During the winter, I was having problems with no heat from the vents unless the engine was under load. If idling, no heat. The lower rad hose was also cold, so I suspected a faulty thermostat.

Then starting a couple weeks ago, the car would be at normal temperature while being driven, but once I was stopped and idling it would overheat all the way to H. Lower rad hose was still cold.

So...

I changed the thermostat, and am pretty sure I put it in the right way ... spring side towards the block, right? But it still overheats! Lower rad hose is still cold.

Some other info:

Coolant was a brown color, but I'm not sure when it was last changed. Car has 187K miles.

Water came freely out the bottom of the rad and the thermostat housing when I flushed the system so I don't think there's a blockage.

When I was bleeding the system according to the manual (idling with rad cap off) coolant was bubbling a lot.

 

warm it up at and see if the fan is going on....if not i would check the fan switch

 

if i was you the first thing i would do is flush the radiator a couple of times and then ad coolant and see if the problem persists. then go from there.

 

Could it be the water pump? no circulation = no cooling.
Check the levels to make sure its not going down.

Oh and bubbling in the radiator is only caused by a blown head gasket, the cylinder is the only thing that PUSHES air into the coolant.. then the air escapes at the top of the radiator.
This means your water pump is probably working though lol 1 good thing.

I'm quessing there is a substatial flow of air in your coolant lines, this causes internal rusting if you don't use coolant at all times (brown) I'm not sure if the heater core ends up being 1/2 air 1/2 coolant.. I think if it sits higher up than the radiator it can contain pressurized air and prevent water from filling the heater core properly. Bleed the system with the heater core hoses open.
And replace your head gasket.

 

Good call on the headgasket. Engine burns oil too.

Fan works.

I don't think the coolant is flowing because the lower rad hose is always cold and I can't see/hear/feel any flow. I don't think it's a clog though because I flushed the system, and as I said, the thermostat is new.

So I'm thinking water pump impeller. That would also explain why when the engine was at higher rpm, the water pump flowed enough to keep the engine cool but as soon as rpms dropped there wasn't enough flow and it overheated.

 

Im going to assume your car is ALSO blowing smoke. What color is it? blue\white is coolent\water, If I remember right.

 

Yes, engine consumes oil (but no blue smoke from exhaust ... weird) and also blows white smoke.

Headgasket is definitely on the to-do list.

 

if the lower rad hose is cold, the thermostat may still be your culprit, even if its new, try a different one, and i know it sounds stupid, but make sure its not in backwards.

the reason i say that is even with a bad headgasket it will still flow, just not as well.

 

I doubt it's the thermostat since it's brand new. It's also a fail-safe type thermostat, so it should stick open if it does.

I'm thinking the bad flow is because of a bad waterpump, not headgasket.

Can someone confirm that the thermostat is supposed to go in with the spring side towards the block?

 

I've had problems with aftermarket thermostats from the generic parts stores either overheating or not cooling enough. I put in a OEM stat from the dealership and problem solved.

I would suspect four things: head gasket, thermostat, water pump or a blocked coolant passage(especially with brown coolant).

 

I'm going to assume the thermostat is OK, because I just replaced it with a new one and if this one fails, it should be stuck open anyways.

How can I differentiate between a dead water pump or a blocked coolant passage? When I flused the system, water came out of both the thermostat housing and the bottom of the rad, so it can't have been a complete blockage.

 

replace headgasket, waterpump and timing belt

 

The blocked coolant passage is the least likely cause. Change out the water pump and head gasket first to see if that solves the problem.

 

Well, I replaced the water pump. Here's the old one:



That explains the lack of flow! The only problem is now that the water pump flows, the engine's sprung a leak. Coolant leaks from between the intake manifold and head ... I think the gasket needs replacing.

 

So yeah, it looks like the impeller disintegrated. But where'd the pieces go?

Alex

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Quik89Si &raquo;</TD></TR><TR><TD CLASS="quote">So yeah, it looks like the impeller disintegrated. But where'd the pieces go?

Alex</TD></TR></TABLE>

I'm not sure ... that worries me though. I hope it's not blocking a coolant passage somewhere, as somebody else mentioned, and causing a buildup of pressure and the leak out of the intake manifold.

BTW, the water pump appeared to be the original (engine has 200k miles).