Low engine temp

[BlkMax]

I purchased an 04 LB7 for a second truck. During the test drive, the coolant temp never came up much beyond 160*. I noticed that there was some cardboard behind the cold front, and figured it was a stuck thermostat.

Anyway, I changed the stats, but the temp is still not coming up.

I checked the radiator hoses, and they are not hard when cold. I also checked the temp gauge with EFI and EFI is reading the same as the temp gauge. The engine is running fine with good oil pressure, so I do not think it is overheating.

When I check the top of the stat housing with a laser temp gauge, it reads about 175*.

What causes the temp to read low unless the truck has a bad temp transmitter? I have not changed the transmitter.

 

[dmaxman06]

humm sounds like the gauge is acting up i know i have heard a few screwing up

 

[JoshH]

I would try installing a new temp sending unit.

 

[THEFERMANATOR]

If the guage is low as well as the temp being low on a scan, but your temp check showed it to be up to temp. All that is left is either your coolant temp sensor, or a bad connection or broken wire somewhere. Poor connections at teh CTS has been known to happen and cause this issue, but a new coolant temp sensor is only about $30 from GM(ONLY use a GM factory one as the aftermarkets are lucky to be within 15-20 degrees brand new out of the box). And if there is any rust or corrosion inside the plug end, replace the CTS plug as well.

 

[BlkMax]

Cool, I was thinking about the transmitter, I will also check the connections.

Thank you.

I just hate to throw parts at something.... like i did with the stats....

 

[baggedLB7]

I had the same prob and changeing the stats fixed it for me. I now run 186 and 182 at a idal and this is going off my cts and efi not the gauge.
Whats the outside temp? If you run it on the freeway and park and idal it does the temp drop alot?
Mine used to run anywere from 158-165 on the freeway and then if I parked and would idal it would drop to like 138.

160ish at the sensor to 175 at the t stat dosent seem like to much of diff depending on the thermometer and sensor calibration and the sensor being located in a diff spot imo.

 

[BlkMax]

I figured it out. I have a bad stepper motor on the ECT gauge. There are some small issues with the IC, so I get to have a new instrument cluster.

It seemed weird,...... the glow plugs would not turn on after a hot restart...I should have known....

I was going to change the bulbs in the IC, and noticed the coolant gauge needle was hosed. Ebay is my friend.

 

[JoshH]

I also checked the temp gauge with EFI and EFI is reading the same as the temp gauge.

I figured it out. I have a bad stepper motor on the ECT gauge. There are some small issues with the IC, so I get to have a new instrument cluster.

 

[BlkMax]

I'm not sure, maybe I did not wait long enough when I was using EFI. I was not logging, just reading the ECT.....Oh well, new stats are not a bad thing at 200K....

 

[AubleAK]

I figured it out. I have a bad stepper motor on the ECT gauge. There are some small issues with the IC, so I get to have a new instrument cluster.

It seemed weird,...... the glow plugs would not turn on after a hot restart...I should have known....

I was going to change the bulbs in the IC, and noticed the coolant gauge needle was hosed. Ebay is my friend.

if you havent already ordered one, this one in this truck worked when i saw it last.. even with the dash pushed back a foot and a half.

http://anchorage.craigslist.org/pts/2949625015.html