I'm at my Wit's end with coolant problem, need some advice...

A few things to consider:

Your coolant temperature does vary some under different conditions, your scan gauge is much more sensitive than the dashboard gauge, the manufacturers don't want customers to panic over normal variances so they make the dashboard gauge less responsive.

Coolant temperature will normally flare up when stopping immediately after a higher speed run.
When traveling at speed, heat is being generated by the engine and given off by the cooling system at a constant rate (normal temp indicated).

When you stop even though the heat production is reduced there is still a high level of heat "in process" yet the ability of the cooling system to dispose of it is now reduced - coolant temp will be higher than set point until the excess heat in the system is given off at the new lower (idling) rate.

You gained over 150 rpm between idling in drive (643) and idling in park (801). The water pump and mechanical cooling fan are spinning almost 25% faster.

 

Let's see what the leak down test shows us. Then go from there.

 

We had A/C troubles and some other issues that needed to be attended to at the house before I could spend time on the Tacoma. So only updates is I had another new OEM radiator cap on order, forgot about it, it showed up so installed it. Only taken the Tacoma on a few short rides to get to running temp the last few days. No coolant loss, but again I just drive a mile or 2 to get up to about 190 then park it.

Compression test still on the agenda

I did notice one thing, keep in mind temps here are 90ish in the morning, to get to work it is about 2 miles. Before the overheating started I would just be reaching my office before coolant got to running temp. After I started noticing the heat abnormalities, coolant would get to running temp in about half a mile. Right now, I can drive almost all the way to work before it reaches running temp. ( I consider running temp 187-190)

 

Wow...you have a great commute. Nearly working from home.

 

It's my company. I live in an historic district. I am very very very involved with the preservation of our little old fashion "island" with yards, a canopy of live oak trees over the streets thats located smack dab in the middle of the chaos downtown. So i of course located my business in our area to be close to home, and to also promote our local economy

The work on the Tacoma is still on hold, hopefully this weekend I can dive back in

Plus gave me an excuse to get a new toy, I ordered one of the borescopes that not only has the camera at the end but also a camera facing to the side

 

The side camera will be super handy.

 

if you don't care to fix it the right way, Chris fix showed the head gasket sealer actually does pretty good, especially since your leak has to be tiny. Obviously the right way to fix this is pull the heads and replace both.

 

Yup! Another 1GR-FE bad head gasket. This one was actually a 2009 J-VIN Japanese made engine. I guess the moral of the story is... 1GR-FE don't like to run above 2500 RPM's for extended periods of time, lol!

I think this is engine #3 for this truck?

Anyways, I have another 1GR-FE almost complete in the shop I can swap in, but I'm thinking about going with an LS instead? Anyone know if there are already made wiring harnesses for these trucks?

Any builds out there?

 

https://www.tacomaworld.com/threads/ls6-swap-2nd-gen-build.779345/page-35#post-29049236