Car heating up on the highway?

[CyFi6]

My car consistently seems to get too hot on the freeway. Cruising at about 65-70 with the ac on high, my temps slowly climb to 210, which is when i turn the ac down/off and it helps get the temps down, with the ac off it seems to hang around 200-205 degrees, which still seems too hot.

The car has all new following:
Radiator
Thermostat
Radiator cap
Composite head gasket
50/50 mix of distilled water and genuine Toyota red coolant

The car has both the fan shroud and the engine under-cover in place and both function fine and are not broken. Once i get into town and low speeds the car seems to cool itself better, though sometimes with the ac on high going slow, the temp starts going up to around 205ish. Im really not sure what to do, how can i diagnose this?

There is NO air at all in the cooling system, and it is fully bled, no waterfall or anything like that. Reservoir is full and stays full. There are no leaks in the system.

The radiator and condenser have been removed and everything thoroughly cleaned, there's no debris stuck anywhere and airflow should be up to par. All the fins on both units are good and not bent/crushed.

My timing is set to the stock 10 degrees BTDC and i run on 87 octane, though i tried running on 91, and it seemed to run slightly cooler, though it may have been a coincidence.

This is when driving in 90-105 degree F weather by the way. My car is a california car and isn't used to seeing these temps, it used to run 190 degrees on the freeway back home.

Im considering an upgraded radiator, but it shouldn't be necessary. The radiator on the car right now is from www.radiatorbarn.com

Thanks for any tips on diagnosing this problem! I don't have an infrared temp gun to monitor radiator temps, so I'm not sure what i can do about that.

 

[snake eyes]

how is the fan clutch? any leaks/movement suggesting the water pump?

<l><l>

p.s. if turbo use premium damnit!

 

[CyFi6]

Fan clutch has no oil leaks, it seems to be working ok, but i dont see why that should affect highway temperatures anyways. Theres little to no play in any of the components from the fan to the water pump, and no wetness at the weep hole in the water pump. Its NA.

 

[IJ.]

If it all checks out mechanically (sounds like it does) check the Damper for true 0 TDC then check the static Ign timing when verified.

 

[Poodles]

When my fan clutch went out it leaked from the center. Didn't know it was leaking until I pulled the fan and clutch off and noticed the leak around the inside...

Has the water pump ever been changed?

 

[CyFi6]

If it all checks out mechanically (sounds like it does) check the Damper for true 0 TDC then check the static Ign timing when verified.

Do you mean check to make sure the engine is really at tdc when the damper is at 0? And by static ignition timing do you mean pulling the cap? I dont know what static timing means.

When my fan clutch went out it leaked from the center. Didn't know it was leaking until I pulled the fan and clutch off and noticed the leak around the inside...

Has the water pump ever been changed?

I have had the fan and clutch off recently and i looked all over it and there were no visible leaks. I'm not sure if the water pump has ever been changed, i doubt it. But the car only has 87k original miles, and unless the bearing failed or something i don't see how the water pump would just stop working. I guess the blades could be corroded, but other areas of the cooling system did not seem damaged.

 

[easternguy2005]

thermostat ? Might not be opening all the way.

Either take it out and see what happens or replace it. Don't trust that garbage (stant etc) that they sell at the auto store cause they fail fast. In fact I had one that didn't even open on a Honda right from the box.

 

[jdub]

Stant SuperStats are actually pretty good...I always cut the jiggle valve off to allow a bit of flow to the rad at all times to prevent a pressure build-up behind the stat that can hold it closed. Helps get air out of the system too. That does not seem to be the case here.

I would check the fan clutch and timing as previously mentioned.
Make sure that it's a turbo fan clutch...it's larger than the NA version to drive the 10 blade GTE fan.

Timing wise, you want to confirm DTC with the damper at "0"...remove the #1 spark plug and use a narrow wooden dowel in the plug hole to confirm the piston is all the way up. Both cam pulleys should be aligned with the index. Then check the CPS for correct position. Then set with a timing with a light with the diag block jumped.

 

[HommerSimpson]

when you put new head gasket on.. did you have head shaved ? and how much if so ?

what is your compression ratio ?

and i would try another thermostat.... as its the easyest to do ...

see if that helps....

If its not closing or stuck open the water can acually travel to fast threw rad and not have enough time to cool...and i have seen this several times ...

 

[jdub]

Hommer - on a 7M, if the stat is stuck open (or no stat), his coolant temps would be low, assuming the system has excess capacity. What you mentioned about coolant traveling too fast through the radiator would require flow well above what the 7M water pump is capable of.

 

[1988SupraDreams]

I am having similar symptoms at highway speeds with the A/C (R12) on. The car is a 88 NA/Auto converted to Turbo/5spd (4.3:1 LSD). I am running the OEM HG (New with ARP Studs) and a Jetjock style coolant filter.

The car has all new/rebuilt following:
Radiator (Modine Aluminum Core plastic Tank)
Thermostat (SuperStat 195 deg with jiggle cut off)
Radiator Cap (Also stant 13 LB)
Fan Clutch (Rebuilt by a distinguished member of the forums and it roars like a freight train when the engines hot)
50/50 Distilled water/Zerex GO-5 Coolant
Radiator hoses

I have confirmed that zero is TDC, and the timing is set to 10 BTDC and I run Chevron 89 Octane on Stock boost. The water pump has ~50k miles on it, and I just had it off recently for my rebuild. Everything on the water pump looked good aside from the minimal corrosion on the fins, it had no play at all. I have no bubbles, no waterfall, no leaks, nothing of that nature. The reservoir is at the same level every time I check it dead cold in the morning.

I'm drawing a blank here so I'll prattle on about my R12 A/C system. It has the original condensor. The compressor has ~50k miles on it and the Reciever/drier is a brand new denso dual refrigerant type. The A/C blows at 41-47 deg (On low). The A/C was charged by a distinguished member of the forums, and I trust his work. When the engine overheats the A/C temp out of the vent rises about 5 degress. I only have one A/C fan (None in front of the Condensor). The A/C doesnt kick on and off like it has excess pressure, it really seems to work fine.

Where should I go next?

Shawn

 

[jetjock]

If its not closing or stuck open the water can acually travel to fast threw rad and not have enough time to cool

It's called Residence Time in fluid mechanics and no, it needn't be considered with the t-stat removed. Residence matters more with airflow. It's why I get a chuckle outta the "my fan(s) pull XXXX cfm" comments...

 

[HommerSimpson]

Over the years i have seen several diferant types of cars run hot on highway with no stat in... chevys fords... and i think it was a honda once.. been long time...


not alot.. but id say 5 -7cars over the years .... once a stat was put back in.. they ran normal temps again...


i have also come across cases were the lower radiator hose would suck shut at highway speed because it was the wrong hose.. as in no spring in it...

had another guy come to me after a year of him and other garages working on his truck.. new rad stat pump fan several waterpumps... new heads...

the idiot put a strait fan on a reverse roating pump.. took me 2 minuts to fix his year long problem.. lucky i smoked to,,, as it was the fact my cig smoke was not being sucked threw rad,,, it was blowing back out grill...

had another guy come to me that nobody could fix,,,, was a camaro or firbird.. lat 80s... that 1.5 inch rubber lip about 2 feet back under car.. he knocked it off in the winter.. summer time came and nobody could figure it out.. he got new lip put on and all problems gone...

Point is.... a cooling system is a funny thing and not all 2 are the same no mater what...and one small thing can make a big deal on temp guage...

 

[jetjock]

Doesn't work that way on this car Hommer and while lower hose collapse occurs on many engines it's nearly unheard of on this car even with old hoses. No spring in them either. Although I know maybe you'd care to offer insight on why?

Frankly the OP worries too much. He should forget about this and just drive the car. There's very likely nothing wrong with it...

 

[jdub]

Ditto - the temps are not that high. He could increase capacity with a bigger radiator and drop temps a bit.

The high OAT is going to have an impact on how well the radiator transfers heat to the air.

I was trying to tell you the same thing Hommer...the 7M cooling system doesn't work that way

 

[HommerSimpson]

yes i relize bashing me is easyer then trying to fix his car..

Im only offering sujestions he can address if all eles fails..

 

[jdub]

yes i relize bashing me is easyer then trying to fix his car..

Im only offering sujestions he can address if all eles fails..

You know Hommer, I can't help that you don't understand how this car works...and that doesn't make you the "victim" either. I (and others) have offered suggestions...heck, it's likely nothing is even wrong.

What you suggested is simply not going to work and will not produce what the OP says is going on. Anyone that knows this cooling system knows that

And, anyone (including you Hommer) that posts a path that is going to lead nowhere is going to be corrected. If you want to call that "bashing", I suggest you grow a thicker skin.

 

[HommerSimpson]

what excally makes this cooling system so much diferant then the rest of the millions of cars on road ?

 

[CyFi6]

So should i consider myself safe when the engine temps rise to 210+? I just don't want to "overheat", whatever that actually means. I don't want to do damage to my engine by running it too hot, which i don't exactly know how hot is too hot. I would replace the thermostat with an oem, but that would mean me losing a ton of coolant, and its probably not the problem.

 

[HommerSimpson]

So should i consider myself safe when the engine temps rise to 210+? I just don't want to "overheat", whatever that actually means. I don't want to do damage to my engine by running it too hot, which i don't exactly know how hot is too hot. I would replace the thermostat with an oem, but that would mean me losing a ton of coolant, and its probably not the problem.

replacing thermostate will only lose a little coolant.. as its at top of the system..