LB7: No heat.....heat...no heat?

[JustinD]

My buddy has an 04 LB7 truck, has about 90k on it, it just started taking a long tme to get heat then if you let it idle it seems like the heat goes away? We changed one of the 2 tstats (only changed one because they gave us one wrong one) it seemed to be ok for a while, now its back doing the same thing? Is possible its air bound? It also puked a little bit of coolant out of the overflow yesterday, checked the upper hose after it sat overnight seems to be normal, not rock hard. It has had a small tune in it for a while now.

 

[Sledhead]

water pump? Its hard to see but look at the weep hole on the bottom of the pump from underneath.

 

[IOWA LLY]

Headgaskets.......

 

[DetailsUnlimited]

Thats what mine did! No heat!!! And the puking of coolant....

 

[DIESELMAFIAPER.LB7]

X3 on headgaskets or a cup

 

[Mike_S]

^^^ we have a few winers...my dollar goes on head gaskets.

 

[JustinD]

I thought HG's too, but why wouldn't the pressure cause the upper hose to be hard after it sits overnight? When I blew a HG it put alot of pressure in the coolant system, hose was rock hard and it would almost blow the cap out of my hand when I loosened it..

 

[LBZ]

Put a coolant pressure tester on it overnight. If the pressure is down check for an external leak from the head area or water pump. If nothing pull all the glow plugs and see if there is coolant in any of the cylinders - crank it over to confirm this.
Sounds like an HG or injector cup to me though......

 

[JustinD]

Ok, I'll tell him to do that, thanks guys!

 

[ChevyTruckGuy78]

subscribed

 

[Mike_S]

Hydrocarbon test will tell you for sure. Simple, cheap, effective, and it doesn't require all the screwing around.