Sulzer RTA 58T-B main bearing failures and excessive vibrations

[xltsport]

For the past three years we have been experiencing repeated failures of the main bearings on our two 5 RTA 58T-B engines, particularly in way of Main Brg #5(the middle bearing).

Does anyone else have such experiences and if so what have they found to be the problem/solution.

On our vessels we have carried out checks of shafting alignment, including laser checks, bearing jack up loadings, fitting of offset bearings to more evenly spread the static loads and still the problem continues, particularly on one vessel.
We have had consultants do metallurgical analysis of the failed bearings and tribology specialists calculate the oil film thicknesses and loadings.

 

[Focht3]

Have you posted this question in one of the automotive fora? There are some pretty fine engineers there that can probably help you.

 

[MP21]

XLTSport,
What does Sulzer have to say? I know there a a few parts of their engines they are still trying to iron out. I'm not sure if the stuffing box blow by issues have been resolved. I'd like to know what you find , if you don't mind, from your other sources, on both your topics.
Thanks,
Matt
There are very few automotive engineers that can fathom crawling aound inside an engine I think this is posted in the right forum.

 

[Focht3]

Whatever. But some of those guys have been tearing down and rebuilding engines of all flavors for decades, including very large diesels. You never know where the right answer may come from -

 

[xltsport]

Sulzer have been very coy as they have now fallen from being a major marine engine builder of the past to merely being the designer and licensor, depending upon their licensees to provide their income. It's a case of the tail wagging the dog and the customer gets shafted in the meantime.

 

[MP21]

I do remember with the stuffing box issue Sulzer seemed to takre any suggestions they could get and passed them a long for others to try. I wonder if any of the repair shops can help. Depending on the coast you're on CMD seems to have a lot of experience with different Sulzers they may be able to help tell what other companies are doing. I don't mean to advertise.

 

[romke]

what exactly happens to the bearing? failures can usually be attributed to one or more causes based on how the bearing damage looks. can you be somewhat more specif about the type of failure?

 

[raj71]

can u give some more details of the problem

(a) some engine specs / where i can get them
(b) the detail of the rest of your shafting including couplings
(c) oil flow to middle bearing / type of oil
(d) material of the bearing

right
raj

 

[BillSalvage]

It seems strange that you would have problems with the same bearing unless it's due to alignment.

Have you checked the main bearing bolts themselves, they may be stretched. On one engine we fitted strain gauges and found that the main bearing bolts of one main bearing lost their tension over a relatively short period of time.

 

[fubar]

Check your #5 cap and saddle "outside" dimentions for distortion. A quick check would be to try and fit a 0.0015 feeler btwn the cap and saddle parting lines. If you find a problem at 5 you should check both adjacent brgs etc..etc.
If you don't have or OEM won't give you the spec, you can reference a good brg cap/saddle. Most OEM bore spec's are in the + or -: 0.0005 to 0.001 range depending on the bore dia.
When brgs fail the heat generated pulls the sides of the cap/saddle in. When you replace the failed brgs, the new brgs sit higher than the rest of the chrank line. This condition places a higher load on the subj brg and also reduces its ability to transfer heat. This does not present a problem on every brg failure as the distortion varies with the amount of heat that is developed. However I have found this to be true in most unexplained, repetitive failure's I been involved with. GOOD LUCK!

 

[Paramagurubaran]

Dear xltsport,
The problem projected seems to be of a peculiar nature. Is it like, only the #5 (middle main bearing) which is getting damaged or other main bearings also-may be to a comparitively lesser extent. What is the duration after renewal when the damage is being noticed & the nature of damage(whether damage is at the edges)? What do the alignment checks indicate? Was hardness of the #5 journal checked? How was its surface condition/how are the remaining journals? How about the L.O. analysis reports? Was the entire crank case oil renewed, after thoroughly cleaning the sump, before the last bearing renewal? How is the engine power balance? Atleast the above information are required to assesss the cause of the main bearing failure.
One cause, which I could suspect with the information available, is that the crank shaft is flexing more than the permissible limits, during operation.
Thanks
Guru

 

[taylorg]

xltsport,

You mentioned that consultants and tribology specialists undertook some analysis - what were their findings? Did they not pinpoint the cause?
I take it you had to grind out the main bearing housings and fit oversize shells after the first failures?

 

[fubar]

Quick easy check if you can, take a set of crankshaft deflection readings. Then check main brg journal run outs. If you have deflection with no run out its a bearing/bore deviation. If you have good deflection with high run out you have a bend/whip in your crank shaft. NO DEFLECTION & NO RUN OUT = NO PROBLEM!

 

[nodnerb]

Hi,

Did anyone ever find out what was causing this persistent problem?

Cheers

Nodnerb

 

[chief]

i previously had problems with main bearing failures on an engine. All the usual checks and analysis did not solve the problem.
The eventual conclusion and solution was external to the engine. Check the stiffeners in the Double bottoms below your engine, ensure the base is sufficiently rigid to prevent flexing of the crankshaft when the engine is running.
Obviously this may not be the problem, but it does need to be eliminated.
Regards
Diesel DAN

 

[chief]

i should also mention that the engine holding down bolts should be torque checked on a regular basis and check the engine mountings.
The engine vibration damper is another suspect in these cases. Check for broken springs.
DIESEL DAN

 

[cjw81]

You haven't given much info on the exact nature of the failure, but if the outer race looks like the spacing that appears on a typical stainless steel hose clamp, eg. evenly spaced holes on the outer surface of the race, you may be getting an electrolysis or harmonic failure. Teh grease then migrates to these holes and you loose lubrication to the bearing even though you have plenty of grease.Try making a small copper brush that will stay in contact with the outer race of the bearing while it is rotating. Ground this copper brush with a conductor (flexible wire). This will conduct stray currents away from the outer bearing race. This is a major problem with variable frequency drives that we run into with HVAC systems and it is cheap effective fix that just happens to work well with a very frustrating problem.

 

[enginebob]

Is there any more information on this? I have some ideas.

 

[GreenRichie]

A recent case I was involved with highlighted the degree of flexing in the engine bed plate between loaded and ballast conditions. It may be wise to investigate the allignment in all the operating conditions and when the engine is "hot". Lloyds Register have a Technical Investigations Department who are specialists at this kind of investigation and can be contacted at csg@lr.org. If I remember the person to ask for is Peter Filcek but that was a couple of years ago.

Good luck

Richie

 

[nodnerb]

Hi,

I think sadly that XLTSPORT is like too many users of online BBS. Post away for a few days get some answers then vanish till ya need help next time.

Nodnerb2