QSM11 engine inspection for purchase

[David Anderson]

Hello.I am looking at a 2002 Sea Ray 48 Sedan tonight and I am trying to do some research as far as things that I should specifically look for around the engines.

I am in Ontario Canada and it is very hard to find Cummins or marine technicians that know diesel marine super well.

I have always done all my own maintenance and like to go the extra mile. Oil samples every year, fresh impellors etc.

Any tips or list of things I should look for would be greatly appreciated.

Topic

[Richard Lynch]

I don’t think it is reasonable for the Sea Ray 480, 500 or 52DB Sedan Bridge with a QSM11 670HP to tune the props enough to get 20GPH at 2100RPM.

[Steve Lewis]

If you really like this boat then you go into the process understanding that with those hours you should look at servicing the cooling circuit. First things first……. When you run the sea trial you will find out how over propped the engine is by plotting the fuel burn as you previously stated. That will lead you/us to some possible conclusions about the manifold health and prop pitch mods.

The cooling circuit service means removing aftercoolers and heat exchangers and having them serviced properly. While those are off the engine(s) you can have the exhaust manifold and gasket assessed. As Rob points out, that last picture is showing the black soot by the manifold so the leak has started. You will not know until things get taken apart for the cooling circuit service if you are looking at just the gasket or if the manifold itself is warped and needs replaced. Parts availability is an issue right now so I would ask your mechanic if those are available.

Getting the fuel burn down to the 20gph @2100rpm spec will be important to keep whatever repairs to that manifold area get done healthy.

So understanding all of that, you can figure out your tolerance for this amount of work and if you are serious about this boat.

I had to go through a similar mental process as the boat my wife and I bought has 2 of the 480CE’s which have their own issues. We chose to go ahead since everything else about the boat was good. We are in the situation where the heads are not available so we are taking things nice and slow and easy until our mechanic can get 2 heads and do the work. Winter layup looks like our reality.

The QSM is a very stout engine. It is the bolt on parts like the manifold and turbo that take the abuse and need looking after.

You have some decisions to make………….

1 user thanked author for this post.

David Anderson

[David Anderson]

Exhaust leak

Is there a way to tell if it is too late to be able to re prop the boat to fix the loading? 1140 hours now

[Rob Schepis]

Your last pic shows that this is going to be an issue:

Propping the Cummins Marine QSM 11 to Prevent Exhaust Issues

[David Anderson]

More pics

I went to get my oil samples tonight before the SAMS survey on Tuesday. I have read through those articles again. Man there is a lot of great info. I plan on documenting the full range of rpm/fuel rate/speed during the sea trial that afternoon.

I have also arranged to have a 25 year diesel mechanic to come on the sea trial with me. Feeling much better having him there.

I also took a few more engine pics.

[Steve Lewis]

You might consider the formal pre-purchase survey first. That might find things with the boat in general that would turn you away. Also the SAMS surveyor might know the reputations of folks for the engine/mechanical inspection……..

My wife and I looked at a couple 480SB’s and ruled them out because of water intrusion in the core of the superstructure, too much to replace on the inside and the hull needed some serious attention, the canvas and all exterior seating vinyl needed replacing. It all added up to too much and we walked before we even got to the engine stuff…………

Did Crates Marina indicate that they had a normal sea trial list and they were just asking if there was anything in particular you wanted checked or where they asking “What do you want us to do while we are there?” I would think twice about using them if it is the latter………

Too much to write that has already been written here on this site so I would re-read the document(which consolidates a lot of that info) that is attached above and focus some time on the following sections:

List Item #3 – Visual Inspection
List Item #4 – What to ask the current owner – SERVICE RECORDS!!
Read the “Process what you have learned” section a few times and pay particular attention to #5
Scenario #1 covers the 52 Sedan Bridge which is the updated model to the 480. Read that again.
Scenario #2 covers QSM’s in a Tiara. It is instructive on fuel burn
And then there is the Sea Trial section.

You can also use the search feature of the forum and search “QSM Survey” I found quite a few good threads that you can read and learn. Again I consolidated a lot of that into the attached article above so if your looking to save time, read the article. If you want to dig in a bit, read the threads that are the result of the search.

[David Anderson]

Next step mechanical inspection

I called around near the boat looking for a Cummins mechanic and the shop told me that Crates Marina was my best bet. When I called them they asked what specically I want inspected. Does anyone have a list of the important specs that should be verified?
Thanks in advance.

I was thinking:
Compression
Turbo bearings
???

[David Anderson]

Looked good

Very little evidence of soot around the manifold. The engines were super clean. Only thing out of sorts was around the starboard turbo. Looked like it had been hot and something melted or dropped on it. The owner had not seen it but had the marina look at it right away.

[Steve Lewis]

How did it go?

Did you make it to the boat last night? What did you see in the engine room? Any of the soot around the exhaust manifold area? Did you take any pictures to share with the forum?

Just curious as to how it went…………

[Steve Lewis]

Give the attached a read. Given the last minute nature of this request you probably do not have time to search this site and find the wealth of info about the QSM11 and it’s well known quirks of the Exhaust Manifold and Turbo not being liquid cooled. I cover that and other main concepts for diesel boat buying in the attached.

https://www.sbmar.com/articles/the-cummins-qsm11-marine-engine-story/

This is a good one

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David Anderson

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