Coolant / heater hose routing

[Oldmactech]

Trying to figure out how air bubbles are getting in my coolant and building pressure and I found something kinda odd. Yes, I’m aware it may be a blown headgasket but not willing to give up yet.

My 03 8/03 production month specifically has an aux pump that seems to be routed incorrectly usingRealOEMs exploded views.

There is a long hose coming straight from the overflow tank to the firewall as it should there is a lower tank outlet that connects by short hose to the aux pump but then goes to to a hose connected to the “hose engine inlet” which connects to the drivers side lower rear of the engine. According to the RealOEM diagram the aux pump should connect to the heater control valve, not the engine inlet. The port where the aux pump hose supposedly attaches has a hose going directly to the firewall and I assume the heater core. Oddly, all look original and nothing appears out of place or been replaced.

Simple question: should the aux pump be pumping directly into the engine or heater valve. Other plausible explanation?

Thanks.

[andrewwynn]

Which engine? Put in your last seven of VIN so we can also check the part blow ups.

[andrewwynn]

If you either a) have decided to let fate decide for you if enough coolant is getting into cylinders to help you make the replace engine or head gasket or b) have already decided to run this engine at the risk of failure then replace the engine of it does, then put a cap on the radiator that opens at a lower psi so it will get out the TOP of the reservoir not the SIDE.

Then to the question: you have gas engine inferred and 3.0 I think I saw in a different post. I can check our cars if somebody else hasn't but photos better than description.

It seems like you have from and to backwards. I'm pretty sure the hot water goes to the heater core valves then the return would be from the firewall.

That said, some HVAC units have a rest mode that pumps heat from the engine core when the car isn't running some don't and I think that difference is what brings up the difference in the part exploded view.

[Oldmactech]

Thanks. Vines LW23803
Went to dealer this AM. Hose routing appears correct based on their exploded view. Figured it was anyway.

Oh well. Time for a new theory.

[andrewwynn]

Didn't you say the test for combustion gas in the coolant indicated true? That should be mystery solved

[Oldmactech]

Oddly, I have run the block test (blue fluid) several times it doesn’t turn yellow. However, shortly after acquiring it the coolant tank faile and it was towed to a shop that said it had a bad headgasket and failed the block test. Didn’t see it.