My mom drives a 97 4Runner 2.7/auto 4wd.

For about a year now there has been on and off overheating issues. The coolant in the rad/overflow looks like dark red clay consistency. It has been flushed now at LEAST 20 times, with no change. The trans fluid level and color/smell, everything does not change, nor is the motor oil. So I don't think the rad itself is mixing ATF/coolant. And that the oil is not mixing with the coolant.

Sometimes under hard acceleration / pulling a tough grade, gargling and a loud sucking noise can be heard behind the dash / heater region. And as of late, there is no heat from the front. (blocked heater core?) But the rear heat works fine.

I don't know what I should replace for her? I would love to start fresh with new rad/hoses/heater core, but I really don't know what the source of the problem is.

Any ideas?

 

I would really look into the getting an external trans cooler, when possible.

Always back flush a radiator You'll be surprised how much more comes out.

How old is the water pump?

Check under the oil cap for chocolate milk looking goo for a head gasket issue...

Has the water pump ever failed in operation? My parents had an heating issue after a failing WP, I back flushed it and tons of metal debris came shooting out. They havent hadnt an issue since.

You can physically test a thermostat with a pot of water on a stove and a thermometer...or replace it

I have no idea about the front heat and rear heat. Not sure if they share heater cores. The only thing I can think of is that one of the levers for the front heat is stuck or broke.

 

Only thing I can think of is some sort of Rad stop leak gunk that the PO used that never left?

 

Radiator rusting out?

 

if the heater core is clogged.. then the radiator is done for as well. Replace both and use only toyota red coolant. That clay can happen when someone mixes green with red coolant.

 

The rear coolant lines will rot out eventually. If you look at some of my old posts last year. I bypassed them because they blew out.

Not exactly the same thing but just to put on your mind.

 

That's what I was leaning towards. We've been running water all summer seeing how I flushed it at least 3 times a week.

Now say I get a new rad, heater core, hoses and such...How would I go about getting this clay like crap out of the block as to not start this all over again running it through the new parts?

Also, what else besides Toyota brand red? Whats it's equivalant at the big name stores (Autozone, Napa, Advance Auto, etc.)

 

Isnt the rad. aluminum? And the lines copper? How do they rust/rot? Or is the mix of red/green coolant by the PO eating them away?

 

While this certainly happens, it must take a lot of salt. I'm in NJ, where they love salt, but don't get all that much snow, and mine (1999 and 131K) are pristine. It is something to look at, but don't assume they will die anytime soon unless they look like they will. Living by the ocean will help make this a bigger problem for you in Newport than for the OP in PA.

To the OP: Front and rear have separate cores, heat valves, fans, water lines and air controls (front only). So all these are your prime suspects on front heat problem, although I assume fan is running. I haven't done it on a 4Runner, but I have done the garden hose flush on a heater core (switching back and forth with a drain hose. You just have to identify the inlet and outlet hoses. A little compressed air at the end followed by a half gal of distilled and some more air will get that evil hose water out.

The overheating is thermostat, radiator, water pump, or engine water jacket. Fan clutch should also be ruled out. The first four are in order of difficulty. So first change or test thermostat.

Then the rad. I don't get the no change in fluid deal. Is it shiny red when you put it in, and then gets like clay 20 times right away? What happens when you pull bottom hose and stick a garden hose in the top? (Get over the distilled obsession, if you have it, you've got bigger problems and almost all the hose water will drain out.) Is there good flow? How does it look at the top? If not flowing well and looking good, swap it or send it to a pro. If all good so far, consider WP/timing belt change. How many miles on TB and WP? Or, at the least, pull the cover and look at the WP. Any sign of leakage and there's your problem.

You just have to hope that the problem, whatever it is, is not inside the engine. That will not be fun.

 

Zerex Asian formula (NAPA, Amazon and other places) is identical to Toyota pink. $11/gal and you use it full strength.

 

I'm not sure what they are, but in the pics I have seen they corrode from the outside in, and in high salt places. The lines (in the pics I saw) were fine where not exposed to road spray. My guess is aluminum, not copper.

 

Thermostat has been changed twice, there is a Failsafe in there now FWIW.
"No change in fluid" was to clear up the quick readers jumping right to headgasket conclusion. As well as the trans cooler mixing with the rad.

Flushing the system never netted true 100% clear H20. Was always tinted red/rust color. And within 2-3 days, was back to clay color & consistency.

The no heat deal has to be due to the core being clogged. All is well on the electrical/cable end of the heating system. One day there will be heat, the next none. There is a "sucking a milkshake through a straw" sound from the center of the dash, usually followed by a rush of fluid sound, followed by some heat.

Im going to say the PO mixed red/green coolant and created this beast of a mix.

 

I'm not doubting you, but do you have a link to something that states that Zerex Asian is the same as Yota pink?

 

http://www.napaonline.com/Search/Det...130_0265450281
http://www.napaonline.com/Search/Mul...130_0265450281

 

http://www.ashland.com/press_room/ne...ail.asp?s=1700

While I can't find an official statement of the make-up of Toyota Pink, there are a number of sources out there that agree that it is a phosphated HOAT coolant with no silicates or borates, as is the Zerex Asian Formula. Google away, I did. Read the BITOG Coolant sub-forum. ZAF is the only after-market coolant that can say that. To be precise, I should have said it is the same base coolant, the same anti-corrosion technology, avoids the same ingredients that Japanese engineers reject-silicates and borates--and is the same color and the same strength.

 

Thermostat was never the most likely, but you have to rule it out because it's cheap. Thanks for clearing up the fluid thing. Coolant maintenance is then probably the problem. As I understand it, the red mixed with old-time green would sludge/gunk up. That kind of green is no longer around. What DOES happen is the different anti-corrosion technologies cancel each other out ("they are antagonistic") and the coolant mix no longer protects against corrosion. So the cause could be mixing or simply never changing the coolant, allowing the whole system to degrade, cores, radiator, water pump, and engine coolant passages. At least that's what it sounds like.