Water pump diagnostics?
 

Last week I posted a thread regarding changing coolant hoses on my 1991 EX Honda and thought I had successfully replaced the radiator and errant hoses. That seemed to be OK for a week or so. Today I took a round trip of about 20 miles and at the end of the trip noticed the temp gauge showing severe overheating up near the red mark. Now along the way I had checked the gauge and it was A-OK until about 2 miles from home. I let it cool off a little and added about 1-1/2 qts and it got me home but started showing overheating as I pulled into the driveway. I let it cool off and checked the radiator again and it was still full to the neck. I let it idle and used the bleeder thinking maybe I had air trapped in the system. It burped a little as it was idling and if I squeezed the hose going into the thermostat I could get a stream of water out. I then took it around the block twice (about 1 mile each trip) and it started to show overheating. As I took it around the block the temp gauage showed some fluctuation from the bottom of the D4 green box to the top of the box and then higher still. Came back to the driveway and now the gauge was showing hot. Cracked the bleeder and it steamed out with fluid. Does this mean the water pump is a goner?

Bob W.
1991 5dr EX Wagon A/T
210,750 miles

Personally, I read this as more of a t-stat issue...we all read things differently.

When this issue is happening (don't let is happen for very long!) Feel the upper and lower rad hoses...is there a difference in the temp? Were the fans running?
IMO, t-stats are cheap, if not sure, replace.

Fan was not running while the engine was, but came on as soon as the engine was turned off. As I recall both were hot, but the top one was hotter.

Bob
1991 5dr EX Wagon A/T
210,750 miles

Check that the fans are coming on when it starts to overheat. Might be a radiator fan switch (thermoswitch) problem. More specifically, the switch on the thermostat housing.

Here's a link with some info. regarding overheating:

"http://techauto.awardspace.com/overheating.html"

Copy and paste link without quotation marks (" ") to view.

It is late (for me) and I'm going to pick on myself-asking about the fans was a poormans method of getting another clue....since thermo a is "before" the t-stat and it would not get hot if the coolant wasn't flowing......back to checking for a stuck/half open-closed t stat....another test would be to turn the car on/pos II (like you were driving)...jump the wires to thermo a (green two wire connector near/on the t-stat-EDIT-lower hose) and see if the fans - BOTH- come one...then you have this down to either two things...IMO

1) T-stat is not opening allowing the hot coolant to flow
2) Something with the fans is not working

...I'm going with a t-stat issue.

I would say the two possible suspects are the thermostat or the thermoswitch. If the fans are not coming on when the engine starts to overheat; but, runs when the car is turned off, this points to the thermoswitch on the thermostat.

As the coolant flows from the engine through the upper hose into the radiator, it will generally be hotter and cool down some as it flow through the radiator (especially if it gets air flow while driving the car and/or from the radiator fan), the coolant coming out the bottom of the radiator would be a little cooler. You may have a faulty thermostat if your fans operate properly with the engine running.

Trying letting the car run for a while and see if the fans come on. Don't let it overheat though.

There's always the boil test for both the thermostat and thermoswitch as shown in the link above.

Sorry my friend....looks like we were posting at about the same time.....thanks as always....:)

Folks your diagnosis is on track. I pulled the old thermostat this morning and sure enough it was in bad condition. The plate at the end had actually become disconnected and the rubber seal at the other end was cracked and brittle. I ran the car on a 5 mile round trip around the neighborhood and the temp gauge did not leave the bottom of the D4 box so I'm pretty sure this was the problem.

Thanks much!
Bob W.

Glad to hear!!!! Another Honda back on the road and rolling :)

THANKS for coming back and letting us know how it turned out....it is the only "payment" we get for doing this......so Thank you!

Poorman212,

BTW I have a son lives in Durham is Youngsville anywhere near there? He drives a a Honda CR-V and the car we're using was originally his purchased at Vann York in High Point.

Bob