overheatng after shutdown

[rb77413]

Anybody know why the water will shoot up to 240F after shutting the car off. I know it will go up a little, but normally the highest I have seen it go is 200. Its a stock 383 2bbl. It just started doing this two days ago. It goes up there within seconds after shutting the engine down. The water level is good, and it runs about 170-180 when driving. It doesn't have A/C and no fan shroud. I don't think that matters as it only happens when the car isn't running. Could I have an air pocket in the cooling system somewhere? Thanks

Bob

[BugEyedValiant]

I think that your problem is that when your motor is not running, neither is the water pump. Your block and cylinders are still way hotter than that, and since your temperature sensor is in the water pump and the water pump is connected to the hottest part of the block, and the heat can no longer be carried away to the radiator so the heat stays in the block. Hopefully this long winded answer helps.

[66Dodge]

How about when you are in stop and go traffic
or waiting in line like for a drive thru carwash. Does the temp gauge start to climb toward the hot side ?
Is the coolant ok?
The engine should get hot right after you shut down because of no more coolant flow.
But, what is weird is that you stated it is now 240 vs. 200 deg.

One thing to consider is the ignition system. If your spark is too weak you will have poor combustion and poor combustion
will cause the engine to work harder thus run hotter. You don't see it while driving because the airflow/fan is cooling enough to make things look normal. But, once you get stuck in traffic the temp will start to climb.

A friend of mine fought a similar problem and found it was due to the points system.
He switched to a Pertronix eletronic drop-in unit and voila!, the car ran cool again and also the car ran stronger.

[Blaine Peterson]

rb,
Are you saying that when idling or driving the car, it runs at the same temp. as before, and that the only difference is that now when you turn it off it registers higher then it did a few days ago?

[dodge_em]

I don't want to step on anybody on this thread, but I have a similar problem and was wondering if anyone could shed any light on it. From time to time, when I shut my '78 Ram off, it will start gurgling and begin to overflow into the coolant reservoir. If I start it back up again for a couple of seconds and then shut it off, it will often stop boiling over at this point. Could this be a water pump problem, thermostat problem or both?

------------------
Mopar Vehicle #1
2001 Quad Cab 2500HD 4x4
Sport - Short Bed - Forest green Pearl
24V Cummins, auto, SLT Plus Package, with absolutely every other option available. (When paying this much for a truck, might as well get it with everything!)
Additions:
305/70R16 Cooper Discoverer AT tires, Grizzly Double Bend Chrome Side Bars, Catch-All Floor Mats
>>No Engine Mods...Yet<<

Mopar Vehicle #2
1978 Dodge Ram W150 4x4
Originally a Reg. cab long bed with a 400.
Now is a Club Cab convertible with a StepSide bed (nice new wooden floor), 440 lurking under the hood. Project not entirely complete, but is driveable and is a real head turner

[dartboy71]

How long has it been since your coolant has been fully flushed? You may be pushing enough water with the pump to keep the water cool while running, but part of your system may have a clog in it somewhere if the radiator has started to corrode in its passages.

[rather]

It all sonds like normal heat soaking to me. Sometimes it can get alot hotter as it depends on the driving enviorment. driving and shut down will have so much heat soak but stop and go driving and shutdown will bring on a little hotter heatsoak. I still would prefer that you have a fan shroud. But the sudden and continous high temps in the same driving enviorment would suggest a sudden failure of some sort.

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1987 Dodge D100, 2wd, 3.7 Slant Six, California Certified, Automatic A904, 2.9something rear gear, K&N Filter Charger, Jacobs Electronics Pro-Street Ultra Team Ignition sytem, Autolite Plugs #25, Basic Timing Set To 14 degrees. Chevron supreme Gasoline, Castro Synthetic 10w-30 Motor Oil, Valvoline Synthetic Rear End Oil,
American Racing Wheels AR-767 15x7, Fully Loaded Clifford Alarm System, and now at 121,250 miles

[1969runner]

Well, I may as well put my two $$$ in.. I had the same problem with my 383 runner. It was also foaming at times. Now I know that most would think "head gasket" and I did as well. But the temp would rise when I shut it down and boil over some too. Here is what I did; I got a tool from a friend that checks for exaust gas in the rad... Clean, no gas. Sooo, I went for the bucks and got a NEW 26 inch rad, put everything back and viola. I put in a 160 therm and it should be a 190 but, I can run this puppy in 90 or more weather and it will not break a sweat.

I can put in the 190 and I know now that it wil still be great in any weather. Hope this helps.

------------------
1969 Road Runnner
Run's like the wind...Fast!!!!!!

[rb77413]

Sorry about the delay in responding to you guys' responses. That sound right? Think so. Well about 4 years ago I had the radiator fixed. Had to have two pasage ways blocked off. It has been running great since until now. I checked the radiator for blockage with the engine running, by feeling the radiator for cold spots. Didn't feel any. I took the interstate home one night, and it started overheating. Ran about 210-220. When I pulled off the I-state and cruised about 45 mph, it cooled down to about 200. When I shut it off, about a minute later I watched the temp rise to about 230, then it blew the overflow hose off the radiator! The next day I started the wagon, opened the cap and I had water flow, so I gussed the thermo was partially stuck open. It also might not open all the way when it needs too either. I got a 180 and put it in. There was some jello like substance on top of the thermostat. I never added anything to the radiator except 4 years ago when the radiator shop that fixed the rad, said to put a cap full of dish soap in the radiator to help clean it out. Does that sound right? I drove it the next day with rad flush in it and it seemed to run a little cooler. I Had an ignition caused overheating problem in the conv. So I already checked the points in this one right away. All checks out. I'll keep everyone posted on the outcome. Since I live in FL would a 50/50 antifreeze-water mix be good? Thanks again guys.

Bob

[PRO]

Most likely suspect in order,Partially plugged Radiator,Bad Rad cap,loose fan belt,T stat not opening all the way,Lower hose sucking flat,failed fan clutch,just some ideas that Ive seen over the years,hope it helps....PRO..

[This message has been edited by PRO (edited November 06, 2000).]

[Chargerdude]

rb, just a note, from my working in auto parts for 7 years, I've heard one tip over and over, a 50/50 mix of water/antifreeze is optimum for any environment. Antifreeze is designed for being evenly mixed with water, no matter if it's Panama or Alaska. Good luck! oh yeah, I'd try the shroud, it will bring the temp down some, and every little bit helps!

[451Mopar]

It sounds like the radiator cap is not holding pressure. I just replaced mine on the RamCharger because it boiled over afrer shutting it off, but ran cool when the engine was running. The cap was a whole $4, and that is the one with the lever pressure relief. The standard cap was about a buck cheaper.

[RDF73Charger]

My 73 Charger has done this since I bought it in '77. I thought it was just a mopar quirk.

[rb77413]

AHH I threw the driveshaft the other day. Luckily the broken bolt in the yoke was able to be tapped out with a punch. Well got it running again and it still starts to overheat on the highway, and cool down in traffic. Wouldn't that be a water flow problem. There is lots of airflow on the interstate, so if it overheats there I guess it is a water flow problem. Since it does cool down in traffic. Maybe the water pump? Thanks

[powerwagon]

Hey dodge_em,

My 1978 powerwagon does the same thing, even though it has a 360. If I shut it off, i can hear it gurgling up and it flows into the overflow sometimes as well. I thought it was just a Dodge thing. I know it will heat up a little, but sometimes it goes pretty far.

powerwagon

[1969runner]

I had MANY of the problems that are being thrown out here with my Runner. It also ran cooler around town than on the interstate (which has to do with not having a fan shrowd). When I bought a NEW 26 inch rad, new 160 therm, it took care of every problem. It now runs cool around town or on the interstate in any temp.. I still have to add the shroud to even out the air flow at high speeds but, that in a minor problem.


[This message has been edited by 1969runner (edited November 17, 2000).]

[djswwg]

The shroud will definitely help cooling in slow traffic (below 35 mph or so). At speeds above that, a fan and shroud are basically dead weight on any vehicle, as vehicle speed should force enough air thru the rad to keep things cool. You can prove this by removing the fan and shroud and go for a cruise down the highway. (I did) If all else is correct, the overheating won't happen no matter how far (or fast) you go. Only do this as a test as you will really overheat bad at slower speeds. Based on your symptoms, I'd say you've got a blockage in the rad or a hose, or the pump no longer moves enough coolant because of a partially slipping belt, or the fins have deteriorated to the point where they don't move enough coolant. But first, try a new thermostat. It's cheap and easy. Also, if you have to go to a cooler thermostat to solve the problem, you haven't solved the problem, you've masked it! Something else is not as efficient at removing engine heat as it once was, and you'd better figure it out. I think we'd all like to know how this one turns out, so let us know. Cheers.

[mtrv8n]

It does sound as if your water pump is shot.
You can releive the problem a bit by adding "water wetter", a redline product. Is your fan thermo, speed sensitive, or just plain solid mounted? Mine is a hipo flex fan, pulls tons of air at idle, helps quite a bit(but it's noisy..)A speed sensitive fan amy cause overheating on the highway, or maybe the fan clutch is burned out..

lotsa things to look into..

[rb77413]

OK here is the latest. First, I put a new 180 thermo in it. Helped a little. Not enough though. Checked the water level as I am currently running flush in it now. It was low. Probably from it boiling over. Topped it off. Looked over the rad and I found a small leak. When I had it rodded out 'bout 4 yrs ago, they had to close off 4 cores. It ran cool after that till recently. It looks like the holes are from rust. It didn't start running hot till I put the flush in. Never changed the water pump yet. The lower rad hose has the spring in it. The rad is leaking from another three cores. Guess a new rad. Before I put the flush in, it never lost water. You could open the rad up a see nice clean green coolant. I never suspected water loss. It never had a fan shroud. A 383 2bbl no a/c. Only p/s and p/b. I'm probably going to chack out an aluminum rad. Any suggestions. BTW, After I filled it up, it still ran hot on the interstate but a little cooler in the city. If I go the alum rad route, should I get the one with the tranny cooler in it or not. Well thanks again

Bob

[powerwagon]

If you are running a 727 (or any other auto tranny), I would keep the tranny cooler in it, because that saves a lot of wer and tear on your internals.

powerwagon