Engine overheats, coolant level drops

Can it be told from looking at the pictures of the old thermostat several posts ago, which I tool last night when I finally got to work on this again?

 

Hard to tell for me from those pictures. Everything looks intact but I'm not a thermostat expert by any means, I had one go bad years ago on a Ford Ranger but it was clearly shot. The safe bet would be to find a cost on a new one and if it's not to bad replace it. If you do want to test it the boiling water trick should open it up.

 

I don't believe that, unless there is obvious physical damage, that you can look at a thermostat to determine if it's still activating as designed.

I don't want to say there's a "high" failure rate for them, but it is the most common cause of overheating if the truck has otherwise been maintained properly and lack of maintenance is not the root cause of the overheating issue.

 

Can you tell if it is in the open or closed position? I tend to think it is closed, even though the valve plate is sprung up, because, by looking at the shape of the socket (opening) it goes in, it looks like the flow is enabled when the spring is engaged (or compressed) and when it is like it is in the picture, it closes the flow. Can you verify my assumption, true or false ?

 

I mean, what the heck, a new thermostat is only $25 and this one is 8 yrs and 125K mi old. Even if it is not dead, it probably ain't in the best of shape so I might as well replace it.

 

Exactly. You're spending more money in time used to bench test and check a part than the part actually costs. And at this vintage/mileage, and the fact that it's already out, simply replace it.

It's like all those threads about "reusable cabin air filters"- that's alot of BS to go through for a $14 filter at Walmart. I get at least a year out of mine by removing it every couple of months to blow forced air through it and sticking it back in. Is it worth all that time to go buy the materials, fabricate the frame, rivet it all together, blah blah blah? Not to me.

You're sitting there with the thermostat in-hand. Take that hand, throw the thermostat into the garbage, drive down to NAPA and buy a new one.

 

If you're really determined to do this repair, I'd recommend getting a new water pump, dismantling the coolant system, replace the pump and then the hoses and thermostat (and the belt- but that's already done), clean off the radiator and flush it, and call it a day. Burp the system and see if the radiator needs replacement.

 

I can't drive without a thermostat

 

Got a friend? Got a neighbor or co-worker? Hell, got a thumb? Hitch a ride.

I'd really hate to see you put it all back together, continue to drive an overheating vehicle to go get the parts to fix said vehicle, and then have to undo it all over again.

 

Yes, I was thinking the same thing. BTW, how many hoses are there in the coolant system? I disconnected the big one that goes from the bottom of the rad into the thermostat. There are a couple little ones that I'm not sure what they do but are hooked into the socket housing that the thermostat goes in. Should I replace those too?

 

of course ... i was just being a smarta$$

 

Vote +1. This would of been basically my plan if I were in OP's shoes.

This is true lol. I'm sure you can find a way around that, but I'd avoid taking the truck. It would suck to get stuck at a light and do more damage if the thermostat stays stuck or the pump isn't working.

 

I just went to Rockauto (that site rocks, BTW) and I saw they have some water pumps with a metal impeller (slightly more $) and some that are not advertised to have a metal impeller (so I assume it's plastic). Is the metal impeller the better choice ?

 

Personally, being rubber, with temp issues, I'd replace every single hose that coolant touches if possible. Also, check where some of those hoses touch metal and look for corrosion before installing new ones. We used to see that often- especially if it had been a while between coolant services.

Keep in mind- coolant does a couple of different things.
One of which is to obviously transfer heat. The other is an anti-corrosive property that as time goes on will lessen in its effects. As coolant gets hot/cold it goes through chemical reactions. Keep in mind, it's also touching Aluminum, Steel, Cast Iron, etc... (different metals in different cars). As it does this, it prohibits rust and corrosion. Well, as it ages and gets hot/cold/hot/cold it loses its ability to protect the system as well as its ability to transfer the heat.

We use to have to grind down the corrosion so that the new hoses would seat well on certain areas.

ALSO- do not reuse the old hose clamps. They are a cheap replacement.

 

A lot of those rock auto parts will have different names but come from the same factory. At the end of the day a metal impeller will tolerate heat better, but either pump is far more likely to blow a bearing in 100-200K than another impeller as long as you get the system cleaned out.

I know this is a few posts early, but are you going to reuse your coolant? When was it replaced last? This would be a great time to switch to new coolant if you have not done so recently. I'd go with whatever you trust. I know Toyota says only to use there crap, but tons of guys on here have switched and I've never heard of an issue. Just remember to add the recommended amount of water.

 

My original coolant is all gone, as explained long ago. It leaked on the first day of the breakage, I had to continuously refill the system with water. When I drained it last night, only about 2 gal of crystal clear water came out, I could almost drink it...

 

Ouch. I wouldn't recommend drinking that (jks).

IMHO I'd switch to non Toyota Coolant. Toyota Coolant is freaking expensive and nothing special. I'd just pick up whatever is compatible with Toyota coolant and use that. This is one of the places where Wal Mart can be your friend.

 

Do I need a water outlet gasket, which is advertised at RockAuto? It looks like a seal between the thermostat housing and the socket it goes into (what is that called and where does it lead to, just curious?). The only thing that was there when I took it apart last night was an O ring (and it looked kindof worn out). Is it possible that I need that outlet gasket and mine was just completely gone, causing leaks? Here is a picture from RockAuto:

 

I'm not sure what that socket would actually be called, but it's basically the flow inlet for the coolant for the engine. Once the thermostat opens it lets more coolant flow through the coolant passages in the block so the heat can be removed.

I can't see how the gasket would be completely gone, usually you can still find shreds or remains of a gasket well after it's broken down. I'd just replace the O-ring myself but someone with more experience on the Tacoma might be able to comment on where that gasket actually goes.

If you had a leak you should be able to tell. Do you change your own oil? Did you ever notice a sweet smell when you were changing the oil? Usually when you have a leak there you can smell it and see the residue.

 

Yes, never had a coolant leak before last Sunday. I think it was leaking out of the water pump weep hole.