No heat and no pressure in cooling system

[canuck-t4r]

Hi everyone,

So about 4-6 weeks ago I noticed my heat was practically gone in my 4Runner. I checked my rad and sure enough it was down quite a bit. I topped it up, ran it for a bit and got some heat back, but not much. I then noticed steam coming from back by the firewall, and some coolant on the ground back there. So I went to check the coolant level again. I opened the cap with the engine hot and there was no pressure in the system at all. So I threw in a half bottle of Barts Rad Sealant in that I had laying around and topped up the rad again. There was still some steam, but not as much and I did have heat. Then on Thursday, I lost all heat again. Of course, it's been -30 or colder here, so not the best time. I checked the rad, and it was down some again, but not very much. Even after topping it up and letting it run for 30 minutes, there is no heat at all.

Any suggestions? I've looked for that leak where the steam, but can't find where it is coming from!

 

[Canuckrz]

For the leak its likely a leak from one of the old heater lines on the back of the engine, its likely dripping onto the rear exhaust manifold which is what is causing the steam.

As for the heat have you checked that the coolant valve on the firewall is operational? Are you getting heat from both heater lines going to and from the core? Are you getting little heat, or literally no heat?

 

[canuck-t4r]

I am getting literally no heat at all up front. Ice cold. The back heater is blowing out some warm air, but I wouldn't call it hot. I will check both sides of the line. That's how you check to see if the valve is working?

 

[Canuckrz]

When the heat is on the arm on the valve should be in the 6 o-clock position. Pop the little cable off the arm and check to make sure it moves freely but has a little resistance so you know the valve inside is actually moving.

 

[Grenvilleter]

Be sure to check the coolant lines running to the rear heater. They are notorious for rusting. The fact that you are losing coolant AND not developing any pressure when warm signals a fairly major leak somewhere.

I replaced mine with 3/8" copper but some just put in a loop bypassing the rear heater core completely.

Your low heat in the front heater cct may be an air lock from the first time you discovered it was really low on coolant.

 

[Gerdo]

A few things, read this if you haven't http://www.toyota-4runner.org/3rd-gen-t4rs/161108-luke-warm-heat.html there is some good trouble shooting info in it. Mainly on the thermostat and if the radiator is getting hot/cooling properly.

There is a freezeout plug on the back of the engine that is know to have leaking issues. This may be where your steam/leak is.

Also, try replacing the radiator cap. It is what regulates the pressure in the system.

Very true, you may have nothing but air in the heater core that must be purged. Do you get heat out of the rear seat heater?

Where is your temp gauge running?

 

[Grenvilleter]

There is a freezeout plug on the back of the engine that is know to have leaking issues. This may be where your steam/leak is.

Gosh...that would suck ! Let's hope it's the rear heater line squirting on the exhaust pipe. Easy fix vs. engine/tranny pull.

 

[canuck-t4r]

Temp guage is running perfect! RIght in the middle and it heats up fairly quickly. I am getting heat out of the rear heater, but not enough to heat the whole vehicle!

 

[Gerdo]

It sounds like either your heater core is clogged or the heat diverted isn't working. Maybe the steam was coming from the lines feeding the heater core.