d_stout

93 4runner 3vz-e. over heats, i replaced the thermostat still nothing. what i have noticed:
no heat in cab of truck, cold air only
bottom radiator hose is cold compared to top
loosing antifreeze somewhere
coolent reservoir seems to spit out everything when it over heats

im not a pro at this but im guessing water pump or blocked radiator.
any recomindations?

shaunneuhaus95

head gaskets!

93toyrunner2

Compression test all 6 cylinders. Did you replace the thermostat with OEM? If not, did you drill a hole in it and place it with the hole at the top when you inserted the thermostat? did you burp the system? Have you looked to see if you have oil in the coolant, or coolant in the oil?

Marc

Sounds like similar symptoms to my 90.
Best I could figure was the waterpump went.
I've parked mine and won't look at it till spring.

d_stout

ok so no coolent in the oil or oil in coolent, thermostat is OEM, and how do you know if you correctly burped the system or how would one burp the system
no compression test yet ill do that tonight

93toyrunner2

1 Remove Radiator Cap (Make sure coolant level is full)

2 Start engine

3Turn heat "on" and to "max heat"

4 Have a bottle Of coolant handy.

5 Better to park on a slight incline but it will work its way out eventually on flat ground.

6 Let truck run

7 Watch for bubbles out of rad fill cap (this is air bleeding out)

As the air is pushed out coolant level will decrease and add coolant as necessary.

This may take 5-15 mins.

Thanks to another post on here for this writeup...

d_stout

i did a compression test on the cillinders and the radiator. the lowest cilinder pressure is 74psi and the highest is 115psi.
when i did the test on the radiator i pumped it up to 13psi, immediatly started loosing pressure, it went from 13psi to 7psi in about a min.

skypilot

iTrader: (1)

Yur done; HG time. I would suggest if you want to keep that engine you get the ARP head stud kit and a set of headers to help keep #6 from blowing. A DIY ECU would help in the MPG dept, since the factory unit runs rich.

What I did was find a 22re to R150F bellhousing and downsized the engine to something more reliable & cheaper to maintain.

93toyrunner2

X2 on the head gasket. If you want to check the piston rings, do another compression test on all the cylinders, but add 1 teaspoon of oil to each before you connect the gauge. Do it dry first, then add the oil. Mark your readings without and with oil to compare. If the rings are bad, your compression will come up after adding the oil. also, be sure you have the throttle wide open when cranking the engine during this.
Your dry compression should be between 142 and 171, with difference between each cylinder of 14 or less.

mattches

Is there a visible antifreeze leak? I can't tell from your posts. If there is, then...
You pressure tested the coolant system right? When you had it pressured up, did you hear any hissing? Like from the radiator or the back of the motor?
What is your fuel mileage like? Does it throw any codes?
It could be a HG. But it also could be a blockage in the rear manifold or waterpump or a stuck thermostat.
Particularly if you don't see antifreeze in the oil (which is damn near impossible without getting it to a lab) or oil in the antifreeze, look for an oily shimmer on the surface in the sunlight.