Random Temp Spikes - Chevy and GMC Duramax Diesel Forum
01-04.5 LB7 Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

 
LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 01-15-2020, 10:38 PM Thread Starter
Junior Member
 
Khyren's Avatar
 
Join Date: Jan 2018
Posts: 50
Garage
Random Temp Spikes

So we made a run from West Yellowstone, MT to Rigby, ID(200ish mile round trip) like we have done several times this winter, but the truck was having random overheating spikes. Going up a hill, I can understand it getting a little warm. But on the flats and cruising at 65 while it's freaking 8 outside is absurd. It got to 219 the first time and then the fan engaged and it dropped the temp like a stone. On the way back, it got to 230 and that's when the fan finally came on. Again, finally it came back down really fast. Several times during this trip it would just start climbing in temp for no reason, stay at 197-199, then drop back down to 177 and stay there for a bunch more miles. Would the thermostats failing cause this?
Khyren is offline  
Sponsored Links
Advertisement
 
post #2 of 6 (permalink) Old 01-15-2020, 10:55 PM
LHN...We ARE the Joneses
 
Hook'em_Horns!'s Avatar
 
Join Date: May 2008
Location: Awww-stin, TX
Posts: 25,936
Send a message via Yahoo to Hook'em_Horns! Send a message via Skype™ to Hook'em_Horns!
Possibly. Stuck open, you don't get the temp cycling in the rad. But that's usually a hot weather thing with your temp spikes. In winter, it just never gets to full OP temp and your heater leaves a lot to be desired.

Your ECT and the fan clutch Temp, are two different sources.

You need a good airflow thru all of the coils up front, in order to reach and trigger the fan clutch to lock up. In the hot months, people towing will see the spikes, then eventually the fan locks up and the ECT plummets.
Recommendation; open up the cooling stack and clean the debris buildup between each coil. With a good airflow, the fan will do a partial engage most times, and you'll never hear a full lock howl.

But seeing it @ 8* out....I'm wondering if you might have a failing water pump.

2007 LBZ 3500 LT3 DRW Crew Cab, Sulastics, Putnam XDR 15K, B&W 30K-Turnover GN+Companion, Ride-Rite Air...EFI'd by Rob
2008 LMM 3500WT DRW Crew Cab, 8 'Flat/GN, Workforce Alum Toolbox, Ride-Rite Air

Use-ta Haves 2006-6.0 3500 WT DRW ExCab Flatbed, 2005-LLY 3500 LS DRW Crew Cab, 2002-LB7 3500 LS DRW Crew Cab
I Live my life in such a way that when my feet hit the floor in the morning...Satan shudders & says "Oh shit, he's awake!"
Hook'em_Horns! is online now  
post #3 of 6 (permalink) Old 01-15-2020, 11:13 PM Thread Starter
Junior Member
 
Khyren's Avatar
 
Join Date: Jan 2018
Posts: 50
Garage
The truck has 213k on it so it is possible that the pump is taking a crap. I will have to check the PO's service records and see if a pump was ever done. We have the winter front on currently but that shouldn't be causing the spikes like that. It should just stay at one temp and stay there unless under load. Mishimoto thermostats are going to be on order in the very near future. The trans temp also rises with the coolant temp. I'm guessing because the trans fluid circuit goes through the radiator as well as the frontal cooler. The pump isn't weeping, but then again, I did flush what looked like mud and two different types of coolant out of the truck when I did the injectors.
Khyren is offline  
Sponsored Links
Advertisement
 
post #4 of 6 (permalink) Old 01-15-2020, 11:38 PM
LHN...We ARE the Joneses
 
Hook'em_Horns!'s Avatar
 
Join Date: May 2008
Location: Awww-stin, TX
Posts: 25,936
Send a message via Yahoo to Hook'em_Horns! Send a message via Skype™ to Hook'em_Horns!
Trans fluid flowing thru the rad, temps mimic the ECT.

Mud is not good.
Still a mystery why people don't trust Dex and stick with it, instead of trying to go green which has a far less lifespan. Where's the gain?

Weep hole check, it's possible to have an internal shaft fail and not leak, and also not turn the gear driven pump.

I wouldn't spend extra $, a set of inexpensive Stants from rock, work just the same.
But again, stuck open T-stats in cold weather, it just never warms up and you have no heater.

But no coolant flow from no pump action....shouldn't have the Trans temps spiking.
It's a mystery.

2007 LBZ 3500 LT3 DRW Crew Cab, Sulastics, Putnam XDR 15K, B&W 30K-Turnover GN+Companion, Ride-Rite Air...EFI'd by Rob
2008 LMM 3500WT DRW Crew Cab, 8 'Flat/GN, Workforce Alum Toolbox, Ride-Rite Air

Use-ta Haves 2006-6.0 3500 WT DRW ExCab Flatbed, 2005-LLY 3500 LS DRW Crew Cab, 2002-LB7 3500 LS DRW Crew Cab
I Live my life in such a way that when my feet hit the floor in the morning...Satan shudders & says "Oh shit, he's awake!"
Hook'em_Horns! is online now  
post #5 of 6 (permalink) Old 01-16-2020, 08:41 AM
Former GM Tech and parts
 
DMAXfirefighter's Avatar
 
Join Date: Jan 2009
Location: West-Central Indiana
Posts: 2,447
Garage
Like Hook'em said, being in temps that cold with an overheating issue is unusual. Thermostats are a good place to start and see if that does cure it. That's a lot easier than a water pump replacement to start with, at the very least. You said you flushed 'mud' out when you did injectors- would it be possible that there is a blockage floating around somewhere that could contribute to this as well... but you'd also think that it would get caught at the thermostat or something and be visible when you crack the t-stat housing off there... But, a pump issue could be too... keep us updated!

Name: Matt
ASE Certified, former GM Parts guy
John Deere Service Manager

Play Truck - 2002 LB7 2500HD Crew Cab Short Bed
Daily/Tow Rig - 2006 LLZ 2500HD Crew Cab Short Bed

SOLD - 2007 LBZ 2500HD Standard Cab Long Bed
SOLD - 2006 LBZ 2500HD Crew Cab Short Bed
SOLD - 2004 LLY 2500HD Crew Cab Long Bed
TRADED - 2002 2500HD Crew Cab Long Bed
SOLD - 2001 2500HD Ext. Cab Long Bed
DMAXfirefighter is offline  
post #6 of 6 (permalink) Old 01-19-2020, 10:54 PM Thread Starter
Junior Member
 
Khyren's Avatar
 
Join Date: Jan 2018
Posts: 50
Garage
Update: I didn't have time to get the thermostats done myself so my wife paid a mechanic friend of ours(yes, he's reputable and is the only one that my wife will let work on her truck besides me) change them for us. The truck on about a 10 mile one way run slowly gets up to temp. Hits 197 and falls back to 180ish then repeats the process until it finally settles at about 188-192. I also did a 0-90 pull and it only went from 185 up to 197 and then went right back down. The stock gauge on the cluster is garbage. It starts coming up indicating hotter than 160 but it is only actually 105. We haven't taken it on any long excursions yet. As for a chunk of mud breaking loose, there might have been one on/near the block heater that dislodged due to daily use now that we live in Montana. I did the initial week long flushing session in June of 2018 and then drove it across the country three times, before settling in Montana. I'll update if anything else changes after this weekend's excursion.
Khyren is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy and GMC Duramax Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome