I’ve got a 2010 Toyota Tundra 5.7l that the dealer said I needed a water pump replaced on. I did that myself but I can’t see any leaking but my radiator keeps going down and the overflow bottle doesn’t fill when hot.

Is it possible I just need more coolant? I added 3 gallons after the pump swap, everything I see says it should only take 2.5gallons for a pump swap. That’s if you don’t drain the block down etc., which I did not. I have a few splatter spots under the hood from what I think was spilled coolant when I changed it.

The pump itself is really hard to see but doesn’t seem to have any buildup around it.

Any white exhaust or water in the oil?

Exhaust seems fine and the oil is nice and dark, changing it now. I’m pretty certain it’s not a head gasket but I’m not a professional.

I did find some more spray evidence on a hose. I hope I didn’t mess it up.

Back in the day, water pumps had a hole, usually on the bottom for purging air. When the bearings start to go in the pump, coolant will come out of that hole. Sometimes not seen without a load on the engine

Maybe try some coolant stop-leak?

Known Tundra maintenance item. 10 years old. Replace water pump. Replace coolant. Use OEM parts.

Just on general principal I would replace the 10 year old radiator cap... if you haven't already.

FYI, they do make Fluorescent Leak Detection Dye for coolant.

Is the level steady In the overflow from day to day after each heat cycle? If so I would say everything is fine. If level is slowly lowering you have a leak and should check that your hose clamps are properly placed and then pressure test the system.

Some of this is restating the obvious, but maybe saying it differently will help.

1 head gasket leak can put coolant in the oil/crankcase. Oil will look Milky or chocolate brown. Could even look like chocolate milk.

2 head gasket leak into one or more of the cylinders. I had it happen sporadically. Leaked when cold, warmed up and stopped leaking. This puts the coolant out the exhaust pipe. It is often harder to start, but not always. You won’t see a leak, it just disappears.

3 carefully pressure wash your engine. A clean engine is easier to determine leaks.

Make sure the system is burped properly. If it is and the radiator is full when the engine is cold, put the radiator cap on and make sure the reservoir is filled to the cold level at the same time. Then when the engine is warmed up the level should be to the hot or warm level on the reservoir.

If you’re losing fluid after that you need to do a pressure test. Most leaks are from the pump, radiator cap or radiator.

I like the burp idea. From past experience a coolant system with air pockets will seem like it's eating coolant as the system self-purges itself.

Try running the engine with the radiator cap off. Top off as needed.

Thanks all. I did have one plug look wonky when I did the plugs, but not bad.

I changed the pump, hoses, thermostat and housing, belt, radiator cap and plugs all at 90,000miles. 100% OEM from a dealer.

I’ll try to purge it better.

I fill the radiator to the bottom of the neck and then the overflow to the cold mark. Coolant dropped down to just a half inch in the reservoir.

Currently, I’m fighting the oil filter that the dealer cranked on.

Worst case on removing an oil filter? Drive a long screwdriver through it, use it as a lever to unscrew it.

One more thought, is it possible you may have over-tightened any of the hose clamps? That can actually cause a leak.

First of all, I know nothing about the Toyota 5.7, but found an owners forum that mentioned an "engine valley cover leak". The symtoms mentioned by the OP were the same as yours.
Here's a link.
https://forum.ih8mud.com/threa...ear-of-motor.937309/

Any coolant on the ground underneath it when you park it? White smoke from the exhaust or milky-looking oil?

If either of those don't point you to an obvious leak, you need to pressure test it and look for leaks. Easiest way is to buy a pressure tester kit that clamps onto the radiator inlet and allows you to pump it up like a bike pump. They're kinda expensive, but worth it, IMO. Throwing parts at it before you're sure where the leak is isn't the answer.

Clamps are spring style, can’t adjust them. may need new ones.

The oil filter is a cartridge type so nothing to drive a screwdriver through.

Keep an eye on it and if the level continues to go down borrow a pressure tester from an auto parts store.

Reading with great interest. Kinda got same problem with 3.7L Jeep Liberty. Keep adding fluid, no leaks, no white smoke, runs good, oil looks good.

https://www.autozone.com/loan-...-22-piece/449951_0_0

Rental from autozone