Cummins 480 CE problem

How far up the Cummins ladder did you go? Beyond the distributor level, I hope.

420 hours is spit.

Oh, welcome to YF, BTW. Sorry to hear of mechanical problems.

I'm not sure that your logic holds water. Hopefully, the problem is isolated and will not occur on the other engine. If you do some clicking around on the net, you may be able to ascertain if there is a pattern to this event.

My experience has been with Caterpillar and their myriad of problems with the 31 series engines. In that case, persistence paid off.

Thats great news. I'm glad to hear that things are working out!

Pete, I know some years have now passed but I have had what sounds like exactly the same problem with my Sea Ray Cummins starboard engine in late 2010 !! I purchased second hand in virtually new condition a Sea Ray 420 Sedan Bridge Sport Cruiser in New Zealand in Feb 2010 with only 350 running hours on the engine. The sale came complete with a Cummins NZ Ltd engine survey. 9 months later, after very little use and running hours of 380 the Cummins starboard engine broke. After the event (and the repair) the sequence of events was - dropped valve seat, valve jams, piston damaged, wall lining damaged and rocker arm snaps in two ! At the time of the repair by local Cummins service agent there was no explanation of why ! Some months later the service agent calls to say he has seen more of this and not just Cummins. After cooling overheating is now suspected as the casue and blocked after cooler filter could be the cause. Port engine filter inspection recommended. Repair bill was $NZ 20,000 ! I have been in dialogue with Cummins NZ for over 1 year now and they have so far declined to help blaming (after the event) "poor after cooler filter maintenance". I find this very unsatisfactory and quite dissapointing. Even now we have only just reached 400 hours. I am about to engage Sea Ray USA as it has been suggested to me by others that this may in fact be a Cummins engine design fault. My Cummins engines are 6CTA8.3M3 450 HP.

Aftercooler maintenance is directly related to marine age and raw water exposure. Engine hours doesnt mean anything. If properly maintained they will last the life of the engine. My experience has seen that the aftercoolers need to be serviced every three years reagrdless of engine hours if exposed to salt water.

Thanks and agreed re regular maintenance but these valve seats appear to fall out way too easily ? The engine head is water cooled and there is no visible signs of increase in water temp on the gauge. So maybe the exhaust gas is hot but how come the valve seats fall out ??

9 out of 10 valve seat failures resulted from overloading the engine. Overload will cause high cylinder temperatures. Cooling capabilities do not apply to valves and valve seats when higher than rated cylinder temperatures are seen. Can your boat reach rated rpm fully loaded? What condition was your aftercooler in at the time of failure? What condition was your exhaust and turbine housing in at the time of failure? I have more questions but do you have accurate data to answer. These are very important questions and the answers will help determine the cause of failure and I want to help you prevent this from happening again. To fix the failure is only part of the solution. Need to fix the true cause so it will not happen again!

ok but I am not yet convinced it is that simple or in fact should be that easy to lose a valve seat. These ARE Marine Engines afterall !! We have no problem reaching rated rpm but generally cruise at lower - around 2,000 rpm @ about 20-22 knots. Have no hard facts on condition of aftercooler filter at the time of failure as this was not mentioned by Cummins repair agent - neither was it confirmed as cause of failure. It was some months later after other engine failures had been seen that the comment of "check your after cooler filters as this MAY be the cause" came. So repair was done early 2011, boat has been hauled out this week for mtce and this morning I have just received "after cooler filter is half blocked again ! - maybe due to "she is not run enough or the height of the engines in this vessel" !! The intrigue continues and as I say I am not yet convinced this is simply a mtce issue - starting to look like "over" mtce is required to over come more basic engine or boat design failings ??

and exhaust and turbine housings all in mint condition - as is everything else on the boat.

High load conditions with blocked aftercooler will raise cylinder temps. The aftercooler is designed to cool the incomming air. An increase in this air will add to the cylinder temps. Understand your engnies are pleasure duty rated. They make more horsepower than comercial duty and on highway engines. The only difference in this specific cylinder head is the exhaust valves are a better material designed for the higher cylinder temps associated with pleasure duty horsepower ratings.

So I dont believe these engines were really under significant load and you CAN'T bely the fact that these are supposed to be commercially made (in the USA) marine diesel engines fitted into a commercially made boat for exactly this purpose. To me these valve seats appear to come out way too easy !

You do realize that most recreational engines are at fully loaded or are overloaded as installed by the boat manufactures? Maybe not at sea trial with 1/4 fuel and a clean bottom but under normal operating conditions they are.

Well that sounds like a design failure all round ? I want and thought I purchased reliability and quality ?

This has happened to me twice now on two different boats. The last time around I purchased a new head directly from cummins, according to what they told me there was an update to the head design that eliminated this problem. It's been two years and the motor is running fine...

This is sounding like a problem I experienced over 20 years ago on a low hour set of 671 naturals I used to help run. After an autopsy, we determined these low hour exhaust valves and seats developed a tint of rust. Salt air coming up the exhaust plumbing. Once the seat started getting hot under load, this slightly stained area started distorting. Heat transfered to this small area differently than the rest of the valve and seat. Almost suddenly, smoke starts coming out of a 300 hour 671N.
Yep, loose, burnt seats. 100 hours later, the other engine does the same thing.
Low hours can be a problem. Lack of loaded hours is an issue.
Run your boats. Lack of use kills them faster. If you can't use your boats and complain when something breaks, then sell and charter/rent when you have the time.

wow very interesting but you still had to buy the newly designed head ?

I have a Searay 390 MY with CE 480's. built in 2005, less than 1,000 hrs. on engines, all maintenance services are up to date. Starboard Valve seat on #5 cylinder broke off and destroyed cylinder and blades on turbine. Marine surveyor said it was a maintenance issue. I called Cummins for technical assistance and they said that had not heard of this issue writing it off to water in fuel???When the engine failed, I checked engine oil and fuel and saw no indication of water. Another marine surveyor who owns a 2003 MY and another friend who owns a 2004 neither have had issues with valve seat failure but indicate they heard there was a change in the head somewhere between 2004 and 2005. Can anyone verify this?? I find this very strange reading all these posts about the starboard engines seat valve failures. Any advice?