Amocat00

My engine keeps overheating. It's getting progressively worse. I removed the thermostat to check it. I can't tell if it's sticking. But, it doesn't really matter. I put the cover back on w/o the thermostat, started it up and let it run for about 10 minutes. I went back to check on it, and it's overheating again. What now?

Thanks,

~Shawn

flecker

If your talking about the 85, well theres only a couple of possibilities aside of the thermostat... wich it sounds like you figured that it's not. The heater core, radiator and the h2o pump. DO NOT let it over heat to much, the 22r series can and do blow head gaskets w/ to much heat! I would first start by going through the entire cooling system and eliminating the good stuff from your list. You can start w/ a Radiotor flush, testing your radiator cap to see it holds pressure, look at the weep hole on your water pump, and examine the heater core. Also put the thermostat back in, that also could cause some issues. Start it cold and let it warm up w/ the cap off, wait and see if you get flow when the thermostat breaks open and see that theres nothing leaking from your heater core. Make sure the fan clutch is working properly... it should have roughly 20-25 inch lbs. of drag. And finally make sure your block/head isn't clogged somewhere... You can fluĊĊĊĊ w/ the hose to makecertain it has flow.

And sometimes the temp sensor gauge just goes bad... have another gauge to test it with? Just for a second opinion.

Amocat00

Thanks for the suggestions. It probably doesn't make much of a difference, but the engine was upgraded to a 22re. I'll still have to check the same things though.

~S

8422r4Runner

Fire it up and let it run a few, once the thing gets to temp or the temp starts to climb, get out and feel the hoses. They will be hot, so watch it, but feel the top and lower hoses to the raditor and the two hoses going into the fire wall to the heater core. All should be the same heat. If one is cooler then the rest you are on the way to finding your problem. Top hose cold, stat stuck..not your problem. Lower hose cold, raditor not working right. One of the two hoses leading to the fire wall. Heater core clogged.

With the stat out and it still over heating, I'm beting one will be cooler. Just for the sport of it I will guess one of the fire wall hoses.

You can test the old stat by droping it in a pot of boiling water. it should open up, give it a minute. it's also a good way to test a new stat before you put it in.

fourwd1

Simple things first, replace the rad cap.

Amocat00

Ok, thanks for the suggestions. I'm going out to work on it right now.

~S

Amocat00

Could the radiator cap not being on correctly/tight cause it to overheat? It didn't look like it was tight, and I just got it back from the shop a few days ago, getting the new rear diff. installed.

brick privy

the cap holds pressure in the system and raises the boiling point of the water. steam doesn't conduct heat like water does.

Amocat00

Ok, I flushed the system and ran it without the radiator cap on for a while, then added more coolant/water. Then, I let it run for 15 min. so far and the temp. is staying steady to this point. the top radiator hose and both heater core hoses are very hot. The bottom radiator hose is pretty warm, but not like the other three...yet...but it seems to be getting warmer...

Oh, and I did put the thermostat back in.

brick privy

the bottom hose should be cooler, the hot water goes in the top of the radiator, as it cools it drops down and goes out the bottom hose. its the opposite of a hot water heater. put the cap on and drive arround the block and see.

don't forget to put some water in the overflow bottle. you don't want to get air in the system again.

Amocat00

I drove it from my house to my wife's work, about 10 miles, no problem. It looks like I'm good...for now...

Thanks!

~Shawn

Amocat00

Drove it all around, about 40 more miles, on the beach for a half hour...still no problems yet. The temp. stayed steady about half way up.

Thanks again.

~S

brick privy

driving on the beach in mid-march? must be great living in kill devil hills. i've been there a couple times, it's way better than say, OC maryland.

glad to hear you got your cooling system figured out. but i have to wonder why your mechanic would remove your radiator cap when he was doing a rear diff install?

Amocat00

yep, it's been awesome weather all winter this year. It only got below freezing maybe 4-5 times.

I'm wondering how the radiator cap got that way too...it's kind of shady...

Amocat00

Ok, now I'm thinking I have a cracked head or something. It was fine that whole day. Yesterday I drove it to work, about 20 miles one way, it was fine. However, on the way home, I noticed the exhaust smoking more than usual and then it started to overheat again. I got it home, but it got dark before it cooled down enough to check it out. Thoughts?

Thanks,

~Shawn

brick privy

bummer!!!!

coolant in the cylinders will give you white smoke from the tailpipe, and the smoke will smell "sweet". oil will give gray smoke and will smell "oily".

if air from the cylinders is leaking into the cooling system it'll definately overheat. you should check the dipstick to see if there is water in the oil. it'll look like mayonaise.

snap-on

mayonaise?

usually it starts with chocholete milk color..... (water in the oil)

Amocat00

I checked the oil yesterday and there didn't appear to be anything abnormal about it. I didn't notice water or milk or mayonnaise...

The exhaust smelled oily the last time I checked. But,I didn't smell it yesterday and I didn't check to see if it was more white or more gray. But, I remember when I cracked the head gasket in my Samurai, it was smoking white...then it just died.

~S

8422r4Runner

Yes it makes since the lower hose was cooler, but it should be close to the others. If it was like you could put your hand on it for a few seconds, while you could not the others. I would suspect the raditor is not flowing freely.

After the motor is up to temp and the stat is open you should be able to see the water moving in the rad with the cap off. If it's not moving, the water is not flowing freely, explaining the over heating.

Of course a bad head gasket will cause both heat and white smoke. QA compression test would tell you that. You can buy one for 20 to 30 bucks real easy to use. Well if you can get to the spark plugs.

Amocat00

I've been thinking (uh-oh)... It ran ok for a whole day and a half. Then it overheated again. And, I checked the radiator, it's low on coolant/water again. Where'd it go? I didn't notice that smoke until it started to overheat again. I think I might flush it again, but put some pressure through it to try and clean it out this time. Any other ideas/suggestions?

~S