C-15 Boost loss

[HollemanA]

My C-15 serial # SDPO6588 is blowing or sucking the hose from CAC to engine, causing total loss of boost. As you face the engine, this hose is very prominent coming off top left of the radiator connecting to a silver pipe that is connected to a frame tab with muffler clamp in front of coolant tank and then rubber 4" hose to a cast iron fitting located behind and below the AC compressor. It is the lower connection on the cast iron pipe that is coming off. There is no room to double clamp this connection like all the other connections on this assembly have been done. The hose is 8" long and is equipped with 3 stainless rings spaced between the connection points.  I have 74,360 miles and never had a problem with boost or hose before. I do not get a check engine light or any warning prior to the hose coming off. I do not get the check engine light after the hose is off unless I try to give it fuel. I can reconnect the hose and maybe go a 100 yards or a 100 miles. At first the problem occurred when I was at full throttle climbing or passing. Last 2 times it occurred easing thru town in 25mph zone at about 12LBS of boost. When hose is reconnected engine will pull the normal boost numbers which range from 32 to 36 depending on gear and pull.    I am not finding this kind of problem on the truckers forum. I will be putting it in a shop for repairs this coming week but would welcome any information on the subject.
Art Holleman
08 Marquis

[Dave Atherton]

Art, leaking air in Charge air Cooler will affect your boost. Having your connect hose coming
off is a big problem as power goes. Problem could be deeper like crack in the Charge Air cooler
along tank on side. Hose keeps coming off, remove hose an checkout real close inside of that 8 inch
hose may surprise you needs replacement, along with that, check both sides of connecting pipe
and see if pipe is egg shape from overtighten clamps. If answer is yes on roundness of connecting
pipes ( out of round ) will be very hard to keep air tight connection to the CNC. Possible bracket
Holding CAC bolts missing or broken shaking pipe loose. Last remove rubber boot from air filter to the center of the turbocharger and check for oil present in housing, on impeller, in rubber boot just removed. Move impeller shaft to the side and see if you can turn impeller with side pressure applied
By your hand movement. If in question on clearance slide a single piece of paper in between turbo housing and impeller and see if you can slide paper out with pressure applied. Piece of paper is
.004 and that is the clearance that is needed for turbo to go limits. Note excess pressure from turbo
seal will blow hose off CAC pipe connections. Dave Atherton Retired Cat Mechanic

[Lee Welbanks]

Art, You probably need a new hose, I've never had any problem with the ones on my C 13 but I have heard of some hoses coming off and replacing the hose and clamps cured the problem. Are you sure there is no oil or anything inside the hose to make it slick and that your clamps are not stripped out?

[HollemanA]

Took RV into Western Cat in Idaho Falls and they put a new hose and new clamps and said good to go. Could not think of anything to look at or work on, which was pretty amazing since there was not  anything in the shop being worked on and the mechanics were playing on their smart phones. I paid for clamps and hose and they did not even write a ticket on the labor.  Amazing!
Art Holleman
08 Marquis

[Dave Atherton]

Art, thanks for report on your engine. It is sure nice to hear about good experience with
Caterpillar service on your engine. Today it seems there are many mixed thoughts on RV.
High dollar repairs for various reasons. Using the BAC forum today to get advise on repairs,
direction, control on high cost estimates. Times have changed, the old guard is mostly
Retired and the new soldiers have not seem battle. Many dollars have been saved because of
members using the forum in today's world. Dave Atherton Retired Cat Mechanic

[Lee Welbanks]

Art,
Good to hear that they got it repaired. I had a great experience with Riggs Cat in Little Rock, Arkansas. Tried to find the problem with the engine just shutting off for no reason, dumped the ECM and checked circuit boards but could not make it shut off. Worked on it twice for a couple hours, no charge not write up.