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Posts: 400
Location: Metro | Hi there everyone,
I am going on a fishing trip this weekend and I am going to be checking out a used boat that I am very interested in buying.
The Boat:
1998 Skeeter Fish and Ski
Seats 5
On Board Charger
2 Live wells
2 Fish finders
Trolling motor
motor compression is 105-120, V6, 150HP.
The boat looks in excellent shape and the motor looks like new. I am just wondering what kind of questions I need to ask and what I need to physically look at and move around to make sure the boat doesn't have serious flaws.
Any information would help. Would be nice to also get some info from people that have bought used boats in the past. Please pm me and I would be willing to send a couple pictures of the boat for you to look over.
This site has always been a great help, thanks guys! |
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Posts: 131
| I have a 1998 1775 T . I love the boat. It handles rough water like a champ. I bought it used 8 yrs ago.... |
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Posts: 25
| i dont like the low comp on one cyl. was the motor warm when it was checked? can always try some engine tuner through it but my opinion is look for a diff boat |
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| agreed..compression should never differ by more than 10%. 8% or less is ideal across all cyl. |
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Posts: 1405
Location: Detroit River | The compression difference between cylinders on that motor is too much. I would steer me clear of that boat. |
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Posts: 153
| same on fiberglass boats always inspect the transom and stringers I purchased my tuffy this spring and got raped I had to put a new transom in and the flour has to be redone since the previous owner who had it didn't install the new flour correctly also look for any delamination around the stringers and transom be patient and shop around with the crummy economy their are a lot of nice pre owned boats out their also talk with a local dealer and ask them if they can do a pre purchase inspection my friend did on his and he dodged a bullet big time good luck |
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Posts: 400
Location: Metro | Sorry I am not very good with motor tech. What is the compression difference and what future problems might I have with this compression difference?
Thanks for pointing that out. |
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Posts: 3469
Location: Elk River, Minnesota | Hiya,
When testing compression, a gauge is screwed into the spark plug hole. Then the motor is turned over which compresses the air/fuel mixture in the cylinder. The gauge will read how much pressure the cylinder is able to hold. Each cylinder is tested independently to determine if there are any potential issues with the motor itself.
In the case of this motor, one cylinder is reading 120 psi, while another is reading 105 psi. psi standing for pounds per square inch..
When checking out a used motor, the general rule of thumb is that each cylinder is within 10% of each other. In this case, take 10% of 120 and you get 12. You would not want any more than 12 psi difference between any two cylinders you compare. In a nutshell, each cylinder should be holding a minimum of 108 psi up to 120 psi. The situation people are worried about here for you is that one cylinder is performing at 105 psi, which would be outside that minimum 108 psi value. That becomes an indicator that something may be amiss with the motor that the seller might not be aware of. I would be interested in knowing the individual compression values of each cylinder to see just how uniform the other cylinders are. If the one cylinder is showing 105 while the others are all 110 or higher, but not over 120, I would be raising a red flag and would not hesitate to make that known with the seller.
The last thing I would ever want to do is purchase another person's problem. If the seller is trying to hide something, a quick question to ask would be can the two of you together take it to a reputable mechanic (who has nothing to gain or lose) and have him or her go through the motor and perform various tests to determine the condition of the engine. If the seller hesitates at all on that request even if you as the buyer are willing to pay for it, this would be a huge red flag to consider and to be truly honest, a boat to walk away from.
Any seller worth their salt would not hesitate to allow a potential buyer to have the motor tested (at the buyer's expense, or an agreed expense).
My last rig I sold (in 2005) the buyer requested this and before he was willing to close the deal, asked if he could have the lower unit tested as it had been replaced and the color of the lower unit was a tad different. Knowing it was in great condition, I was not worried at all about it. For him, it was money well spent for peace of mind. Very much worth it for him.
Steve
Edited by VMS 10/22/2014 7:40 PM
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| ^^ its the difference in pressure in the cylinders. Rings on the piston(s) are wearing and or cyliders too. could also have head gasket issues.. In short, the motor is showing signs it is on its way out, less power than rated and needing rebuilding. eventually, The motor will seize if left to continue wearing.
Edited by mnmusky 10/22/2014 7:49 PM
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Location: 31 | mnmusky - 10/22/2014 7:39 PM
^^ its the difference in pressure in the cylinders. Rings on the piston(s) are wearing and or cyliders too. could also have head gasket issues.. In short, the motor is showing signs it is on its way out, less power than rated and needing rebuilding. eventually, The motor will seize if left to continue wearing.
x2... nice post Steve!
Edited by Jerry Newman 10/22/2014 10:15 PM
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Posts: 400
Location: Metro | Thank you guys so much! I would have never thought of these things. I will definitely have a list of questions about the motor. The price is only $7000 so I thought it was kinda fishy. Hopefully we can get it tested and hopefully nothing major is wrong :/ the boat itself looks great but would kind of be a deal breaker if it isn't going to last. Do you guys know on average something like that would be to fix? can you fix it?
VMS thank you so much for the in-depth details I really appreciate it. |
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| no idea on cost to rebuild but yes, they can be rebuilt. You know what "boat" stands for? Bust Out Another Thousand. Definitely have a marine mechanic go through the motor before purchasing. nothing worse than buying someone else s headache. |
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Posts: 619
| I would try to test drive it and get it on the water for a few hours. Then check if the boat is taking on water.
I learned the hard way and bought a boat that had small leaks all over in the hull/rivets.
I asked the seller if it had any leaks and he said NO. Very expensive to fix as well. |
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Location: 31 | Slow Rollin - 10/23/2014 7:47 AM
I would try to test drive it and get it on the water for a few hours. Then check if the boat is taking on water.
I learned the hard way and bought a boat that had small leaks all over in the hull/rivets.
I asked the seller if it had any leaks and he said NO. Very expensive to fix as well.
I’m sure lesson learned; never take anyone's “word for it”... that guy obviously lied as he sold it to you.
I would get the motor issue cleared up with a neutral mechanic first before even considering a test ride (if still considering). I think this boat is an older fiberglass model, so the transom and stringers should be professionally inspected too. If you don't know what to look for with large items, always seek the advise of somebody who does.
When I bought my last boat (2008 621), that guy lied about its condition too! I was not happy after driving five hours only to notice the lower units “skeg guard” before I even got out of my vehicle. I immediately asked about it and he said there was no damage to the lower unit (right?), I noticed damage on the stainless steel prop and spun it… yep, it wobbled.
I told him there was no need to go out for a test drive unless he agreed to pay for the repair of the lower unit and prop, as well as some other minor items. As it turned out, the guy had no business owning a boat of this caliber… amazingly enough, he didn't even know how to operate the jack plate, and then he asked if I could dock/recover for him!
Edited by Jerry Newman 10/23/2014 11:42 AM
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Posts: 400
Location: Metro | I am going to ask him if he can bring it to a mechanic. I was going to ask him before going out to where he lives. But since I am going to be out there anyway I am going to wait. I just want to see the reaction on his face. Maybe he was trying to hide something (idk). I would like to meet the guy and talk to him about the whole situation. I hope he is a cool guy and I hope that a potential fix for this problem isn't too expensive. |
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Posts: 107
Location: milwaukee | FWIW I would have agreed with the opinions on the compression readings until I ran across this in a service manual for my motor:
"In order to maintain proper cylinder temperature on 3-cylinder and V6 engines, Yamaha varies the cylinder head volume on some models. A V6 will normally show the highest compression on cylinders 1 and 2 with cylinders 5 and 6 showing the lowest reading..."
It goes on to say that "A variation of of more than 15 psi between two cylinders indicates a problem...".
I didn't see any mention of the motor brand. The 105-120 variance on that motor may well be within spec if its a Yamaha. Not perfect, but still within spec. |
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Posts: 134
| Ask to have a leak down performed as well. Some motors show ok or even good on compression, while they can fail a leak down test. Any reputable outboard mechanic will be able to do this test. Good luck, we all have some pretty wild used boat buying stories. |
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Posts: 400
Location: Metro | EsoxRookie - 10/26/2014 9:40 AM
FWIW I would have agreed with the opinions on the compression readings until I ran across this in a service manual for my motor:
"In order to maintain proper cylinder temperature on 3-cylinder and V6 engines, Yamaha varies the cylinder head volume on some models. A V6 will normally show the highest compression on cylinders 1 and 2 with cylinders 5 and 6 showing the lowest reading..."
It goes on to say that "A variation of of more than 15 psi between two cylinders indicates a problem...".
I didn't see any mention of the motor brand. The 105-120 variance on that motor may well be within spec if its a Yamaha. Not perfect, but still within spec.
Thanks for posting this. When I took a look at the boat this week the guy said it runs great but they have a kid so need to get rid of it. He said he would be willing to take it too a lake for a test drive and also I told him I would probably want to take it into a mechanic just to get a run through.
Somewhat of a relief to see one good comment about the compression. And it is a Yamaha so.... I guess we will see what the mechanic says. |
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Location: 31 | BBT - 10/28/2014 9:38 AM
Ask to have a leak down performed as well. Some motors show ok or even good on compression, while they can fail a leak down test. Any reputable outboard mechanic will be able to do this test. Good luck, we all have some pretty wild used boat buying stories.
I just learned something, thanks for posting!
http://en.wikipedia.org/wiki/Leak-down_tester |
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Posts: 134
| Jerry Newman - 10/29/2014 9:55 AM
BBT - 10/28/2014 9:38 AM
Ask to have a leak down performed as well. Some motors show ok or even good on compression, while they can fail a leak down test. Any reputable outboard mechanic will be able to do this test. Good luck, we all have some pretty wild used boat buying stories.
I just learned something, thanks for posting!
http://en.wikipedia.org/wiki/Leak-down_tester
FYI 2 stroke outboards no more than 12% |
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