I have seen several posts regarding head-gaskets and cooling issues, but it seems that after problems are fixed, nobody ever replies to let us know what fixed the problem. So, sorry to beat a dead horse, but here goes.... Drove from Indiana to Florida last week. Things were fine til the Smokey Mtns. First big climb and the temp went to the far end of normal. Ambient temp was @ 85, and falling due to nightfall. By the time we got to the last few hills it was dark and the temp was fine. On the way home, however, it was a much different story. We hit the mtns in the middle of the day. 95 degrees. First hill temp went up and we had to turn the a/c off. Got high enough that the "check gauges" light came on, but not to the "red" line. Once we crested the hill it was a long down-hill into Knoxville and temp went back down. We were lucky to hit some rain showers through the other hills and that kept temps down. We made it home and today I took it to my buddies shop. We determined that the fan clutch was bad and he replaced it. I had also taken the rad cap off to check the coolant and didnt get it back on tight. So, after driving a few minutes, I was loosing coolant. Filled it back up and it seemd to get quite hot just idling. Seems like a lot of pressure when the cap is removed. Put in new t stat too. Thinking maybe the sytem is not bled completely, but we let it run a LONG time with the cap off. It seems that there is some foamy stuff that comes to the top after a few minutes. No sign of coolant in the oil, or vice-versa. After bleeding again one more time, I took it and drove @ 50 miles. Interstate and city. Now I cant get the gauge over half-way with the a/c on!! Whats going on???

 

One last thing that I forgot. It seems that when the cap is off and the engine running, coolant dribbles out of the filler opening. Is that because it is taking the path of least resistance? Maybe that the radiator has some restriction and its easier to pump water out the open filler hole than to force it thru the radiator?

 

Did you check to see if your efan was working? My D overheated one day while driving in heavy stop and go traffic. It went into "limp mode" to help save the engine. Found out from my buddy's shop that the efan was broke so I replaced it and now it never overheats. Did you replace the t-stat with a 180 one? I think our Ds need the 180 instead of the 195 aftermarket ones. You did the right thing by bleeding the coolant. Did you leave the rad cap on? Did you use the bleeder screw? Yeah, the coolant will take the path of least resistance by coming out of the biggest and most accessible opening. Maybe you can go to your local autoparts store and rent an IR thermometer and read your radiator to see if you have any cold spots. Cold spots = blocked lines. I think you can use the filler neck to pump water through the engine, but what about the rad? Don't you want to flush it as well? Just my .02.

 

Sounds right on Dan.

The OEM T-stat is 195 but it's too high. You need to put a 180 in it and that helps the head gaskets! I don't think you did anything but I will attach the proper way to bleed the system. Remember to turn the heater on full bore when doing it both front and rear if equipt.

 

Errr!

4.7s need to run the 195 stat... preferrably a stocker stat. Then make sure the system is properly burped to ensure cooling works correctly.

Aftermarket stats for the 4.7s usually don't have the correct weep hole like the stockers do. When overheating on a 4.7 occurs, it is:

A) not burped correctly
B) low coolant
C) eFan not working
D) if the stat has been swapped out, then move this "D" up to "B" and consider it a badly designed aftermarket stat. Swap the stat for a OEM stocker and burp correctly

If you are running a 5.2 or 5.9, get a "failsafe to open" 180 stat ASAP.

The above poster has a 4.7l thus read A-D above.

IndyDurango

 

Hmmmm!

Judging from the metals used in the engine building I would be more willing to place my money on cooling the motor down? I've heard the 4.7L like the 195 OEM but with aluminum heads and a iron block flexing at different intervals because of heat and cooling (expansion and retraction at different intervals) causes the head gaskets to slowly rip apart? This is the main reason that these engines that incorporate this kind of building under higher than normal range (lets say 250 F) usually blows the head gasket?

Edelbrock aluminum heads (or other aluminum heads) used to replace OEM iron ones in performance engine building has documented this fact?

Can you describe why upping heat back to OEM is going to help except for emissions?

 

Your 180 or 195 stat is only setting the opening point for the cooling system to allow the RADIATOR and COOLANT to do their work. If your D is going to get to 200 degrees, it is going to do so with either stat due to the other factors, not the temp at which the stat opened. A great fan/radiator/coolant mix will drop the temp... and close the stat... just as fast regardless of when it opened. Holding 15 degrees isn't going to kill anything on the opening on a 4.7l. Regardless of the engine size, it is only on a poor system that can't get the coolant back down to 160, 170 or so that does the damage. The stat opening temp has no relevance on systems that allow the temp to get to 200/205/210 etc.

Since the 5.2s and 5.9s are bigger and hold more heat, it is advisable to get the stat opened at 180 to start the process sooner. Remember, the 4.7s have plastic intakes, different ignitions, etc and thus the thermodynamics are different. 195 is fine for their starting points pending that they have the rest of their system (burped, coolant levels, fresh coolant, working efan, etc) is in proper working order.

Edlebrock and performance engines are not usually in the same sentences as 4.7ls.

IndyD

 

I had the same problem. Change the thermostat and it did good for 2 days, then I couldn't drive 2miles before it would go to the red. Replaced the radiator 2 weeks ago and haven't had any problems. If u replace it yourself, take out the front support right above the radiator (only 6 bolts) this will make the job alot easier and will save you from busted knuckles and cussing. I found out the hard way at the re-install. Good luck

 

Right it is ony the set point. But:

Thats when it starts to open and not when it fully opens. Now the hotter it is the faster it can overheat. Regardless, it's only 15 degrees and that 15 degrees helps.

Emissions is the only reason (unless you count the heater) that the goverment made the 195 standered and not because it does the best job for the motor. Simple aluminum head design wether it is Edelbrock or OEM is still aluminum. They are to different metals that expand and retract differently thus creating a push and pull effect on the head gasket. Aluminum heats faster and cools faster than metal thus shapeshifting the gasket over the metal block. Do this a lot and you'll get one go out on you. As for intake manifolds, that has nothing to do with heat retention of heats to block?

On the 5.2L and 5.9L the heads are metal and block metal expanding and retracting the same. There is a reason they are using this block form 1962. The problem is the heads crack between the exhust and intake valves because they were never made for the continueous heat differences. It's not just because it's bigger. Now the 4.7L was made for the heat including the 5.7L HEMI having aluminum heads as well.

Mainly, this is just my personal opinion and race backed information. If the engine gets hot head gasket failure is iminate. Cooling the motor and running 180 is ones helping hand.....IMHO

 

Destructo, I have the exact same problems as you ('03 with 4.7, 43,000 miles). It all started under high demand while pulling a camper this weekend. The foam out of the radiator cap has me a bit concerned that I have a blown head gasket but the truck seems to run fine after I reservice the coolant system. I did not bleed the system through the bleeder screw that has been mentioned. Could this be just air in the system, or compression blowing by the head gasket into the the water jackets. The guys arguing about which thermostat is better are not helping, we need good info as they seem to be quite knowledgeable. Wednesday I will put a pressure gauge on the coolant system and let you know what I find. Please keep me updated and I will return the favor. Thanks, Nate.