For what it's worth, I replaced the radiator, timing belt, water pump, and thermostat when I first purchased my runner a couple months ago. The gates thermostat that came with my kit ran the vehicle up to 205 before I got concerned and switched it to the OEM thermostat. Both thermostats had the jiggle valves at 6 (completely opposite of every gm that I've worked on with a jiggle valve) and thoroughly burped the system with a spill free funnel. I used toyota red coolant as well. now my coolant temps haven't exceeded 192 degrees. I'm monitoring temperature via ultraguage.

It was not OEM but it did have a jiggle valve. I don't remember the correct orientation off the top of my head but I do remember researching it and making sure it was installed correctly. I've actually replaced it twice since purchasing the truck 3 years ago. The first time when I first got it, the second about a year ago when I noticed leaking.

So, the OEM thermostat opened earlier? I might have to switch out the thermostat if thats the case. I haven't ever tried to read the temps on mine. What are you using to do this?

OEM thermostat opened earlier for me. I was monitoring engine coolant temp with my UltraGuage.

My 96 ran 186-188 with the jiggle valve at 12 like all normal jiggle valves get installed at. It’s job is to allow a place for air to escape during the filling process. After the system is filled its job is done.


Sent from my iPhone using Tapatalk

Toyota 4Runner 3.4L instructions on ProDemand state jiggle valve should be located at 6 o'clock position. To each their own. Multiple threads on this forum stating a big difference in coolant temps based on jiggle valve locations. whether the change was from the proper orientation of the jiggle valve or doing a better job purging the cooling system is up for debate.

You have to wonder WHY it is in the literature. Logic tells me that if they've made such a point to orient it in a different location than is generally standard, they've done some sort of testing. Why make it complicated? There has to be a reason. I'll orient mine at 6 o'clock as I've done with my last two.

I just purchased a thermostat and gasket, upper and lower rad hoses, and an outlet heater hose all OEM from the stealership. I'll use my two oetiker clamps on the engine end of the upper and lower rad hoses, and just use worm clamps for the radiator ends. I'll be picking up some clear tubing, an adapter for a garden hose, and some strong white vinegar as well.

I think whats going on, is I thought I had one issue causing both of my symptoms. I think now, I have three separate issues:

- The hoses not being OEM therefore not fitting as tight as they should.

- Aftermarket thermostat not opening at an ideal temperature.

- Clogged heater core.

I'll update when I'm finished!

Back flush the heater core first. Anything loose and packed into the inlet of the core will be pushed out.

I installed my last two jiggle valves at 6. When I pulled the 96 engine apart i had put it at 12 and it’s engine temps were identical to the two engines at 6. All three were with an OEM t-stat


Sent from my iPhone using Tapatalk

Back flushed the heater core a few times with low pressure garden hose water, switching the direction of flow each time. Its now sitting in 6% vinegar overnight (I could not, for the life of me, find anything higher than 6% at any store I could think of).

On about the third flush a piece of stretchy rubber came out (see picture). It is about 2 inches long when straight, and about 1/2" - 3/4" in diameter. Its pretty stretchy, like a rubber band. I'm certain its not from me pulling off the heater core hoses or rigging up my flushing system. What the heck is it? is there some kind of rubber inside the heater core that might be corroding? I guess it could really be from anywhere in the cooling system that made its way back to the heater core at some point. Should I be concerned?

This pretty much all thats come out of the flush with using water only, that and a few tiny calcium deposits. I expect to see more tomorrow after that vinegar bath.

Shouldn't I be expecting quite a bit more gunk if my heater core really is plugged up?

Attached Images

 

I used compressed air on my Saturn without hose clamps.

Pulled the stat and removed the inlet to the block from the heater core and blew compressed air in a piece of heater hose I slipped over the pipe. Figuring it will blow off if it’s too much pressure.

It did the trick and I had nasty stuff come out the hole where the stat mounted. Then I filled that hose with water and kept shooting it through the core until it was clear of debris.

I then ran flush through it.


Sent from my iPhone using Tapatalk

If you flushed it with a garden hose and water flowed through both ways it is not plugged. With the engine running and heat on hot are both heater hoses hot or is one hot and the other cool? That would be a good indicator of a plugged heater core. I see Toyotas get a build up of dried coolant and corrosion at hose inlets and outlets that will cause leaks usually after being disturbed and not cleaned off before the hose is reinstalled. The thermostat brand or orientation is not likely the problem, it sounds like you are chasing a blown head gasket around to me. Loosing coolant, but no major leaks, over pressurization of system causing small leaks at hose connections and no heat are classic symptoms. Does the overflow tank or radiator have a nasty acrid smell inside them? You need to do a combustion leak test or block test. A glass tube is placed on the radiator neck with a blue liquid in it. The engine is run and if combustion (exhaust gas) is leaking into the cooling system the blue dye will turn yellow. If it is really bad it will bubble and turn yellow instantly, if it is minor it might take and hour to turn. BTW the factory spring clamps are the best, but they do rust, crack or just lose spring tension after 20 years.

So, I figured out the no cabin heat issue.

It was the %$#@&*! blend door actuator!

I haven't had a good look at the actuator to see what exactly is wrong with it, but after doing a little reading about them, I guess its a common issue with these vehicles. I was able to manually open the switch, and VOILA! Hot air coming through the vents. All that time flushing, for nothing.

I did a pressure test on the vehicle last night, and it did not hold pressure. It almost seems like this pressure tester i've been using isn't sealing properly at the radiator. I'm not seeing any leaks anywhere. I'll probably pull the spark plugs either today or tomorrow (they likely need to be changed anyway) and put my borescope down in to check for any coolant.

I did another combustion fluid test at the radiator, and I did it for an hour. The fluid stayed blue, and I verified that the fluid worked properly afterward by sucking the exhaust at the tailpipe. The oil and Transmission fluid look good as well.

I' haven't driven it around enough to see if any over pressurization happens again and hoses if the hoses still leak, i'll update when I do.

Those dye test are worthless. I had a bad HG and the blue dye never even remotely changed color. I then did a leak down test which 100% confirmed I did in fact have a bad HG.

Leak down test is what you need to do.

The dye test works, just not all the time. It's just one tool to help diagnose a problem.

The dye tests work once there is so much combustion gases in the coolant that it will already be pretty obvious that you have a HG leak. I didn't throw my kit away because it is a quick way to check but in the end, a leak down test is king.