'02-'03 4.7L Dakota DCooling?

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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Mar 10, 2005
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My pappy has a late(r) model Dakota with 4.7L...

It'll push the recovery bottle full of coolant every couple weeks and overheat. He pumps it from the recovery bottle back into the rad. and all is well until the next time. Collant will NOT get sucked back into the rad...

Anyone have any ideas? Rad., cap, t-stat, and hoses are new Mopar replacements...

I was wondering if this system might benefit from conversion like the late model Cherokees? If so, what does that entail?
 
I've seen some head gaskets leak on those. Some only under a heavy load. If the combustion gas leaks into the coolant it will make too much pressure and blow it out the cap into the recovery bottle. Go to napa and get the block tester. Check it with a load on the engine.
 
A block tester is basically a tube that sits on top of your radiator fill neck. You put fluid in it and run the engine, if the fluid changes from blue to yellow, you either have a head gasket leak, or a crack somewhere in the block or head. If you go to a parts store they will know what your looking for.
 
Yeah, the coolant test has been around a long time but not commonly talked about unless you are in the radiator or service business. Had it done on a 67 GTO and color change confirmed blown head gasket. May just be a bad radiator cap since it is not allowing the radiator vacuum, created when fluid cools, to draw overflow coolant back into the radiator?
Possible cheap fix?
 
I've heard of pressure testing the cooling system to find leak, just never heard of anything that changed colors to indicate headgasket failure. Guessing it looks for elevated CO/CO2/other levels in the coolant to indicate the failure?

Pretty sure he said the cap had been replaced... by every tech that's touched it so far! :rolleyes: (3-4 stealerships to date)
 
Pressure test may show the culprit too Dave. If there is a leak somewhere in the cooling system it may be pushing the fluid out like it's supposed to, and then sucking air back in instead of the reservoir fluid.

I have never heard of the color change thing either, I am interested in how this pans out.
 
Well, talked to my dad today...

He said that when it started the overheating/not suctioning the coolant deal, the first thing done was the block test. The wrenches saw NO change in the color to indicate anything wrong with the heads, gaskets, or block. They also pressure tested the system to no avail. The cap & thermostat have been changed numerous times during the troubleshooting too.

My dad thinks it may be the funky reverse flow setup or a flaw in the recovery tank?

He says it will very randomly (sometimes days, weeks, or even months between) begin to overheat. He says he'll wind it out a bit harder to keep the rpms up and the temp will drop, but he always finds the recovery bottle full. When it does get full, he says the only relief is to pump it back into the radiator... as it will not pull back in regardless of how long it sits (hot or cold).

Any more ideas?

And THANKS for all the answers so far! :beer:
 
AlphaFourWheelDrive said:
Does it have a mechanical fan? May be fan clutch not working properly?
Click to expand...

New fan clutch (when it started approx 2 years ago) and electric PULLER fan mounted in front of the mech. (electric looks factory). I've confirmed both are good... electric runs after shutdown and clutch locks/tightens when warm.

As long as the AF *stays* in the rad., there's never a problem... it's just when it gets pushed into the recovery bottle and never suctions back!
 
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