OneBad87

93 runner 3.0 140k
Just did head gasket last week.
flushed radiator (good flow)
new water pump
160degree stat.
new clutch for fan

It wants to overheat when running under 3k rpm's. You can sit in park and it will start heating up, then you give it gas and it starts cooling down. I put a aftermarket gauge in so I can read the temp more accurately. I have not let it get over 120-130 degree's, and in my opinion I think that is way to hot. The new head gasket to my knowledge is not blown either. Oil is still clean and no moisture out the muffler. I gutted the cat, but have a exshaust leak from having holes in the muffler. Could this have anything to do with it?

If anybody has any suggestions. I've done my searching and have not found an answer. Thanks, Mike

myyota

The 160 degree thermostat is way to low, it won`t allow the engine to warm up to normal operating temperature. The stock thermostat is 195 degrees, but if you want to run a colder thermostat i wouldn`t go any lower than a 180 degree thermostat.

OneBad87

I put that one in to try and prevent the overheating issue. It had a stock 195 in there and was still doing it.

As stated in the first post, the engine is getting way above the normal temp.

myyota

Have your radiator checked, if its plugged then no matter what you do or change, your truck is going to over heat. if its the original radiator then just replace it, you can get a three core radiator from www.radiatorbarn.com for a good price. I have one in my 86 4Runner and it works great.

OneBad87

I'm no expert. But when I flushed it, it had plenty of flow threw it. I even flushed it backwards. And all of the fins are in good shape, for air to flow threw them. I don't know what else I could have checked out on a radiator. Any other ideas?

Mandi

If you havent gotten your oil changed recently it could make it wierd... cause when I let my truck go a little longer than 3000 miles it will start shaking and overheat quicker just a thought.

myyota

Just because you flushed the radiator out with a hose doesn`t mean its good, the engine pulls water through the radiator alot faster than running water from a garden hose. Have you always taken care of the cooling system, changed the antifreeze when needed ?, because the only other thing that i can think of that could cause over heating problems is the water pump.

texasc1985

Over heating problems 1.Check belt/belt tension and check hoses!! 2. Check fan is it sucking air through radiator, more air at higher temps 3.Undo radiator cap while engine is COLD to check for water pump flow 4.Double check radiator and try a flush with solvent 5. All else pull radiator to have it cleaned

OneBad87

As far as the oil goes. It only has about 3-400 miles on it. I changed it a couple times when I did the headgasket.

myyota - So should I be able to see some sort of flow through the cap? At an idle with the cap off there is NO movement. If you give it gas, it will start to over flow out of the cap. I've only had the truck for a couple weeks. I bought it with blown headgaskets.

texasc1985 - When you say check belt tension, are you talking about timing belt? Is it possible for the water pump to slip on the timming belt?

I'm going to flush the rad again today with some kind of solvant. I'll let you guys know how it goes.

bugs1961

"check belt tension" would refer to the 4 cylinder engines. The timing belt wouldn't slip on the water pump because it is on the tension side of the cam pulleys and is always pulled tight.

I would suggest taking the radiator into a radiator shop that can rod out the core and remove built up deposits that can restrict flow under pressure. This will cost about $80 but will give you an essentially new radiator. They will normally fix any pin-hole leaks and replace the gaskets on the top and bottom tanks. I've had this done to several radiators with great success.

If the radiator is too corroded to repair, they will let you know and you can get a new one for about $150 or so.

And I can't recommend enough the stock Toyota thermostat! They are WAY better built and will last until your next timing belt. It the engine overheats with the Toyota stat, then there is another problem. The engine needs to be running at stock temperature for the EFI to function properly.

texasc1985

The belt that drives the water pump, if it is loose it will not turn the pump fast enough to circulate the coolant. What engine do you have?

OneBad87

It's a 3.0 v6, so it's powered by the timing belt.

I replaced the rad today and another new stat. It is still having the overheating issue.

calcuta

120 or 130 is not even hot enough to get the thermostat to open so its not running hot yet,

bugs1961

^^^^ Correct. The proper temp is about 190 degrees.

OneBad87

sorry I ment to write 220-230degree's

senior2010

i have a 92 toyota w/ 178k on it and it has been doing the same thing so i replaced the t-stat and water pump and it was still overheating... so tonight i went out and pulled the t-stat out and put the housing back on w/o the t-stat in and it has ran fine so far....

limon32

These symptoms are typical of an airlock in the cooling system. THere are several threads on here about how to fix this issue. I have personally seen this issue a few times, its a cheap and easy fix, follow the threads on here...

OneBad87

Well I believe my problem is solved. I ended up taking one of the t-stat's and drilling two small holes in it. So far it seems to work great. I ran it with no stat in it, and ran too cold, never warmed up, and wouldn't shift into overdrive. With the dilled stat in there it runs at about 175-185.