Dodge Repair Questions? Ask a Mechanic for Answers ASAP
Hello and welcome to Just Answer, my name is Matt.
Let's start by bleeding the air from the system.
Look by the upper radiator hose...where it connects to the engine...see the fitting? It is a hex fitting
yep, did that.
you took that fitting out to bleed it?
not all the way. parked slightly uphill, topped it off, ran it, opened the bleeder, when coolant started coming out i tightened it back up. also read about filling it, starting it, running up to 3000 rpm for 10 seconds
You might be OK as far as air in the system, but the correct procedure is to pull the fitting and fill it until it comes out...with the engine OFF
okay. i'll try that. also, making noise when i shut it off. thought it was ac, but isn't the heater core over there too? not losing fluid tho, till the resevoir fills up. then i lose it. why does it keep backing up into the resevoir?
If coolant keeps going into the reservior....then the pressure in the cooling system is exceeding the pressure rating on the cap. Either the radiator cap is faulty.....or the engine is overheating....which creates excess pressure---which goes to the reservoir.
Or....a head gasket is bad....which causes excessive pressure in the cooling system
So it's either the cap or too much pressure
so i should try replacing the cap again.
either that or have the cap pressure tested
how do you have the cap pressure tested?
you have to use a cooling system pressure tester...with an adapter for the cap. possibly the auto parts store will have one you can use
mmm, sounds like easier to just replace cap
had the system pressure tested (i watched) and no leakdown. could there still be a leaking head gasket?
It is possible. It is hard to detect a leaking head gasket, when it's not very bad.
There is a special test for this as well.
4.7 is easy to get air trapped in. I would focus on that first
Let me tell you about a 'trick' I use to bleed these.....
first, bleed from the hex fitting, as we discussed earlier
you will need an extra radiator cap
see how the cap has 2 seals on it?
cut off the smaller seal....the bottom one
i'll go get it
fill the radiator
okay, i see it
cut off the smaller seal, the bottom one
fill the radiator, and the reservoir
put the modified cap on
then start the engine
fill the resevoir all the way? or just to the full mark on the stick?
what stic k are you referring to?
Oh, sorry, now I remember....dodge has a stick...I was thinking of Jeep
it doesn't matter, really. anyway, start the engine, and any air will go past the missing seal and go into the reservoir. and coolant should go back into the radiator to replace the air.
it's a good way to do it...less mess
i'll give that a try tomorrow. thanks :)
just remember to put a good cap on it when you're done
hey, would a simple compression test find a leaky gasket on one of those 4.7's?
Not usually...it would have to be pretty bad...you would have a misfire
i have a compression tester, it's just such a hassle to pull the plugs
why would you have a missfire?
if you has low compression, the check engine light would be on, and there would be a misfire code
had that happen. turns out it still had OE plugs :( new plugs and 60 miles or so cleared the trouble code.
if the code cleared on it's own, that is a really good sign
plug in the #2 had dissapeared electrode. all other plugs were looking at around 1/4 in. gap instead of 40 thou
anyhow, i hope it's just air. thanks for all the help
someone got their money's worth out of those plugs!
you're welcome. thanks for using Just Answer again.
Hey Matt, you still there?
Today i siphoned all the old coolant out of the overflow resevoir and filled it back up to full with fresh coolant.
I removed the bleeder bolt and topped off the radiator. I tried your trick with the old radiator cap, but couldn't tell if it was working or not. After about ten minutes i could still remove the radiator cap???
Shouldn't it have been pretty hot? I just drove it home from work (30 min drive) and it had only been sitting about 15 minutes before i started tinkering.
So i opened the bleeder again and let it run for awhile, watching the air bubbles and occasionally adding a little more coolant.
Ran it approximately 45 minutes. Shouldn't the thermostat have kicked open and it start spewing coolant out of the cap and bleeder i had opened?
Where is the air still coming from?
Remember, do not run the engine with the bleeder fitting out.
All you do is fill the radiator until coolant comes from the bleeder hole, then put the fitting back in. This does the initial bleed. Then do the cap trick to get the last air out. The system will not build any pressure with the modified cap on. Then install the regular radiator cap and see if the cooling system builds pressure. The upper radiator hose should get a bit firm.