nc_growler

So, after replacing the WP installed by the PO less than 1500 miles ago, I've just completed the installation of one of Ed's new "improved" WP's.

After reassembly, I have an overheating problem.

Here's what I know so far (with help from SharkSkin)...

Disabled hood switch, pushed in A/C button on dash, turned ignition on. Both cooling fans running on high.

Pulled lower radiator temperature sensor connector and jumpered. With A/C off, and car running, cooling fans on full.

Reconnected lower radiator temperature sensor, started car and ran until beyond last white mark but still just below red mark... Observations:

1) Fans never came on
2) Level in reservoir is rising
3) Top hose to radiator is very hot to touch
4) Bottom hose coming to thermostat is cool to touch

after the engine cooled overnight, I also noted:

5) squeezing top hose resulted in fluid levels changing in reservior
6) squeezing bottom hose resulted in fluid levels changing in reservior

SharkSkin's recommendations at this point included picking up an infrared thermometer and cheking the following (but I have not yet done this):

* was the lower radiator sensor hot?
* was the radiator uniformly warm (looking for flow blockage)?

So, place your bets on root cause:

1) Thermostat
2) Radiator sensor
3) Blocked radiator flow
4) Something I haven't yet considered

Good luck!

I'll update this thread with what I discover in the next 72 hours... Suggestions and ideas welcome!

S4ordie

Did you remove the thermostat? If yes it may have been installed backwards. Also if yes, did you replace the inner seal of the housing?

Jim M.

The lower radiator temp sensor is bad. You proved that all the wiring and the fans are good by jumping the sensor. But when reinstalled in the system it's not closing the circuit to power the fans. Get the IF gun on both of the hoses. I'm still concerned that the lower hose was "Cool to the touch". Cooler than the upper or downright ambient temp., if ambient then you may also have a flow problem.

Imo000

If the thermostat housing hose is cold then there is no cicualtion. If there is no circulation, the fans will never come on as the lower rad sensor will always be in the cold zone.......check the thermostat. I had this same problem with an S4 I worked on a year ago. After the second heat cycle the T-stat never openned.

blown 87

You have no coolant flow for what ever reason, t-stat, or bad water pump would be the first place I would look.

mark kibort

sensor at the bottom is probably fine by the fact that the lower hose was cool and top hose was hot.
bad pump, or t-stat, or clogged radator.

blown 87

The radiator is not going to suddenly fail (plug up) by just doing a water pump, same goes for the T-stat unless it was removed.

But I agree that the lower hose being cool is the tell tale sign, the sensor is not getting hot enough to command the fans on with no coolant flow.

nc_growler

I would have definitely replaced the inner seal, but I did not remove the thermostat on this job... Thanks.

nc_growler

Jim... SharkSkin was worried about flow too.. Not sure what to think about my "hose squeeze test" when cool though. I definitely had solid and similar backflow to the reservoir.

I am hoping that IF thermometer will help reveal any flow issues.

I also agree with your opening statement (unless the lower sensor never got hot?)... Need to check that too.

nc_growler

I think the IF is going to be my friend. Hose going from radiator to thermostat was cold while engine was nearly over heating.

If the thermostat doesn't open, I'm assuming there is no flow into the radiator and thus, the lower radiator sensor could be absolutely fine (because it never got hot enough to flip on the fans)...

I love a good mystery! How about you guys?! :-)

nc_growler

Oh please no! If my new and improved waterpump is toast, I'm going to pass out!

I'll take that as a wager on the t-stat!

blown 87

Not one like this when I have just done a water pump.

nc_growler

I'm extremely optimistic about the WP.

Sounds like another vote for pulling the t-stat...

The old WP failed by leak-out on the weep hole... No disintegration or impact... I would have suspected that the t-stat was fine before the job.

Radiator obstruction? Hmmm.

nc_growler

You ever have one of those sinking feelings? All this talk of coolant flow, blockage, or obstruction has me wondering... Is it possible that I forgot to pull a paper towel out of one of the openings during reassembly? That can't be it...

nc_growler

Tell me about it Greg. I'm a bit freaked out. I thought I was golden when she started up and ran like a champ.