Need advice on overheating

[tricky lugnuts]

So, my trip to the Nats did not go so well . . . Any insight would be appreciated.

Car is a 1971 Charger with stock 440, essentially an all original, 39-year-old engine that I put new gaskets on several years ago before installing. Car has a flex fan, 26 inch radiator, no shroud, and had NOT been overheating at all even on extended drives and during extended idling before I left to go to the Nats Friday night. In fact, the overheating came as a complete shock to me.

I was following state roads, traveling at about 55 mph. I noticed the engine was running a little bit hotter than the usual 185-190 degrees, maybe 195-200 degrees, according to the mechanical gauge I have installed. I noticed it, but didn't think much of it.

When I got onto the interstate, traveling 70 mph, the temperature started to creep up - 200, 210, 220, 230. It happened fairly slowly over several miles, but continued to climb. At that point, 230-240, I pulled off on an exit, turned off the car, popped the hood and went in to a restaurant with my girlfriend to get a root beer float while we waited for things to cool down. Coolant was steaming, bubbling and boiling out of the radiator overflow hose and cap, visibly overheated.

At a loss of what to do, I pulled out the thermostat thinking it might be stuck closed and restarted the car.

It went back up to 190 and stayed there so we hit the road headed back home. I figured I'd silicone the t-stat housing to stop a small leak after I'd removed the t-stat and then hit the road Saturday morning. The car made it all the way back home, about 35 miles, never going above 195 or so while cruising or sitting at a light.

So when we got back I resealed the t-stat housing without a t-stat in it. Small leak was stopped. I figured everything was good.

Hit the road early Saturday morning, car started right up and ran fine. About five miles out the engine hit 190 and slowly climbed from there - 200, 210, 220, 230. I stopped turned around and made it back home with the temp at 230. Shut it down. Minor overheating out of the overflow hose.

Any ideas what could have caused this? I think I can ruling out tuning issues - timing, mixture - and shroud issues because the car was not overheating before. It may have run a little hotter than I liked when stuck in the backed up drive thru lane, but it never overheated and NEVER had the temperature creep up like that while driving. It always held a steady 185-195 degrees while cruising, and if it crept up at idle it would quickly go down once I got moving again.

So this morning I went to start it up and it runs weak, barely idling, sputtering - poorly enough that I couldn't even drive it a mile and a half and I had to take my girlfriend's Jeep.

The other strange thing I noticed: When I went to fill up my gas tank before leaving for the Nats, the tank would only take about 6.5 or 7 gallons before the pump hose would auto shutoff. I could see fuel backed in the filler tube like the tank was full, but I know the tank wasn't actually full, based on it being a 21-gallon tank and how much fuel I had put in before. Is there anything that could cause that or am I just losing my mind as a result of my engine overheating and screwing me out of a trip to the Nats?

[tricky lugnuts]

Alright then . . . Well, I guess I'll try and go it alone. 

For what it's worth, upon further examination yesterday evening, I'm thinking there are head gasket/cylinder sealing issues because of the bubbles I see in the coolant when the engine is running. Yippy frickin' skippy. 

[tan top]

not a good sign  , bubbles in the system ,  sounds like head gasket ,  hope thats all it is  , are they iron heads ??

[tricky lugnuts]

Yes, iron heads, I think the original 906 pieces . . . All original engine I put together in March 2007 with nothing but a new gasket set, so I guess I may have been running on borrowed time . . .

Just figuring, should I pull the heads first and look for signs of a failed gasket?

I ask because I intended to have the engine rebuilt this fall, but now I can't drive it the couple hundred miles I need to drive it to get it to a buddy's shop for tear down and reassembly.

I guess I'm figuring a Hail Mary replace the head gaskets approach could save me some money compared to a 350 mile tow. It would also allow me to inspect the heads for cracks or warping, and mean minimal loss if it fails to solve the problem, which would then indicate problems in the block.

Thanks for the response! I was just about to post a haiku my girlfriend came up with:

Help, engine is fucked
Internet, what should I do?
Answered by silence . . .

[tan top]

if it were me i would do a compression check  & or a leak down test  
will give you an idea whats going on  ,  some of that colored dye that changes color if there is combustion gasses in the coolent ,

silly questions i know  , but there is a spring in the lower hose & the water pump is ok & belt not slipping   

[tricky lugnuts]

Water pump should be OK - it's three years old and the belt is working as it should. I'm seeing pretty healthy coolant flow in the radiator with the cap off, so stuff seems to be circulating OK.

It's just that a couple of big bubbles are always floating by (big being about the size of a dime or nickel in terms of diameter) when the engine is running and the bubbling gets worse and builds up when I rev the engine.

Lower radiator hose has no spring, but it appears to be stiff and fool of coolant when the engine is warm and running.

I'll have to see what I can do about a compression test - I don't have that tool. Probably should own one, though. I'm assuming I would use that to try and pinpoint exactly which cylinder is potentially having an issue, as evident by a lower cylinder pressure reading.

I like the idea of using the coolant dye to check for combustion gases (I assume you can get it at NAPA or something), but is there really any other possible cause of bubbles in the coolant other than a head gasket failure, head crack, or engine block crack?

I haven't touched it to watch the bubbles floating by in the coolant. Temporary despair has set in! 

[elacruze]

It's easy to test for combustion gasses in your coolant;

http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm

You can also pull your spark plugs and have a look, you may see a significant difference in a hole with a head leak. You may even find rust on the plug if it sits overnight with any coolant in the hole.

Given the history, sudden change and symptoms I'd say it's a safe bet that you have a combustion leak.

[tricky lugnuts]

Well, I made it out yesterday and ran a compression test and spark plug check on each cylinder. All eight cylinders measured 120, 125 or 130 psi. None of the spark plugs looked visually "rusted" like they were soaked in coolant - a couple had some wet fouling, indicating oil control issues - but nothing incredibly out of the ordinary.

Comparing those compression results with the factory service manual - which calls for 100 psi and no variance of more than 40 pounds - if it's a cylinder sealing issue it must be a minor one.

I haven't done the check for gases in my coolant yet. I had to buy the compression tester: $29.95 at Auto Zone. Works great.

I'm leaning toward checking for combustion gases today - that or doing a cooling system pressure check. Either will require a new tool purchase.

When I run the engine in park at about 2,500 rpm for a while I eventually start to see a little leaking around the radiator cap. Am I missing something obvious: i.e. faulty radiator cap or trapped air in the cooling system?

Because when I look in the radiator with the engine running, it's not so much "bubbles" passing by as it is a foaming. If I rev the engine the foam will build up and sometimes come out the top of the radiator. Should I start with a thorough flush and refill, new thermostat and new radiator cap and see if that solves the problem?

My memory is slowly coming back to me trying to recreate this whole ordeal: The radiator foamed up like this for the first time some while ago. It did it once visibly, coming out the overflow hose, which made me take off the radiator cap for a look inside. That's when I saw I was low on coolant, so I added in about a one third to one half of a gallon of generic NAPA coolant. Then it drove fine for close to two or three weeks - 50 miles up to Indianapolis and 50 miles back, for instance. But when I went on the road to the Nats, it only made it about 20 miles before overheating.

[W4ATL]

Do the easy things first. I would put in the proper radiator hose with spring on the bottom. Ones without the spring may close at high speeds but not at idle when you are looking at it. Also replace the radiator cap if the current one leaks.

[tricky lugnuts]

Thanks for the reply, W4ATL! I think I will try a new lower hose with a spring in it.

I rented a chemical block tester from Auto Zone this afternoon to test for combustion gases in the cooling system. I tested the cooling system once at low temperature (about 120-140 degrees) as it was warming up: the blue fluid in tester remained blue even after three minutes of squeezing the little bulb.

I tested the system again at operating temperature, about 185 degrees, to make sure that nothing was changing after everything had properly warmed up to operating temperature: the blue fluid in tester again remained blue even after three minutes of squeezing the little bulb.

So, at this point, the engine has passed a compression test: All cylinders measured between 120 and 130 psi on cold crank. And the engine has also passed a test to see if there are combustion gases in the cooling system: none found since blue chemical solution failed to turn yellow.

At this point I will try the easy things first.

First, I plan on draining and refilling the cooling system with fresh coolant. The stuff I have in here is disgusting looking and smells funky, kind of like fish. And the coolant even foams a little bit when coming out of the radiator into a drain pan - maybe that's some sort of indicator.  I haven't changed the coolant in three years, and I never flushed the engine block out before I put it in my car (original 1971 engine never rebuilt, about 70,000 miles estimated).

I will then replace radiator cap and thermostat and refill the cooling system with fresh coolant, jack the front end of the car up to make sure there are no air bubbles in the system, and keep my fingers crossed.

I hope that is not a bad plan of attack? At this point it seems like it would make more sense than pulling off both heads and hoping to find something that doesn't seem to be there in terms of a bad or leaking head gasket or cracked head or block.

The three photos: the foam I'm seeing in the radiator; the blue fluid after the chemical test; and the coolant as it appears in the drain pan. Gross looking stuff, eh?

[pistolgrip]

im about 99% positive you have a blown head gasket. went through the same problem with another vehicle. rented the same tester from autozone, got the same results. see if u can smell exhaust fumes when you remove the radiator cap. i replaced the head gasket, problem fixed.   GOOD LUCK

pistolgrip

[Cooter]

I personally have never blown a steel shim, factory head gasket...Not to say it isn't possible with all that "River water" that came out of the radiator...

Do any of you guys reallize that coolant breaks down to an acid base over time from grounding the ignition system through it? After about 2 years, it begins....I've seen this MANY times before at the shop....People pretty much know to change the oil, but never flush the cooling system...

Unless someone's been into that engine and put those thick Fel Pro "Blue" head gaskets on it in the past 30 years, I'd see if a good 'ol fashioned Flushing out could help cool that beast down a little before I pulled those heads..

[mhinders]

...
The other strange thing I noticed: When I went to fill up my gas tank before leaving for the Nats, the tank would only take about 6.5 or 7 gallons before the pump hose would auto shutoff. I could see fuel backed in the filler tube like the tank was full, but I know the tank wasn't actually full, based on it being a 21-gallon tank and how much fuel I had put in before. Is there anything that could cause that or am I just losing my mind as a result of my engine overheating and screwing me out of a trip to the Nats?

Don't forget this phenomenon...bad ventilation in the gas tank could cause a lean mixture and increased heat generation...
Martin

[tricky lugnuts]

"Do any of you guys reallize that coolant breaks down to an acid base over time from grounding the ignition system through it? After about 2 years, it begins....I've seen this MANY times before at the shop....People pretty much know to change the oil, but never flush the cooling system..."

Thanks Cooter, that seems to be the case here - poor maintenance! I took the car in for a flush and refill last week and now I can't get it to overheat. Foaming is gone.

I saw "foaming" in the factory service manual listed as a symptom of worn-out coolant.

That's what kept me from pulling off the heads - that and it failed to test positive for combustion gases in the radiator - and broken down coolant appears to be the case in this instance. I put it all back together with a new thermostat and cap and it will idle all day at 180 degrees . . .

Of course, now I'm chasing down a new engine surging issue that is slowly driving me crazy, so I haven't taken it out for a long drive yet. Damn thing doesn't want to idle steady and occasionally surges at idle/low speeds.

But yes, the lesson of this thread should be that there is a BIG difference between broken-down coolant foaming, and coolant bubbling from a blown head gasket.

I appear to have gotten lucky this time and will keep this in mind going forward. The lesson: Change your damn coolant! Especially if you're running an older engine that hasn't been properly cleaned out. I've learned it . . .

As for the gas tank anomaly:

"bad ventilation in the gas tank could cause a lean mixture and increased heat generation...
Martin"

Do you know of any way to test or fix this? I'm running the stock set up, I believe, with the hoses running out of the gas tank and to the vapor separator behind the driver's side wheel well.

[elacruze]

...
The other strange thing I noticed: When I went to fill up my gas tank before leaving for the Nats, the tank would only take about 6.5 or 7 gallons before the pump hose would auto shutoff. I could see fuel backed in the filler tube like the tank was full, but I know the tank wasn't actually full, based on it being a 21-gallon tank and how much fuel I had put in before. Is there anything that could cause that or am I just losing my mind as a result of my engine overheating and screwing me out of a trip to the Nats?

Don't forget this phenomenon...bad ventilation in the gas tank could cause a lean mixture and increased heat generation...
Martin

I was thinking this exactly when I read that the tank had more in it than expected. Could be fuel pump, poorly vented tank, fuel line breaking down etc. Unusual but not at all impossible.

[Paul G]

I had a problem in a Ford years back that had my coolant bubble out,a white foamy color. Turned out to be the trans cooler in the radiator had leaked trans fluid in to the coolant. Ended up with a new radiator and a trans rebuild. Check your trans fluid just to be on the safe side. (If it is an automatic)