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I have a 2001 Civic that usually runs fine with temp gauge right in the middle. For the past 6 months I have been having problems with it overheating while sitting in traffic. Most times in traffic temp stays normal, but sometimes it just shoots off high and climbs rapidly. Shut off and allowed to cool and it is normal again.

Radiator with slight leak has been changed months ago. Temp switch controlling fan and relays were checked good, but later changed just in case. Thermostat has been changed twice and bench checked good. Flushed a few times. Block test says good head gasket and no pressure buildup or bubbles or other sign of a bad head gasket. Water flows in radiator and can run 100 miles without overheating so thinking water pump is fine. Installed bypass switch to manually turn on both fans just in case and that did not help. I have had it start to overheat while stopped then get better when moving and got home and checked water and not even two cups filled it so don't suspect a leak.

I am at my wits end and don't know where else to look. Any suggestions?

 
Rep Power: 366

read first post for proper diagnosing methods

https://www.civicforums.com/forums/3...reference.html

 
Rep Power: 209

blown head gasket,

how is the coolant level in the overflow bottle?

is it filled right up? or very high?

 
Rep Power: 517

So WHY is it a pint low?

The radiator is designed to ALWAYS stay completely full under all conditions.


You need to realize that test only finds the worst of the bad ones, it doesn't detect the slight leakage these begin with in the early stages of failure.

 
Rep Power: 0

I had the same problem b4 but it was with a pontiac Bonneville I did all the same work/fix you did, the car never had a problem b4 I started a job in NYC working on a move set. The car did not like the city life but ran fine upstate. stop and go. Long story. it turned out to be a week water pump, at low idle only in the hot slow traffic in NYC I had the problem. A week pump at idle will act this way in any car.

 
Rep Power: 145

The pump is just a impeller blade run by the timing belt. It is not literally a "pump" in the true meaning. As in, it is not a motor that drives the impeller.

The pump would most likely work or not work at all.

There is never a "mystery" overheating problem.... Pretty much 99% of you who type that title in get a pretty simple and quick response... head gasket...look through the forums and you will have your answer...

 
Rep Power: 209

yeah i agree,

i was going to say.....how can a water pump get weak?

 
Rep Power: 517

^Pick one.^ (Don't pick the one on the top row, center.)

Shave all the fins down to about half height on any of those impellers in the pic and tell me just how efficient that pump becomes.

Now tell me how you'd figure out the new problem if you didn't already know about the damage.

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The poster above (Blazz) is absolutely correct, a worn pump impeller can and does happen and can cause some complaints that would seem quite unusual if you've never had to deal with the situation before.

It can happen to stamped steel and cast iron impellers as well as molded plastic impellers. Wear can occur to the block casting the pump is bolted to as well.

I've seen several pumps over the years with varying degrees of damage, and some were real hair pullers to figure out.

If this OP has been running excessively diluted antifreeze or straight water or has a contaminated cooling system, I could certainly visualize that sort of wear happening to the pump.





What I cannot discern from the post is if this would apply to the OP here, I don't think there is enough info and OP seems to be MIA/one-hit-wonder so far.

I think some heater output testing and radiator fan-heat tests could lead me to some decision about whether or not it's worth pulling the pump.