades are good and the factory fan shroud is installed and in good shape.

Thanks, Thanks, Thanks for any help!!!
Click to expand...

Any luck figuring this issue out!??? I seem to be having the exact same problem with my 93 4runner! Please let me know if you have solved the mystery! I am currently beating my head!
 
Yep, BHG is definitely possible! Time to do a leakdown test or at least a cylinder compression test to rule a BHG out.

If its not a BHG, then there could be a pocket of air in the system causing it to not flow properly, extremely common with toyotas of the 80's/90's.

I've said it a ton of times before, but I'll post it again, as it won't cost anything to check...

While driving, engine completely warmed up, around 2500rpm or so, change the temp to full heat in the cab. If you hear a gurgling sound, you have air in the system and it needs to be burped!

To burp it, start with cold engine. Get nose of truck in the air as high as possible. Ramps on a steep inclined driveway or road is the easiest way to do this.

Open rad cap, start cold engine, let idle up to temp, keep the cab's temp on full heat. You'll know when its at temp when the water in the radiator starts moving quickly. a couple of very light revs (nothing over 1200rpm) to get the water moving will do it. Top off radiator and put cap on, you should be good.

Of course, if you do this and it still overheats, chances are its a BHG. Only other thing that will cause this is a water pump that has only seen water and no antifreeze, and over the years the fins on the pump has disintegrated. No way to really tell this without pulling the pump off the engine though...
 
ok so here's what I found, eventually the head gasket did fail and I started to see white gunk on the oil cap. so I changed the head gaskets and found that the gaskets that were installed were freaking reversed!! left side on right side and vice Versa. actually, no. it was two left side gaskets and I could see where the mechanic actually had tried to modify the gasket with his pocket knife probably. there were coolant flow ports that were completely blocked for crying out loud. hats off to the engine for doing as well as it did in this condition. after replacing the gaskets, it's been bullet proof and temp hasn't budged a tick over normal temp range. so running strong for 3 years still.

just goes to show you that u really gotta be careful what mechanic you use.
 
I know this is an old thread. Did it ever get figured out? I have a 1999 with the 5vzfe V6. Same symptoms. Overheats on idle only. I have a new Gates T-Belt and Waterpump kit, new thermostat, I flushed the heater core, thought maybe it was clogged. No leaks whatsoever.
 
You must log in or register to reply here.

Members online

No members online now.
Total: 389 (members: 0, guests: 389)

Forum statistics

Threads
278,310
Messages
3,554,080
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top