2500 Hours On Volvo AD31 Diesel - Is It Done?

[GPBoatNut]

I am considering buying a boat with a Voloa AD31 diesel I/O that has 2500 hours on it. I plan to re-power it. But just curious what the general life span is for this motor? Just a general range of hours. I understand it can very radically depending on how it was used and maintained.

Thanks

 

[Chris_d]

All depends on how well it's been looked after, I would think 10000 hrs for the basic engine but a lot of ancillaries maybe need changing along the way. Did see an ex Met police Targa 30 advertised with 25000hrs on its AD41's which are basically the same as AD31's with two more cylinders, but that would have been pampered.

 

[vandy]

There's a fishing boat with one of those next to my berth - the engine hours are over 12000! and I doubt if the owner looks after them that well as the oil change is never done earlier than 300hrs intervals - he has a point, he does sometimes 50hrs/week so can't afford to change oil every month!!

Still going strong!

 

[GPBoatNut]

Thanks all. I have read that the real average lifespan on a pleasure boat diesel is 1500 hours. And that short life is mostly do to lack of regular use and so corrosion sets in. Apparently an old boat with a diesel that has low hours is something to be wary of.

The boat has a 290 drive leg with dual prop with some corrosion evident.

If I had the motor and drive rebuilt what is the ballpark price of the costs if I pull it and install it myself?

 

[TQA]

If it starts easily from cold, maintains normal oil pressure and does not emit much smoke then it is probably OK for at least another 2500 hours.

 

[A_8]

Based on other threads on this forum and service etc done as per schedule I think I concluded that the VP type KAD or AD engines should run up to around 3000h (typically maybe less for the kad 300 and more for the ad41/31) before needing to be opened up or refurbish after which the engine should give you another 3000h.
Engine life is more based on the amount of diesel used/consumed so hours are not the best metric to use. Engine running heavy equals more diesel used per hour so you need to understand that better before making an assessment.

 

[CX54WEK]

Have the 2500 hours been run on the river?

River boats tend to rack up more hours as they are travelling much slower over a given distance. A 20 mile trip on the coast might take 1 hour, on the river this could be 5 hours or more.

 

[Firefly625]

Thanks all. I have read that the real average lifespan on a pleasure boat diesel is 1500 hours. And that short life is mostly do to lack of regular use and so corrosion sets in. Apparently an old boat with a diesel that has low hours is something to be wary of.

The boat has a 290 drive leg with dual prop with some corrosion evident.

If I had the motor and drive rebuilt what is the ballpark price of the costs if I pull it and install it myself?

as others have said a well maintained engine will last far longer than 1500hrs, people that have told you they last 1500 hours perhaps want you to buy a new engine from them?.

I would have thought 10000hrs more realistic for one of those. Does the engine not run as just wondering why you are asking about a rebuild, may well be a far more easy fix than a strip down and rebuild as after 1500 hrs that engine should be still going strong unless its has been abused.

However outdrives.....don't get me started, those are busy fizzing away the moment the boat is launched, seals, hoses, rams, etc etc have to be constantly checked and replaced to ensure you don't have any large bills, you certainly add another lump on your annual maintenance costs with an outdrive.

 

[No Regrets]

In truck talk, at an average of 30mph, every 1000 hours is the equivelant of 30,000 miles.

Truck engines will do in excess of 500,000 miles, so 15-20,000 hours would be expected from the basic engine internals of a boat...

That is assuming it's not been overheated, poorly serviced, drowned, misused....which is most of them... :ambivalence:

My Volvo TAMD40b's have 2300 hours, and run very sweetly, with the usual puff of smoke on a cold start and a bit when being thrashed, but most likely tired injectors or turbo. No oil use whatsoever

 

[Trundlebug]

My twin MD31A's have just clocked up 2000 hours, after 27 years.

They're still in as new mechanical condition, verified by a Volvo engineer's report when we purchased 9 years ago.
I'm expecting that at about 25,000 hrs they could be considered a bit tired.
They have always had an annual oil change, and will continue to do so.