Mechanical Survey Questions

Hi folks,

I am getting ready to have a mechanical survey done on my soon to be boat (if all goes well). It has twin Cat 3208s, plus an Onan generator. I should have the genny checked while the guy is there, right? How long does a mechanical survey generally take for each engine? If I am having the regular survey done at the same time, does the mechanic go along for the sea trial to observe the engines under load? Any idea what prices would be reasonable? The boat is in La Paz, Mexico.

Sorry for all the questions, but I've never had a mechanical survey done before.

Thanks in advance, Bill

The hull surveyor will need a half hour in the engine compartment before the engine surveyor gets started. That's to check the infrastructure in there. Get the two of them to talk and they will sort that out. If they are from the same area they probably know each other anyway.
The engine surveyor absolutely goes along for the sea trail in fact that is mainly for him as the hull surveyor can do most of what he needs tied up at the slip.
Are you getting a haul out to check the bottom?

The engine surveyor will have diagnostic tools with him that he needs to set up. He will monitor the cold start, fuel flow (vacumn through the filters), fresh water and raw water flows including aftercoolers if any and heat exchangers. He will ask the captain to go up through the RPMs, idle, 1300, 1500, 2000, max etc. He will check exhaust, controls, air induction, mounting system, electrical system, transmissions and also compression (you may have to pay a little extra). He will also ask if you want oil samples taken for about $50 each (engines, trannies, and genset). I would do that as the foreign matter in the oil can indicate proper wear versus unusual wear.
He will do pretty much the same with the genset.

Don't know what the costs would be in Mexico, but from a recent thread where I asked the same, ~$1000 for twin diesels and a genny in the US seems right.

Some tests below (from my last survey)

1) SET RPM (VESSEL TACHOMETER READINGS)
2) ENG. RPM (ACTUAL ENGINE SPEED)
3) SHAFT RPM (PROPELLER SPEED)
4) OIL PRESSURE (ENGINE OIL PRESSURE)
5) GEAR PRESSURE* (MARINE TRANSMISSION PRESSURE)
6) BOOST PRESSURE* (TURBOCHARGER AIR PRESSURE)
7) C/C PRESSURE (BASE CRANKCASE PRESSURE)
8) FUEL GPH** (FUEL USAGE GALLONS PER HOUR)
9) FUEL RESTRICTION (VACUUM NEEDED FOR FUEL SUCTION)
10) WATER TEMP. (ENGINE FRESH WATER COOLING)
11) R/W TEMP. (SEA WATER DISCHARGE TEMPERATURE)
12) OIL TEMP. (ENGINE OIL TEMPERATURE)
13) GEAR TEMP. (GEAR OIL TEMPERATURE)
14) CHARGE AIR TEMP (INTAKE MANIFOLD AIR TEMPERATURE)
15) EXHAUST TEMP.* (ENGINE EXHAUST DISCHARGE TEMP.)
16) D/C VOLTAGE (ALTERNATOR OUTPUT VOLTAGE)

menzies said:

The hull surveyor will need a half hour in the engine compartment before the engine surveyor gets started.

Some tests below (from my last survey)

1) SET RPM (VESSEL TACHOMETER READINGS)
2) ENG. RPM (ACTUAL ENGINE SPEED)
3) SHAFT RPM (PROPELLER SPEED)
4) OIL PRESSURE (ENGINE OIL PRESSURE)
5) GEAR PRESSURE* (MARINE TRANSMISSION PRESSURE)
6) BOOST PRESSURE* (TURBOCHARGER AIR PRESSURE)
7) C/C PRESSURE (BASE CRANKCASE PRESSURE)
8) FUEL GPH** (FUEL USAGE GALLONS PER HOUR)
9) FUEL RESTRICTION (VACUUM NEEDED FOR FUEL SUCTION)
10) WATER TEMP. (ENGINE FRESH WATER COOLING)
11) R/W TEMP. (SEA WATER DISCHARGE TEMPERATURE)
12) OIL TEMP. (ENGINE OIL TEMPERATURE)
13) GEAR TEMP. (GEAR OIL TEMPERATURE)
14) CHARGE AIR TEMP (INTAKE MANIFOLD AIR TEMPERATURE)
15) EXHAUST TEMP.* (ENGINE EXHAUST DISCHARGE TEMP.)
16) D/C VOLTAGE (ALTERNATOR OUTPUT VOLTAGE)

Click to expand...

As a surveyor I can tell you that in a typical boat with two 3208's and a genny I would need 3-4hrs in the engine compartment and do everything on your list except compression, #5,7 9, 22, 13, 14 and 15 plus a few thing you have not mentioned.

boatpoker said:

As a surveyor I can tell you that in a typical boat with two 3208's and a genny I would need 3-4hrs in the engine compartment and do everything on your list except compression, #5,7 9, 22, 13, 14 and 15 plus a few thing you have not mentioned.

Click to expand...

To do the hull survey only? The half hour I mentioned was for the hull surveyor to get access BEFORE the engine surveyor got to work.

I would be shocked if my hull surveyor spent 3-4 hours in the engine compartment.

Or are we at cross-purposes here?

Thanks Menzies,
That was the kind of info I was looking for. I will have the two surveyors play nice together to get things coordinated.

Thanks again, Bill

If the boat in question has a dingy with an outboard, don't forget that also.
We also found a few minor problems when we lifted the dingy off the fly bridge/ boat deck and lower into the water to start and run the outboard.

menzies said:

To do the hull survey only? The half hour I mentioned was for the hull surveyor to get access BEFORE the engine surveyor got to work.

Click to expand...

Yes. The engine compartment contains 90% of the boats systems and I spend more time there than anywhere else.

boatpoker said:

Yes. The engine compartment contains 90% of the boats systems and I spend more time there than anywhere else.

Click to expand...

Are you doing both hull and engines though?

menzies said:

Are you doing both hull and engines though?

Click to expand...

See post #3 for what I do regarding the engines and I don't consider that an "Engine survey".

Samples of my surveys can be found at Sample Survey Reports

A diesel engine mechanical survey that requires wrenches and tearing things apart best be spelled out in the offer sheet and who bears responsibility for fixing what the mechanic breaks. This would include removing exhaust elbows, injectors, valve cover, and water pump cover.

Few owners would agree to a tear apart initial survey, which is why good maintenance records are important. Records from a good yard normally trump DIYers and better yet allowable discussions with that same yard. A visual examination reveals much to the trained eye. A sea trial involving running the vessel and engine as intended will reveal over heating, wrong props, malfunctioning chargers, inoperable systems, misalignment, and exhaust color.

Issues found and respective checks, wrenching and costs then become part of the negotiations. Or the buyer can walk if issues prove too onerous.

I can tell you that if you hire the Cummins factory guys they do not take apart anything for a engine survey.

What they do do is to install a pressure gauge setup on the breather and check blow by both at idle and under load.

There is allot they look at but they don't take things apart to do it.

ksanders said:

I can tell you that if you hire the Cummins factory guys they do not take apart anything for a engine survey.

What they do do is to install a pressure gauge setup on the breather and check blow by both at idle and under load.

There is allot they look at but they don't take things apart to do it.

Click to expand...

Unless you specifically ask for a compression test which is very expensive on a diesel

Here is a copy of my pre purchase engine survey checklist that I published on this TF thread: http://www.trawlerforum.com/forums/s6/engine-survey-checklist-13125.html

It is specific to Yanmar engines with an aluminum exhaust manifold and a turbocharger with aftercooler, neither of which your engine has. But you can use it with some modifications for your engines. Just ignore the antifreeze and turbo/aftercooler checks. But the 12" rule of thumb is equally valid for NA engines and a look inside the exhaust manifold might tell you about past sea water corrosion problems. However I rarely if ever have heard of such reported for NA engines on boatdiesel. Maybe turbos are much more susceptible to sea water damage because they are always on the low end of the engine slope.

No hull surveyor and few engine surveyors will do all of the above, but it might be useful to go over it with your selected engine surveyor and see what he suggests. If he poo- poos the hand on the vent tube check for blowby and wants to do a compression test sight unseen instead, then think about getting another engine surveyor. That one just wants to waste your money.

David

Be sure re to DEMAND that the engine be at least overnight cold before the engine guy gets there for the first start.

The crank time and smoke from the warm up are good clues to engine condition.

On less pricy boats lots of folks do without an expensive engine check, and simply use the exhaust smoke vs engine temp as a quick check.

Second check is to loosen one injector fuel nut at a time to see if RPM drop with each non working cylinder is the same , this is done warm on return to the dock.

The biggest indication of proper engine operation is if it will make its WOT RPM and keep it there without overheating.

If it can do that then it's making full power and the cooling system is in good shape.

If there are boost and EGT gauges better yet!

Here is what I did on both previous boats...

Go on about your business with a regular survey. Those surveys will include a sea trial and the surveyor will spend a bunch of time looking at the engine. Should any red flags go up, then MAYBE consider spending your extra coin on an engine survey. In addition, I haven't had a seller say no to allowing me to take my own oil sample for analysis. That is extra cheap to do (like $12 at the local heavy equipment store). An oil sample will give you another very good indicator into engine health.

IMHO, engine surveys are WAY over-priced for what you get. All they really do is take oil samples, check a lot of temps, and compare speed to RPMs. All stuff you can do yourself without shelling out $500-$1000 per engine. That effectively DOUBLED the survey price and I wasn't willing to do that. Sure, some call it cheap insurance and that peace of mind MAY be valuable to some, but I think that unless a tech can start pulling off parts (which they can NOT do), you can only know the real health of the motor thru an oil sample test and maintenance records.

you can only know the real health of the motor thru an oil sample test and maintenance records.

Perhaps , but a good eye on the exhaust smoke during warm-up , can frequently spot a boat you DONT want to buy.

In my opinion oil samples at survey are of limited value. My reasons are simple. First, the real utility of oil samples is comparing them over time to look for trends. Ideally the samples should be taken at each oil change over a period of years. Second, at the time of survey you don't know how long the oil has been in the engine or how much and how hard the engine has been run since the last oil change. If the oil was recently changed, an oil sample is pretty much useless except in the case of major problems.

I do engine surveys as part of my business. In general, there is no major disassembly. Boost gauges, temp guns, pressure gauges, blow by flow test rigs, etc, are the basic tools used.

But the biggest part of doing it is knowing what to look for. Much can be told by the sound of the engine at start and various speeds. Exhaust smoke at various temps and loads.

And each brand/model has specific things to look for. Each engine has its weak spots and it takes years of experience to get a handle on that. For example, cold start smoke on a Volvo 41 or Yanmar 6LP means something completely different than on a Detroit 671 or Cummins QSB.

Exhaust systems get a high level of scrutiny. Even systems that "look good" can be gradually killing the engine, or in some unusual operating situation flood the engine. Most of the engines I have rebuilt have been due to water getting where it should not. Those situations paid for the construction of my boat!!! It is that important.

Oil sample is a tool of limited value, but still worth doing. Biggest thing is finding evidence of sea water, coolant or fuel presence, the wear metals are not going to tell you much unless off the charts.

What constitutes an "engine survey" varies widely. I have seen someone plug in the laptop and get sea trial data and not even notice sea water spraying from a leak in the engine room. I like at least a couple hours crawling around down there under way.

Compression checks are available, but are mostly used as a diagnostic tool when there is something already known to be wrong. If engine passes all the non intrusive tests, it is not usually done. Detroits are a bit different, the c-test is a more standard test. Since it is intrusive, it has to be negotiated with the owner, it is still his boat and I am hired by the buyer. Usually if a compression test is indicated, the deal is off anyway.

In about 90% of the boats I check out, the problems found well exceed my fee, so it is generally worth it. Occasionally, I find almost nothing wrong and those are the "gems" of the boat world, so few out there.

Not enough time to write more, off to work.

Thank you everybody for your great replies.

Yes, I am doing a regular survey as well. I am pretty handy with tools and motors and this will be my 4th boat, but first trawler. I will spend the day before the surveys crawling all around and inside the boat doing my own pre-survey inspection.

I am at a bit of a disadvantage because the boat is in Mexico. I have lined up reputable surveyors for the boat and engines, and have a haul out booked. They are raping me on the haul out, $500 USD, but it is what they get down there. I will try to apply that towards future work at the yard.

The sale on my sailboat closes today, with money changing hands.

If all goes well, I will be a proud owner of a Californian 42 LRC in a couple of weeks.

Thanks again, Bill