My 62 Lancer 170 ci runs extremely hot on the freeway. It seems to get super hot when I get above 2800 rpm. Here is what puzzles me; as soon as I exit the freeway it cools down almost instantly. I mean by the end of the exit ramp. It runs nice and cool in stop and go traffic as well as extended idling.

The radiator core is new, I'm running 10 btdc HEI, valves lash 10/20 with a new Holley Economaster. I chemical and garden hose flushed the block, but it could still have some crud?

What could this be?

B

_________________
These ones go to eleven...

Problem with airflow across the radiator? Hose collapsing?

How sure are you that the fan is on right way round?

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Water pump cavitation, maybe? I don't recall if that's a known problem with the slant. Do you know what RPMs you're running on the freeway? If not, what's your rear end gearing?

If not cavitation, maybe the belt slipping under heavy load?

_________________
Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

No that's not a problem on the slant...

I would say I would look at the fan, and if the radiator has full flow....the next item on my list is checking to see if you are running a little lean at highway speeds and how your timing is at those speeds, a little lean will add plenty of heat on the system on the highway...also what kind of thermostat are you running?

I'm using a 180 thermostat, 3.23 gears and about 3000 rpm highway. The fan is on correctly and almost touching the radiator. The fan belt is tight and the airflow is unobstructed.

The top radiator hose has a spring, but the bottom one does not. Is it likely that the pump could collapse a hose at 13 PSI?

As soon as I slow down,less than 30 seconds the temp goes from nearly pegged down to 180. My other car gets a bit hotter when I leave the highway and come to a stop.

_________________
These ones go to eleven...

You may have a flushed the car but that does not mean you go the rad core clean. I would bet that the issue is that you have gotten a lot of crud in the rad core that is blocking a significant number of the tubes... or there is a hose collapsing....or the circulation hole in the back of the head is mostly blocked. Do you have the spring inside the lower hose to keep it open?

Your symptoms are typical of low coolant flow. Make sure there is a spring in the lower hose, and take out the rad and back flush it (bottom to top, with the bottom hose outlet sealed) while tapping with a plastic or wooden handle and see if a lot of cruddy bits come out. You may also back fill the rad from the lower outlet and put in very short bursts of air pressure to help dislodge crud. Also, take out the thermostat, put the housing back on, pump water in there and and seal up around the housing hole to see if a lot of back pressure builds in the head, and make sure it flows freely out of the bottom of the block (pump or block plug hole)

Also, pull out the back block plug and put you finger in to see how much crud/goo/gunk there is at that point in the block.

Are you sure it's really hot? Maybe there is a weird current/voltage issue at higher rpm's and your gauge is misreading? Try running her at 3000 rpm in your driveway in park, see if the temp rises there.

Do you happen to have an IR thermometer to check actual temperature during operation? Seems odd that it would cool down so quickly if it were overheated.

brian

_________________
https://tinyurl.com/yynpj4v2

I don't think it is electrical. When I rev it to 3000 it does the gauge does not immediately get pegged. It takes about 10 minutes of freeway driving for it to get there. But as soon as I slow down it drops in seconds. And when I get back on the freeway it slowly creeps up again?

I just put in a new radiator core less than 200 miles ago. I could push some air and or get everything back flushed. There is no visible blockage at the top of the core.

I will replace the bottom hose with a spring-ed one.

_________________
These ones go to eleven...

What is best brand for lower radiator hose? After sifting through the forum it appears that the hose with the spring is no loner manufactured.


I could try and put the spring from my old hose in it?

B

_________________
These ones go to eleven...

Then it seems to suggest the other commentary on a radiator hose collapse. That at least would be consistent with it getting hot slowly (higher flow of air through the rad at highway speeds, but insufficient/restricted coolant flow) but cooling off quickly on the ramp, coolant flow restored, less stress, less air but plenty for cooling...

brian

_________________
https://tinyurl.com/yynpj4v2

The radiator hose is not collapsing -- not unless the radiator is severely clogged and the cooling system is not pressurised. No spring is needed or beneficial in either hose.

It's also not water pump cavitation, and the radiator itself isn't causing the problem unless the new core is grossly underspecified for the task (not likely) or an enormous amount of trash was loosened up but not removed from the block (thus proceeding to clog up the radiator core).

The engine will naturally produce more heat when it's under load (on the highway) than when it's being run, at any speed, in Neutral with the car stopped. The trouble could easily be nothing more complicated than a temp gauge or sender with a response curve that is no longer what it should be, such that past a certain coolant temperature its resistance drops off much more than it should.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

We' ll it looks like I'm buying an after market gauge and new sending unit.

Thanks!

_________________
These ones go to eleven...

Smoking gun? I just finished letting the car idle for half an hour and the bottom radiator hose never even got warm. I revved it up to 3000 and there were no collapsing hoses and they stayed firm.

Could this point to a failed water pump?

B

_________________
These ones go to eleven...

Water pumps are fairly simple devices. The only way it can fail in a manner to cause overheating is if the rotor got corroded to the point where it doesn't exist anymore. If this happened you'd have overheating in all conditions though. For your sanity check though - open the cap when cars cold and let it warm up - when the thermostat opens you should see obvious water flow.

The lower hose will be cooler then the top, otherwise the rad's not doing it's job. If there's not enough load on the engine (and consequently heat in the water) then yes, I can imagine the lower hose will be cool.