2004 Ram 1500 4.7L v8 coolant issue

[patrickbancroft]

I am new to Dodge trucks, have a 2004 Ram 1500 with 4.7L V8 I bought used. I live in Texas and I have begun to have an issue with the cooling as the temperatures get warmer. It seems the coolant releases into the auxiliary reservoir when the engine heats up but then does not go back into the radiator when it cools off. So the coolant level in the radiator gets progressively lower and then I have to stop it, let it cool, then open the radiator cap and unbolt the auxiliary reservoir and raise it
up and let the coolant gravity fill back into the radiator. The first time it heated up and I opened the radiator and found the level low, I changed the radiator cap. I bought a 16 psi cap. But it is still doing what I described above. There is no evidence of a system leak, and no coolant coming out of the tailpipe, so I doubt I have any head gasket issues. Also, the engine isn't throwing any codes other than a random misfire P0300 and P0308 cylinder 8 misfire. This only happens occasionally on startup (low Rpm) and not all the time. The engine is not running rough.
Do I need a different pressure cap?
I am mixing the coolant 50/50 with distilled water, does that boil too low for the Texas Heat?

 

[Harley Harrold]

 

[1999 White C5 Coupe]

I am new to Dodge trucks, have a 2004 Ram 1500 with 4.7L V8 I bought used. I live in Texas and I have begun to have an issue with the cooling as the temperatures get warmer. It seems the coolant releases into the auxiliary reservoir when the engine heats up but then does not go back into the radiator when it cools off. So the coolant level in the radiator gets progressively lower and then I have to stop it, let it cool, then open the radiator cap and unbolt the auxiliary reservoir and raise it
up and let the coolant gravity fill back into the radiator. The first time it heated up and I opened the radiator and found the level low, I changed the radiator cap. I bought a 16 psi cap. But it is still doing what I described above. There is no evidence of a system leak, and no coolant coming out of the tailpipe, so I doubt I have any head gasket issues. Also, the engine isn't throwing any codes other than a random misfire P0300 and P0308 cylinder 8 misfire. This only happens occasionally on startup (low Rpm) and not all the time. The engine is not running rough.
Do I need a different pressure cap?
I am mixing the coolant 50/50 with distilled water, does that boil too low for the Texas Heat?

Did you use an OEM cap, which would have the correct PSI rating?

A problem I have seen is the overflow / return hose could have pinholes in it, or not be properly fastened at both ends (no or weak clamps). This allows air to be sucked into the radiator, when the engine and radiator begins to cool.

Once I had a vehicle that had a small crack in the plastic nipple on the coolant reservoir jug, where the hose attached (allowing an air leak). It would only leak if the nipple was wiggled.

Does your coolant reservoir have a pressure cap, in addition to the radiator? Or is it a snap-on cap, which allows air into or out of the reservoir?

 

[Papa Red]

Welcome to the forum.

Red

 

[patrickbancroft]

Thanks for the reply, Harley Harrold.
I did not buy the radiator cap from Chrysler, I bought at O' Reilly but as far as I know the OEM Cap is a 16 psi rating. At least that's what O'Reilly told me.
Regarding your second question, the reservoir is a snap on cap and appears to me it does let air into the reservoir.
Also, thanks for your insight into the issues with leaks in the return hose, and possible cracks in the reservoir, I need to check that out more closely. I haven't seen any coolant leaks around the reservoir and the reservoir level does not seem to drop so I doubt that is an issue, but worth double checking

 

[patrickbancroft]

I justt checked the reservoir and return hose, there was no clamp on the return hose on the radiator, so I added a hose clamp. I will see if that helps.

 

[spoolinlust]

The cheap caps and t stats for that matter are notorious for being defective, at least in my neck of the woods.
Also check the bottom of the overflow if clean. If it's got junk in it you will be able to push coolant in but not pull back out. Had that on a Tahoe

 

[Rambeau]

I have the factory cap on my truck and it's a 16 PSI. 2013 with a 5.7L, but probably the same cap. I've had an issue with sludge, so I'm flushing etc. In the process, I found that the overflow was so sludged up that the radiator would push off the overflow hose because it couldn't push anything into the overflow. I was able to blow out the plug and now have to clean out the container.

BTW, I'm in this mess because a parts store clerk sold me "universal" coolant and assured me that it was compatible. BIG mistake!