96 3.4 4runner overheating and stumped
#1
96 3.4 4runner overheating and stumped
So ive searched and searched....for over a week now. Im starting to lose hope.
96 3.4 auto 4X4 - 216k miles.
3 months ago i overheated briefly going up a mtn. Changed thermostat as a precaution and started watching coolant. Noticed coolant was getting low repeatedly with zero leaks and no other overheating episodes. So you know what that means lol. Dreaded milky oil and sweet smelling white smoke out the exhaust was next.
So i changed the head gaskets and got her all back together. Engine runs excellently. Smoother, quieter, and more power than ever before (i bought it a year ago with 203k miles on it). Only one little problem.... It overheats now. Only when driving. Never at idle.
List of things that are new - head gaskets, intake manifold gaskets, knock sensor wire, valve cover gaskets, intake plenum gaskets, tbermostat, water pump, timing belt, added oil to fan clutch, and radiator.
I am just completely stumped. Please help. Thank you.
Eric
UPDATE SOLVED PAGE THREE!!!!!
96 3.4 auto 4X4 - 216k miles.
3 months ago i overheated briefly going up a mtn. Changed thermostat as a precaution and started watching coolant. Noticed coolant was getting low repeatedly with zero leaks and no other overheating episodes. So you know what that means lol. Dreaded milky oil and sweet smelling white smoke out the exhaust was next.
So i changed the head gaskets and got her all back together. Engine runs excellently. Smoother, quieter, and more power than ever before (i bought it a year ago with 203k miles on it). Only one little problem.... It overheats now. Only when driving. Never at idle.
List of things that are new - head gaskets, intake manifold gaskets, knock sensor wire, valve cover gaskets, intake plenum gaskets, tbermostat, water pump, timing belt, added oil to fan clutch, and radiator.
I am just completely stumped. Please help. Thank you.
Eric
UPDATE SOLVED PAGE THREE!!!!!
Last edited by enapa; 12-28-2011 at 08:46 PM.
#2
Registered User
Join Date: Aug 2010
Location: Oregon, USA
Posts: 2,027
Likes: 0
Received 0 Likes
on
0 Posts
First thing that comes to mind...if the thermostat doesn't have a 'jiggle' valve, you will need to drill a 1/8" hole in the top of it. Otherwise a pocket of air builds up behind it and it won't open (hot air can't transfer enough heat to open it).
If that's not the problem, check your compression.
If that's not the problem, check your compression.
Last edited by BMcEL; 11-29-2011 at 08:31 PM.
#6
Registered User
Join Date: Aug 2010
Location: Oregon, USA
Posts: 2,027
Likes: 0
Received 0 Likes
on
0 Posts
The hole should be about where the jiggle valve is below:
I would recommend installing an OEM unit since you're gonna be in there anyway. All OEM Toyota thermostats have a jiggle valve and are superior to any aftermarket unit.
I would recommend installing an OEM unit since you're gonna be in there anyway. All OEM Toyota thermostats have a jiggle valve and are superior to any aftermarket unit.
Last edited by BMcEL; 03-19-2012 at 10:21 AM. Reason: Fixed image link.
Trending Topics
#9
Registered User
Join Date: Aug 2010
Location: Oregon, USA
Posts: 2,027
Likes: 0
Received 0 Likes
on
0 Posts
#10
you can start it cooled off and wait for it to warm up , watch the temp guage and when it gets about halfway the t-stat should open .
You can feel the radiator getting warm at the bottom (being careful not to lose fingers) and squeeze the top hose to confirm that coolant is flowing
another way to confirm that coolant is flowing is to turn on the heater , if it is not blowing hot it could be because it is not pumping coolant
sometimes a mystery coolant loss can be explained by a faulty radiator cap that blows off to early
if it is pumping coolant and still overheating , check for plugged exhaust, plugged cats , cooling fan operation , or ignition timing
the fan clutch should engage when the engine warms
when I was a kid in 1971 I got a great deal on a cherry 66 mustang because the guy couldnt figure out why it was overheating, he gave up and sold it cheep , turned out to be that the muffler was filled with sand
You can feel the radiator getting warm at the bottom (being careful not to lose fingers) and squeeze the top hose to confirm that coolant is flowing
another way to confirm that coolant is flowing is to turn on the heater , if it is not blowing hot it could be because it is not pumping coolant
sometimes a mystery coolant loss can be explained by a faulty radiator cap that blows off to early
if it is pumping coolant and still overheating , check for plugged exhaust, plugged cats , cooling fan operation , or ignition timing
the fan clutch should engage when the engine warms
when I was a kid in 1971 I got a great deal on a cherry 66 mustang because the guy couldnt figure out why it was overheating, he gave up and sold it cheep , turned out to be that the muffler was filled with sand
#11
Ok so i drilled the hole in thermostat and bled the air out on an incline, 2 big ass rocks i rolled into driveway i drove up on lmao. It is better but still overheating. I now realize that my fan is not increasing speed when the engine starts to get hot. Time for a new one i guess. Anyone have a link for the oem one for less than an arm and a leg? Lol. Thanks for all the great replies. I think i will be sticking around here for a while.
#12
Registered User
Ok so i drilled the hole in thermostat and bled the air out on an incline, 2 big ass rocks i rolled into driveway i drove up on lmao. It is better but still overheating. I now realize that my fan is not increasing speed when the engine starts to get hot. Time for a new one i guess. Anyone have a link for the oem one for less than an arm and a leg? Lol. Thanks for all the great replies. I think i will be sticking around here for a while.
http://www.partsgeek.com/catalog/199...an_clutch.html
A healthy fan clutch makes a noticeable roar when started up cold.No roar = bad clutch. If you can stop the fan with a rolled-up magazine or newspaper when hot = bad clutch.
You may find this thread useful:https://www.yotatech.com/forums/f2/1...l#post51509656
Last edited by TheDurk; 11-30-2011 at 07:54 PM.
#14
New aisin clutch fan installed....... Still overheating. Now i turn heater on full blast and the temp goes back to normal, but only if heater is on full blast. Im really getting depressed here. Engine runs great and has tons of power. Could a bad lower raditor hose be the culprit?
#15
New aisin clutch fan installed....... Still overheating. Now i turn heater on full blast and the temp goes back to normal, but only if heater is on full blast. Im really getting depressed here. Engine runs great and has tons of power. Could a bad lower raditor hose be the culprit?
#16
Registered User
Join Date: Jun 2008
Location: Washougal Washington
Posts: 413
Likes: 0
Received 0 Likes
on
0 Posts
HEAD GASKET nobody gonna say this?
when they are installed wrong u can blow it quick. i would check your oil make sure theres no water in there. if there is change it all again. also could be something farther internally
when they are installed wrong u can blow it quick. i would check your oil make sure theres no water in there. if there is change it all again. also could be something farther internally
Last edited by Countryhick; 12-08-2011 at 02:40 PM.
#17
I put head gaskets on exactly the way old ones came off. Im pretty sure of that. I just put new lower hose on and old one was really soft compared to new. I need to get some more coolant and bleed the air out, man these things are a pain to bleed lol. No coolant in oil and no white smoke so im fairly confident the hg. are good. However, if this doesnt work i guess i have to tear it all down again and buy another hg and bolts. Real fun being unemployed and going through this......
#18
Contributing Member
Join Date: Nov 2010
Location: Columbia River Gorge, Oregon...east side
Posts: 5,125
Likes: 0
Received 2 Likes
on
2 Posts
Were the heads checked by a machine shop for cracks after you overheated it and did the HG job? It could be the HG was installed incorrectly somehow and is blocking a water jacket....
#19
Registered User
Join Date: Aug 2010
Location: Oregon, USA
Posts: 2,027
Likes: 0
Received 0 Likes
on
0 Posts
Burping the system is the first thing you need to do. Remember to leave the radiator cap off when doing this. Only once you are certain there is no air remaining should you start looking for other possible causes.