Blow off valve

[stownsend]

Hi all,



I'm a new Cummins owner as of June 2001 I'm trying to figure out how the darn things work so bare with me.



I assume that the Cummins 24V have a blow off valve on the turbo? Is there any reason to upgrade the stock valve?



Also, I read a thread about it might be worth checking the air temp sensor periodically to clean it. Where is it located?



Thanks,



Steve

 

[JKloppe]

Welcome to the TDR.

If you do a search you could find the answer to your question. This helps avoid the same question asked over and over.



Our trucks have waste gates not blow off valves like gasers. I think the main reason is because diesels dont have butterflies to stop the air from entering the motor. The blow off valves are easier on the turbo. FYI



JK

 

[Alan Reagan]

The Intake Air Temp sensor can be found on the back of the engine, drivers side.



Go here for a picture:



http://dodgeram.org/tech/dsl/mt_2_feb98/fuel_sys_comp.htm



They don't appear to get that dirty unless you have an Ebrake on your truck. Maybe at 20,000 you might want to check it and clean it. It takes a 22mm socket or a large spark plug socket if you don't have a 22mm. Tip o' the day, get the socket and an extension no longer than 6 inches to do the job. I found it easier if I go from the front of the engine, left hand on the valve cover and just lean right over and take it out. Mine was loose when I checked it. When I went in from the side, I was too twisted out of shape to unscrew the thing because of the fuel filter, brake and steering components.

 

[hammong]

JK is right. The reason there's no blow-off valve is because there is no "throttle body" on these trucks. In a gasser, when you slam the throttle shut, there is no place for the boost in the intake tract to go. On a diesel like the mighty Cummins, when you take your foot off the gas - the only thing that happens it the injection pump stops shooting fuel into the cylinders. The excess boost can continue to flow through the engine.



If you're under max boost and suddenly take your foot off, sometimes you'll here a big WHOOSH. This is some of the boost leaking back past the turbo in the reverse direction. This back-lash is bad, and you should consider easing off the throttle a bit when coming off max-boost. A blow-off valve COULD be rigged into the intake tract, but you can't use engine vacuum to actuate it. There IS NO vacuum when you let-off the throttle, just "less boost". A solenoid-actuated BOV that uses vacuum from the brake booster or the vacuum line system (there's a vacuum PUMP in these beasts).



Greg