iam_turner

Just bought this 90 Runner with the 3.slow and it's overheating when I don't have the heat on full blast.

I have filled the radiator with coolant, and also the resevoir, but this still did not help. I helped my mechanic friend change the head gaskets last summer. After changing these the thermostat crapped out and has since been changed. After changing this the engine appeared to run fine and there were no issues.

However, after starting the truck up today and driving it around, as I mentioned earlier it starts to over heat (when heater is off). However, when the blower is on with heat on full it does not seem to over heat.

Wondering if anyone has any suggestions on how to fix this problem?>

wcc_71

mine did the same thing and we took the water pump off it looked like there was no problem with it but i got a new one anyway and put it on and it fixed it

iam_turner

I am wondering if it could be the thermostat, but like I said, it was just changed. I also wonder if it is gummed up and stuck closed? Could it also be the rad being plugged up, or ice block?

I am freaking and don't know what to do...

904_runner

Well just because you replaced the thermostat, doesn't mean it couldn't have gone out, Also check the waterpump

iam_turner

I was thinking about the water pump, but the heater is blowing hot air...If the water pump was not working would it not be circulating heat therefore blowing cold air?

iam_turner

Alright,
I have taken out my t-stat and am not getting any heat at all. I have to bleed the heater hoses as there seems to be an air lock/bubble and the truck is not idling properly.

I have a question though, I read the searches on overheating and discovered someone saying it is possible to have installed the wrong gasket on the wrong side (i.e. the left head gasket installed on the right side and vise versa). I am wondering if this is the problem because when I flushed out the rad (with water and air) there did not seem to be too much gunk or anything.

I've heard of people running fine without their t-stat in, but as soon as they install their t-stat (cooler or hotter) they still over heat.

I don't know what to do. Should I buy the cooler t-stat, and hope for the best - I don't know how to check if the head gaskets are on wrong a side from ripping appart the motor again.

ugh, stuck, please help...

iam_turner

I've just read all the recent posts on people having trouble with overheating - seems to be a common problem.

Anyway, I have just installed a new t-stat and am running into the same problem as above. I hate the fact that this could mean the HG's were mixed up and in the wrong location, left vs right.

But. I am going to take the t-stat out tomorrow and drill two small holes in it to see if that helps the cooling issue. I am wondering if anyone knows the desired whole size that I should use?

I'll also ask this questions again. If the HG's were installed wrong, wouldn't the truck over heat without the T-stat installed?

pruney81

check the water pump, even if it was going you would still get hot air. The 3.0 is not an engine you want to run hot either. I would park it until you figure out the problem.

MonsterMaxx

If the head gaskets are on the wrong sides it won't run very long w/o overheating because the passage that allows hot water to reach the t-stat is blocked. You won't get a mile. And it wouldn't go from OK to bad, it'd be like that as soon as you fired it up after putting the heads back on. If you've been driving it since doing the gaskets this isn't the problem. If it was like this as soon as you did the HGs, then it likely is the problem.

The water pump is an extremely simple device. Unless someone has put some substandard pump on there w/ a steel impeller that's rotted away, it's very unlikely the water pump is the problem. With one exception every impeller I've seen is stainless.

Just because you put a new t-stat in doesn't mean you put a good one in, these can be bad out of the box. Also, are you sure you didn't put it in upside down? I would take a real good look at this item as it's your most likely cause.


You should also drain a little fluid from the radiator until you can see the cores thru the cap. Do they look clogged? This is a very common problem in older trucks because coolant goes bad over time and people don't change it. You can drop it off at a radiator shop and they'll acid boil it out for you or get a new one.

I'm assuming you don't have any funky electric fan setup and that your stock mechanical is in good working order and the shrouds are in place, belts are tight and all that. When you first fire your truck up you should hear the fan be very loud, then within a minute or so the clutch should release and it'll quiet down.


as others note, the 3.slow is NOT an engine you want to overheat. They die very quickly. If I were you, I wouldn't drive it until the problem is solved.

Squiddy

1) New thermostat (quick, cheap)
2) Water pump
3) Radiator
Best --> Go to good radiator repair place and have them flush and pressure test it, etc.

iam_turner

monster max, I am relieved with your post...Because it does take approximately 15 minutes to run hot and start to overheat.

Does anyone know the coolant flow? I wonder if a belt is on backwards and if the water pump is running the wrong way? Currently the top of the radiator is hot and the bottom of the Rad is cold....Top Rad hose hot, bottom is cold - shouldn't it be the other way?

zlathim

This is a no-brainer, I'm sure you've looked at it, but---
Are the cooling fins at the front of the radiator clean and clear?, ie. not full of mud or so packed with bugs as to inhibit airflow...

904_runner

I agree, but i would still check and see if the radiator is cloged internally. Also check the waterpump.

MonsterMaxx

When you say 15 minutes, is that idling in the driveway or running down the road?

No, the belt cannot be on backwards. and I'm pretty sure the 3VZE is not an engine which will run backwards (not as impossible as you would think, particularly with 2-strokes.)

Engine outlet is at the top (where the hottest will be) and inlet is the bottom (cold.)

From your description it's not flowing well. t-stat, clogged rad or water pump and I doubt it's the water pump. Water pump failures are normally bearing or seal related.


Again, check for a clogged rad (or gummed up with trash on the outside) or a stuck or improperly installed t-stat.

mt_goat

http://personal.utulsa.edu/~nathan-b...05descript.pdf

No way, the water pump is run off the timing belt on the V6, its a pain to get to as you have to take the timing belt off. I also doubt its the water pump.

Nope, the top gets hot first (engine output on top). That's a sure sign that either the t-stat isn't opening or the radiator flow sucks. Radiator flow problems could be water flow or air flow but if it was an air flow problem the lower hose would also be hot wouldn't it.

MonsterMaxx

Right...w/ the bottom of the radiator cold and the engine overheating I'd be very suspicious of the t-stat. You might want to try taking it out just to test it. (truck will probably run like crap because it won't come up to temp and the comp will be in freak out mode.)


Then again, come back to the 15 minute thing. W/ head gaskets on backwards it'll run about that long at idle before overheating. If 15 minutes is running down the road and 'workin' it's not headgaskets on backwards.


***edit, this may be a dumb question, but....How do you know it's overheating? Idiot lights? Factory gauge? or a real temp gauge? or other 'overheating' indicators?

iam_turner

Okay, new development...
I took the truck for a drive at highway speeds, it took about 10 minutes to get HOT (let it touch the red, took it out of gear, revd' the truck to 3500 and coasted, the temp came down). Continued driving as the temp went just above the middle on the cluster gauge.

Once back in town I noticed that there was a bunch of snow/ice built up on the rad - it seems like the coolant is not flowing in the rad. Like the rad is blocked.

When I have the truck at idle, if I rev the truck to nearly 4000 the truck warms up, the thermostat opens and the temp cools. Did this for about twenty minutes without a problem. But when the truck is at highway speeds, and not revd' above 3500 it over heats.

I did inspect the front of the rad, there was no debris/clogs in the fins. As mentioned before after taking it for the drive at highway speeds (while snowing) there was about a 5 inch span of snow/ice crystals built up from the bottom tank.

Does this sound like a blockage in the Rad, which would cauise overheating issues?

Thank you guy's so much for your help and nowledge!

904_runner

Listen to his advice on that one

MonsterMaxx

Jeez, it's 76deg here today, where the heck are you that you are getting snow and ice buildup?:eek:
brrrrrrr

iam_turner

I'm in the NWT (Canada) above the 60'th parallel, ugh, I'm so sick of the white stuff. Makes it even more awesome working in the driveway without a garage!

whatiya think? definitely flow problem in the rad? For starters anyway?