Dodge Cummins Diesel Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
799 Posts
Discussion Starter #1
Hey guys, I've got another question for ya.

I've noticed lately while warming up I have a knock. It sounds like a lifter knock or exhaust leak but sounds like it's coming from the drivers side of the engine. The weird thing is it goes away when the motor gets up to about 170*.

Also when it's first warming and I drive it the temp goes all the way to the line past the 190* (not sure exactly what temp that is) it hangs out there for a few minutes then drops back to 190* and stays there for the rest of the drive. Do you think that could be the thermostat?

The knock has only developed recently, not till after I messed with my map sensor and boost plug, but I have checked both and neither have leaks.

Any Ideas?

Thanks
Jason
 

·
Registered
Joined
·
992 Posts
First if the engine is already at 190*F and the gauge begins to fluctuate then its normal. Mine has done this forever with no issues. In fact a lot of modern engines run in the 200-230*F range as they are more efficient here. At 240*F i would worry.

If the temp is going from full cold to hot back and forth i would suspect either the system is low and pulling in air as a result, or the sender is bad.

Warm up knock can be normal, because of pump timing. But mine gets bad when the #6 exhaust bolt backs out. I guess its better than the manifold cracking but it gets old tightening it up.
 

·
Registered
Joined
·
799 Posts
Discussion Starter #3
Well it's the initial warm up that it does it and it's the only time. I've just never seen this before and it kinda got me the first time. It goes from cold to the high side but not out of the hash marks then down slowly to 190. And you can feel the change in the heater so I know it's getting warm.

And when I first got the truck it didn't knock, sound like my bronco did when before I adjusted the lifters but it sounds like it's only one cylinder... If that makes any sense.
 

·
cumminsforum.com
Joined
·
26,302 Posts
Ok... As for coolant temp...

I see about 204-210*F for a high mark for first opening of the day. Then it slides back down to about 193*F to 197*F as a normal run range. This is what I see from my ScanGauge II... But if the cycling is continueous then the t-stat is starting to stick.

As for timing knock I got rather a harsh one when cold. My Edge comp is on 5x5 daily never turned down. As I get out on the pavement and start gaining speed to 65 MPH it rattles quite well. But as the boost pressure clear 7 PSI the knock is gone. This is because the as boost pressure increases the timing retards.

The autoignition temperature or kindling point of a substance is the lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical will ignite decreases (Advance Timing) as the pressure increases (Boost) or oxygen concentration increases. It is usually applied to a combustible fuel mixture.

So the VP44 must retard as the boost goes up other than that the timing would be over advanced... You can see this if you have a smoke switch...
 
1 - 4 of 4 Posts
Top