Boiling 6.5TD

[maxzig]

Recently had dealer replace second injector pump on my 98 3500HD tow truck, 85,000 mi. Replaced first at 45,000. After a couple of days my low coolant light came on. Thinking that it was just not bled properly, I added coolant and rebled it. After two months the problem has escalated to the point where I get no heat until the thermostat opens, but temp is fine until I back out of the throttle and it idles a few minutes, then the temp will shoot up and boil out the overflow, heater flow will also stop. If I rev it up, temp returns to normal and heater flow resumes, but I,ve already lost a large amount of coolant. I've flushed the system, replace the thermostats, rad cap, and water pump with no change. Being a tow truck, it kinda cants forward, I was wondering if jacking the front may help in bleeding to make sure all the air is out of the block. Hate to go back to the dealer because the truck is always tied up for days at a time when I need it most. Any new ideas will be greatly appreciated.

98 3500HD tow truck, luk clutch, flywheel

[diesel65]

Sorry to say but sounds like you got a head gasket that failed.
When replacing the IP, the coolant system is usually not touched unless the infamous heater hose connector starts to leak or breaks off.

[maxzig]

Forgot to mention, the first thing I replaced was the leaky heater hose connector, the dealer apparently jimmied it around when they disconnected it destroying the seal. This leaked for several days before I found it.

[ucdavis]

Still doesn't sound like a bleeding problem to me. Going from hard accel to idle should drop EGTs like a rock & amount of heat to be scavanged along w/EGT.
I'd take it to a hot-rod radiator shop (most of these guys do off-the-shelf-auto work for bread & butter, but because they do so much speed & custom work, have an eye for overheating trouble. Should take <20 min. to diagnose. Call a local hot-rod or speed shop for a recommendation.
Heat kills diesels, so I'd not dally if it was me.

[Cowracer]

sorry, never mind!

[cudaaa]

I just got done fighting a airlock on my 6.5 I had the opposite problem. Driving down the road the truck would warm up and the heater would blow warm air not hot! When I would stop the temp gage would drop and the heater would blow cold! My guess for you would be head gasket. Hope this helps!

[maxzig]

Just a quick update. Two cracked heads and a bad Turbo shaft. Thank God for warranties. :eek:
Truck is still in the shop from 12/14.