Coolant missing from radiator

I noticed my radiator was low and that was the first time in 27,000 miles of my ownership that this had occurred. I added antifreeze and maybe put 300 miles on it and it was low again. I then added antifreeze to the expansion tank and drove it a few miles. After it cooled the radiator was full and the expansion tank was noticeably lower. No leaks out if the expansion tank so that took that off the table as the culprit.

I then pulled the 15 amp EFI fuse and removed the radiator cap and cranked the engine with the starter. No coolant shot out of the radiator. Not even a little splash. This should eliminate a head gasket leak right?

I looked at my oil filler cap. Clean as the day I last changed the oil.

I’ve checked the hoses and the ground underneath the engine. No drips. I looked at the radiator cap. It’s pretty new and looks it. No drips at the cap either.

Two things:

I have to do the valve cover gaskets and all the associated seals and such that go along with that. I’ve had smoke coming off the driver’s side exhaust manifold from oil dripping. It’s bad enough that I’m not using the truck for anything other than short drives so that I don’t burn it to the ground. Anyway, I think possibly some of the smoke is steam. If so maybe my leak is at the heater bypass pipe? And if so I can deal with it when I go after the valve cover gaskets. I am uncertain where the heater bypass pipe is but I saw a reference to “under the intake plenum” in some forum post that I now can’t find.

Also, I may have the beginnings of a water pump failure. There is a new noise under the hood and I’m getting a sense it’s the water pump. I don’t have a ton of water pump failure experience but it sounds like what I’ve heard a few times on buddies rigs that turned out to be water pump failures. But, I can’t see any leaks in that area.

Okay, that’s pretty much all I’ve got. I’m hoping for some guidance on this before I jump in to finally do my valve cover gaskets. I don’t want to misdiagnose the coolant issue and then have to rip it all apart to do the head gaskets.

Thanks in advance!

 

Any coolant loss from the plastic end tanks itself? They tend to crack over time and coolant can just seep out as seen here below -

 

Could test the radiator for exhaust gases. Pretty easy to do and I believe autozone rents the tester. Have to buy your own fluid though.

 

I went out this morning and really studied it with good light and I think the radiator is leaking from a few spots. Really tough to see but there is moisture on the top plastic and I finally found two drips that are definitely antifreeze. One off the drivers side of the radiator and one on the skid plate. They didn’t drip while I ran it. The little drops just hung there taunting me.
I also think I have a lot of moisture around the thermostat housing. Possibly need to regasket that?

I’m uncertain if the water pump is failing. But I have bad ears so it’s tough to tell.
I’d much rather replace the radiator, water pump, and timing belt (since I’m in that deep) than pull the heads off!

I think I’ll do the much postponed valve cover gasket job and then if that goes well I’ll go after the coolant problem.

Thanks for the photos and your assessment!

 

I had coolant disappearing in my old 03 prerunner. Turned out it had like a seeping leak along the side of my radiator. Tough to pinpoint when watching it run since it wouldn’t really drip that much, but I would have to add coolant ever few days.

When I pulled the radiator it was obvious where it was leaking, just hard to tell while installed.