How long do you think is too much for an engine to be NOT used?

[MapisM]

I mean, while an engine is not used, there are obviously some valve springs which stay compressed - and possibly other parts which can suffer due to a static position (like bearings, maybe?).
Now, I understand it's a bit of a "how long is a piece of string" question, but what would you guys think could be a worrying timeframe, after which some parts of an engine left completely unused could be damaged - and which ones?
Fwiw, the engines for which I thought to ask your views have not been used for 4 years, if not more...

 

[alt]

Whatever about not being used... what about preventative lay-up maintenance? ie. flushed out, engine room (and boat) cleaned out etc.

It's a thing I take for granted on fresh water, but recently viewed a boat (for a friend) laid up in a salt water (air?!) environment... the engine room was in a terrible state.

 

[Latestarter1]

I purchased some crated Cummins 732 motors ex Algerian Army which had stood crated for 30 years.

Properly inhibited but not expected to be effective for that long, no failures reported and one engine was removed from the crate bolted on to a genny, nothing else and breezed past 20,000 hours.

Good quality valve springs if they have passed the nitrogen migration phase before winding (sometimes not the case today) stand compression for long long periods without taking a set.

 

[oldgit]

Depends..
Surely when thinking about buying such a boat then its all down to how much risk you are prepared to take and the asking price.
There was a 1989 Princess 330 down in Spain with asking price of £15k,one engine had seized, would that have been worth buying or not ?, probably if you were prepared to take a risk.

 

[Momac]

I think you could anticipate a potential for issues but they may not all be apparent until the engines have been run a while.
I would also be concerned about the fuel in the tanks and corrosion of the tanks due to any water in constant contact with the tank bottom.

 

[MapisM]

I purchased some crated Cummins 732 motors ex Algerian Army which had stood crated for 30 years.

Properly inhibited but not expected to be effective for that long, no failures reported and one engine was removed from the crate bolted on to a genny, nothing else and breezed past 20,000 hours.

Good quality valve springs if they have passed the nitrogen migration phase before winding (sometimes not the case today) stand compression for long long periods without taking a set.

Wow, THIRTY years...?!? That's reassuring!
If I may ask, did you follow any special procedure/check before firing them up? I mean, valves cover removal and check, borescope cylinders inspection, or anything else?

For the records, the engines I'm interested in are early 90s MTU, 183TE92 series.
According to an MTU engineer with 30+ years experience I had a chat with, he would rather have those than brand new modern engines in his boat, unless a much better power to weight ratio is a must (which is something I am totally NOT interested in).
So, I would think/hope that valve springs should fall within your "good quality" criteria.

 

[MapisM]

I would also be concerned about the fuel in the tanks and corrosion of the tanks due to any water in constant contact with the tank bottom.

Yep, plenty of other stuff to check of course - pumps, A/C, fridges... you name it.
My main concern are the engines just because a big problem in even just one of them would defeat the whole purpose of purchasing the thing!

 

[BruceK]

I think it's not how long it's been stored for but in what conditions it's been stored in. Corrosion is the biggest enemy.

 

[Latestarter1]

Wow, THIRTY years...?!? That's reassuring!
If I may ask, did you follow any special procedure/check before firing them up? I mean, valves cover removal and check, borescope cylinders inspection, or anything else?

For the records, the engines I'm interested in are early 90s MTU, 183TE92 series.
According to an MTU engineer with 30+ years experience I had a chat with, he would rather have those than brand new modern engines in his boat, unless a much better power to weight ratio is a must (which is something I am totally NOT interested in).
So, I would think/hope that valve springs should fall within your "good quality" criteria.

No nothing whatsoever, straight out of the crate onto a generator end, re-calibrated PT fuel pump to 1,500 rpm so that was effectively overhauled, pumped main oil rife to 25 psi before cranking an hit the button.

Have a real bee in my bonnet, valve spring manufacturers used to draw valve spring wire and rest it. Spring was only wound after material had settled. No guarantee done with sufficient care in our era of crash bang wallop manufacturing.

 

[Pinnacle]

C'ommon P - open the kimono a bit more. :encouragement:

 

[rogerthebodger]

The only thing I would be concerned about is the rubber seals can harden over time.

My engine had been standing for some years and I started to have oil leaks from the shaft lip seals in the engine and gearbox. I just replaces then all and no more leaks.

 

[MapisM]

pumped main oil rife to 25 psi before cranking

Sounds like a good idea indeed.
But hoping you don't mind a possibly silly question, how do you that in practice...???

 

[MapisM]

C'ommon P - open the kimono a bit more. :encouragement:

LOL, bear with me for a while, P.
By the end of next month, I might post a thread titled something like "Here, I did something silly. Now what?!"...
Or I could have a momentary lapse of reason in the meantime, not sure yet!

 

[MapisM]

The only thing I would be concerned about is the rubber seals can harden over time.

That's a sensible suggestion, but trust me, in the context of the boat I'm considering, the replacement of some seals is the very last of my concerns...
ATM, what I'm worried about is that if even just one of the engines is wrecked, replace or rebuild it would cost twice the price of the whole thing!

 

[rafiki_]

Sounds like a good idea indeed.
But hoping you don't mind a possibly silly question, how do you that in practice...???

Hold your finger on the stop button, and crank the engine till you see the oil pressure register.

 

[MapisM]

Hold your finger on the stop button, and crank the engine till you see the oil pressure register.

Yeah, but is that what LS1 actually meant?
When he said "before cranking", I understood that he pressurized the oil circuit with the engine completely static, and only afterwards he turned it on - hence my question...

PS: coming to think of it, one suggestion of that MTU engineer which I mentioned before is somewhat related to this point.
In fact, he suggested as first check to spin the engine manually for 2 complete turns.
If what LS1 meant is what I understood, wouldn't it be better to pressurize the oil before doing that, even if it isn't a "full" cranking?
And if yes, how? I'm puzzled....

 

[SAMYL]

Four years is not really a long time for an engine to sit unused. Valve springs possibly could be weakened a bit but they will still work ok.

Make sure it turns freely, check oil levels and crank it but don't let it start until the pressure is up.

If all goes well, bring it up to operating temp without revving it too much. Stop and change the oil and check all ancillaries are working ok and also for leaks.

 

[Latestarter1]

Yeah, but is that what LS1 actually meant?
When he said "before cranking", I understood that he pressurized the oil circuit with the engine completely static, and only afterwards he turned it on - hence my question...

PS: coming to think of it, one suggestion of that MTU engineer which I mentioned before is somewhat related to this point.
In fact, he suggested as first check to spin the engine manually for 2 complete turns.
If what LS1 meant is what I understood, wouldn't it be better to pressurize the oil before doing that, even if it isn't a "full" cranking?
And if yes, how? I'm puzzled....

My apologies for not being clear.

My father gave me a 'Ki-gas' fuel priming pump long ago, standard kit on any WW2 aircraft with RR Merlin engine, although mine came Centurion tank which had the Meteor version of the Merlin.

Cummins always have 1/8 NPT or 10 mm straight 'O' ring plug on the main oil rifle on all engine models. My Ki-gas pump has non return valve and you connect it direct into the oil rifle and pump away, by the time you get to 25 psi pumping is hard!

Probably a better way is using a commercial side lever grease gun filled with lubricant, however since the engine room explosion aboard the Cape Town Castle they were banned from ships engine rooms so I stupidly have a blind side about them.

 

[MapisM]

Thanks SAMYL+LS1, all understood.
I will check with the MTU engineer if it's possible to pressurize the oil circuit before even cranking, and surely will not fire them up before allowing pressure to build up, anyway.

Just one doubt about something that guy should do in the next days, i.e. check if the engine turns freely by making two slow full turns: I'm pretty sure that he's NOT thinking to pressurize oil, before doing that.
Now, since those two turns would be the first after a long time, do you think this could make any damage, if done dry?

 

[burgundyben]

Cummins always have 1/8 NPT or 10 mm straight 'O' ring plug on the main oil rifle on all engine models. My Ki-gas pump has non return valve and you connect it direct into the oil rifle and pump away, by the time you get to 25 psi pumping is hard!

But this does create a risk of adding foreign objects into the gallery, bearing life directly correlates to lube hygiene.