Allpar Forums banner

1 - 20 of 40 Posts

·
Registered
Joined
·
41 Posts
Discussion Starter · #1 ·
Hey all, I've had a 75 Cordoba for a while now and have battled overheating issues the last several years. I've replaced the water pump, radiator hoses, thermostat (and boiled to check, it's working), had heater core redone and cleaned, had radiator repaired and cleaned (told it's in very good shape by reputable radiator shop), did the paper test to check fan (it pulled very tightly on radiator), replaced intake manifold gaskets, two different new radiator caps, timing is dialed in to proper spec (both mechanical and vac advance), air/fuel seems to be good, done full block and radiator flush kit (did get a lot of crap out of it), have OE shroud and good OE fan on it, and have ensured all air is out of the system, extensively burping any and all air out of it... I'm basically at a loss of what to do. I can drive the car 5-10 miles before the temp gauge gets to over half, and if I turn around and go home that far, I am pegged out on a warm day. Thermometer to intake/radiator shows upwards of 250-260 coolant temp when pegged so I know the gauge is correct, though I rarely let it get that high. Even blasting full heat (hotter than the surface of the sun) the car will still overheat. The car runs great aside from the overheating, I'd love to take it on longer trips but am unable to due to the issue. I've covered all the things I can think of that would cause the overheating, but the issue persists. Any ideas would be greatly appreciated. Thanks, Tyler.
 

·
Registered
Joined
·
189 Posts
Get a new Radiator....

I had the same problem back in 1989 with my 1978 Magnum GT...It was doing like your car..I changed the thermostat and no difference(I didnt change as many parts as you but)...I had the radiator checked out /cleaned at a well known shop, they said it was fine..Car still overheated !!! Wasnt impressed,as I spent money I didnt have (hey I was young)..

The next day,I went to local performance shop where there were always Mopars parked around and a few guys came out and they checked my car out (being a rare model and them Mopar guys) They said get a radiator,I guess the look on my face they knew I was broke lol..Lucky me I was young enough they helped me out big time !!! They actually gave me a old radiator for free,I just pulled it out of a parts car they had and put it in my car and I never had a problem with it ,car ran cool for years ! I even used their tools and coolant !!!! I returned about 2 weeks later and offered them some money,they kindly said NO ! But,I got a job with them and was there for many years ! Maybe they hired me because I bought them a case of Beer when I went back ,and I was under age lol..Hey those days guys drank at the shop !!

I even had a radiator recored on another car after it was leaking and it still was overheating. Get a new one thats the problem,easily done and they are not that expensive ! These cars stay cool even on hot 100 degree days in traffic !

Good Luck..
 

·
Super Moderator
Joined
·
37,870 Posts
These cars don’t have a lot of excess cooling capacity. My bet is on the radiator too.
 
  • Like
Reactions: tylerwrage1

·
Super Moderator
Joined
·
32,335 Posts
Could also be scale built up in the block, especially if it has drain plugs for coolant that have never been used.
Had a slant-6 that had never had the block drain open, had to hammer a nail through the scale under the plug to get it to flow. Then the coolant came out like chocolate.
 

·
Super Moderator
Joined
·
37,870 Posts
If it was a problem with the viscous fan, the car should run cool on the highway and heat up at lower speeds. That's a good idea that's easy to test.
 
  • Like
Reactions: tylerwrage1

·
Virginia Gentleman
Joined
·
15,027 Posts
My Dad has a '75 Fury with the 360. Compared to the 318 in his '72 Charger, it ran hotter. I'm guessing the radiator even when new barely could keep the engine at proper operating temperature. Just my observation.

I'd suspect a scaled up radiator if it overheats or gets hot at low speeds and stay relatively cool at highway speeds. Had those symptoms with a '92 Acclaim 2.5L I had - the gauge would show normal at idle and climb to 3/4 at highway speeds. A new radiator cured it.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #8 ·
Get a new Radiator....

I had the same problem back in 1989 with my 1978 Magnum GT...It was doing like your car..I changed the thermostat and no difference(I didnt change as many parts as you but)...I had the radiator checked out /cleaned at a well known shop, they said it was fine..Car still overheated !!! Wasnt impressed,as I spent money I didnt have (hey I was young)..

The next day,I went to local performance shop where there were always Mopars parked around and a few guys came out and they checked my car out (being a rare model and them Mopar guys) They said get a radiator,I guess the look on my face they knew I was broke lol..Lucky me I was young enough they helped me out big time !!! They actually gave me a old radiator for free,I just pulled it out of a parts car they had and put it in my car and I never had a problem with it ,car ran cool for years ! I even used their tools and coolant !!!! I returned about 2 weeks later and offered them some money,they kindly said NO ! But,I got a job with them and was there for many years ! Maybe they hired me because I bought them a case of Beer when I went back ,and I was under age lol..Hey those days guys drank at the shop !!

I even had a radiator recored on another car after it was leaking and it still was overheating. Get a new one thats the problem,easily done and they are not that expensive ! These cars stay cool even on hot 100 degree days in traffic !

Good Luck..
I always enjoy the stories I find on these forums. :) I do have a 76 Gran Fury Sport Suburban sitting out back, I didn't really want to rob parts off it but I may grab that radiator and put it in the car to test. Sounds like you've already learned from what I am going through right now, thanks for the knowledge!
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #9 ·
What engine do you have?

Before replacing the radiator, you might check the fan clutch. If it's lost viscosity, it might not be spinning the fan fast enough.
It's a 360 with small "RV" Edelbrock cam/intake/carb, nothing crazy. I forgot to mention that, I checked the clutch as well, it spins up nicely as rpms increase. Good thing to remember checking, I've had a fan clutch issue on a 90's Dodge truck that had me stumped, thanks for the tip.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #10 ·
What engine do you have?

Before replacing the radiator, you might check the fan clutch. If it's lost viscosity, it might not be spinning the fan fast enough.
Could also be scale built up in the block, especially if it has drain plugs for coolant that have never been used.
Had a slant-6 that had never had the block drain open, had to hammer a nail through the scale under the plug to get it to flow. Then the coolant came out like chocolate.
That is entirely possible I guess, since I have had it (6 yrs) I have been careful to have a proper antifreeze mix in it, but the last owners might not have been so careful. I looked at the drain but labeled it a last resort, kinda tricky to get to. I did a Prestone coolant system flush last fall and did get a ton of nasty crap out of both the block and radiator, but it ran very clean after that, even after a second dose of cooling system flush designed to eat that stuff away. Could it be so scaled up that the flush kit couldn't even eat away all the way?
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #11 ·
My Dad has a '75 Fury with the 360. Compared to the 318 in his '72 Charger, it ran hotter. I'm guessing the radiator even when new barely could keep the engine at proper operating temperature. Just my observation.

I'd suspect a scaled up radiator if it overheats or gets hot at low speeds and stay relatively cool at highway speeds. Had those symptoms with a '92 Acclaim 2.5L I had - the gauge would show normal at idle and climb to 3/4 at highway speeds. A new radiator cured it.
The thing is, it pegs out even going down the road with heat on blast. My car has the "heavy duty" factory radiator, but I guess it's just past its expiration date, the insides of it do look pretty skanky, even after a coolant flush additive. Thanks!
 

·
Virginia Gentleman
Joined
·
15,027 Posts
The thing is, it pegs out even going down the road with heat on blast. My car has the "heavy duty" factory radiator, but I guess it's just past its expiration date, the insides of it do look pretty skanky, even after a coolant flush additive. Thanks!
That's a sign the radiator simply cannot displace the heat adequately. I meant to say my Dad "had" a 75 Fury back in the day. He sold it long ago and has since passed away. As Bob Lincoln posted, it is also possible the block has scaling that cannot be removed with a flush.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #13 ·
That's a sign the radiator simply cannot displace the heat adequately. I meant to say my Dad "had" a 75 Fury back in the day. He sold it long ago and has since passed away. As Bob Lincoln posted, it is also possible the block has scaling that cannot be removed with a flush.
This is a photo of the inside of the radiator... Look screwed?
 

Attachments

·
Super Moderator
Joined
·
32,335 Posts
You're getting VERY little flow through those tubes. Time for a new radiator.
 
  • Like
Reactions: slyfox58

·
Registered
Joined
·
41 Posts
Discussion Starter · #17 ·
You're getting VERY little flow through those tubes. Time for a new radiator.
Do you think to get me by until the new one comes I could pull the thermostat to help it flow more through, or would that just make the problem worse from moving coolant too quickly through the engine, not so much the radiator?
 

·
Got parts?
Joined
·
2,610 Posts
I do have a 76 Gran Fury Sport Suburban sitting out back, I didn't really want to rob parts off it but I may grab that radiator and put it in the car to test.
Make sure that it's the same radiator, or at least that it lines up with the hoses and fittings.

I second Bob's recommendation to remove your block plugs to drain the coolant more completely. When I did this on my Dakota, it wasn't as congealed as what Bob described, but it came out brown for several flushes. Even if you can only reach one side, that's far preferable to leaving all of the gunk inside to potentially clog your system after you drain it. It's easier to get to mine from under the vehicle, so you might want to try that.

$118 plus shipping from Rockauto.com
The latest radiator for my Dakota was $120 plus tax at Advance, and they had it in stock. If you determine that the radiator needs replacing, research for the best price.

If you remove the thermostat, replace it. Make sure it's the temperature that your owner's manual calls for.
 

·
Super Moderator
Joined
·
32,335 Posts
Do you think to get me by until the new one comes I could pull the thermostat to help it flow more through, or would that just make the problem worse from moving coolant too quickly through the engine, not so much the radiator?
Removing the thermostat will not improve the bottleneck at the radiator, and will make the car run richer as it will take longer to warm up.
 

·
Registered
Joined
·
41 Posts
Discussion Starter · #20 ·
Make sure that it's the same radiator, or at least that it lines up with the hoses and fittings.

I second Bob's recommendation to remove your block plugs to drain the coolant more completely. When I did this on my Dakota, it wasn't as congealed as what Bob described, but it came out brown for several flushes. Even if you can only reach one side, that's far preferable to leaving all of the gunk inside to potentially clog your system after you drain it. It's easier to get to mine from under the vehicle, so you might want to try that.



The latest radiator for my Dakota was $120 plus tax at Advance, and they had it in stock. If you determine that the radiator needs replacing, research for the best price.

If you remove the thermostat, replace it. Make sure it's the temperature that your owner's manual calls for.
Checked the 76 Plymouth radiator, it won't work, it's a 440 so top inlet is on the wrong side. I'll look into the drain plugs on the block a bit more, but as of right now it looks like it's time for a new radiator. I'm going to check with a few mopar guys around here to see if they have a radiator laying around I could slap in to test. I boiled my thermostat, and at 194 water temp it opened, it's I believe a 190 thermostat so that'll work. Trying to throw around the idea of getting a larger aluminum rad that will support engine mods down the line, but hard to justify the extra 100 bucks. Thanks again for the continued assistance!
 
1 - 20 of 40 Posts
Top