The Dodge Challenger Message Board

My 70 challenger doesn't overheat but does get a little warmer than I would like. I have a 2 row 22" radiator in front of my 72 340 motor that has checked out ok at the radiator shop. Alot of the challengers came with 26" radiator supports instead of the 22" that came in my original 318 car. I was wondering what others are doing with similar cars especially those that do the small block to big block or hemi conversions. I don't plan on swapping to a big block but would like the car to run slightly cooler. I am running a viscous fan without a shroud and am not sure if 22" radiators came with shrouds. The car runs warm on the highway as well so I don't believe the shroud to be the problem. I'm almost certain the radiator is the cause. I did see radiators in Paddock for Darts that were 22" and were 3 row instead of 2 row for 318 and 340 cars but they don't have tech support and I'm not sure if this radiator would fit. Year One doesn't sell 22" radiators and only sells the 26". Has anyone swapped out a 2 row 22" radiator with anything bigger without drilling or cutting the car. I would prefer to keep the stock look and bolt up to the 22" supports and not buy a "Be Cool" aluminum radiator or other aluminum customs. The car runs slightly above half way to about 2/3 of the way up on hot days. I'll be checking out every challenger at Carlisle this year looking for solutions. Any suggestions?

Is the temp sender and dial OK? What about the hoses? Any feel soft (could collapse)? Is the bypass hose present between the intake manifold and the pump housing? Could be a thermostat not opening fully, or even a 'winter use' thermostat. I'd take the easy and cheap option first and replace the 'stat.

You can get a 'stat that opens at a lower temp. You can also get a bigger (thicker) radiator core fitted to your existing radiator using your existing top and bottom tanks so it still looks stock.

(Message edited by admin on April 02, 2003)

My 72 was was built with a 318, it is now a 440. I have also done a fair bit of engine and tranny modifications. The 22" 2 core rad would not keep the car cool. I put in a 26" 3 core rad and have had no problems since. The rad I put in was for a big Crystler "Boat" so I had to drill some holes and modify, "cut" some hoses. For a 340 I think Dave might be on the right track by re-coring your rad to keep the stock look.

Thanks for the replies, tried the 'stat tricks last summer and it did help some; put a 160 in and it did help but not enough. I didn't try removing the 'stat altogether but believe it would aggravate the problem but will try that as well. Hoses feel ok and the bypass hose is present; haven't replaced the temp sending unit yet but will; i'm assuming the dial is ok and don't have a clue as to how to tell (just know it moves). I bought some Redline Water Wetter to put in also for this coming summer since they claim a possible 30 degree drop in temp even though I don't like to bandaid anything. Dave's idea of recoring sounds like what I'm looking for and I'll give my local radiator shop a call and see what they can do for me.

How hot is it getting?

Depends on how modified your 340 is John. Last summer mine ran hot during traffic jams with a 26" 3 enlarged cores radiator and the fan shroud. Now I replaced the shroud for a solid fan and it seems to cool much better although i haven't been into traffic jams yet.

I'm not sure on temperature but the guage in the spring time will run about where I want it which is below half way. In the hot summer it will run slightly hot 2/3 of the way and I actually shut it off once at a carshow as it headed for the red. I did see some radiators in paddock for dusters and darts that were 22" 3 core radiators. Anybody know if these would be a direct bolt in for the challenger? Probably the recoring suggestion would be cheaper and who knows maybe they could even give me 4 rows

The 340 is modified some; but before I did the modifications the temp problem was even worse. I put a mild cam with some lope into it and did go to some heads with larger valves but other than that nothing too serious and I did freshen bottom half as well and is .30 over. I did think about trying a shroud but not sure if it would fit since the fan isn't centered on the radiator.

Connect your temp sender to a good aftermarket temp gauge and see what the temp actually is. Don't rely on the factory gauge. You can always remove the aftermarket meter after you are sure the temp is ok.

I'll try that and see what the temp is even though I already "think" I know the answer but it wouldn't be the first time I've been wrong.

http://cgi.ebay.com/ebaymotors/ws/eBayIS API.dll?ViewItem&category=33602&item=240 9215654
thought maybe this guy might help also you can click ask question and email them.

I had similar problems with another car I owned and restored. I eventually installed a 5 core radiator, however even this didn't solve the problem entirely. The final remedy was to put in spacers to allow better air-flow. The rad was mounted to the support with 1" deep spacers. This brought the rad closer to the fan and drew more air through it. This I found was the best result and reduced the temp guage reading from 3/4 on a warm day, to less than 1/2 believe it or not.
My '71 JH23 with a/c and 26" rad, was showing less than 1/2 on the guage on my trip across the country 2 months ago. This was driving in 41C heat with the a/c on occasionally only. 41C for you would be around 105F so pretty damn hot.
The only item I think that has not been suggested so far is the possibility of your water pump being sad. If the fins have corrosion, they will circulate less water, therefore less cooling - hope this helps.

I sent them an email, thanks for the info. Hopefully they can give me a little insight also. Maybe I'm a little too critical with this whole situation since it doesn't boil over but we all strive to make our cars better and I will do just that and figure this out.

John, with your present radiator, are the inlet and outlet at the same side or is one at the passenger side and the other at the driverside? If they're at the same side that will be your problem. (remember Dave? )

Yep. That was my problem.

Nope, wish it were that easy. They are on opposite sides. I did see the posts about that causing Dave's problem and went out and checked to make sure it wasn't that. Temperature can be a funny thing for sure.

FWIW I have a massive 29" rad (late C-body rad, I think - I will copy down part number, if needed) with 3 'staggered' cores cooling my big block in my Challenger. It has the inlet and outlet on the same side (passenger side), and I run an ex-Dave Robson electric fan (the shroud was too small Dave!!). The highest I saw the temp gauge rise to last year in heavy traffic was 1/2 way. Things may be different this year, though, as the engine has been 'fiddled' with...

You must tell me exactly what you have been up to since I last saw the car Phil.

Email sent, Dave!

what size fan do you have and how many blades does it have? I have a 18 inch fan maybe without the shroud you can go bigger. also you might want to try flushing to system at some point somebody might have tried some sealent in there that might clog your system slightly!!

Somehow I missed Roger's response and just went out and checked how close my fan was to the radiator. It measures about 1 1/2 inches from the radiator. What is the closest that I would want the fan from the radiator without flexing into it and destroying my radiator? The spacers were something I never even considered and that sure would be easy to do. The fan is an 18" fan with 5 blades and maybe a larger fan would work; something worth trying. Great ideas for sure. As far as some clog in the cooling areas; ditto there since motor was dipped and freshened, whole nine yards last winter. I believe the water pump to be ok, when the motor was all apart pump looked good.

John - start with half inch spacers and see what happens. This should still provide you with ample clearance and plenty of support for the rad. I would also consider investing in a 7 blade fan and check to make sure the clutch of the fan is working properly (the viscous hub if yours is fitted with one).

John, I am working on a similar problem with my 318 car, which now has a rebored 318. My non-ac car came with a very small radiator (I forget the measurement) which is still in it. It is hopelessly inadequate, so I recently bought a two-row 440 radiator. Unfortunately, it is wide to fit the holes for the original and I would have to use spacers and drill holes to use it (doh!). I also have another radiator ( believe the 22 inch - I don't have the specs in front of me) - it is off a 318 a/c car and needs recoring. If I can't figure out how to rig up the big radiator, I will use it. I am using an electric fan (from Summit) with a Painless relay and 160 deg thermostat. The electric fan does help and I expect it to do well with whichever radiator I put in.

Does anyone know if the 440 radiator will go into the small-block with just the spacers and new holes? Do you have to hack anything up, like the battery tray?

If you have a rad from an a/c car, I would assume it to be the 26" one (that's what my 318 a/c car has).
More core rows, more fan blades and lower value thermostat is what you need to keep things cool. I'm talking from experience of driving in a hot country where all imported cars are modified to cope with our temps. Remove the top and bottom tanks and clean the core tubes before doing anything (get a pro to do this for you) - then use a corrosion inhibitor with rainwater or distilled water only - never use tap water if you can avoid it. Flush the system every year, with the heater tap on, to flush the heater core too. Check to make sure you have good air-flow through the rad and keep things clean (the rad cores free of bugs and grass seeds). You should have a really "cool" car then.

I overlooked something that really didn't make me think it could possibly be part of the problem until now. I do have a screen in front of the radiator to keep the bugs out and am wondering if this could possibly be causing some of my problem. The screen has been there since I've owned it. We're getting a good rain here (New York) today to wash the roads off good and I plan on taking the car out tomorrow for the first time this year after a rough winter. I will remove that screen and see what happens; but am wondering of anybody's experiences with screens in front of radiators. It is time to tinker with alot of your suggestions and see what happens. I'll post after with what worked and didn't work. The hotter days are yet to come.

John, I just purchased a 22" 3 core radiator off e-bay last week and it arrived today. All bolt holes mearsure the same as my old one, although I haven't swapped them out yet. Item number was 2436598095 you should be able to go on E-bay and search for this item number and it will come up and then contact this guy. Hopefully this helps. Troy

Something I've tried on the big block cars is ,if you decide to recore your radiator, ask about using offset rows. It makes a big difference and using your original top and bottom bowls keeps the radiator looking stock. And it costs the same while they are doing the recore anyway. Around my neck of the woods about $175.00 USD.