Case of the Coolant - Timing Chain Cover & Oil Pan

Hello all! Paying another visit here doing some research on a problem that has been bothering me for a few weeks now. And being this is the best place for troubleshooting minds, if I may ask of your help once again I would be most appreciative!

2001 Ranger - 3.0L, 2WD with 125k miles.

Several weeks ago, when driving into work, I turned the defroster on, after a few minutes switched back over to heat. A few more minutes went by and I noticed my feet were freezing. I reached down and felt stone cold air blowing in through the floor vent despite having the temp dial on full blast heat. I looked up at the temperature gauge on the console and saw the engine was running hot (about halfway above the middle and H). Realizing there was a problem, I began fiddling with the temperature knob, turning it back to cold then back to hot and suddenly the temp gauge dropped back to normal range, engine ran fine the remainder of the trip. No problems coming home.

It happened again about a week later. Similar issue, cold air blowing, temp gauge running hot, messed with the control knob, temp fell back to normal. Not once during these events did I smell any coolant in the cabin.

I check the coolant reservoir to find it empty. So I fill it back up and drive it again. On this drive, the temperature gauge shot up to H, check engine light came on, I fiddled with the temperature control knob again and it fell back to normal. I get home, let the engine cool, and the coolant reservoir is empty again. I check in the radiator cap to find the coolant is pretty low in the radiator. So I go on the hunt under the truck for any signs of leaks.

Thermostat housing all looks clean, hoses are fine, no leaks around either hose or on the radiator. I did some research here and other places online to find that a common problem is the timing chain cover gasket goes bad. So I look around under the truck again and find some telltale coolant signs around the passenger side of the water pump bolts (see pictures below) and coagulated oil around the lip of the oil pan, where it has been mixing with coolant.

Here is my educated guess, and please tell me if what I'm thinking is agreeable based on my aforementioned description and the attached photos...
TC cover is leaking coolant, when the block gets hot and coolant system pressurized coolant rapidly leaks out of the TC gasket (no coolant puddles observed on the garage floor so its not leaking when not in use). This has mixed with oil leaking around the pan gasket and coagulated.

Or, does this look like something else? I know there are a few other possibilities, hoping for some advice on whether I'm on the right road or not.

If this is a TC cover gasket issue, I've been looking online and in manuals on how to do this without having to pull the engine to replace the oil pan gasket at the same time. Looks like some people have had success jacking the engine from underneath after popping the motor mounts, transmission bolts, and portion of front suspension to remove pan. Any thoughts on that too?

Side note - no signs of coolant in the oil. Drained the oil, no water or coolant drained out first. Also no signs of oil in coolant when looking down into radiator.

Thanks all for the help!!
- Closeup of the passenger side of the water pump housing - front of engine is down.

- Zoomed out view of the passenger side of the water pump housing, looking toward the top of where the dampness begins.

- View of the oil pan gasket

Correction, I do have some oil in the coolant. Just drained the radiator and got a little dark liquid mixing in...not much though.

Since you are losing coolant and from your pics I would say that you probably have a leaking timing chain cover gasket. Even being a little low on coolant your truck should not overheat. Sounds like your thermostat is sticking closed which could cause overheating and the heater not to get warm coolant. I highly recommend NOT driving the truck when it starts running hot or you will be replacing the head gaskets and possibly the heads.

The timing chain cover gasket was leaking on my truck but it was leaking externally and not into the crankcase. I was able to carefully remove the timing chain cover without damaging the oil pan gasket. When I put everything back together I really cleaned all mating surfaces with the old oil pan gasket and the block and coated it with Toyota FIPG RTV (the best I have every used). That was 5 years ago and no leaks since. I seem to recall loosening the oil pan a little when I took it apart.

You'll have to remove the radiator and fan so be prepared to drain the coolant. Also cut a thick piece of cardboard to protect the AC condenser which is in front of the radiator since you will be working close to it. While you are in there I would replace the water pump, timing chain, and timing chain sprockets. Depending on how old they are, radiator hoses and the t-stat as well.

I'm going through this leak right now with my '98. At 148k miles, it's in the shop and their estimate is around $2,200 for replacing t-stat (my request), water pump and timing chain/sprocket set. That price also includes a new timing chain cover which he will only install if the current one is pitted or otherwise damaged; all related gaskets and fluids; and dealing with the A/C system.

It was originally misdiagnosed as a head gasket leak since it was spraying directly where the heads & block meet.

I would say you have a timing cover/water pump coolant leak as I had.

No reason to pull the engine. Remove timing cover and apply new gasket/pump. The timing cover does seal against the pan gasket at the front, but if you're careful you can leave the pan gasket alone.

I actually had trouble replacing the timing cover and getting a good seal at the pan gasket, which gave me an oil leak. I ended up cleaning the pan seal area and squeezing in RTV, let it dry, and the fix has lasted 3 years now.

There's a lot of bolts and some need sealant as they screw into the water jacket. Get a good manual.