I always try to refrain from posting for help without doing my own research first, but I need to fix this ASAP. From the little bits I have read I think my thermostat is going out.

Here's what I have so far: Car gets up to operating temp no problem. Slowly starts heating up more as I'm driving, freeway makes it much worse. Heat is intermittent, only works well when car is dangerously hot, but sometimes it doesn't. My lower radiator hose is also lukewarm at best, even when the car is super hot. Any thoughts?

Wanna get this sorted out quick as this is my daily and I wasted a vacation day today to fix it

 

I'd put it this way. Assuming there is plenty of coolant, you have a blockage. The blockage might be caused by a stuck thermostat, or it might be elsewhere. The stat is a pretty easy/cheap swap on a 1.8, I'd start with that.

 

Agreed, start on the thermostat, cheap part. I had the same problem but the other way around, my car struggled to heat up, thermostat was stuck open, replaced it and all good now.

 

Usually the thermostat fails open as a fail safe to keep the car from over heating.

It could be that your water pump is shot. If the impeller looses its fins then it really cant circulate coolant.

Jason

 

Thanks for the response guys. Changed out the t-stat and come to find that the old one was okay. Boiled in water and it opened right up. I changed my water pump 2 years ago, and replaced it with one that has a metal propeller so I'm sure that's fine.

This started happening after I replaced my coolant flange, I thought it was cause I had air in the system but that doesn't explain the cool lower hose.

Pulling the radiator now to check for blockage.

 

Update: Radiator is fine water flows out the other end.

I've been using tap water for coolant for a little while now, what are the odds that it rusted out the impeller on the water pump? I noticed some debris in my reservoir that could definitely be rust..

I haven't been leaking cooltant (water) anywhere though, but my coolant (water) has been lowering and I have to keep topping it off.

 

Sometimes that stop-leak s--t looks like rust. Any chance it's stop-leak? That crap will block parts of the radiator and you'll still see flow out the bottom. Can clog your oil cooler too.

People who use that should be put on the rack.

 

Getting my radiator flow tested tomorrow. If thats not it I'm afraid it's probably my head gasket. My coolant tank smells like exhaust so I'm thinking thats what it is

 

Did you bleed the coolant system after you did the coolant flange?

Also, I wouldn't rule out a faulty water pump even though it's only two years old.

 

Yes I bled the system. I've had a water pump fail on me before and there are no symptoms of that. If the impeller on it failed I would be able to hear it.