Overheating Issue
08-16-2017, 10:37 PM
#1
Overheating Issue
Stock and untouched 2005 4.8L (heads are stock and are 862 castings)
One month ago the truck started to overheat (245* on the cluster). I changed the thermostat (NAPA, OEM temp), but had a hell of a time getting the air out of the cooling system. I saw a post where dude said filling the res., then filling the upper radiator hose is one way to purge the air out of the system. For 2-3 weeks that seemed to be the fix. I went on a 400 mile road trip and I didn't have any issues. Today the truck got hot during my lunch break, 255*ish. The coolant res. had plenty of water in it. I noticed a coolant drip down the driver side of the timing cover. But there was no puddle under the truck, as a failed water pump would indicate. After work I got a few miles down the highway before it started getting hot. I turned the heat on full blast and the temp never got below 225*. I limped it back home. There was still plenty of coolant in the res. When I squeezed the upper radiator hose there was no water in it. I performed the same air bleed procedure and now the truck is running normal temp (210*). The OEM/original cooling fans both work and spin faster when the truck gets hot. Even though the cluster has been rebuilt, I take the change in pitch of the cooling fans as the temp is actually getting high. I will log the next few days and compare the gauge readout vs. what HP Tuners says.
What are you guys using to bleed the air out of the cooling system? I don't mind spending the money on a good tool, but don't know which one to get. Today would indicate that I still had air in the system, or air is making its way in (not sure how). That drip down the timing cover has me scratching my head. I have to get this sorted out asap. Let me know if anyone has any bright ideas.
One month ago the truck started to overheat (245* on the cluster). I changed the thermostat (NAPA, OEM temp), but had a hell of a time getting the air out of the cooling system. I saw a post where dude said filling the res., then filling the upper radiator hose is one way to purge the air out of the system. For 2-3 weeks that seemed to be the fix. I went on a 400 mile road trip and I didn't have any issues. Today the truck got hot during my lunch break, 255*ish. The coolant res. had plenty of water in it. I noticed a coolant drip down the driver side of the timing cover. But there was no puddle under the truck, as a failed water pump would indicate. After work I got a few miles down the highway before it started getting hot. I turned the heat on full blast and the temp never got below 225*. I limped it back home. There was still plenty of coolant in the res. When I squeezed the upper radiator hose there was no water in it. I performed the same air bleed procedure and now the truck is running normal temp (210*). The OEM/original cooling fans both work and spin faster when the truck gets hot. Even though the cluster has been rebuilt, I take the change in pitch of the cooling fans as the temp is actually getting high. I will log the next few days and compare the gauge readout vs. what HP Tuners says.
What are you guys using to bleed the air out of the cooling system? I don't mind spending the money on a good tool, but don't know which one to get. Today would indicate that I still had air in the system, or air is making its way in (not sure how). That drip down the timing cover has me scratching my head. I have to get this sorted out asap. Let me know if anyone has any bright ideas.
08-16-2017, 10:44 PM
#2
The gauge to HP Tuners number difference is going to be 10-15 degrees easy. The real temp is always floating around 190-198 in any of the trucks I've had. I wouldn't rule out a temp sensor itself too.
As for bleeding the system I just add coolant to the res tank and let it run with a cap off for a while and add as needed. Shut it down, let it burp, add more and let it run again and take it for a drive. Haven't had a single issue doing it this way.
As for bleeding the system I just add coolant to the res tank and let it run with a cap off for a while and add as needed. Shut it down, let it burp, add more and let it run again and take it for a drive. Haven't had a single issue doing it this way.
08-17-2017, 07:16 AM
#3
Thanks for the reply. When I replaced the thermostat I tried adding coolant to the res while running, then all of a sudden it came pouring out like crazy. I suppose shutting it down 90 seconds prior was the ticket. I will keep an eye on it. I am mostly curious if anyone had their overheating issues come back.
The oil doesn't have coolant in it. The coolant doesn't have oil in it. Since the level in the res hasn't changed, I can deduce that neither heads are cracked. If the radiator was plugged, I would never got the thing to run cool. The water pump isn't leaking from the shaft seal, so I suppose that is fine also. Perhaps the thermostat got lazy yesterday, or I never got all the air out of the engine. I may pull the thermostat and drill a few small holes in it, as suggested by a few threads I searched.
The oil doesn't have coolant in it. The coolant doesn't have oil in it. Since the level in the res hasn't changed, I can deduce that neither heads are cracked. If the radiator was plugged, I would never got the thing to run cool. The water pump isn't leaking from the shaft seal, so I suppose that is fine also. Perhaps the thermostat got lazy yesterday, or I never got all the air out of the engine. I may pull the thermostat and drill a few small holes in it, as suggested by a few threads I searched.
08-17-2017, 01:21 PM
#5
Yesterday after I refilled the upper hose and res, the truck came to temp and the upper hose was ripping hot.
I popped the hood after cruising around at lunch today and again there is a drip down the driver side of the timing cover. It didn't get hot on the way to work or at lunch. My last "cheap" fix at this point is the water pump. I sure hope that's it. I'll report back Friday evening with my findings.
I popped the hood after cruising around at lunch today and again there is a drip down the driver side of the timing cover. It didn't get hot on the way to work or at lunch. My last "cheap" fix at this point is the water pump. I sure hope that's it. I'll report back Friday evening with my findings.
08-17-2017, 04:28 PM
#6
While it's cool.
Pull the belt off and wiggle the water pump pulley. Side to side then up and down. I bet it wiggles.
As far as bleeding goes, unplug the fans while it comes up to temp to ensure that the thermostat opens all the way.
With the cap off of course.
Your issue is lack of fluid circulation within the system.
Pull the belt off and wiggle the water pump pulley. Side to side then up and down. I bet it wiggles.
As far as bleeding goes, unplug the fans while it comes up to temp to ensure that the thermostat opens all the way.
With the cap off of course.
Your issue is lack of fluid circulation within the system.
08-17-2017, 10:38 PM
#7
While it's cool.
Pull the belt off and wiggle the water pump pulley. Side to side then up and down. I bet it wiggles.
As far as bleeding goes, unplug the fans while it comes up to temp to ensure that the thermostat opens all the way.
With the cap off of course.
Your issue is lack of fluid circulation within the system.
Pull the belt off and wiggle the water pump pulley. Side to side then up and down. I bet it wiggles.
As far as bleeding goes, unplug the fans while it comes up to temp to ensure that the thermostat opens all the way.
With the cap off of course.
Your issue is lack of fluid circulation within the system.
I appreciate the replies and I'll let you know how my buddy is doing.
