99 SR5, issues during test drive

[Mopar_Mike]

I found a 1999 SR5 4WD that I want, It has 197,000 miles. Owner told me over the phone before I ever looked at it that it needed a brake booster and shocks. Nothing too bad. Anyways I showed up to test drive, and hopefully buy it, it ran smooth, shifted good, A/C worked, no dummy lights on the dash, but I did notice the Temperature gauge wasn't working. I asked the owner and he said he changed a sensor and it hasn't worked since then, but assured me it doesn't over heat.
Anyways, as we were finishing up the test drive and almost to his subdivison I notice the heat stopped blowing hot. When we came to a stop at the next stop light it was smoking and you could smell anti-freeze. Popped the hood, and found that a line against the firewall had come off. I put it back on, filled it back up with coolant, turned it back on, let it run for a few minutes, but the heat never came back.
In the end I didn't buy it, but I told the owner I'm still interested, I would just come back in a couple days with a truck and trailer and have it hauled home. I'm thinking either the heater core is clogged up, or possibly the thermostat is stuck open, but I'm not very familiar with 4Runners either. I just find it odd that it was working up until the line came off. You would think after we put the line back on and filled back with antifreeze, that the heat would come back too. The engine bay was spotless, so I'm assuming he power washed it, maybe that made the line a little loose? With the Temp Gauge not working, I don't want to take a chance and drive it the 80 miles back home. Any help or advice is appreciated. He's selling it really cheap too, which makes me kind of weary, but it ran awesome up until the heat quit working. Body is in good shape, with the exception of a little bit of hail damage, and the interior is perfect.

 

[Kenworth]

Motor got hot and blew line off from pressure ? If you buy
You should factor in a motor rebuild/ replacement ???

 

[BlackCat914]

I'd be leary of it, but it's not the end of the world. Having heat originally lets you know the thermostat was at least working, if it was hot heat and not lukewarm heat. After filling it back up with coolant the system needs to be bled, which is probably why it didn't have heat right away.

 

[Mopar_Mike]

Well we let it run for at least 10 minutes while we filled the coolant back up. I don't get why that line would come off unless it was already loose. I know it lossed a lot of coolant when it happened but I don't think I drove it long enough to hurt the engine.
The image attached shows which line came off.

 

[RichardLillard1]

The heater valves used on the 4Runner are the same ones used on the Land Cruiser, second gen 4runner, Camrys, other mini trucks, and I would assume, a good number of other Toyotas that I haven't been under the hoods of.

We've seen a rash of them going out on Cruisers and mini trucks lately, with something like four or five this summer. One of which was out on a trail and had to be bypassed to get back home. Not the most comfortable solution as it leaves your heater on, even if a little bit, for the entire drive home (you have to fold the hose over and kink it just right, but it will not be a 100% stop of flow). I wouldn't buy the dealer heater valve; the best replacement we've found is from Parts Authority for around $20. If the valve is failing or has failed (blowing the hose off is typical of valve failure, from what I've seen), it could explain the reason for the heat not working once filled back up. I'll check at the shop today and see if I can find one of the blown out valves to take a closer look at how well it works and it's overall shape.

I'm not saying this is the problem, but it's worth mentioning that these valves are starting to become a weak point in Toyota coolant/heater systems. This isn't a flaw, just a part that takes a lot of abuse and gets tired. The hose that blew off is the same side that is blowing out on trucks here in Phoenix.

If the gauge isn't working, I would plug in some sort of OBDII gauge to it and watch things. This is also good for checking codes. I've seen trucks with codes cleared listed on the market before. In fact, I almost bought one. Toyota temp gauges aren't all that anyway. They tend to not move much until the temperature is already much higher than it should be and are really more of an idiot light than anything. This is especially the case on Cruisers, but should be noted for 4Runners, too.

As for oil leaks, just look around the common leak points for fresh oil. Valve covers and rear mains are common, so don't sweat those.