Yet another overheating question... LOL

[ehostler]

Alright, here's the situation...

For the first couple Summers that I've owned this car, the cooling system worked great.

Towards the begining of last Summer, she would start to get hot at the lower RPM range. I replaced the T-stat witha Mr G 180 Hi flow. This didn't help or make things worse.

I then drained out all of the coolant and replaced a leaking freeze plug. I refilled the system with a 50/50 mixture. Problem stayed the same.

As the Summer progressed the problem got worse. Now this Summer, in town driving will push the needle to the far right. I found that If I drive around (in town) in 1 or 2, to keep the RPMs up, it will do a great job in bringing the temp back down.

Today, it was deep in the H. Once I got home, I placed the nose in the garage and brought the RPMs up to about 3,000. I watched as the needle gradually moved down to mid point in about 2 minutes.

I will not believe that the hot temp of my garage took the cooling system down that fast,

I believe that the problem is a restriction in the system. I have checked the hoses and they ar not collapsing.

As this problem was begining before I replaced the T-stat, I have pretty much well ruled that out.

So, that leaves me believeing that I either have a slow radiator or the water pump isn't moving the water as it is supposed to.

Is there any way that the water pump could be failing to cause this, or is it most likely a pluged up radiator or am I looking in the wrong place for this problem???

[dave571]

I have seen impellers start to slip on the drive hub of the water pump. EXTREMELY rare failure. You could pull the pump, and see how tight it is on the hub.

It definately sounds like a radiator. Especially with the gradual failure. As the pasages start to plug, they plug up faster, due to the restricted flow.

A rad shop should be able to test it, if you yank the rad, and take it to them.

[ehostler]

Thanks for the input. I was kind of thinking radiator as well. I was just hoping for it to be the pump, since I intend on replacing it with a Moroso or Milodon unit.

[Mister Fiberglass]

What type of fan do you use? Have you ever tried running the car with OUT the fan.....just to see where you are at?

[1972roadrunner]

is your guage correct?? ....i agree with the others, have a radiator shop look at the radiator...

before we rebuilt my roadrunner, it would run 180-190 all day long (with a 160 stat) in the summer. when we rebuilt the motor, we had the radiator fixed (mounting bracket came unwelded) and checked for any plugs or leaks... turns out, it was partially plugged. NOW the thing runs no hotter than 175 on a 100* day!

4core radiator
MP Water pump? (got from advance auto)
160* stat from advance auto (brand?)
Flex Fan! noisy bastard, but it works nicely

[Mr.Mopar]

I had the exact same problem, I took out the rad and added another row, to make it a 3 row rad and now it barely reaches 1/4 or at the most 1/2 way on the guage. Best thing I ever did. I am also running a 160* stat which could be changed to a 180* if I need to when it gets cooler outside.

[ehostler]

I've already rulled out the fan and the shroud as they have not been touched. It was running good with this combo for over three years.

Core size of the radiator shouldn't be a problem either as it ran great with this radiator for over three years as well.

Even though it is the stock POS gauge I trust that it is telling me the truth (as compared to before), because when the needle passes the halfway point, she pings like a mother when you try to accelerate to hard.

When the engine is first run, the gauge goes to just about the ¼ mark and hangs out there for about 10 minutes, then it just begins creeping higher.

I'll probably just take the radiator in and see what's going on with it. Just looking straight in, I can sometimes see some small fragments sitting inside. I'm sure that there must be more deeper in the radiator (that I can't see), that is restricting the fluid flow

[Tomasso B Cuda]

My vote is for the rad plugging up over time as I have experienced this problem myself...

[b-1ken]

I had a water pump impeller slip on the shaft once on a dyno engine. It did not give the symptoms that you have. It just flat overheated. I would think that your radiator might just need a flush job.

[maumau]

I don't think I would disconnect the fan....it would o/heat for sure then...My vote is for the radiator being partially plugged up. Maybe try a good long term cooling system flush, the type you pour into the radiator and run the vehicle for an extented period of time...like two or three days...may help

[6pakman]

its the rad. shit can it or get it recored. one way or the other it might cost the same. depends on how original you want to keep it. just dont use that garbage that poop boys or any other auto parts store sells that is an additive for overheating problems. leave that for the boys in the hood!

[ehostler]

As far as originality goes, this is a recored radiator from a GTX.

I would NEVER buy anything from Pep Boys. They are anti-American and have violated the rights of their employees that are also military reserve.

I'll probably just pull that radiator and get it rodded out. I'll probably give it a good flushing first, so that I can get any remaining crap out of the block, before a clean rad is put back in.

[Bigdog340]

You guys are funny...But the rad should fix it. I had the same problem. My test... I called a radiator shop and asked how much water the unit should contain. Then I took my rad off and filled it. Hmmm 3/4 gallon. I just found my problem. A recore ( I wanted to keep the orig mopar tanks) and we are coooool. By the way, adding an extra core gains you very little if your current rad is clean and flowing. The only way to get more cooling is more width.
Thats why in later years rads were much wider across the front and thin.

71 Duster 340
3.23 Posi

[Mr.Mopar]

Adding another core doesn't get you much more cooling.....mmmm....I went from a 2 row to 3 rows and now I don't even think about overheating whereas before I needed an extra 14" electric fan in front to push more air through to cool it off. I have at least 40% more cooling now, and the rad was cleaned and boiled out before. Now the electric fan sits in my garage collecting dust. I think you are misinformed.

[ehostler]

The extra core means more water in the radiator. The more water that is in the radiator, the longer it takes for the engine to pull it all out. The longer the water sits in the radiator, the more amount of time it has to cool down. A wider radiator will accomplish much the same thing, so long as the entire surface area is exposed.

In my situation, I have a radiator that the cooling fins are about ½" wider the the hole for the radiator. The cooling fins are also flush with the tank edges. I'm pretty sure that I have the largest cooling area that can possibly work with the stock tanks, in this car

[dwc43]

It's either a stopped up rad or the viscous fan clutch could be failing if you use one of these.

[ehostler]

It's easy to rule out the viscous fan clutch, as I haven't put one in yet. It is a power robbing, direct drive, metal fan.

[23T]

Ed, looks like your going to have the front off any way, but once I had a plastic impeler on a water pump and when the temp got to a certain point the impeler would slip on the shaft/ when it cooled would work for a while, I know this is not a direct relation to what you are having, just a thought, but the rad treatment would be a good idea since you will be down for a while

[dkn1997]

if you plan on flushing the rad in the car, bypass the heater core. It could leak if you run the flush stuff through it. happened to me once and my dad once...ughhhh