Coolant temp question.

[entropy1049]

While driving my (new to me) 69 Road Runner 440 6bbl on the highway this weekend, over a 3 hour trip at highway speeds (60-70 mph) the engine ran within 3 or 4 degrees of 180 the entire trip with the exception of 2 or 3 times when the coolant temp gauge suddenly registered a rise in a matter of about 5 seconds to about 240 degrees. As I had one eye on the gauges, as soon as it rose above 210 I'd pulled her out of gear and was headed to the shoulder to shut down. By the time I'd gotten the vehicle to a stop, the temp was dropped back down to a happy 180 again.

Any ideas on what's going on? It does have the Wizard Cooling radiator and electric fans.

Thanks for any help!

Mike

 

[quikbird]

thoughts of possible things
blockage somewhere in system, check lower hose to make sure doesn't get sucked flat, check coolant level to make sure enough present, water pump starting to go, water pump pulling air for some reason, lower damper starting to fail and letting pulleys slack off. \

there is a few thoughts. only so many parts of system to mess up so let us know what you find

 

[entropy1049]

About 1500 miles on car/engine since resto-overhaul, so hopefully not part failure yet, though we'll see. The car has been only infrequently driven over the last 4 years by the previous owner, so a flush and fill is a good place to start. I'll knock that out and report back.

Thanks for the ideas!

 

[quikbird]

if not driven much, definitely check lower coolant hose. it has a metal spring inside it to keep it open and that rusts sometimes. can change the hose dia. and restrict flow

 

[69hemibeep]

Quikbird is right on the money with the lower hose. High RPMs will suck it closed without a spring.

 

[Goon]

Could be a stuck thermostat.
I've been reading up on different coolants for my car. Found a product call Evans coolant, contains no water, boiling point is in the 300's, where as antifreeze and water is around 215. Car will get hot but not build pressure. I went with flushing out coolant system with distilled water, adding a bottle of Red Line Water Wetter & filler rest with distilled water(will freeze in winter)

 

[entropy1049]

All this is very helpful and appreciated! Thanks for the comments so far, I feel I have some very logical things to look in to and some possible remedies.

I'll be doing some troubleshooting tomorrow and will post findings here. Thanks a lot for helping with great ideas!

 

[entropy1049]

As you folks predicted, the lower radiator hose is very pliable and not at all stiff. Additionally has about a 17 inch length so little structural rigidity. Also the radiator cap was a little dirty and the pressure relief valve probably not functioning the best, so I gave it a good cleaning. I'll order either a stainless insert spring or a length of good Gates green stripe wire reenforced hose this evening. Between the pressure cap and the bottom hose fix, I'd predict I won't see any more temp spikes .

 

[quikbird]

it sounds like it is an original hose. order a new one. old hoses tend to blow with no warning.

 

[Coyote]

Replace All Of Them!

QUOTE=quikbird;155109]it sounds like it is an original hose. order a new one. old hoses tend to blow with no warning.[/QUOTE]

If one's bad, the others are probably on the way South too!:yeathat:

Cheap insurance (as much as I hate to agree with QB on ANYTHING!).

 

[entropy1049]

Hoses are all nearly new and in good repair. Just surprisingly flaccid on the bottom end of the radiator . T clamps are heavy duty and in good shape.

 

[69hemibeep]

The lower hose is pretty soft new is why it requires a spring in it

 

[rm6p]

Entropy1049, Where are you ordering the lower radiator hose internal spring from? I have never found one the correct size. When I run the freeway for any extended time my temp creeps up very slowly. 180 thermostat and it will get to 205 in an hour or driving at freeway speeds.I have not run the freeway more than an hour at a time since flushing the block and replacing the 26" radiator (4 core copper), shroud, thermostat (Milodon), water pump (stock 8 blade with impeller blades facing the correct way), all hoses, fan clutch, and original mopar 2-1/2" pitch 7 blade fan. All I can think of is the lower hose collapsing slightly at speed and impeding flow. 1970 Roadrunner 440.

 

[69hemibeep]

Entropy1049, Where are you ordering the lower radiator hose internal spring from? I have never found one the correct size. When I run the freeway for any extended time my temp creeps up very slowly. 180 thermostat and it will get to 205 in an hour or driving at freeway speeds.I have not run the freeway more than an hour at a time since flushing the block and replacing the 26" radiator (4 core copper), shroud, thermostat (Milodon), water pump (stock 8 blade with impeller blades facing the correct way), all hoses, fan clutch, and original mopar 2-1/2" pitch 7 blade fan. All I can think of is the lower hose collapsing slightly at speed and impeding flow. 1970 Roadrunner 440.

Does it cool down pretty quick when you slow down?

 

[entropy1049]

Entropy1049, Where are you ordering the lower radiator hose internal spring from? I have never found one the correct size. When I run the freeway for any extended time my temp creeps up very slowly. 180 thermostat and it will get to 205 in an hour or driving at freeway speeds.I have not run the freeway more than an hour at a time since flushing the block and replacing the 26" radiator (4 core copper), shroud, thermostat (Milodon), water pump (stock 8 blade with impeller blades facing the correct way), all hoses, fan clutch, and original mopar 2-1/2" pitch 7 blade fan. All I can think of is the lower hose collapsing slightly at speed and impeding flow. 1970 Roadrunner 440.

O'Reilly Auto has the Gates Green Stripe wire reenforced. My radiator uses the 1.75 inch I/D. Your hose will be on this page: http://www.oreillyauto.com/site/c/search/Radiator+Hose+&+Kits/N0937/C0108.oap?year=1969&make=Plymouth&model=Roadrunner&vi=5144699&brand=Gates

Does it cool down pretty quick when you slow down?

Cools down FAST, like in about 5-10 seconds. EDIT: Whoops! Just realized you're possibly addressing rm6p.

 

[69hemibeep]

O'Reilly Auto has the Gates Green Stripe wire reenforced. My radiator uses the 1.75 inch I/D. Your hose will be on this page: http://www.oreillyauto.com/site/c/search/Radiator+Hose+&+Kits/N0937/C0108.oap?year=1969&make=Plymouth&model=Roadrunner&vi=5144699&brand=Gates




Cools down FAST, like in about 5-10 seconds. EDIT: Whoops! Just realized you're possibly addressing rm6p.

Oops yes but I should have quoted him Yours is for sure a hose when it cools like that.

 

[69B5]

I had all the same as you with the mystery car.
I tried everything.
I finally solved the problem by installing a "Wizard" radiator
I drove 6 hrs. to Carlisle and 5 to Inlet with no problems

 

[rm6p]

The temp does go down fairly quick once I am off the freeway. Maybe couple minutes in traffic and I am dropping rapidly to 180 degree.

 

[quikbird]

Rm6p, it does sound like not enough water flow at speed. On freeway is when temp should be lowest, not city. Start tracking the path and make sure every part actually works. Even though it is new does not mean that it is really working well.

 

[69hemibeep]

Squeeze the lower hose to see if it will flatten that would be a lack of an internal spring. Your cooling system sounds good if it cools back down off the open road. Like Quikbird said you have a restriction at speed, a lower hose a thermostat There are also some cheap after market aluminum water pump housings that the passages are to small on. Also there is a filler piece of steel that bolts between the front bumper and radiator support that helps force air through the radiator at speed rather than to allow it to go around it. If you look down between the grill and radiator support and have a clear view of the ground that is missing.