How to handle potential coolant leak?

Bought a used 4.6L 2018 tundra, 30k miles. I noticed that the coolant level was below the min line after buying it, i know, stupid mistake. I topped it off and brought it into dealer they did a pressure test but said it was fine.

Its been a week and about 500 miles and the level is now an inch below the max line after cooling off over night. So i am pretty certain there is a small leak. Nothing is on the ground or around the hoses or caps in the engine. I am bringing in back into the dealer next week and telling them to search MORE and find the leak...

How do you recommend i have the dealer actually find the leak? What questions should I ask to make sure they are doing a thorough check of the engine? I don't want to worry about this on such a new vehicle... There is always the chance that there is no leak, but considering the level is dropping; i am very confident in this.

Thanks

 

1. Keep a couple of gallons of coolant in your truck.
2. Check your coolant daily. If it keeps dropping, insist that they fix it. If they won’t or can’t take it to another dealer. Call Toyota corporate and open a case if you get no resolution. Your truck should still be under the power train warranty.

 

Good idea about calling corporate. Thanks. Do you think the power train warranty covers coolant leaks? Like water pump? Etc.. not sure where the leak would be

 

You’re under 36k? Pretty much everything is covered until 36k. After then I’m not sure exactly what is covered under the power train warranty. If your coolant level is going down because of a blown head gasket, it should be covered. If it’s something else, who knows but it won’t hurt to push them on it a bit.

 

Did you buy an extended warranty when you bought the truck? If you did, it should be covered regardless.

 

Bet it's the radiator...check the hose connections first.. if you can't visually see a thing, talk to Toyota corporate and get it fixed!

 

Yes kind of silly tho to buy it for a Toyota but whatever

 

It’s the same principle as a condom. You’d rather have one and not need it than need one and not have it.

 

My waterpump was weeping coolant when I bought mine, but wasnt dripping on the ground. Check the bottom of your pump and see if it has caked up pink antifreeze.

 

This^^^^^ Look for a pink crust at the bottom of the water pump although 30K isn't many miles at all.

 

Ok thanks. Can I see it if I crawl under the engine?

 

Yep. Water pump is located at the bottom front of the engine. I am assuming the 4.6 is somewhat similar to the 5.7 layout.

 

Are you sure it’s leaking? Unless I’m reading it wrong, you are checking the overflow tank. The fluid level in that tank changes depending on how hot the coolant is. It’s an overflow for expanding fluid. Look around the engine for pink splashes and keep an eye on it. If it doesn’t get lower in the radiator under the cap, you’re good like they said.

 

Yes i am checking the overflow tank, but it seems lower even after cooling off for 8 hours...What do you mean by radiator under the cap, how do i check that?

Thanks

 

Please see below, if that's my water pump from under the engine..It looks good, correct? I did notice some red residue under the hose, perhaps the small leak, easy fix eh? Posted that picture below

**Nevermind, this is not the pump. See new post below, i should have located it now

 

Pretty sure this stills apply's past year 2011.
Water Pump Inspection and Diagnostic:
http://media.fixed-ops.com/Toy_ServiceBulletins/sb0117t11.pdf

 

water pump looks like this>>

 

Now i see, please see below. I am pretty sure i am pointing at the pump. It is connected to the shaft of the fan, correct? I see no red residue...(The second picture i am pointing at the belt for reference, the pump should be mounted behind this belt...unless I'm crazy)

 

I meant check under the actual radiator cap, not the overflow tank and see if it’s low. Your engine looks clean to me. I don’t see any coolant leaks. Just that little bit by the radiator cap. You could try changing the cap. Those go bad sometimes.

 

Thanks

 

Your water pump looks fine. No ink crud present.

 

Thanks for this EXCELLENT TSB!

 

That appears to be a replacement cap, which may indicate previous issues with coolant loss or overheating. There also appears to be coolant residue on the tank directly under the cap. The cap has either been loosened when the coolant was still hot or the gasket is leaking. It is a Denso cap but the OEM cap on my 2017 is yellow/black. As a minimum, replace the cap with one from your Toyota dealer.

Your arrow is pointing to the mounting bracket for the fan/fluid coupling pulley. Not that it matters, but will you notice that the fan is not centered on the engine, or mounted on the water pump pulley like old school V8s; the fan/fluid coupling is offset to the driver-side. The water pump drive pulley is directly above your white arrow in your photo. The area you're showing in the lower part of that photo is exactly where seepage/crystalline debris from the pump drain should accumulate. The pump shaft drain is on the driver side of the pulley. No leakage residue there.

Having said that, there appears to be some pink residue directly below the thermostat housing that I've marked with green in the photo below. That residue is not crystalline, and is on the opposite side of the water pump pulley from where seepage or leakage from the pump would be expected. That residue is probably from a coolant boil over, but I would make a very close inspection of the water pump. You are new owner and, not knowing what to expect on your new vehicle, are more observant. If the pink is from the water pump, it is either temporary as the TSB said, or it will get worse. Keep an eye on water pump until you don't lose coolant any more.

Meantime, keep a constant vigil on your coolant reservoir level and make up any deficiency with Toyota coolant. These aluminum engines do not handle overheating well at all. There are multiple cases of people not checking their coolant level on a long trip, or, knowing that they were overheated, tried to limp home. Try "limping home" only if you can easily afford a $7K engine.

 

This is very helpful, i really appreciate it. I am going back to the dealer Tuesday and will request a new cap as you mentioned. And I will show them this picture with your arrow of the residue. Let me ask you about the overflow tank level because I am still not clear how this works.

So i understand coolant expands when hot, obviously, but my thinking is that if I check it every day or so after it has been cold for 8+hours over night then the level in the overflow tank should be constant. Is that accurate? If not, then really really close.

Currently, i have driven about 1000 miles after filling the tank to the max line (when cold) and I checked this morning the level is about 3/4'' below the max line and I have not seen the level at the max line since a few days after topping it off. That leads me to believe there must be a leak present? Also, as I stated, right after buying the truck I noticed that the cold level was actually BELOW the min mark...With only 30k miles, that would mean there was a leak before I bought it correct? What else would explain such a low level?

I will be very direct with the dealer about the cap, and the pink residue you pointed out and will request a detailed inspection of the water pump. I hope I can resolve this soon.

Thanks again

 

Yes, if you are not actually losing coolant, then your thinking is correct.

You (and we) are looking at a relatively short-term "snap-shot" at this point. If there isn't a coolant leak, then one possible explanation would be there was a previous incident of overheating, or a continuing tendency to overheat, and the air wasn't thoroughly purged out of the cooling system when refilled (note replacement radiator cap). In that case, you shouldn't have to keep adding coolant...one or two additions should correct the problem.

If there is another cause for overheating that hasn't been discovered yet (faulty thermostat, bad water pump, other), the high operating temperatures would cause the reservoir to overfill and gradually lose coolant that way until you actually do overheat and boil over.

Another possible explanation for slight loss of coolant in hot, dry climates is evaporation from the reservoir, but your loss is too rapid for that to be the cause.

 

I will continue to keep a daily check on the cold level. As well as bringing it in the dealer on Tuesday. So bottom line, if I keep noticing the cold level lowering over time, then there is definitely a leak? I will stay vigilant with the dealer and Toyota corporate if I keep noticing this and this particular dealer is unable to find the issue.

 

Is there any white smoke from your exhaust? That indicates a coolant leak also. Id say replace your cap and, depending on what they tell you about that little spot next to the cap and circled above, clean it all off and keep an eye on it.

I wouldn’t start arguing with the dealer and calling Toyota corporate yet. There might not even be anything wrong. You’ll end up being that guy that they don’t want to help cause they think you’ll argue everything. Do you want them to start tearing your truck apart if nothing is wrong?

 

That would be my conclusion. And, if there isn't any evidence of leakage in the usual external locations in the system, I would worry about the internal leak scenario @timsp8 outlined. You'll need a powertrain warranty if that's the case.

How did your temperature gauge behave during that 1000 miles of driving? Was there any evidence of overheating on the gauge?

 

I had an old Chevy that would pass pressure test but would leak when it was cold. Finally found where the bottom of the top inlet flange wasn't soldered inside. Under pressure it would seal up but when cool the coolant leaked around the hose inlet and that bottom part. Nothing more to add except just because it passes pressure test doesn't mean there's not a leak.