Toyota owners, I need your help!

[Trigger T4R]

I’m having a problem with my 4runner (04 4.0L V6) and hoping I can get some input from the Toyota owners out there.

It keeps spewing coolant out of the overflow reservoir for some reason and I can’t figure out why. I’ve taken it in to my mechanic 5 times now and spent about $600. They keep giving it back to me saying it’s good to go and the next drive I take it does it again. I had them replace the thermostat the last visit and same result. Drove to Tustin today with ac on and got home to see more had come out. They said water pump shows no signs of failure, they checked for head gasket failure and said there was none. So if it’s not the thermostat, water pump or head gasket, & never overheating, what is the problem?? Something is making the overflow reservoir fill with coolant and come out the tube near the cap. I’m at a loss.
Any suggestions?

I’m missing out on trail runs because of this and I need it fixed!

thanks for your help in advance.

 

[Trigger T4R]

Clogged radiator or heater core maybe?

 

[Offroadnutz]

Has the radiator been replaced with a larger one?
When I replaced my 2row with a 3row I had the same problem because the reservoir was then undersized. I installed a larger reservoir and solved the problem.

 

[Offroadnutz]

You might also try over at yotatech.com

 

[Trigger T4R]

Thank for the reply!

the radiator was replaced with an aftermarket replacement before I bought it. I believe it’s similar to oem as in not upgraded. I’ve had the truck for 3yrs now and never had this problem until recently. My thoughts after reading the 4runner forums is that the radiator may be clogged somewhere or the hose from the ac compressor is clogged. It only seems to do it on long drives with ac on.

I’m taking it back to my mechanic this week and asking why they can’t recreate the problem? They said they drove it about 80 miles up hills and gave it back to me saying it’s all fixed but I take it out once and it does it yet again.

I’ll be getting a second opinion at this point. Ya I see yotatech online & was going to give them a try, they have decent reviews. Do you have any experience with them?

 

[Trigger T4R]

Oh you mean the yotatech forums. There’s a shop with the same name near me I thought you we’re talking about.

 

[Trigger T4R]

Trying toyota-4runner.org as well but I haven’t posted enough to start a new thread.

Thanks again for your advice!

 

[Offroadnutz]

No problem. Let us know what you eventually find out.

 

[ryanorr280]

Does it overheat at all? Or just push coolant out of reservoir?

 

[Trigger T4R]

Does it overheat at all? Or just push coolant out of reservoir?

No overheating at all. Stays cool as a cucumber, just below half on the gauge. Just pushing coolant out of the overflow. I also replaced the radiator cap hoping that was the cause to no avail.

 

[Brett L.]

Does it overheat at all? Or just push coolant out of reservoir?

No overheating at all. Stays cool as a cucumber, just below half on the gauge. Just pushing coolant out of the overflow. I also replaced the radiator cap hoping that was the cause to no avail.

I'm not a mechanic. Now that that's out of the way.

A quick search online keeps coming back to either too much coolant in the system or a bad radiator cap. It seems you've covered everything else that comes up as a possible cause.

 

[Brett L.]

Just realized that you replaced the cap. I'm blind!

 

[Trigger T4R]

I'm not a mechanic. Now that that's out of the way.

A quick search online keeps coming back to either too much coolant in the system or a bad radiator cap. It seems you've covered everything else that comes up as a possible cause.

That’s why it’s so frustrating lol. I checked the level when I picked it up from the shop and it was at the full line, after the drive to Tustin it was full to the top again. Idk
It’s probably something simple that is being easily overlooked like it usually is. I hope anyway.

 

[Smileyshaun]

Just because the temp gauge says it’s running cool doesn’t mean it is . Borrow or pick up a remote temp sensor ( the kind of thing you pull the trigger and get a temp reading ) and check the radiator all over for cool spots , check everywhere coolant runs through . If it’s easy to get to replace the coolant temp sensor .

 

[Trigger T4R]

Just because the temp gauge says it’s running cool doesn’t mean it is . Borrow or pick up a remote temp sensor ( the kind of thing you pull the trigger and get a temp reading ) and check the radiator all over for cool spots , check everywhere coolant runs through . If it’s easy to get to replace the coolant temp sensor .

Ah great idea! I have one of those, I’ll try it tomorrow. As for the coolant temp sensor I didn’t realize that could be a problem so I’ll have them check that out.

The coolant never sprayed out like an overheat would do, and ac blows cold as it should consistently so I don’t suspect it’s overheating even if the sensor is giving false readings. But something I will double check now for sure.

thanks!

 

[RJB46250]

Great idea, I use the same method to check the thermostats on my outboard motor

 

[ryanorr280]

Yep, that’s a great plan to try. Always better to double check temperatures to be safe.

Also worth asking, does it do it if you start off with the coolant at the lowest “in range” level in the reservoir? Or only if filled to the “max” to start with? I only ask because I know some vehicles will puke coolant out of the reservoir overflow if filled to the “max” line when cold since they do push coolant out of the radiator as it heats up. But leaving them at the lower level will allow the fluid to fluctuate levels without overflowing.

 

[Trigger T4R]

Latest report:
Spoke to my mechanic today, as well as another shop for second opinion.

My mechanic did a thermal camera test on all components and said they found no “cold” spots on radiator or hoses which indicates no blockages. I asked about the coolant sensor and he told me it has a coolant switch and a sensor. The switch would throw a code if it were failing (no codes thrown) and the sensor controls the dash gauge, so if it were failing, the temp gauge would not show cool on start up and rise to temp when it comes to running temperature, the gauge simply wouldn’t work at all (it is currently working properly). I also mentioned the overfilling of the reservoir, and he told me they use a vacuum to fill the coolant and there wasn’t any reason for a full reservoir to evacuate coolant as there is plenty of room for levels to raise and fall at that setting.

The other shop I spoke to (he used to be head tech at crown Toyota) went through all possibilities with me and came the the same conclusion, no idea. Lol

So... I monitored the level in the reservoir today before I started it, and after the drive to and from work. Levels stayed pretty much the same just under the fill line. I’m thinking there was just a bit too much coolant in there and it just needed to level itself out. I will continue to monitor the same this week and hopefully it continues to be stable. I will let everyone know if it happens again and we’ll go from there.

Here’s a before starting pic from today:
And the pic after the drive:
This is a pic of the residue left from the trip to Tustin this weekend (after we picked it up from mechanic on Friday and cleaned it thoroughly so we could see any new drainage (so you all can see what I’m talking about)
Thank you to all that posted suggestions, I very much appreciate your help on this and your input has been crucial to helping me figure this out!
Hopefully this issue is resolved, I’ll let you know at the end of the week.

 

[Shakes355]

Don't trust your gauge for minor temperature fluctuations. Additionally, the ECM will only throw codes for temp if A) The engine doesn't warm up fast enough or B) The ECT sensor reaches it's designed voltage range limit (normally about 250 degrees).

While cheap caps with weak springs, hard seals, and poor fitment are a very common cause for your concern, it's quite possible that you have a minor over temp problem. Pushing coolant into the bottle is the normal operation in this case (as opposed to bursting hoses and radiator tanks).

The 4.0's have a somewhat systemic head gasket problem. I've done a handful of them so be absolutely sure that's not the case.

You might check your clutch fan. After you get to work, shut the engine off and see how easy the fan turns by hand. It should give you a fair bit of resistance (it locks up when hot and free wheels when cold). If it spins freely fresh off your long commute, that's a good place to start.

 

[Trigger T4R]

Don't trust your gauge for minor temperature fluctuations. Additionally, the ECM will only throw codes for temp if A) The engine doesn't warm up fast enough or B) The ECT sensor reaches it's designed voltage range limit (normally about 250 degrees).

While cheap caps with weak springs, hard seals, and poor fitment are a very common cause for your concern, it's quite possible that you have a minor over temp problem. Pushing coolant into the bottle is the normal operation in this case (as opposed to bursting hoses and radiator tanks).

The 4.0's have a somewhat systemic head gasket problem. I've done a handful of them so be absolutely sure that's not the case.

You might check your clutch fan. After you get to work, shut the engine off and see how easy the fan turns by hand. It should give you a fair bit of resistance (it locks up when hot and free wheels when cold). If it spins freely fresh off your long commute, that's a good place to start.

Thanks for that advice!

My mechanic assured me there is no head gasket failure as they did 3 different test to check and they do have state of the art diagnostic equipment.

Don't know If you can tell from pics but I replaced the radiator cap with an oem TRD 1.3 bar. The factory cap is 1.1 bar. From what I’ve read and was told by dealership it won’t negatively impact the system, should actually help by raising the boiling temp of the coolant. Says it’s for high load conditions. Given my lift and tires I assume that would be better. Let me know if you disagree.

I will check the clutch fan tomorrow as you discribed and report back.

latest update:
I’ve taken pics of before starting and after drive levels of coolant in the reservoir as well as cleaned all residue left by the last overflow. As of yet, the level has dropped to the low fill line before starting and just below full line after driving. No overflowing at all so far. I will continue this monitoring for the rest of the week and hopefully I don’t see any further drops in the levels. Fingers crossed.

Thanks again!