Still overheating

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FrozenCaveman

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Hey guys,

I'm looking for a little help with troubleshooting an overheating issue.

My Scamp has a /6 with maybe 15k miles on the rebuild - bone stock. Radiator and hoses were replaced at the same time (about 6 years ago). The symptoms are that it slowly runs to the hot end of the temperature gauge (over the course of several highway miles or sitting in city traffic) and spews coolant from the overflow hose when I shut it down. It usually diesels as well, so I've taken to shutting it off in Drive. Besides the overheating, it drives and idles fairly well.

I replaced the stock 195 thermostat with a 180 performance. Still overheated.
I adjusted the timing from 5 degrees advance to TDC and readjusted idle to 750 rpm in Neutral. Still overheats.

Dwell reads at about 39, which is slightly low (manual says 41-46 :read2:). I'm not great at adjusting points, so I was going to hold off on that until I thought it might be the cause of my troubles.

The upper hose is hot, so water is circulating. Water pump sounds OK - I mean, no bearing noises. I rechecked the coolant level last time and it was OK after topping off for the lost coolant.

I'm a little frustrated because this 225 should be bulletproof, and before Winter, I had an extended drive in high ambient temperatures without a problem - temperature sat so low I thought the gauge was wrong. Any help/ideas would be appreciated. I want to start commuting in this car again as soon as I can.
 
spews coolant from the overflow hose when I shut it down. It usually diesels as well, so I've taken to shutting it off in Drive.
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sure the timing is correct? shouldn't have to put it in drive to shut it off. could it be running lean? 6 years on the rad? was it a new rad? you sure its clean and none of the tubes are clogged?
 
abodyjoe said:
sure the timing is correct? shouldn't have to put it in drive to shut it off. could it be running lean? 6 years on the rad? was it a new rad? you sure its clean and none of the tubes are clogged?
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I'm pretty sure the timing is correct. I have a timing gun and double-checked it after tightening the distributor down.

It could be running lean, I suppose, but it doesn't feel like it when I step on the gas hard. I haven't adjusted the mixture at all. I'll start from scratch with the carb then. As a baseline, do you know how many turns out should I start with the mixture screw before dialing it in?

I guess can't vouch for the radiator not being clogged, but it doesn't look very crusty inside. Is there a way to test it myself? It was new at the time. I think I picked it up from Kragen, though. :-?

I was thinking yesterday that maybe the radiator cap is not holding pressure, but then I'd be seeing some other symptoms, wouldn't I? Like coolant spewing out the cap?
 
Don't you have an overflow bottle installed yet? We have them on all our Darts. Also my sons 69 6 cyl had EVERYTHING replaced including 2 new radiators from parts store. They had micro cracks along seams. Also finally went back to the original 69 thermostat all brass. We were getiing some bad ones (New) Check them in pot of boiling water on stove. Good Luck!
 
also you mentioned the upperhose as being hot so you know the antifreeze is circulating. next time before the car gets hot. start it up and take the cap off. the thermostat will open up and the circulation will start. when it does see how much flow you have. the water pump should be able to have a small current flowing in the radiator. if it is barely moving (i use my finger to check) then the radiator is either clogged or the water pump is not doing it's job....
 
64dart170 said:
Don't you have an overflow bottle installed yet? We have them on all our Darts. Also my sons 69 6 cyl had EVERYTHING replaced including 2 new radiators from parts store. They had micro cracks along seams. Also finally went back to the original 69 thermostat all brass. We were getiing some bad ones (New) Check them in pot of boiling water on stove. Good Luck!
Click to expand...

The new thermostat I used is all brass. I think it was close to $12 from Summit Racing. The sad thing is that I overtorqued the bolts on the thermostat housing when I replaced it and cracked the original aluminum housing. Had to install a new cast iron one.


7demon2 said:
just throwing this out here if you want to try a better radiator & shroud which will help! http://www.forabodiesonly.com/mopar/showthread.php?t=49833&highlight=recored+19'+radiator
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Shroud? Should there be a shroud on my stock 71 with /6? I can't see any obvious places to attach one, but maybe it did get lost somewhere in the last 38 years. :dontknow: This car belonged to my mom, who bought it new in 71. I didn't start looking at it until I rebuilt the motor in 2003, so I don't remember if there ever was one.

This weekend I'll get to work on it a bit more. I'll try running it with the radiator cap off to check the flow. I should've done this anyway after replacing the thermostat - maybe I have an air bubble trapped in there somewhere...

Thanks for the advice,

John
 
no there was not a shroud with the /6 in 71. what i did was take the brackets from a radiator that had a shroud and had them added to the original radiator so i would have a mounting location for a shroud. i then found a correct shroud that fits the 19' radiator i had recored. it worked well together. like i said i was throwing this out as an option. it would really cool your car well....
 
7demon2 said:
also you mentioned the upperhose as being hot so you know the antifreeze is circulating. next time before the car gets hot. start it up and take the cap off. the thermostat will open up and the circulation will start. when it does see how much flow you have. the water pump should be able to have a small current flowing in the radiator. if it is barely moving (i use my finger to check) then the radiator is either clogged or the water pump is not doing it's job....
Click to expand...

One thing I didn't mention - the heater core is bypassed and the hoses that were previously routed through the core have an elbow connector connecting them. I don't know if this would contribute heavily towards overheating.

I ran it with the cap off and there was immediate flow coming through from the upper hose. So the thermostat is apparently in an open position at ambient temperature. The coolant level was just above the radiator core, so I added a bit more water. The flow was then less visible, but the water warmed up fairly quickly since it was an open thermostat. After running it for maybe 5 minutes, the temp had creeped up a little. I'll take it to the store and back to see if it still gets hot. Maybe I worked some air out of it.

I took a picture through the top in case you think the radiator looks clogged. There's some buildup, I guess, but I've seen worse.

Regards,

John

scamp_radiator.jpg
 
Take it out and have it flow tested at a radiator shop. Then you won't have to guess at the problem.
The stat should not be open at ambient temp. either.
 
Don't ya just hate it when your car runs hot? Pressure test the cooling system. Then I'd replace everything that's cheap and easy first and make sure the timing is spot on. Six year old hoses gotta go. Thermostats are cheap. Soun ds like the one in there is faulty. Use the right one for the car as prescribed by the manufacturer, don't go to a 180 just because you think it's gonna make the car run cooler. That's not gonna address the real problem. The coolant (not water) has to stay in the motor long enough to transfer heat and the engine will run better at a certain( sometimes higher but usually around 195-200 degrees). Pull the plugs just to take a look see- maybe signs of water or indications of a lean condition or timing problem. That stuffs cheap and easy. If all is well then look into bigger stuff like radiator flow, water pump ( new pump is cheap too, actually). Every car should have a shroud whether the factory put one on or not. You don't see anything without one after about 1970 because they are cheap and make alot of difference in pulling air through the rad (especially in slow, trafficky driving in hot weather) Oh yeah, almost forgot, no water with minerals (tap water) use 50/50 anti-freeze or distilled water. The minerals ( iron and what-not) decrease the boiling temp and increase clogging and gook. On your carb idle mixture, use a vacuum guage to achieve max vacuum while messing with the screws. Check that tee to make sure it's not clogging up. On the subject of air pockets, they're getting in there because it's getting too hot and steam is forming. That's gonna cause more heat and more steam and more air pockets. Gotta get the air out and figure out what started the whole vicous cycle.I look at it like this, I'll gladly spend a few dollars ($50-$200 or whatever) to cherry out the cooling system so I don't have to spend alot later! Good Luck!
 
Wow, thanks for all the advice!

I'll be able to replace hoses and look into the problem further on Friday. Won't have time until then, unfortunately. But on my 4-mile test drive on Saturday, it spewed again. So it's still not good.

But now I'm starting to lean (no pun intended) towards the fuel mixture being too lean. The first mile of my drive was about 45-55mph, then the 2nd and 3rd miles were at 35-45mph, then back to 45-55mph on the last mile. Once the engine was fully warmed up, the temp stayed constant on the bottom edge of the gauge for the two middle miles. Being more confident at that point, I stomped on it a little for the last mile and the temperature creeped up to about 1/3 through the gauge. Dieseled briefly and shut off by itself, then spewed a little.

In reading the carb adjustment section of my manual, it didn't say how many turns from bottoming the air mixture screw to turn the screw out as a baseline for tuning. Just something about getting max idle, then turning back in until you get a dropoff of 20-30 rpm. Other carbs I've gone 2 1/2 or 3 turns out to start with. Would this be a safe bet on the Holley singlejet?

Thanks,

John
 
I'd use where you are now as a base. Count how many turns to get to " won't go no more" and bring it back out the same. Then 1/2 turn it in/out each 'til you find the sweet spot (max idle) and then drop it down the smidgen. Hows that for technical talk? That's just for the idle mixture. When driving your not using the idle circuit. But, if you think you're running lean, check the plugs. They tell everything. ( as long as you know what you're looking at ) I think every D.I.Y manual ever made has those pictures of plugs operating under rich/lean/just right conditions. Speaking of which, make sure you have the right plugs in there too and , of course, they're gapped correctly. Make sure you don't have a vacuum leak as well 'coz that will cause a lean condition too.Good Luck
 
Just another update:

I had some spare time last night and ended up backing out the air mixture screw maybe half a turn, maybe 3/4 of a turn, from where it was. Adjusted the idle screw out to compensate for the increased RPM and took it for a couple test drives of about the same distance as previously. No issues with spewing, no dieseling.

But it does take more work to start than it used to. Previously I was able to turn the key and the engine would immediately fire up. Now it takes both some cranking and accelerator work to start it. Still, I'm closer to where I think I want it to be.

I'll take a look at the plugs later this week to see if there's any obvious damage from a lean mixture. I'll probably pick up a new set anyway. I don't trust my mom's mechanic at this point to have serviced it well. Did I ever mention that it had a massive oil leak when she gave it to me? Her "mechanic" had not tightened the valve cover screws... Must not have been used to anything without a computer.

-John
 
Oh, I meant to ask on the topic of overflow bottles - is there a common place to install them? I'm not keen on drilling new holes. Do they have to be installed a certain level below the overflow hose from the radiator?
 
my 74 has a funky overheating issue. its pissing me off. when i got it the rad was backed up. i tried 50/50 water and vinegar to clean the system i kept flushing it every time i drove it but finally got fed up and bought a new rad. it definitely helped i had to keep flushing out the heater core it was like a dumping ground for all the crap that was loosening up. so when it got to the point the water was staying clear i put 50/50 anitfreeze water. that day it started running hot. makes no sense to me, but it takes over an hour of driving, closer to 2 hrs, or strictly stop and go for it to get hot. im pretty sure i need a shroud and im working on one. you can pull the hoses off your rad and run a garden hose through the fill neck, you will be able to tell how its flowing. you can pull a factory overflow off a later abody
 
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