cbodom

thanks for this great forum, ive changed my maf and starter in the past but ive had enough learning experiences for me ...
anyways i searched and couldnt find...


check engine light came on, autozone pulled P0115 Engine Coolant Temperature Circuit Malfunction Trouble

the truck can only drive 10mins or so till the temp gauge hits red (and i panic and pulled off and let it cool down), it smelled hot when i got home
starts and drives fine for the 10mins though...

2000 4runner limited
111k miles

nothing major changed so my uneducated guess was water pump failed?
radiator flush? the red coolant is full...

just trying to do some research before i walk into a mechanic (btw if someone happens to know naperville il area could you recommend a mechanic for me)

stir_fry_boy

usually the water pump leaks through the weep hole and you loose coolant. Maybe consider a thermostat sticking, I know it is really rare, but can happen. Also consider that usually when something is blocking the radiator, it is progressive. Don't know if it was or not.
Captain obvious wants to mention that never drive with an overheated engine especially a Japanese engine. The aluminum heads will warp soooo quick!

cbodom

appreciate the response, ill limp into the shop and see what they say

mt_goat

Check the coolant flow in and out of the radiator and the air flow through the radiator. Is your return radiator hose getting hot? If not, the radiator might be clogged or a bad water pump or stuck t-stat.

stir_fry_boy

Good idea mt_goat!
He is right, idle the engine - be careful not to overheat and put one hand on the lower hose and one on the upper after the engine is warmed up with the engine stopped and they should be the same temp. If they are not, you can determine that there is no coolant flow. Check the t-stat if they are not the same temp. Also, if the water pump is leaking there should be dried coolant at the bottom of the timing belt cover around the area of the crankshaft pulley. If there is, it has been leaking for a while.

GSGALLANT

When the engine's hot, the lower hose should always be cooler than the upper hose. Otherwise, what would be the point of having a radiator?

Also, as far as your water pump goes, try this test: With the truck at normal running temperature, but not overheating (so 6 or 7 minutes after you start it), put your heat selector in the 4Runner on full hot, and turn the heater fan on high. Do you get continuous hot air from your vents? Leave the fan on high for a few minutes and make sure the air stays hot. If it stays hot, that tells you the circulation in your heater core is probably fine, so your waterpump is OK. Anyways, like mentioned above already, typical water pump failure would be bad bearing or seal leak... both of which would be noticeable (noise or puddle of coolant). I would think that it would be rare for the W.P. shaft to shear (so that the impeller is not turning) or for the impeller to be worn enough so that the W.P. stops developping pressure on the outlet. Those would be the two cases that would cause the W.P to stop generating coolant flow.

I'm not sure that your two problems are related. Did they (overheating problem and P0115) start at the same time? P0115 doesn't come on to report an overheating situation. It comes on to signal a short or open circuit in your engine coolant temp circuit, and neither of those two problems would cause your engine to overheat.

mt_goat

Yeah the return line should be cooler but it will still feel warm if the coolant is flowing through it. If your return hose (lower hose) is just as hot as the top hose then you might have an air flow problem, check the fan clutch.

cbodom

awesome i love this forum

autozone pulled p0115, 5mins later the needle went red... i never noticed the needle moving before that (but i never payed attention)



just had a chance to look at it after it sat in the garage 2 days... all the red coolant leaked out all over the floor ( the resevoir is now empty)

do i just put any prestone coolant in and drive to mechanic. or do i need the red stuff from a toyota dealership... thanks everyone

stir_fry_boy

being consistent is the key......

GSGALLANT

Stick with what's in there... Toyota red and distilled water mixed at 50:50 or so.

So... where's the leak coming from? Water pump? Hose? Rad?

stir_fry_boy

Is there really that big of a difference from idling? I wouldn't think so becuase the t-stat is opening and closing instead of just being open and letting hotter coolant flow to the radiator and therefore cooling it down before returning it to the engine. Wouldn't it be hard to feel the difference just by feeling the hoses if the t-stat was opening and closing and maintaining a temp of 83 or whatever it is when it opens at idle?

stir_fry_boy

Your engine may not be overheating at all..... Here is directly from the FSM:
Troubled areas:

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
If I am not mistaken, the engine coolant temp sensor is in the bottom of the radiator somewhere. I don't know if this helps. It doesn't mention anything about the engine truly overheating.

GSGALLANT

Well, unless he has some other method of measuring coolant temperature at his disposal, it's best to trust the instruments that are available to him on the truck (he said that his coolant temperature needle is hitting the red).

Since the coolant temperature gauge and sender are totally seperate instruments and circuit from the coolant temperature sensor that communicates with the ECM (and is throwing the CEL), the prudent thing to do is not drive the vehicle when the coolant temp gauge is showing hot.

GSGALLANT

I'm not following exactly what you mean here. Is it the word "hot" that I used in the first paragraph that you're questioning? If so, I guess I should have written "normal running temperature" instead... or "not cold". I didn't mean when it's hotter than normal.

On a vehicle with a radiator that is functionning well, after a long drive, I can get home and hold my hand on the bottom of the radiator (the metal parts). There's not a chance that I can do that on the top of the radiator without burning myself.

Could you clarify what you're asking with respect to the "idling" part?

stir_fry_boy

I don't disagree at all that the car shouldn't be driven with the temp gauge at hot. All I was trying to contribute is what the FSM says about the code that was thrown. I completely agree with you.

stir_fry_boy

Sure thing. I was trying to explain that without much air moving through the radiator, running the engine and not driving (my idling reference) with the t-stat opening and closing frequently that the temperature of the coolant should be about the same (or relatively equal) between the upper and lower radiator hose if it is working properly. Because the t-stat is opening and closing, it more maintains the temperature of whatever it opens/closes at. Of course you would feel a difference in the hoses if you went for a long drive and felt the hoses because the t-stat would be open almost all the time. But how would they feel if the t-stat is stuck closed? The top hose would feel cold and the bottom hose would feel hot close to the t-stat and less warm near the radiator right? There should be a pin in the t-stat to still let coolant pass if the thermostat does stick closed.
He probably overheated the engine a little due to the antifreeze spilling out onto the ground and was probably above the pressure of 13 psi (when temp increases, so does volume). It may have overfilled the overfill reservoir onto the ground.

cbodom

shop called and said

antifreeze coolant had mixed into the transmission fluid??

(this explains some gear shifting roughness )

theyre replacing radiator and flushing out things.. hopefully the trans wasnt damaged..

thanks for the suggestions though yotatech..

mt_goat

That's happen to a few others too:

https://www.yotatech.com/forums/f2/b...cooler-126953/

cbodom

you sir mr goat are amazing
i see your help in all those other threads too

anyways shop flushed it 4times and is still coming out pink...
he wanted to flush it some more and i approved it $$$

not much choice on my end, from reading the old threads no bulletins from toyota on this?

really unacceptable for such catastrophic failure to occur destroying a transmission when all recommended maintenance has been followed...

GSGALLANT

That's unfortunate. Had you mentioned the rough shifting in your original symptoms list, it wouldn't have taken two posts in this thread to diagnose your overheating problem. Those two symptoms together yell out "blown tranny cooler".

Hopefully you caught it early enough so that you didn't ruin your tranny. Your engine should be fine.