The 3 Biggest Problems With The C15 and 3406E. 

Never really had these issues until I had almost 1 million miles on them. My 500hp, 1850tq 6NZ made it to almost 1 million miles before the head gasket went. I had an MXS C15 Acert tuned by PDI that was around 700 hp at the flywheel make it to just over 960,000 miles before the head gasket went on that. The spacer plate gasket was seeping a little for a number of months on the Acert, but it wasn't dripping oil on the ground or anything before overhaul. This was all pulling tri axle hopper bottom trailers grossing 94,000 to over 100,000 lbs. Oil changes at around 10,000 miles. 15w40 Rotella, no additives.

Wow, scary stuff! I've been blessed over my career...only had two C-15 6NZ's in my life...changed the oil every 10-12k miles and substituted a gallon of Lucas Oil treatment. After an oil service, the technician would remark at how clean the dipstick would look....ran Overheads at CAT, both got great gas mileage (6.5-8mpg, depending on load and terrain), and both had over 1.2M before eventually selling them. Worst mistake I ever made..but blessed I never experienced these issues represented in the video. Thank you for sharing! 👍

I owned two E-Models...a 95 rated at 475 and the last a 2000 rated at 550, other than sensor issues with the 95 and one structure oil leak they were bullet proof. 👍

Love yer videos...enjoy the technical approach and solid technical information.

Love your presentation and no nonsense, easy to understand style. You have the voice tone and pace down perfectly and your knowledge is impressive. I personally prefer linger videos- but that's not a critique. Thanks for taking the time to do these.

Adept Ape I really appreciate your effort God bless you, I have a c15 generator that just started bringing blue smoke

Always very interesting Josh thanks for sharing 👍🇦🇺👀

Awesome video, very informative. I love learning from you and also my small local shop here at home.. small, family run business and the owner has been working on Cat motors for over 30 years now. I can never get enough knowledge and I learn something new every day! Would you ever consider doing a "common failures" video on the C-12? That's what's in my truck. My next truck will have a big Cat, but until then, I love my C-12. Pulls great for what it is and I do the maintenance on it to the best of my abilities, running good oil, overhead adjustment every year, etc., etc. I've heard they like to flatten camshaft lobes if they aren't maintained properly, not sure if that's true or not. Either way, keep on keepin' on man! Thanks again!

Very informative. Thanks Josh.

Thanks for the video. The explanations and causes along with details that you explain in your vids are spot on. Learned a lot from your vids and have done a lot of work on my 99 3406e 2ws. If it wasn't for your vids, I don't think I would have tried alot of the work I did myself. Thanks again n keep em coming..

Your a good teacher, thanks for sharing your knowledge

Even with these issues, it’s still a crying shame these engines aren’t offered in on Highway trucks anymore..

Thanks for your knowledge adept ape hopefully one day i can have that experience and knowledge on my belt. thanks again

Your video is a blessing to my carrier

Thank you for sharing !!!

Your bad ass thanks for take my time for us!

you have so much knowledge, wow

Great video. Thank you for your info.

Great video as always... My 3406E 1LW still strong after 1.1 million miles Oil cooler,turbo and few leaks but still pulling like a train... I try to learn from you and I do everything I can on my truck to save some money... I did the overhead by my self just by watching your videos... Thanks from Costa Rica

A well presented video. I had a 5EK in a '96 Marmon. Trouble spots included the following: 1. Major oil leak when the oil pan cracked at the transition between the front half and the front wall of the deep sump. This was concealed by the sound damping shield, which was subsequently discarded when Cat did the warranty work on the pan. A noticeable increase in cab noise with the shield removed. 2. Protective sleeve on the front engine harness wore through where it was routed around a sharp edge of the head casting above the air compressor. I had taken it in several times for intermittent fault codes, and finally discovered the damage to the harness on the side of the road. Warranty repaired. 3. Major turbo failure when an insulator sleeve inside one exhaust port fractured. This resulted from the sharp edge of the counterbore on the manifold mating side of the head casting wearing a notch into the formed radius of the sleeve. A couple of the other sleeves were similarly affected, and near failure themselves. Fortunately, this occurred around 30 days before my warranty expired. The $15k repair bill would've sunk me! While this engine was a fairly reliable workhorse, mostly hauling heavy loads in the Pacific Northwest, I was always a little nervous about its copious blow-by. It kept the chassis well-oiled and free of rust. Fortunately I was not visited by any of the demons in your video! Thanks for the detailed insights.

Right on Professor once again word's all Cat owners SHOULD KNOW even of u don't twist ur on bolts this information is priceless as to keep from being ripped off @ repair shop .Nice work Josh really appreciate the time / effort u put into these videos .

I agree with all you said! Found a set screw from jake housing in oil pan during service on C15. Pulled covers and found jake housing cracked in half right beside bolts like you said. I have a 3406C in 96 Peterbilt now. [For Sale BTW]. I have small oil leaks on pan gasket. Other than that i can't complain much. I floated valves in September 2016, backroads of WV, 9% grade, jakes not working. Didn't realize what happened but it stayed together until February 2017 when valves melted into #3 piston. New head and cylinder pack. No problems since. Thx for the videos

I’m bidding on a 2003 pete 379 sleeper with 3406e , blowing white smoke. Assuming it’s the HG and hopefully not needing new liners and counterbores. I’m buying the truck to use as my RV puller. I’m a diy diesel nut. Self taught. I’ve rebuilt smaller Cummins (isb 5.9s/6.7s/ duramax 6.6s, 7.6 dt466, 3126 baby cats), want to thank you for the great videos and information you provide!

Hi, good video like always good job, sad not see in the new trucks any more, thank you...

Another great video.. thanks!

Josh Good afternoon Thank You so much for this video It makes a lot of sense. This COVID issue has been painful Your video help me to keep my mind easy on this time Thank You

Thank you very much, for all this information!!!

Great video thank you

extremely interesting....many thanks

You have knowledge and thank you sharing with us.you are a great man 👍

I've owned 1 cat but drove many others. Hands down if taken care of these are my favorite engine.😍😍😍

Josh IPD has solved the liner walking issue i have hard running cattle haulers using their new sleeves and pistons over 1 million miles and still going strong and they run fast n hard.enjoy your experience thanks.

Keep up the good work bro

I have rebuilt many 3406B,C,E and C15,C16 and I have never seen one leak under the spacer plate gasket ever! But just the other day a buddy of my buys a Pete out of Cali, with a "MBN bridge C15" cat. And there it is, the first ever one I have seen leaking under the spacer plate gasket. Luckily that night @theadeptape loads a video about common problems, and there it is... Thanks Josh for your knowledge and videos! The other thing you could add to the video was exhaust manifold sections on a twin turbo ACCERT. I did a bunch of those. P.S. The C13 motors (after the liner update) are one of the most under rated engines. You can compare them directly to a B model as far as HP and Torque, but sipping on fuel in economy. 👍👍

Ok. Thanks once again for your videos. I'm kinda confused with Problem#1 and #3. So they must go together right? A gasket and the plate gasket.

Driving a 2000 long nose pete just under 53000 hours on an all original c15 just started to have the head gasket issue awesome engine

Good job bro your every video is usefull In my work ❤️ please make electrical work of generator in new video please with programming

Agreed. We replace it everytime we pull the head. Expensive yes. After all, it's not a 318. Again agreed. They break and if you're lucky it makes a hell of a racket til you get to a safe haven. Thank you for sharing your knowledge. Nice to meet you finally sir if you actually read this. Oh wait. Head gaskets have got my ass chewed more than once. 2 heads once. I heard, "we'll not do this again" followed by the you ain't watching your gages. Oil temp too

Great videos.!

I’ve found Loctite 515 or 518 is a good solution for the spacer plate issue, as it is an anaerobic sealant and “bonds” the metal. Rocker shaft and rocker arm problems are compounded by Jake brake use. I don’t have those Jake problems on my 3408 as it has the CAT hydraulic Brakesaver. Heavy, and plenty of pipes and the control valve which make it a bastard to get the oil pan off, but the engine has lasted for tens of thousands of hours.

Seems remarkably similar to Cummins (BC 3 & 4)on the gasket/liner issue, though I never had a catstrophic failure. Had bubbling and all, but no real failures.

I had 1.3 mil on my C15 before I inframed it and it could have kept going but I didn't want to push it much harder with our heavy loads of 106,000. After the inframe the metal gasket did start leaking oil and the mechanic had to go back in and permatex it which solved the oil leak all the way around the block. Use to break rocker arms on this MBN but I stopped engine braking above 1800rpm and haven't had a problem since. I have three kenworths all with C15s, two acerts and one single turbo. I'm a diehard cat guy and I've ran them all my life and they're just a damn good engine! TA1693, 3406B,E , C15.

I was assigned a 95 FLD-120 with 300,000 miles on it in 98 with a 3406E 425 horse Cat. I have no idea what repairs were done on this engine before then. All I know is that I drove this tractor until 2010. It never left me on the side of the road ever. The company retired this tractor out from under me with 1,045,000 miles on it when a rocker arm broke. I'd be happily driving that old Freightshaker today if they'd fixed it.

Woo new vid! Could you do another video like this on the C10 and C12? (I can't remember I'm about to go look if you've already done so) even so do another one even if you have lol. I can always count on you to pop up with a new video on a topic that I've recently been wondering about. I've seriously been wondering what the different known problems of each cat engine were. Keep up the good work!

Thanks again

This is a useful RU-vid video. Not just a silly blog like most new videos are

My first CAT experience was with a C15. it was in a 2001 Peterbilt 379 and it had just shy of 1.1 Million miles on the clock. And it was hauling 132,000lbs gross everyday in hot weather. It was a great experience. Never had a problem with it. However I have been hearing about the problems with head gaskets at around 800,000 Miles. I want to buy my own Peterbilt 379 with a C15 or C15 ACERT perhaps, but don't know if I should go with Detroit 60 for reliability. The truck I currently Drive is a 389 with a PACCAR MX13 with about 347,000 miles on it. I have to change the Crankcase Filter on it this week. Last month I dropped a Driveshaft on it. And I had a trans cooling line leak. all within the space of 6 weeks. It hauls heavy also, pulls when she needs to. But I feel I am overworking it. I would expect these kinds of problems to occur a lot later at around 600 -800k miles. I am scratching my head as to which motor to haul with on heavier spec up to 132,000lbs.

Another great video! Looking forward to class #3 of Diesel 101.

Great video, all the problems you talk about only happen with truck engines, is your shop many trucks??

I think the counter bore is some of the problems my buddies have had. And I’m having that rocker arm issue NOW

Was working at a farm and their C15 Western star just had head gasket done. Another local farmer pulls in with his truck pulls in freaking out with his truck boiling over trying to get some water. Opens the hood and there's a 3406!

Mr. Adept, what is an estimated cost to replace spacer plate gasket on Cat 3406e model that is leaking. very informative video as usual as we expect from you. Thank you.

Any time I had to put in inserts under the liners, tried to do them all! the stainless steal helps to dissipate the heat between the liner and cylinder block, ever notice it is right where the valves are close to the liners! Their opening and closing heats and cools the liner causing movement of the liner on the cylinder block, very small but over time it adds up! Seen this on all the engines, I use to do the insert jobs in the field and shop for years! Next time you pull the liners compare where the valves are to the wear area! Did the filler band do more harm than good, it moved the coolant down the liner about 3/8 of an inch from the liner flange, just a thought?

Enjoyed that thanks

Very good vid bud!! 👍🏽👍🏽

Thank you

The issues i had with them, were broken exhaust studs, broken injector rockers, cam, hand pump, injector barrells. In the early 2000s.

Great videos and excellent information. I'm looking at a 2008 Country Coach with a C15 50000 miles. It seems to run great and has a lot of power when driving. When returning from a test drive there is oil coming out of the dipstick tube. Any ideas on this? Is there a crankcase vent or filter that may be plugged? Thanks in advance, Dave

Excellent

I've driven 2 of those and the first time I see is that gasket leak.

We work mostly on local and vocational trucks. The biggest problem we see with them are the liner O-Rings leaking coolant into the oil. Mostly seems to be older but low mileage trucks. How well the coolant has been tested/conditioned is kinda unknown. They are mostly construction trucks, so,,,,,,,,,,,,,,,

They are available we just put two into kits. Ordered directly from Butler

I’m Dealing with the liner issue & bubbling pressure gasses in coolant right now as we speak

Hey bro i like your videos I’m been seeing it for quite some time. Nice information. I have a 2005 peterbilt c15 mxs i can see that problem coming up, What oil brand will be good for this engine? I try delo 400 and rotella i just put in Mystik tj8 15/50 what do you think?

Great video 📹 Thank you for Sharing the faults with these engines Australia 🌏

The greatest engine ever made I hade some 6NZ at 550 HP. My only complaint was camshafts every one of them hade a camshaft go out do to a cam follower failure at one time or another. All fails be for the end of the warranty thankfully. All ran over a million mills. I wish I could by trucks with motor to day.

Hi Josh. I hope you will continue in your searies of videos for beginners. Since you last video, I have been out on a farm working for a mate to remove and exchange a V8 petrol engine for a 6cylinder perkins in a 1974 C1800 Butterbox International twinn steer tipper which has twinn sticks. It's been great for the confidence. Cheers Adrian. Emerald Queensland Australia

You are pretty knowledgeable, so which engine would you look for in a trk?

Nice video

This reminds me of the 02 land Rover discovery that was put into production with known slipping cylinder sleeves.

Good information.. Im a 60 Series guy 😁

I cant even Fathom the knowledge it takes to DIAGNOSE much less BUILD these motors..GREAT VIDEOS..LONG LIVE DIESEL!!!

Thankyou

Derek, that's not two mufflers. Front thing is a muffler, rear thing is a resonator, to dampen harmonic vibrations. Lots of small touches in this car to keep it quiet and smooth, like constant velocity joints in the driveshaft too, looks like two u-joints back to back with a centering ball joint between them.

Just curious . How do the Similar Cummins and Detroits compare on these issues . I have driven all three in this Category and have some ideas of my own . I would like to hear YOUR ideas on these 15 litre Engines .

good jobs

Cat has a fix for the spacer plate oil leak, it comes in the head gasket set now. Had mine fixed.

Forgot one, the oil return from the head to the block. The epoxy fix. I still thick it is the best engine Cat ever made Had a "b" model and an "e" model. The "c" well not so much

Good videos have picked up on a few little tricks with these cats from you thanks for that,can i ask what is the likelihood of an ECU powering up after being unplugged for 5 years cheers from australia.

Also another issue with that engine. The coolant sensor by the back of the water pump. Diverter valve on ACERT engines.

Very nice video. Just a regular question. How much carbon deposits are on the valves on those huge engines? Does carbon cleaning additives actually work?

Worked for Cat Reman almost 20 years now. You know your shit buddy

Hi i was wondering if you’ve ever ran in to this? I start truck in the morning when it is cold, it starts out at 600 RPM, than air pressure reaches 60 psi and goes up to 700 and never returns to ideal. I was wondering if a temp sensor controls this or could it be my TPI on the computer it is saying it is at a 3, should that be at 0 at ideal? Thank you for your Chanel it is so useful and really enjoy watching what you do!!

Hey Adept! I have a cat c7 on a generator. Wont start. Changed ecu, ran for 1 hour then stopped again. Coukd it be the ecu? Can the IAPCV injectioan actuator vve be replaced if faulty?

Do you like the minus 3 spacers if they get you the protrusion you want vs the shims ?

Is it possible to negate the rocker shaft problem by re-tensioning the bolts whenever you run the overheads?

I drive a trusty ole 96 Pete with the 3406E block set at 600 h.p. a sweet baby !!!!

The rocker shaft wear is a bigger problem in engine brake engines. Construction and gen set engines don't show that much wear.

I use cats thinner spacer plate and shoot for 12-13 thousands protrusion. Yes I know........its a sheet of paper extra.....its fine....its all about cylinder seal, why not add a little pressure in the spot that needs it.... I then use coppercoat on both gaskets, takes up 3 thousands and it seals it. New bolts every time. Make sure head is flat. 600hp motors lots of miles no head gasket failures or even leaks for that matter..........haven't had many rocker arm problems, but this fixes two of your issues with a cat. Permanently....

I too have had that liner problem an it got expensive to fix... I couldn't at the time and had the spare parts truck powered by cummins and it was a low miles till accident made it parts. I kinda stayed away from cat because of the repair costs and my own lack of knowledge to fix myself. I saw my head gasket what it looked like and they told me a price to fix..... I ask them how much they would give me for it and we decided they should own it. I missed the torque right away

Good info. Are the c10 any good?

Should've seen this video last year when i still had a warranty.

I am really glad I sold my truck

A Cat c15 acert; I have a question for ya. What would replacing the front cover & plate Gasket cost & usual # of hrs to do job be?

Just the other day i had to fix broken rocker shaft bolts on an acert, not the first one and won’t be the last one!

Where is the garage you work out of Josh?

Couldn't you use the copper head gasket spray on like what you use on old flat heads

My 6nz will not start has plenty of fuel pressure and will run on ether but will not crank I'm now thinking its a electric problem can u help me?

My fix for the oil leak on the spacer plate was to pressure was it once a week and keep a can of Cat yellow paint handy. Then a lot of prayer when I went through the Bannock scales.

Long life to the yellow cat !