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Old 03-07-2014, 06:27 AM   #21
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Thanks, all, for the great advice.

I've learned that the owner has installed air compressor filters on the valve covers to manage, I suppose, blow by.

I've read that a certain amount of blow by is typical for these older engines, but don't know if I should insist on a compression check or not. I will use a mechanic in addition to the surveyor if this proceeds to survey and will try to contact Brian or Bob Smith at American Diesel for an opinion.

Will let you know how it turns out.
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Old 03-07-2014, 10:01 AM   #22
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Be careful on who you select, get references from others. They must have depth of experience working on the engine involved, and they must have surveying as part of their professional portfolio. That will mean they have a form and format for their surveys, ask to see a few. The really good ones are very articulate and happy to teach you about the engines and how to take care of them. Some will include an after-purchase orientation in their fee, and provide phone support. Good luck!
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Old 03-07-2014, 10:30 AM   #23
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Angus

It seems you have this well figured out. Let us know how it all turns out after getting our collective "Lehmans need a Swiss watch kinda guy to survey them" knickers in a twist.
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Old 03-07-2014, 12:33 PM   #24
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We chose to have a engine survey. It was around $500. We took the diesel mechanic and the surveyor along on the sea trial. It proved to be a good choice. During the trial, one of the high pressure lines to an injector failed. The mechanic was the first to notice the smell of fuel. We shut the engine down and found fuel sprayed liberally around the engine room. The seller paid for the repair and cleanup.
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Old 03-07-2014, 01:40 PM   #25
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Another twist.

I spoke with Brian Smith, at American Diesel, (a guru on the Ford Lehman) who said he would NOT recommend an engine survey unless the sea trial showed problems with either engine reaching or sustaining full RPMs, running hot or having poor oil pressure. He said any competent surveyor should be able to identify if there is a problem in any of these areas because the Lehmans are such basic, naturally aspirated engines. (he wasn't speaking for all diesels.) He also did not recommend a compression test because they are "intrusive," requiring partial disassembly on the Lehman, and compression problems would likely evidence themselves elsewhere. If either engine fails the sea trial, that would be the time to call in a mechanic.

He strongly advocated oil analyses on the crank cases of the engines and generator as well as the two transmissions. Most important, he said: read the analyses, compare them to prior analyses and ask questions.

So, the world turns and the stomach churns . . .
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Old 03-07-2014, 02:28 PM   #26
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This is what I know about a diesel compression test:

Measured values are highly variable for several reasons: cranking rpms, but just as importantly diesel rings don't seal unless significant ie combustion pressures are applied. Many manufacturer's refuse to publish a spec.

Paul Foulston a former Cummins developmental engineer said on boatdiesel that diesels can show good compression almost up until the day they croak (my words). He believes that compression testing is a total waste of money and is promoted by the uninformed.

A compression test can be useful to isolate one bad piston. But there are easier ways like cracking the injector pipes and watching the rpms change.

A blowby test IF THE MANUFACTURER GIVES A PROCEDURE AND SPEC is much more useful. Cummins does this. The blowby test is not very invasive and can be done with an hour of mechanic time. But it takes a specific procedeure- orifice sizes, etc and the manufacturer has to publish a spec.

I suppose that it could be done on any engine, spec or no spec, procedure or no procedure using the Cummins procedure and making adjustments for displacement.

Blowby will definitively tell you if the rings are bad. A related test is leakdown- pressure up a cyinder and see how long it takes for the pressure to bleed down.

I suspect that both are done by smart mechanics and the results are interpreted based on their experience.

David
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Old 03-07-2014, 03:26 PM   #27
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Taking a measurement doesn't make any sense if there is no standard to judge it by. And I certainly would take American Diesel's Brian's advice very seriously. My personal experience with surveys, most recently with Detroit 2 stroke 8v92Tis is that there is a raft of standards, and the complete surveys were absolutely invaluable when done by specialists in same. So i wouldn't/shouldn't make generalizations about surveys. My personal bent would be to hire a mechanic to give the initial once over unless the hull surveyor has a deep experience in the engines at hand, with plenty of boater references.
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Old 03-07-2014, 04:49 PM   #28
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If the engine starts easily when cold it doesn't have a compression problem.
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Old 03-07-2014, 06:11 PM   #29
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Quote:
Originally Posted by angus99 View Post
So, the world turns and the stomach churns . . .
Ahh, the acid reflux due to over analyzing. It is not our decision, not our money, not our "why didn't I" thoughts after the fact - all these are yours.


And, you can not do a pre purchase engine survey after you buy the boat.
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Old 03-07-2014, 07:09 PM   #30
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Quote:
Originally Posted by RickB View Post
If the engine starts easily when cold it doesn't have a compression problem.
The voice of reason speaks. Thanks.
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Old 03-07-2014, 10:53 PM   #31
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You have 3 engines and ancillaries deserving a proper survey. The cost is modest compared to repairing a major defect you or a general surveyor may miss.
For the current boat I had both surveyors present same time, but if one side of the survey, ie mechanical or general, has you more concerned, do the one of concern first, if it fails, you`ve the option to cancel the other. I hope it goes well and turns out a great boat.
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Old 03-08-2014, 06:05 AM   #32
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>The cost of the engine surveyor was easily worth the lower renegotiated price.<

Perhaps sometimes,

Many boats are sold as they are .

No promise from the seller to a perfect boat , just what you see.

It is up to the purchaser to decide if the boat has enough value to justify the price , with no dream of 100% as new.
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Old 03-08-2014, 08:35 AM   #33
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And here I was expecting universal agreement . . . .

Oh well, just like anchors, galley up or down and singles vs twins, variety is the spice of life.

I'm leaning toward spending the money for most of the reasons already stated . . . and learning maintenance from a pro on the spot can't hurt. Also, I think the obsessiveness from my formative years in a nuclear plant is kicking in.

Thanks again for the advice. I'll post the outcome in mid-April after the survey(s).
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Old 03-08-2014, 11:44 AM   #34
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We had a separate mechanical survey done when we did the haul out and survey when we had an offer on our boat. In addition we had oil samples taken and analyzed. The mechanic monitored the main during the sea trial and also the genset. Nothing jumped out, but the mechanic we used identified a leak from the head gasket. Brian Smith felt it was more likely due to weeping from the fuel return lines. It was part of my desire for due diligence during a very stressful first time purchase of a large boat.

The mechanic's written report wasn't particularly detailed, and I probably should have sourced someone more familiar with the Lehman engine.

Jim,

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Old 03-08-2014, 11:48 AM   #35
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I have done hundreds of pre-purchase engine inspections. Most on fast sportfish, but also about 20 (??) Lehman boats. So my Lehman experience is not super detailed.

In virtually all the go-fast sportfishers, there were problems found that were WAY more costly than my fee. Defiinitely worthwhile.

In the Lehman boats (non turbo), some had significant problems, some did not. So it is a bit of a crapshoot as to whether the mech survey is worth it.

The approach that seems to work best is to break the mech inspection into parts: Get a knowledgeable mechanic or engine surveyor (must know the engine) to ride along for the running portion of the sea trial. The hull surveyor is busy then so having a second set of eyes dedicated to the machinery space is worth it for that reason alone. Have the mechanic check for rusty valve gear, do a cold start, running temps, blowby, look for leaks, check rpms, shaft vibes, alt volts, motor mounts, exh smoke etc. Usually can be done in 3-4-5hrs of his time. Not really a full "engine survey", but uses the 80/20 rule. Someone take oil samples at the end.

IF something major is found, there may be further investigation to do. But if everything checks out, none of that further stuff is likely worth it.

Another often worthwhile step is to have the mech do a "quick look" dockside before the whole survey ball gets rolling. If mech is local, this can take an hour or so. Big problems are usually pretty obvious the moment you hop into the ER.
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