Power Generation: Product Operation and Maintenance

[egrant9]

Hello all, I work at a remote site in northern Canada and we are running 9 3616's and 2 3612's on diesel. We conduct our own rebuilds on these units here onsite, without dealer support. We have run into issues with intake valves, 4P-2854 specifically. We rebuild our own heads here as well, as we have had problems with Reman heads.

In the last 36 hours we have had 2 intake valve failures on separate overhauled engines. We have become aware that Caterpillar has started to use 4 exhaust valves (9Y-6232 valve, 160-5770 seat) and seats in all 4 locations in their Reman heads. I have been unable to locate any literature regarding this change. Valve failure was 8000 hours (since overhaul) on the first engine and the second one at 4000 hours (since overhaul). We have taken steps to run the valve a little cooler to see if this rectifies the problem. Both valves that have failed have had perfect contact patches (full face) and have failed in an identical manner both times. Inlet air temp is running at 60-65 degrees C, we are running misting pumps on all engines, turbo boost is at 30-35 psi. Load typically is 3.8-4.2 MW. Avg. cylinder temp is 400-420 degrees C.

Does anybody out there have any similar issues and if so what steps have you taken to mitigate them? Is there any literature out there that indicates the reasons for changing over to 4 exhaust valves?

[egrant9]

Just a quick update on our valve issue. Turns out the four exhaust valve heads are for cyclic load applications. Has anyone tried using these heads on non-cyclic applications? Is there an advantage, ie no broken valves? It seems that the exhaust valves are much tougher, as we have never had on fail. Any help is greatly appreciated. Thanks.

[egrant9]

Really? Come on guys. No one has anything for us?

[dave10010]

While the exhaust valve (9Y6232) is used for both intake and exhaust, the intake seat is 1605769 and exhaust seat is 1605770. These seats are pre-machined.

[egrant9]

Thanks for the reply.

When we install new seats we never trust that valve will hit the seat dead center. In 64 heads we have rebuilt we have never had one be dead on, very close but doesn't meet our standards. We ALWAYS machine the seats to the guide as we have the same tool (out of Germany) that CAT does.

We are now running our intake valves a little cooler and have opened up our misting pumps a bit. This seems to have resolved the problem for now. In the future we plan on building all the heads to cyclic load application specs, for extra reliability. We are doing a set right now.

Also we have overhauled 3 engines with the new pistons, rings and liners and we will let you know our thoughts on that on Monday.

[egrant9]

Hey guys, no help on the valve stuff. Maybe you can help us out with this one.

Pistons, newest generation. We have installed the newest pistons (314-2700) with new liners (179-3167) and the corresponding ring pack (314-2691, 314-2692, 314-2693). We found that it was bad idea to reuse the liners due to cracking in the flange area. We now install new ones as a matter of course. We have installed these pistons in 3 3616's (diesel), 4 of our engines have them from the factory and 2 3612's have them from dealer rebuilt. We have found higher than expected oil consumption (MDY-40 Imperial oil).  We almost needed a tanker truck connected to the engine to keep up.

Our question is why is the second ring end gap almost double what the top ring and oil control ring gap is?

Also, what is the story behind the 4 big slots machined in the skirt up to the bottom of the oil ring groove?

Can anybody shed some light on this one?

[njc1979]

Suggestion for you to get some data that may assist- contact your local dealer with all of your inquiry and have them put a request into CAT LEC which is the product group that can better assist you.  3600s are a different breed of engine and each can be a bit different based on sales design and such.  Give them as much trend data as possible hours, records of repairs, oil samples, etc.  Load them with data.  

The CAT 3600 engineers can then possibly trend or provide any updates with your units.  Use your dealer to your benefit.  Ask the dealer technical coordinator to put the inquiry in to the CAT DSN.  It will be logged, assigned, and categorized to the 3600 folks.  This position is responsible for your type of inquiries.

This probably isnt what you want to hear but it is a sound way to get your questions answered.  Moreover, the DSN is designed to better assist with specific product health/quality/application issues.  Keep in mind your question may need more review depending on your engine characteristics and application/operation.

Also, not ever area is plentiful with 3600 product therefore your inquiries may take a little bit longer for those with your experiences or needs to answer back.  The CAT dealer is the quickest more reliable medium than message board that is voluntary.  DSN applications are assigned priority and are timely.

Also, do you have all of the ENGINE NEWS and Services letters for your serial numbers?  (Give your dealer your serial numbers and have them review these and get you copies if you need them.) There were past articles in both relating to piston and liner usage guidelines with updated part numbers, etc..  I may have them and if I can find them I will upload to you.   

[egrant9]

Thanks for the reply njc1979.

I believe that we have all the current info from Cat regarding this matter. I also have access to SIS, which I believe is as current as it gets. However, I hate to say this, but our dealer has been no help on this matter. We have posed these questions to them several times, as well as other issues we have had, and have not recieved any useful information or support. That is why I have resorted to posting on this site. I am hoping to hear from some people who run/maintain these engines in the field and have had some "front line" experience on them so to speak.

We have a very sophisticated engine monitoring system in place on these units and every conceivable datapoint is collected, measured and analyzed. We have been monitoring things like oil consumption for almost ten years now, before and after rebuilds.

As far as the piston issue goes, I have posed the question to the manufacturer of the pistons themselves. I hope to hear back from them soon. I will post any info I can.

Thank you.

[pervin]

Egrant9,

Didn't you mention that you increased the oil flow to the piston cooling misters? Is this carrying more oil out with the exhaust?

Just a thought on the oil issues.

[njc1979]

If your dealer is not responding then you should contact this site's admin which is a CAT employee and instruct them who you are dealing with.  3600s tend to get attention from the factory.  Your dealer should be following through.  Also, you could attempt to contact another dealer close to you and explain the scenario- either way let CAT know so they can correct any issues.