Overheating - Help figure out why

OK my 4runner is being a turd. Its been overheating due to the waterpump leaking and rad getting low, but now its still doing it after I got the pats cannon out.

Symptoms:

Generally its ok, runs a little hot (196 on the scangauge) but its been creeping up. Yesterday in traffic it was ~210 ish when I got home and shut down, it was hot so the AC was on as well. When it gets hot, putting it in neutral and reving to ~2k beings the temps back down.

Rad is full. No leaks. No milkshake. 

Work done:

Replaced waterpump, T stat, and radiator. New coolant. New serp belt. 

Could it be fan clutch? Fan is able to be turned by hand with some resistance when the engine is off. Spins up with engine on, and stops immediately on shut down.

Thoughts?

sounds like the fan to me.

In reply to bobzilla :

Its the only part I didn't touch..... 

Fan was my thought too.    Does the temperature go down when you get up to speed on the highway ?

The cooling at 2k pm indicates that the fan is doing some work.

In reply to iceracer :

It did previously, I have not done any long highway stretches since the new parts went on.

What temperature thermostat does that engine run?  If it's a 195* t-stat, 210 isn't really hot at all, that's about where the stat would be getting to fully open.  But I'll agree with the others that it's likely a fan issue.  

In reply to rslifkin :

IDK what the temp is. It used to always run 186, and has krept up over the last year with the leaking WP etc. Maybe that should be a sign the fan is toast. Just used an OE replacement Tstat.

I'm going to say a head gasket failure is likely because it has been tortured by being run low on coolant. A small head gasket leak will make air bubbles in the head which creates hot spots that create more steam, more revs will push the steam out.

Check rad core for scale inside tubes?

Check radiator core for even temps across the surface?

Check cap for holding pressure?

Check coolant recovery bottle, hose, fitting, cap to insure no air is admitted to the radiator?

As stated 210 is not hot. It's not overheating unless it is lifting the cap.

In reply to bentwrench :

I'm going to say a head gasket failure is likely because it has been tortured by being run low on coolant. A small head gasket leak will make air bubbles in the head which creates hot spots that create more steam, more revs will push the steam out.

HG leak is a possibilty, which supuured all of this in the first place. I get an occasional misfire on startup when its been sitting a few days. Upon opening the rad ca (previous to the work) it smelled "exhausty"

Check rad core for scale inside tubes?

New rad

Check radiator core for even temps across the surface?

Will do!

Check cap for holding pressure?

How does one check?

Check coolant recovery bottle, hose, fitting, cap to insure no air is admitted to the radiator?

All good, full, rad is full.

As stated 210 is not hot. It's not overheating unless it is lifting the cap.

Right, but its heading upwards, I dont want to run it any hotter..... Trying to avoid the previously stated HG issues.

It did get a bottle of blue deveil before all the new parts went in.

java230 said:

In reply to rslifkin :

IDK what the temp is. It used to always run 186, and has krept up over the last year with the leaking WP etc. Maybe that should be a sign the fan is toast. Just used an OE replacement Tstat.

Based on that, I'd guess it's a 180* stat.  In which case anything from 180-ish to about 200* is pretty normal, above that isn't necessarily an immediate problem but it's likely a sign of something not working right unless the cooling system is being worked to its limits on a hot day with a heavy load on the engine.  

Use the Roadkill method: Take the hood off

In reply to rslifkin :

Right, 210 is ok, but its going up, I dont want to create problems....

I am still leaning to fan clutch I think

Your description of the fan operation changes my mind.    Now I'm thinking poor coolant circulation due to corrosion build up.

You should be able to hear the fan when it kicks in.  Driving, with enough hot air coming through the rad to engage the fan, you should hear it spin up, then drop off as the temp drops.

Also, quit staring at the gauge.  210 at idle with the ac on is fine.

Streetwiseguy said:

You should be able to hear the fan when it kicks in.  Driving, with enough hot air coming through the rad to engage the fan, you should hear it spin up, then drop off as the temp drops.

Also, quit staring at the gauge.  210 at idle with the ac on is fine.

Unless it's my truck. Now it's 165* at idle in the heat. I love that massive radiator and all new cooling system. 

In reply to iceracer :

Coolant was pretty clean, as was the water after I drained the blue devil out. 

Did you flush the system when you installed the new rad? You could have plugged it up if your system was full of scale.

Feel the radiator if you can. If the temp is fairly even then it's probably ok. If it has hot and cold spots, it's probably plugged.

In reply to ShawnG :

I did as best I could with a hose on the upper rad hose. No pressure built up, I'll take the or temp gun to the rad when I get home. 

FWIW the inside of the coolant passover thing, the Tstat and wp were all spotless. 

Make sure your condenser and radiator aren’t clogged up with leaves, bugs and other crap.

Just cuz the rad is full doesn't mean there isn't air in the system.  I had that issue on my rx7.

Did you run the heater after first fill?  Can you jack the front way up and squeeze all the hoses and see if it burps?

Might be worth renting a cooling system pressure tester just to be sure.

Just had a thought, you can buy test strips that will tell you if combustion gasses are getting into the coolant.

I've never tried them, all of my BHG situations have been very obvious.

Might be worth a shot if you're at the parts store anyway.

Rad temp is within a few degress all across it. 

In reply to maj75 :

New Rad. Condenser is decently clean.

In reply to wvumtnbkr :

Double checked the heat this morning, works great. Ran for a few mins.

In reply to buzzboy :

Maybe so.

In reply to ShawnG :

Ever used them? I saw very mixed reviews online. The coolant also all just got changed. May need a bit more drive time. 

How's the lower radiator hose ?    

In reply to iceracer :

Original, but appeared ok, it was completely removed.