QSB 5.9 305 engine rebuilding

[Matthew]

Hello guys.

Have an question regarding thi engine,it has over 10 000 hours,and is starting to burn oil,around 1L on 50hours,that was latest info from skipper,not sure which rpm’s nor weather condition.

Does those engine have wet liners? Wanting to know some infos regarding rebuilding it,cylinder head,injectors,crankshaft,camshaft,is enough to do just liners with pistons,or better everything?

Engine still runs strong,pulls good,starts right away,but oil consumption and blowby is noticeable.

Thank you very much.

Topic

[Matthew]

I know Tony,have read many of your articles,seen all of those photos,and also have somewhat of experience.

This particular boat i am not working on it,just seing that engineer once and awhile in shipyard now,or marina,and then i am just interested to know how they are progressing.

Before i was working on that boat with former company where i was,but since i moved on with my small bussines,that engineer decide to stick with them.

[Tony Athens]

“change siphon breaker and check exhaust system completely”

Just changing the siphon break will accomplish nothing.. It’s all about the design on the total system….Hopefully your “engineer” has the right experience to to do this.

Don’t forget, all the pictures you “see” about setting up below water line installs in the Vetus , Northern Lights, Centek , etc. catalogs were done by “engineers”. Yet 100’s +++ of installs have lost engines relying on these designs all based on a “siphon break”.

[Matthew]

Hello Tony.

Thank you for pictures and explanation. I am not working on other boat,but i did told that engineer that he change syphon breaker and check exhaust system completely.

He is already waiting for new long block,it was last one here in Europe,not sure exactly in which country it is,but is coming to him as we speak.

[Tony Athens]

Genuine Cummins QSB 5.9 Long Block

A genuine Cummins QSB 5.9 long block will come like these pics less the CR pump, bell housing and starter ( we had already swapped those over).

You do have to remove the front cover to install the CR fuel pump & drive gear.

Hope you redo the exhaust–Never, and I mean never rely on a typical anti-siphon valve set-up to protect your engine.. Re-design the system accordingly

[Matthew]

Hello Tony,thanks for reply.

I did install your Enviroment system on it,before engine did have Airsep system,which skipper didn’t like it so much,filter insert is expensive in Europe,and till recently only option was to order it directly from the States,not so fast and economical option.

I will ask him to measure fuel-oil consumption to follow it more acurately,but like always,in pleasure yachts 10 000 hours is a lot,and owner thinks also that is time to replace the engine.

Or me as trusted mechanic,need to guarantee them that engine is still safe to use,which i don’t want to do it.

As we speak,other boat did remove their QSB 355,seawater ingestion due faulty syphone breaker,and they order it long block from Cummins. That term,long block,what does it mean exactly?

Just engine block with pistons,cam and crankshaft,or something else?

[Tony Athens]

High Hour QSB 5.9

All B series engines have Parent Bore blocks, meaning they can be bored oversize……… .25 & .50 MM oversize is common. Never bore & dry sleeve the marine B blocks. Genuine Cummins long block are also an option.

Blow-by can be mitigated with a proper CCV system to where you don’t really have to deal with it…If you have a foot of height above the engines valve cover, , then it’s real easy to contain blow-by to where it’s out of sight & out of mind………………

Oil consumption should be measured against fuel consumption, meaning how much oil do you consume per 100 gallons of fuel used. .25% would be normal for a high hour engine, with .5% is at the upper limit to where you might consider a “top end”.. But if the engine starts easy when cold, then burning oil at 1 gallon per 100 gallows of fuel used ( 1%) may still be a less expensive option…Think of it a pricey “fuel”…. We have seen this engine go over 30,000 hours and still be decent daily use shape.

[Author]

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