fbgh2o

About a month ago I emptied the cooling system to replace a leaky hose and posted about engine temperature climbing while at stop lights, although it never gets above the second mark. I am running a 50:50 mix with Water Wetter.

As suggested, I have repreatedly bled the system (my mechanic did it too) and replaced the expansion tank cap, but the problem continues to persist and I have noticed another behaviour.

• While cruising at 60 to 65 mph, the temperature indicator needle sits just above the first mark for a while. However, after about 5 to 10 mins of constant speed, it will gradually creep up to the mid-point (or just above).
• If I (1) down shift into 4th; or (2) set the temperature controller on the heater to 21C; or (3) turn on the A/C [which engages the 2nd fan] the needle drops back to just above the first line
• Interestingly, if I slow down to 30- to 40 mph sustained (in 4th gear) the needle will settle to just above the first mark.
• If I stop at a light it will climb to the top half of the area between the first and second lines on the gauge (say between the 9 and 10 o'clock position) and immediate drop off the minute I accelerate away from the light.

Does this sound like a water pump that is not functioning correctly at idle?
Alternately, could it be the radiator that is not cooling well. I am thinking of doing a flush of the systems to clean out scale etc.

Any thoughts? Many thanks for the help.

Airflite40

sounds just like my car..... I was told that 951's run a little hotter than N/A's do.

Tom M'Guinn

As long as the needle stays below the upper white line, I'd say it is "normal". However, if it runs in the upper half of the gauge regularly on mild days, your system may not be cooling as well as it could. If the pump is not leaking or making noise, it is probably ok. Start by pressure testing the system to make sure there are zero leaks. Little pin-hole leaks can be impossible to see (just venting a little steam under pressure), but will let air into the system over time and cause the temp gauge to fluctuate more than you'd want. Next make sure the fans are working as intended -- clark's garage has a complete diagnostic to make sure the relay, temp switch and fans are all working as they should. Also make sure you are getting good air flow to the radiator -- not caked with bugs/debris, blocked by bras, driving lights, etc. Also make sure the thermostat is working and that the seal in the throat of the waterpump is good. You can boil the t-stat and watch to make sure it opens. Also, if you need a 50/50 misture up there in Canada, then so be it, but moving to more water/less coolant will help a bit. Adding a bottle of Water Wetter will help a bit also, regardless of the mixture. Finally, over time the radiator's flow reduces as minerals, etc. build up -- a new radiator will almost always yield additional cooling.

I struggled to get my temps down too, and came to realize that (unless something is malfunctioning), it is really a combination of all these little things that add up to make it run cooler.

fbgh2o

Thanks Tom.

It only runs in the upper half when the car is not moving.

1. No odd water pump noises.
2. Have replaced all the hoses at the front of the car and did a pressure test. Everything seems okay.
3. Fans are definitely good. Did the Clark tests and rewired the resistors.
4. Air flow appears okay visually.
5. Have not checked the thermostat. If I have to remove it to test, based on everything that I have read about the snap ring I will just replace it
6. I think that I will have the radiator flushed to see what kind of crud may be inside.

Will continue to see what we can do to fix the issue.

ehall

Use the preasure tester and re-bleed the system. It's very common to have residual air in the system. Do this four or five times. You have to be absolutely certain. Then start looking at more complicated problems.

fbgh2o

ehall,

PM sent...

ehall

replied. good luck. Let us know.

Auto_Werks 3.6

sounds completely normal to me

fbgh2o

A big thanks to ehall and all those who responded. Followed his advice on re-bleeding the system by jacking up the front of the cars and using a pressure tester to pressurize the system and then to bleed it. On the second iteration air blew out. Just to be safe I did the process 10 times (dumping a bunch of coolant on the floor in the process).

Now the needle does not go above the mid-point at stop lights and is steady just above the first line while cruising.