So I fiinally bought the vehicle I have been wanting for years, and now it has been giving me overheating issues. Every component of the cooling system is brand new and I just did the head gaskets because one went. I had the heads checked for cracks/warping, pressure tested, and resurfaced. I live in the mountains and it only overheats while going up the mountain. Normal driving, even with the A/C on, doesn't cause it to overheat. And no I don't run it while driving up the mtn. I've done some searching and have found nothing that I haven't already checked or replaced. It never overheated on a trip to Death Valley driving up a long grade while pulling a small travel trailer. I'm stumped.
1997 4Runner 3.4 overheating still...
- Thread starter Koch13351
- Start date
Register to hide this ad
zgensler31
Senior Member
Burping the coolant sounds like an idea to me. Do you have rear heat?
the great him
Elite Member
are you sure the head gaskets are on correctly? there is a left and right side, and if they are swapped they can block coolant passages.
AZ4Running
New member
Going up steep long hills can cause it to run hot and even over heat especially in the hot summer months. Try bleeding the cooling system again. A heavy duty fan clutch and or larger core rad may be in order. An electric fan in front of the rad might be a good idea as well. So its fine around town, stop and go and ac on but only get hot up hills?
19963.4lsr5
New member
have you tried a different T-stat? AKA a toyota brand?
Do you have a temp gun? it is almost a required tool as a do it yourself'r
Do you have a temp gun? it is almost a required tool as a do it yourself'r
Head gaskets are definitely on correctly. I was very meticulous with everything. I had an OEM thermostat in it and it was in question with the overheating issues so I replaced it. Not sure of the orientation of it though. I've also considered getting electric fans for it too. I'm just wondering if there are any other little things I might not yet be aware of as far as cooling problems and solutions. I had both heaters going when I was purging the system, and had the vehicle on an incline to assist.
TheDurk
Elite Member
As Doc2012 said above, jiggle valve down is spec'd by the FSM and improves cooling according to several who have posted on here. (Or did you mean you are unsure which way it was done...if so, worth checking for sure...it makes a difference.)
Otherwise, you have a definite head-scratcher. Are you sure coolant mix is 50/50? You didn't dilute pre-diluted or vice-versa? Easy to check with a specific gravity checker. I'd hook up a live scanner and see what ECU temp readout is when it overheats (different sensor than dash gauge). Check your trans temp at same time, long shot your trans is putting too much load on the rad when doing the mountains. Maybe it needs a flush or an external cooler is your answer.
Any chance air flow through the A/C condenser is obstructed by crud? Missing a shroud?...grasping at straws, here.
Attachments
Last edited:
ajonesnv
New member
On the drive consider locking into gear rather than jumping back and fourth. It is far fetched that the trans temp will raise the coolant temp that much, BUT going back and fourth between gears raise the tranny temp quite a bit and if you are slow going there won't be as much air flow as regular driving.
Definitely a head scratcher. Any reason to think there could be a partial blockage?
I usually drive about 45-50 going up the highway, with ECT power on and o/d on. It downshifts out of turns so perhaps keeping o/d off and trying to keep the converter locked up could help. I also thought about plumbing the external trans cooler as the first in the circuit since the one in the radiator is first right now.
19963.4lsr5
New member
BrianSD_42
New member
How can you tell it is overheating? Is it the dash gauge or do you have a SG?
