Overheating after head gaskets

[alumarine]

Thanks again, I ended up doing this and it was indeed easy and quick. The most annoying part was draining the coolant and removing my dynamic tensioner (sits right in front of the thermostat housing)

Glad you got the gasket made.
I'm confused about having to remove a dynamic tensioner.
Other than draining the rad I've never has to remove anything else to remove the thermostat housing.

You can check your current thermostat in a pot of boiling water.

 

[DJRodriguez88]

I say try the new T-stat and rad cap and see what happens. Make sure you’re not sucking your lower rad hose flat.

My lower rad hose is actually bent a little extra because of the 1.5" body lift. I'll have to make sure it's not going flat. Thanks for the tips and the education on cooling system operation!

I'm confused about having to remove a dynamic tensioner ... You can check your current thermostat in a pot of boiling water.

It's for the supercharger's drive pulley. It sits directly in the way of the thermostat housing. I'll check my thermostat as soon as I can find a thermometer thanks for the reminder I totally forgot I can do that

 

[19963.4lsr5]

How old is your Rad since you have a supercharger on it? If it’s never been replaced I’d replace it as well, unless it looks super clean inside.

For the record I’ve never had to “Burp” a cooling system.

The closest I ever got was my 04 grand Cherokee with the 4.7 V8. There is a high spot in the engine that collects the air. And *****footing won’t push the air into the rad. So I did some spirted driving after the engine got fully up to temp. The high rpm’s pushed the air pocket into the rad. That eliminated the waterfall sound from my heater core.


Sent from my iPhone using Tapatalk

 

[DJRodriguez88]

How old is your Rad since you have a supercharger on it? ... I did some spirted driving after the engine got fully up to temp. The high rpm’s pushed the air pocket into the rad.

The radiator, radiator cap, and thermostat are all ~2 years old.

I couldn't do any spirited driving as I overheated in the first mile of neighborhood driving on my previous test drive (before pulling the thermostat out), but that sounds worth a try once i get it healthy enough to do so!

 

[DJRodriguez88]

I tested my thermostat today.

Here's a short video showing the results: 170 degree Motorad Thermostat operation - YouTube

I couldn't find any other videos showing how it should open at a given temperature, so I'm not totally sure what to conclude from the test but i can at least say it opens. It cracks open later (~178 degrees) than it's rated (170 degrees) then doesnt really open wide until nearly 190 and fully open at 195+.

Like i said, idk if that's completely normal operation, but it does open and shut.

If we can agree that the thermostat is working well enough, the only things left to do is make sure the lower hose isn't collapsing (it's already more bent than normal because of a body lift) and take it to a shop for a chemical flush. The coolant passages on the head that wasn't replaced, the block, the radiator, and everything i could see when i had the heads and water pump off looked very clean. But the junkyard head that I put in had coolant passages that looked like they had a lot of crap in them... I really shouldve had that cleaned out when it was at the machine shop.

 

[DJRodriguez88]

Pressure tested the cooling system today.

After applying pressure to the system I was able to see a super obvious leak in the upper radiator hose that somehow didn't show itself before.

I guess when the coolant is hot and flowing the leak would allow air to get in but not coolant to come out. Then when I pressurized the system, the coolant was static so it easily came out where air was getting in.

Ok.. tightened the hose clamp. It broke. Put a new one on and now system holds 15+ psi solid for 20min. In retrospect the dial on the gauge was sticky so it could have been leaking pressure slowly and not showing on the gauge...

Anyways, I'll throw the thermostat in next and see what happens!

 

[3ToyGuy]

The thermostat will stay closed, if you're just pressurizing the system with a pressure tester. You need to get it up to the operating temp of the engine. 190° F I think is right, but I may well be wrong on that.

Also, the kind of hose clamps that come from the factory, the clamps Toyota puts on, seem to work better than the screw down clamps you get from the auto parts store. They are readily available from Toyota parts sources.

Good fortune to you!
Pat☺

 

[DJRodriguez88]

The thermostat will stay closed, if you're just pressurizing the system with a pressure tester ... Also, the kind of hose clamps that come from the factory, the clamps Toyota puts on, seem to work better

I thought pressure would hit both sides of a closed thermostat because it's going in both directions unlike coolant flow which goes in 1 direction. Either way, my thermostat is still out so I didn't have that problem lol.

Thx for the tip on the clamps I'll see how much toyota wants for them!

 

[DJRodriguez88]

Finally got some time to work on the 4runner today...

I put the thermostat back in, bled/burp using no-spill funnel, heaters on, etc...

With the heaters on full blast I'm hovering at 195-198°F. As soon as I turn them off I start creeping up to 205+.

My lower radiator hose stays cool to the touch the whole time, sounds like my t Stat is either opening too slowly or not opening as much as it should.

I thought my test showed that it was working bit I guess not as well as it should be. I'll order a new unit and test it before install so I can compare the behavior

 

[phattyduck]

Finally got some time to work on the 4runner today...

I put the thermostat back in, bled/burp using no-spill funnel, heaters on, etc...

With the heaters on full blast I'm hovering at 195-198°F. As soon as I turn them off I start creeping up to 205+.

My lower radiator hose stays cool to the touch the whole time, sounds like my t Stat is either opening too slowly or not opening as much as it should.

I thought my test showed that it was working bit I guess not as well as it should be. I'll order a new unit and test it before install so I can compare the behavior

Don't try that test in the summer. The heater core is a reasonable fraction of the radiator in size (maybe 1/8 or so?) and its coolant flow bypasses the thermostat. Your test is showing there is no (or near no) flow to/from the radiator. Even when run 'upside down' the thermostat will keep the engine below 205*F, especially at idle.

-Charlie

 

[19963.4lsr5]

How old is your rad? How clean is it when you look in the top?

It’s easy to tell when the stat is open and coolant is flowing through the rad with the cap off. It will flow by the cap opening really well if you leave enough of an air pocket. Something you’ll never see with that “burp” funnel sticking in the hole…..

When I fill a cooling system I fill until I have a 1” gap under the cap and start the engine, and leave the cooling fan off. Just the heat lever on max temp.

As the air pushes out I keep adding coolant until it stops dropping. As the engine warms up and the coolant expands….when the level hits the top of the rad I’ll put the cap on.

When you say “turn them off” are you turning off the fan and putting the temp lever to cold or just turning off the fan?


Sent from my iPhone using Tapatalk

 

[DJRodriguez88]

How old is your rad? How clean is it when you look in the top?

Radiator and cap are ~2 years old. It looks very clean. I've filled and drained my coolant a few times since the head gaskets and it comes out basically the same clean pink color every time

When you say “turn them off” are you turning off the fan and putting the temp lever to cold

Yep!

Your test is showing there is no (or near no) flow to/from the radiator.
-Charlie

Ok, so that sounds like either my t stat isn't opening, there's a blockage, or the water pump isn't pumping.

The tstat seemed to operate correctly when I boiled it (see video). Also, it was working just fine before the head gasket work, so idk how it would go bad just sitting on the bench. I'll try a new one anyway just to be double triple extra sure.

The water pump is a brand new aisin unit being driven by a new timing belt which is being tensioned by a new tensioner.

As far as a blockage, is there any way to test for that? It stayed cold (~145-155°, max 167° up a long steep climb) without a thermostat so it seems like there isn't a blockage, unless it's only partially blocked and would have actually been even colder.

 

[19963.4lsr5]

Leave your temp setting on max heat. That shuts off the external coolant loop.

Leave it on max heat.


Sent from my iPhone using Tapatalk

 

[19963.4lsr5]

Head gaskets could be on backwards blocking flow.

One of the gaskets could be leaking depending on surface prep.


Sent from my iPhone using Tapatalk

 

[alumarine]

Might try a new thermostat.

 

[DJRodriguez88]

Radiator, Radiator Cap, Thermostat, Water Pump, Timing Belt, Timing Belt Tensioner all new or nearly new.

Thermostat removed and tested anyway just to make sure... it works fine (vid).

Coolant coming out is the same color as the coolant that goes in.

Air in the system has been thoroughly bled/burped multiple times.

I'm still gonna try another thermostat even tho mine tested well. I already have the new one in hand and I boiled it and it performed almost identically so I don't see any reason why it would work.

I think it's time to start considering...

You can literally put the heads or head gaskets on the wrong side. If the HG is on the wrong side it will block the coolant passages.

Are you sure you put the left gasket on the left head and the right gasket on the right head?

Head gaskets could be on backwards blocking flow.

These other 2 threads I found describe my exact symptoms as well. So it may be time for me to start digging in again

Help! Overheating issues after new head gasket, can't figure it out


(toyotanation.com) 97 Overheating..Help

By the way, another observation I had:
sometimes my dash temp gauge begins moving well past halfway to redline when my computer still saying 185 degrees. If i leave it alone the gauge will continue on to red and my computer will read 210+ but what I believe this is confirming is that the coolant is not circulating and even with the thermostat out it will probably suffer from hotspots.

 

[DJRodriguez88]

Confirmed, Head Gaskets are on wrong heads.

This is a DRIVER-SIDE gasket i got from yotashop.com. On one corner it has L marked on it.

And here is a picture of my PASSENGER-SIDE head viewed from the wheel well with the splash guard taken down

<iframe src="https://drive.google.com/file/d/1q_HyynmEToc6AdkSQ8o3hn4L01sTpbKM/preview" width="640" height="480" allow="autoplay"></iframe>

 

[alumarine]

Glad you figured out your problem.

 

[phattyduck]

Glad you figured out your problem.

You get the gold star for guessing the issue first!

-Charlie

 

[alumarine]

You get the gold star for guessing the issue first!

-Charlie

Even a blind squirrel finds a nut once in awhile!