2004 Tundra 4WD keeps blowing off coolant.

You are probably going to think that I'm a proper pain in the ass, I don't mean to be.
It makes sense that mechanics want to get a job sorted in short times rather than waiting for several cycles but referring back to my Frontier, it gave me grief to varying degrees for the first three weeks that I had it, in which time I put nearly 4000 miles on it. That is somewhat more than a few cycles and more importantly I've done 2000 miles in it since refilling and burping it and had no further loss of fluid.
Mine was simple to burp and that is the only thing I did differently between the first 4k and the last 2k, I'm not saying that burping is the OP's issue but it is one that shouldn't necessarily be overlooked.

One would hope that with the passing of several days that the OP has performed this procedure as per the FSM, thus eliminated an airlock as the problem and either cured the problem or having to look at other causes.

 

Yeah as @assassin10000 said, your cap pressure is too high if it really is 24 psi. Should be 13 psi.

 

I believe you. You're not being a PITA. I know nothing about Nissans, I'm just saying, it wasn't an issue for my truck, other than the first cycle as I mentioned. I had do nothing more than fill the radiator, and keep filling it with the cap off while the truck idled for a few minutes until no more would go in, close her up, fill up the reservoir, let it all get hot, and then shut it off and let the system top itself off. This is the same thing I've done on all my vehicles, subarus and Toyotas, and its always worked the same.

 

Nah.... Not seeing you as a PITA.... I do have to ask what is the difference in a "Proper" PITA and your typical "Garden Variety" PITA?

I never take anything regarding help as untoward or undesirable, particularly post having asked for the help.

I did a search on the Google Monster and it was recommended that the Truck be parked facing uphill on a incline, allowing it to cool, remove cap, turn Heater to Maximum setting, start truck and run to reach operating temperature. The instruction was to watch for any bubbles. When, if, bubbles cease, top of reservoir, reinstall cap. Another poster suggested if the incline trick did not solve the issue there was a "bleeder valve" under the Intake Hose behind the Thermostat housing to vent air that did not cooperate.The process for getting access and operating the bleeder required a hose to rout coolant. etc... and did seem to be a bit of a PITA...

 

13 it will be then...

 

A proper PITA is like those little bastard Chihuahua's who don't know when to give up.

 

Welp.... First day I've had a chance to properly fool with the Big Gray Machine... From the description and what I saw the thing needed the burp sequence big time. I took the cap off, turned the heater on high, and ran the thing up to temp and then about 10-15 minutes more. At first it didn't seem much was going on then I began "Flexing" the hoses and was gratified to see bubbles coming up to the radiator neck. None were huge but they were about nickle sized and after each one, or two, per series repeated a number of times, the fluid level in the neck went down. I added more coolant and repeated. It took a while for the bubbles to slow and the addition of coolant to cease, but I do feel confident at least something changed. I added about a pint to a quart beyond what I had been doing as a preventative measure.

It does seem now that air was indeed A problem if not THE problem.

 

Update: Radiator has a small leak. Wondering if the over spec radiator cap did that?...

 

Could be, but 20 year old radiators get cracks, holes etc. In any case, we know the problem now. Its probably sucking air in that hole everytime the system cools down. Get yourself a new Denso radiator and your good to go.

 

That's the plan!

I still wonder that a Toyota website gave me that cap by VIN. I'm wondering how that happens?

 

It's possible they packed the wrong part. I've had that happen with a gas cap. The part # on the bag was correct but the cap inside was wrong.

 

Very possible. I hadn't noted it when I opened the cellophane. I didn't even remember, or notice more like it, if the OEM part even HAD a number or pressure rating stamped on it (It was immediately tossed). It did have a different decal / label on it. The new cap had the 24.1 on it, the one on order has 8.8Kpa stamped on it which is something like 12.9psi....

 

Are you positive about the 3001 portion of the part # ?

According to McGeorge Toyota for your vehicle it should be 3100

1998-2007 Toyota Engine Coolant Thermostat 90916-03100 | Toyota Parts (mcgeorgetoyota.com)

 

That IS the one I received via the # on the bag it came in. In poking around it seems the 24.1 PSI is not correct and the 13psi is the correct value... You know any different?

I am looking around for the bag, heck, the 3100 was the Thermostat.... The Radiator cap was something else...

 

Pardon my ignorance but which one are you saying you received….3100 or 3001

 

Not your ignorance. The discourse has become somewhat conflated. I received the

$22 90916-03100 Thermostat

90916-03100 Thermostat (Which is correct). What I received that I have reason to believe is incorrect is the actual radiator cap I was sent (same source). I'm pretty sure it is stamped with 24.1psi and I am told it is supposed to be 13psi.

The Radiator replacement will be Denso via Rockauto....

 

Ah, you probably got Amazoned. Happens all the time.

 

Amazon has it's uses but dang... That IS a common occurrence...

 

Yup. We tend to warn everyone. We call it scAmazon around here for a reason. 50/50 chance you're getting a counterfeit. These days it's more like 75/25 and the odds aren't in your favor on that ratio. scAmazon is the new fleaBay.

 

I would avoid eBay and Amazon at all costs. Too many counterfeit Chinese Toyota parts from "authorized Dealers." There's absolutely no means of verification from Amazon or ebay.

 

Update!

Thanks to all that contributed.... It seems to have been the radiator in the end (Hence I quote the first comment to list it.) . Replaced that and all has seemed well.

It is interesting that for all the efforts, and it WAS a lot of effort, I did not find the radiator leak until I went thru the burping procedure that seemed to allow a good bit more coolant into the system than had been allowed prior to that. In short all the advice, including where to buy parts, etc, came in very handy for doing the thing the way it needed to be done.

 

This turned out to be the way I found the leak... The Goddess did the revving and I did the watching.... It was a pretty good stream when it finally started spewing but it DID take several attempts and holding at the 3,000 mark +- for it to start. When it started it was consistent.