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Coolant Temps all over the place....

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97gst_spyder

10+ Year Contributor
2,264
16
Sep 1, 2008
Lakeland, Florida
I've been having the issues with my coolant temps for the last two weeks. First the heater core hose blew, simple fix on the side of the road...I thought.

After replacing the hose, topping of the coolant, I had high temp problems. I was in the 210-215 range cruising. I figured that I didn't tighten everything down, re-checked it fine. I checked the radiator hoses, not as hard as normal. I got a pressure tester, It was loosing a lb per 3 min. Not that bad. Checked everything, looped the heater hoses, and turbo, still loosing pressure. Found the TB hoses were hard as rocks.

I ended up replacing the heater hoses, TB hoses, Turbo hoses, and radiator hoses. I have correct pressure, but now my temps are all over the ####ing place.

Tonight its about 65* out. I was at 80 on the interstate, 192*. It would randomly jump to 204-208*. NO difference in load. Just cruising.

It has been getting as high as 218* randomly. I would be cruising, then spike. If I floor it rpms go up, temp goes down.

Re-cap -

All new hoses, new cap, thermostat, flush. Currently running distilled water and water wetter only. Temps all over the place. RPM's go up, temp will drop 90% of the time.
 
Check the terminal for the temp sensor. Get rid of any and all corrosion and check the wire to make sure it isn't rubbing on anything and has a bare spot. Have you done a pressure test again after replacing everything?
 
Check the terminal for the temp sensor. Get rid of any and all corrosion and check the wire to make sure it isn't rubbing on anything and has a bare spot. Have you done a pressure test again after replacing everything?

I 2nd this!!! And also recommend doing a 50/50 mix of coolant and water. Also are your fans kicking on as they should? and is anything blocking your air dam or at that matter loose/ fluttering in your air dam?
 
Yes, system holds 30lb's with no issues for over 30 min. Then I took the tester off.

For the sensors. Both are brand new, both pigtails are new also. Both the single (gauge) and double (ECU) senders are basically reading the same. Once 215* is hit on the ECU sender, the gauge is not far behind.
 
While all though I don't have crazy fluctuating temps and maintain a steady 183-186F in this weather, I too see a temp drop when a good amount of throttle is applied.
 
Your only problem im sure is you didn't bleed the cooling system...take the radiator cap off,then turn the car is on.let it warm up and start filling the cooling system you will see you have way less colant than you think you do.
 
I'll try that again today. Thanks for the replies!
 
Given you seem to have done all the rest correctly,

+3 on bleeding the air that is likely in the system.

Start the car cold, let it run with the cap off (A/C off but heater lever to full hot side so the water is flowing through the heater core also). You will likely see at the open cap air bubbling along with the water - let it idle and occasionally blip the throttle and keep on adding water a little at a time as the level seems to and keep it filled until it (hopefully) flows free of air bubbles.

The process is basically letting the car pass gas, or the burping of a baby and still letting it drink milk :) via the open fill point cap. This can take a good 10-15 mins to complete.

Let us know if it solves the issue.
 
THanks everyone for the info!

I ended up draining everything. Then flushing it out with a hose, then running a flush. After that I ran a 25%/75% anti-freeze/distilled water. Then 'burped' it for about 20 min. I've been running at 188-194 all day!!!!!

Thanks everyone! Sometimes it is just that easy.
 
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