Contour Enthusiasts Group Archives Forums General Troubleshooting Lower engine temps caused by metal WP??

Sorry for the redundancy. I posted the following as a reply to an earlier post today, but felt I needed to do a 2nd post as a new topic.

I replaced the WP on my E0 SVT over the holiday weekend using the GMB AutoZone pump.

Looks like I caught it just in time too at just over 30K. The stock unit w/ black impeller had just started to scrape against the back of the pump housing and a hairline crack was starting to form on the impeller.

My car has always run cool usually between the letters N and O and never over the half way mark during extended idling in hot (90F+) summer traffic.

With the new pump, new Ford thermostat and new Ford temp gauge sender, the needle on the gauge sits just below N and sometimes just barely in the normal range scale.

Obviously the new metal pump does work, but are the lower temps caused by the pump? Can anybody concur these findings on their cars? Yes, I am using the same 50/50 concentration as before using Ford premium coolant along with a bottle of Red Line Water Wetter. BTW, I was already running Water Wetter before the pump change.

IIRC, the stock black had only 6 blades on the impeller and the GMB unit has 7 or 8.

I don't know much about water pumps but I had mine replaced with the metal impellar also and it hardly EVER goes to the O it almost always sits on the N or little bit below.

Have you noticed a change for the worse on your Miles Per Gallon since your cars are running cooler? I pose this question cause I have noticed ever since my water pump was changed, and I do not know what type was installed, the MPG have gotten worse although the car runs much cooler. I do not know if the thermostat was changed too, but if they did I would hope they kept the higher temp rating. Thats something I want to verify when I get some time off in Dec. I sort of suspect this over cooling of our engines is also messing up our emissions control by causing our engines to run richer, creating more carbon deposits/clogging ports etc.. and thereby using more fuel in the process. If you have noticed any difference in performance due to decrease in operating temperature, let me know, thanks.

My MPG has stayed identical to what it was before the WP change. As I mentioned in my post, I also replaced the thermostat and temp gauge sender unit using Motorcraft parts.

As far as performance goes, I feel no difference whatsoever. This is good, since I wasn't looking to get any gains out of the WP swap. If the EEC-V was that sensitive to a WP swap, I'd be really concerned in re. to its intelligence (either too smart or too dumb or a bit of both).

My main reason for posting was because I am concerned (like you) that the computer might not be going to closed loop operation and hence run richer and blow through O2 sensors and cats at a much quicker pace than before the coolant system service.

FWIW, I do feel that the max heater output is a little less (5-10%) than it used to be. Hard to tell, the lowest temp around here is usually around 40F.

I wouldn't take the readings of the stock temperature gauge too seriously. They are notoriously innaccurate. "N" on one gauge may be the same temperature as "O" or even "R" on another.
Unless the thermostat has been changed to a drastically different temperature rating, the new pump should not have much of an affect on engine temperature. An 195 degree F thermostat swapped out for an 160 degree unit can make a difference in performance and emissions, especially in cold weather. Also, a cold running engine is subject to more wear since typical motor oil additives work better at temperatures above 180 degrees.
I would not woory too much also about carbon deposits based on changing the water pump alone.

DanB/Steven,

If the thermostat is stuck open or leaking, the coolant will take longer in heating up correct? I suppose where I am leading towards is if the thermostat is not changed during the pump replacement and it is somewhat faulty or it is changed to a lower temp rating, this would cause the coolant to run at lower temp because we have a more effecient pump. Anyhow, I tested my suspect coolant temp situation this morning by monitoring the ECT with my OBD2 scanner from a cold start. I drove the vehicle to work and noticed the temperature took quite a while to get up to the higer temperatures. Outside temp was in the upper 60's. It liked the lower temperatures (low to mid 180's) and hardly ran into the 190's except when it slowed down or idle after a long drive. I did get the fans to turn on a couple of times after a long idle time, they switched in at about 212 deg. I had the heater blower on from the start and I notice the air got warmer as the engine coolant temp increased. After an ECT reading of 150-160 deg, I could not tell the difference in the heater air temp via my feel. During the latter part of the test, the temp gauge reached the mid point between O and R, it spent most of the time below N or just above it. The fans switched in as the gauge approached R and then headed down again.

Let me know if this is what you have experienced with your vehicle. It looks like I need to look at the thermostat a bit closer unless this is normal.

After the swap of the WP, stat and temp gauge sender unit my car heats up about as quick as it did before.

I think you're possibly on the right track by suspecting your stat might be failing or leaking.

FWIW, last night I put in the old temp gauge sender unit and same results.

Since I don't have a OBD-II scanner I might try to use my infra-red heat gun and see what kind of reading I get off the stat housing unit after its fully warmed up.

Before the swap, it was showing approx 190F after a 20min drive.

If the t-stat is stuck open, the engine will take longer to get to normal operating temperature.
Also, thermostats, like stock dash gauges are not precision devices, so any two of the same rating can behave differently in operation.