Another coolant loss thread. Advice needed...

[zguy1]

Hello everyone. It's been a while since I have posted here. Life has been crazy this past year.

For the past year or so, I have noticed that the coolant level in the overflow reservoir has been going down. I have been topping it off every now and then. I would say maybe a half cup or every 1000 miles or so. It could be more or less as I have really not measured it precisely.

Some background info on the vehicle. The car has 293k miles on it. It is 2008 V6 and I bought it in 2019 with 206k miles. For the first 40 or 50k the coolant never went low. I never had to add any. Around 255k or so, I noticed the coolant going down with no visible leaks. With the help of this forum, I was able to figure out that the radiator was leaking. I replaced that and all was well.

Around 275k or so, I started noticing loss again. The issue still exists but I believe I am loosing more coolant now and I would like to fix it if possible. There are no visible leaks anywhere. The only thing I could find is a tiny crust spot near the thermostat housing. See image below.

Any thoughts on what to check or replace?
Should I pull the spark plugs and check those?
Do I just replace the water pump since I have no information on when it was changed?

I want to do another road trip but am hesitant this time around.
Appreciate the help as always!

 

[Drcoffee]

Change the water pump, thermostat, belt and pulleys. If its not been done, do it before the fail.

 

[zguy1]

Change the water pump, thermostat, belt and pulleys. If its not been done, do it before the fail.

Thanks. I can't wait for Rock Auto parts so I was able to find a Toyota water pump and ASIN thermostat at Amazon that I could get in 1 day. The Toyota water pump is about $25 cheaper than my local Toyota dealer.

Any recommendation on brand and parts for pulleys?

 

[phatcheeks]

Any recommendation on brand and parts for pulleys?

Gates is usually to go to for those parts. I've been running the Continental belt and pulley kit for a little over a year now with no issues.

 

[5thToy]

Have you tested oil for presence of coolant?

 

[AuSeeker]

What year, V8 or V6?

 

[zguy1]

What year, V8 or V6?

It’s a 2008 with a V6. I just updated the original post as well as I forgot to put that information in it.

 

[AuSeeker]

It’s a 2008 with a V6. I just updated the original post as well as I forgot to put that information in it.

Ok, just wanted to know if it was one of the early model V6s that had head gasket problems from the factory, so since it's not a early model the question by [MENTION=360870]5thToy[/MENTION] is hopefully a mute question..but if the new water pump and thermostat doesn't solve the coolant lost issue then you may want to do some checking into a possible head gasket being bad just to rule it out, i.e. checking the coolant for exhaust gases and as mentioned checking the oil for coolant.

 

[zguy1]

Gates is usually to go to for those parts. I've been running the Continental belt and pulley kit for a little over a year now with no issues.

Okay, I will take a look at their pulleys. I already replaced the belt a year ago and I believe I put a Gates one on then.

Have you tested oil for presence of coolant?

I have not done any formal test. But I have not noticed anything obvious. I will be doing an oil change in the next day or so.

 

[5thToy]

Ok, just wanted to know if it was one of the early model V6s that had head gasket problems from the factory, so since it's not a early model the question by [MENTION=360870]5thToy[/MENTION] is hopefully a mute question..but if the new water pump and thermostat doesn't solve the coolant lost issue then you may want to do some checking into a possible head gasket being bad just to rule it out, i.e. checking the coolant for exhaust gases and as mentioned checking the oil for coolant.

Thanks, it occurred to me afterward I should have asked about exhaust gas as well. If If the system isn't leaking, it's either going through combustion cycle or getting in to oil.

 

[Drcoffee]

The oem toyota water pumps seem to fail quickly. I prefer Aisin parts

 

[TLChip]

Just had my timing belt getting done today, friend sent pictures of the old timing belt and water pump just starting to seep. Some was sitting on my belt. 84k -> 183k on the belt 7 years. Rad was leaking as well at the top drivers side.

Oddly though my other runner went 194k on the first belt (bought at 192k) and it was cracking but no leaks from the water pump. Original rad still on that too. 225k now
[MENTION=78997]Drcoffee[/MENTION] indeed the leaky pump was an oem toyota pump.

Edit: just noticed this was for v6 sorry I have 2 V8s

 

[zguy1]

Is there a way to avoid losing a lot of coolant when removing the thermostat and water pump housings? I would like to avoid a big mess and also to keep as much of my coolant as possible since it was recently changed.

 

[Drcoffee]

Is there a way to avoid losing a lot of coolant when removing the thermostat and water pump housings? I would like to avoid a big mess and also to keep as much of my coolant as possible since it was recently changed.

Yes. There are two drain cocks, one on either side of the block with a 10mm hex head that let you drain the block which is where the residual coolant sits after disconnecting the radiator. Open the radiator cap, and open the block drains.

What I did on mine was duct tape a plastic garbage bag to the engine under the water pump and draped the plastic into a bucket to catch the coolant that spilled out. A bath towel would be handy to wipe up the mess.

 

[phatcheeks]

The oem toyota water pumps seem to fail quickly. I prefer Aisin parts

Isnt Aisin the OEM supplier for Toyota? The new Aisin water pump I bought from Rockauto had the Toyota label scratched out.

 

[gm350reratliff]

Is there a way to avoid losing a lot of coolant when removing the thermostat and water pump housings? I would like to avoid a big mess and also to keep as much of my coolant as possible since it was recently changed.

Drain the radiator and the engine block and it will help minimize the mess when changing the T-stat and WP out. If you start out with clean buckets/drain pans you could filter the anti-freeze to re-use it but I would rather just start out with new coolant.

 

[Drcoffee]

Isnt Aisin the OEM supplier for Toyota? The new Aisin water pump I bought from Rockauto had the Toyota label scratched out.

Yes they are one of them. The question is, are all water pumps for toyota made by Aisin? You might get a different manufactured part when purchased at a dealer.

Aisin is a known quantity/quality.

 

[zguy1]

So I spent some time on the truck today. I have the new water pump and thermostat but I have not changed them yet as I couldn't find any leaks by the water pump, pulleys or anywhere on the truck. I even removed the shroud to check the radiator too. The radiator was replaced last year but I wanted to double check.

I proceeded to remove the spark plugs to check them and look inside the cylinders with a small camera. These plugs have been for about 35k miles. I noticed on cylinder #6 that the ceramic was whiter than expected or at least compared to the others. The piston also has some white spotting on it too. All of the other plugs are darker in comparison. Cylinder #4 piston had some white spotting but to a lesser degree. All of the other pistons (5, 3, 1 and 2) looked to be mostly carbon colored. I also noticed oil on spark plug #6 too. #2 had some as well so I am guessing there is a valve cover gasket issue also.

I also tried to use a combustion leak tester on the radiator but it never changed color to yellow.

I have attached the pictures below. I also included a picture of spark plug #6 when I changed the previous plugs at 258k miles. Those plugs were on the truck for at least 52k miles as they were on there when I bought it. You can see the plug looked different then.

Thoughts? Head gasket issue?

Spark plug #6

Spark plug #4

Spak plug #2

Piston #6

Piston #4

Piston #2

Spark plug hole #6

Spark plug hole #4

Spark plug #6 from last charge at 258k miles

 

[Drcoffee]

#6 looks fine. Id be concerned about #4. I havent seen a plug that bad in any toyota I have owned. Thats way too much carbon. I would seafoam the top end and add 1qt MMO to the oil on the next oil change to clean the piston rings. Change your pcv valve. It might be sucking in too much oil

Did you use a vacuum port to draw vapors from the radiator or the squeeze bulb? I was worried about mine when I bought. I ran a vacuum line from the intake to the device and bubbled it for 5 minutes. Still no change to the fluid color. If it didnt change color then you need to keep looking for the leak.

Re-gap the plugs

 

[waypoint]

#6 piston crown and spark plug look suspiciously clean, usually caused by coolant ingestion. Steam is an excellent carbon remover.

My next diagnostic step would be renting a cooling system pressure test kit from Autozone/Advance Auto and pumping it up to the cap's rated pressure. A head gasket will drop pressure slowly and steadily as soon as you stop pumping.

Are you having any rough engine idle on cold startup and/or hearing gurgling/waterfall noises from the dash (heater core)? These are often reliable indicators of head gasket failure when combined with coolant loss.