TemP 198 to 200 after head swap

**RealLiveMD** · 02-15-2012, 06:17 PM

I recently repaired my heads and changed the lifters. Before the swap. my car temp was 186 going as high as 201 when spraying 3 times in 99 degree weather. I broke the coolant sensor during the swap but bough a new ac delco one from napa. Now the temp range won't go below 198 and ofter hist 201 without spray in 30 degree weather. I flushed the bubble by removive the hose on driver side of the motor and not reattach until a stead flow of fluid is coming out. This use to work. The fluid should at least be cleaner than the old fluid because i am using completlely new fluid. Im using hptuners for the temp readings. Any ideas???

**0rion** · 02-15-2012, 08:56 PM

where are your fans set in the tune? Are they running all the time? Also....are these temp readings from a scanner or are you guestimating it with the stock gauge? It sounds like scanner temps since you're so accurate but thought I'd ask. Sometimes you may have to purge air a couple of times. Just take the cap off the radiator and run it until you see coolant flowing ( some will purge out the hole until the stat opens). Run it like that with the coolant flowing for a few minutes then top it off and put the cap on. All the air should be purged using that method. The other explanation is it's just coincidence. I'm saying this assuming you're tuned for a 160 or 180 stat though which is where your fans will try to keep the temp. If you still have the stock fan settings then your temp is where it should be.

**RealLiveMD** · 02-16-2012, 02:03 PM

I'll chec but I think the fans are set at 180. I'm using hp tuners to scan. Oddly, I didn't have this problem prior to the head swap and and coolant temp sensor swap. I dont' know if its simply a bad sensor. I've purged the air by removing the hose going to the intake. I'll try your method though. It's weird.

**0rion** · 02-16-2012, 02:08 PM

well....like I say....sometimes you may have to purge it a couple of times to get the air out. Especially after a head swap. Lots of places for air pockets to hide.

**pajeff02** · 02-16-2012, 02:27 PM

Did you coat the sensor threads with anything prior to installation?

**RealLiveMD** · 02-16-2012, 07:41 PM

Originally Posted by 0rion

well....like I say....sometimes you may have to purge it a couple of times to get the air out. Especially after a head swap. Lots of places for air pockets to hide.

Thanks,
and pajeff02 the thread had teflon tape preinstalled.

**pajeff02** · 02-17-2012, 02:58 AM

Should be ok -- the threads would cut through that to create good metal-to-metal contact. A poor contact with increased resistance can alter a sender's output... same for any corrosion on the contacts.

**RealLiveMD** · 02-17-2012, 09:22 PM

It's not screwed in flush to the motor. The header is in the way. Could this cause it. I thought the sensor was at the tip being bathed by coolant. What's does metal to metal have to do with it?. Just asking.

**pajeff02** · 02-18-2012, 04:12 AM

Most temp senders operate by simply measuring the resistance to the flow of electrical current. In this case, the sensor is grounded through its threads to the head. Changes in temperature cause a change in resistance (measured in Ohms) and this is transmitted by the wiring to the gauge. If the sender does not have a good ground contact with the head, or if there is corrosion or damage to the connector or wiring, there is a corresponding change in resistance (generally higher resistance) and this throws off the gauge.