06 yamaha f-250 4 stroke compression test question

dansly56

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Jan 13, 2015
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dan sly
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2007 key west 225dc
Hello BD members, I have a question about a 2006 Yamaha F250 4stroke that I'm looking to buy. I had a local shop do a compression test on this motor the motor had 46 hours and the numbers came in at 140's across. They said it was done with throttle wide open and if they did it with throttle closed that the numbers would be higher in the 180's. Is that right? Also are those numbers right if that's the way a compression is done? Only thing I can find on the manual is the minimum compression which is 104.4. Any advice on this topic would be greatly appreciated. Thanks
 
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Reel Kahuna

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Mar 24, 2011
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Seon
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23.5' Navigator Duckworth F150 Yamaha
I recently asked about an F150 that's been sitting in a Marine shop boxed in a crate for over a year and one main answer I got was to do a leak down test which is way better than a compression test. Just sharing...

BTW I'm sure you are aware that the F225 and F250 has/had corrosion problems so that should also be a concern.

Best of luck.
 
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dansly56

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Jan 13, 2015
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dan sly
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2007 key west 225dc
I recently asked about an F150 that's been sitting in a Marine shop boxed in a crate for over a year and one main answer I got was to do a leak down test which is way better than a compression test. Just sharing...

BTW I'm sure you are aware that the F225 and F250 has/had corrosion problems so that should also be a concern.

Best of luck.

I thought that was from 2000-2004 and more of the f225 at least that's what the article from boatus said.
http://www.boatus.com/magazine/2012/october/Yamaha-F225-Corrosion-Complaints.asp
 
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ShadBurke

Just a Guy and his Boston Whaler
Oct 28, 2005
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exhaust corrosion 2002-2005 ish 3.3l yamaha and mercahama four strokes. f200, f225 and f250 all have potental issue. some incidents found in bookend year motors like 2006 so be safe and have leg dropped and camera scoped.

compression should be taken when motor has been warmed up and throttle is wide open. motors worthy of purchase should be at least 195 psi and all cylinders within 5 psi, has been my standard and served me well.

i had a set of f250s with 5,400 hours and compression accross all 12 cylinders were 180-185 psi.

yes, cold vs hot as well as closed vs open throttle will produce variances, often as high as 50-60 psi......

make sure ecm data looks good and sea trial motor if possible. ive seen way too many tricks having the motor idle on the stand to be satisfied.... fuel system issues which present themselves under load is most common and most costly...

And I heard rebuild spec for that 3.3l motor was 137 psi per yamaha.

hope that helps and if you need to borrow my compression gauge, let me know......
 
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towerfab

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Jun 15, 2004
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Beware. Several red flags flying. Anytime I see an older motor, in this case 10 years old, with less than 200-300 hours I'm suspicious. If the ecu was replaced the hours would start over at zero. With only 46 hours on a ten year old motor there better be a pretty good story. Also, at 46 hours the compression should be perfect, 210 pounds in all six cylinders. At 46 hours there should be almost no carbon in the exhaust housing of the lower unit. At 46 hours there probably would not be any paint worn off the skeg, you also can remove a spark plug, both the plug and the top of the piston should look new, shining a light into the cylinder should show no carbon, i.e. clean shiny metal on the piston. At 46 hours the aesthetics of the power head and mid should be "rediculous clean" . If you have any questions feel free to get in touch. Shad B is also very knowledgeable of the 3.3 yamahas. TR
 
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dansly56

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dan sly
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2007 key west 225dc
Beware. Several red flags flying. Anytime I see an older motor, in this case 10 years old, with less than 200-300 hours I'm suspicious. If the ecu was replaced the hours would start over at zero. With only 46 hours on a ten year old motor there better be a pretty good story. Also, at 46 hours the compression should be perfect, 210 pounds in all six cylinders. At 46 hours there should be almost no carbon in the exhaust housing of the lower unit. At 46 hours there probably would not be any paint worn off the skeg, you also can remove a spark plug, both the plug and the top of the piston should look new, shining a light into the cylinder should show no carbon, i.e. clean shiny metal on the piston. At 46 hours the aesthetics of the power head and mid should be "rediculous clean" . If you have any questions feel free to get in touch. Shad B is also very knowledgeable of the 3.3 yamahas. TR
Towerfab, I to had same red flags pop up in my head about that motor and I posted here because I know you guys that are replying are very knowledgeable about these motors and situations. The good thing is the shop where it's at, is now allowing me to take it to a yamaha authorized shop for a second opinion. The shop that it's at now told me earlier they did a cold compression check with throttle wide open and got 145's across, but I didn't feel comfortable with that so now I'll take to a shop were they will do a leak down, warm up the motor wide open throttle compression check, Running it on the dyno, checking for codes, carbon build ups, and corrosion check. Than if all that checks out good than the seller will also let me do a sea trail to make sure rpm are good under load. I really appreciate you guys input and I did reach out to shad b through convo. Thanks again.
 
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Billy V

Seabass Commando
Aug 26, 2007
603
378
San Diego
Name
Billy
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Parker 2310 DV / Kayak
Hello BD members, I have a question about a 2006 Yamaha F250 4stroke that I'm looking to buy. I had a local shop do a compression test on this motor the motor had 46 hours and the numbers came in at 140's across. They said it was done with throttle wide open and if they did it with throttle closed that the numbers would be higher in the 180's. Is that right? Also are those numbers right if that's the way a compression is done? Only thing I can find on the manual is the minimum compression which is 104.4. Any advice on this topic would be greatly appreciated. Thanks

Where did you have the compression test done?
 
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ShadBurke

Just a Guy and his Boston Whaler
Oct 28, 2005
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you should be upset with your parker fuel tank, not the motor.......

2 micron racor will help in your situation.

and its all the white powder that is hammering the vst filters
 
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dansly56

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dan sly
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2007 key west 225dc
Compression check was re-done at a Yamaha authorized dealership and numbers came in at 185 across. The engine was warmed and throttle was wide open. Diagnosic report came back clean with 47hrs on that motor. What do you guys think?
 
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ShadBurke

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what did the ecm data show?

185 on a 47 hour motor not great. may clean up with use if its been sitting

i had a set of f250s with 5,400 hours and they had 185lbs psi even on compression........
 
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dansly56

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dan sly
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2007 key west 225dc
what did the ecm data show?

185 on a 47 hour motor not great. may clean up with use if its been sitting

I had a set of f250s with 5,400 hours and they had 185lbs psi even on compression........
Yeah it's been sitting for a yr or so. I'll have the ecm data later on today from shop. I called Yamaha as well, All they had was the minimum spec for that motor which is 107.3 PSI and the rep said 185 across was good. See that's what making me iffy about it is that you had 2 250's with 5400 hrs and this motor on this boat is basically new and they all have the same psi's.
 
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ShadBurke

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if its been sitting, the psi should come up (aka clean up) once you get out and run it a bit. shock treatment with ringfree for 50-100 gals and you might be suprised.... or yiec dealer service
 
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dansly56

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dan sly
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if its been sitting, the psi should come up (aka clean up) once you get out and run it a bit. shock treatment with ringfree for 50-100 gals and you might be suprised.... or yiec dealer service

IMG_6440.PNG IMG_6441.PNG IMG_6442.PNG
 
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ShadBurke

Just a Guy and his Boston Whaler
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if i were a betting man, that motor will clean up and compression will come up since its been sitting for some time. ecm info looks good.
 
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Capt. Paul

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Jan 23, 2017
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Capt Paul Primeaux
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Got it! Thanks!
Hard to say on this.

I can tell you that I am running a 2003 F225 Yamaha that was in the corrosion era.

Acquired with 441 hours and have 1312 as of today over 2 1/2 years running with no issues. Today I was doing my semi annual maintenance. Decided to do a compression test and had from 185psi to 195psi. only one cylinder was 185, the top left the rest were 190 to 195. Tested after warmed up with throttle wide open as I have always tested compression. I have notes somewhere of when I bought it and tested it cold and was getting 165ish psi.

Capt Paul,
Sanibel, FL
 
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dcarlisle

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Jun 25, 2008
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You guys also have to remember that not everyone’s pressure guage is calibrated. In some shops (or personal gauges) these get tossed around and never calibrated so there is a chance that the pressure reading is not true pressure. However, the cylinders should all be similar reading if they are all good even if the gauge is off.
You can always ask the mechanic if it is calibrated.
We have three radiator pressure test gauges at the shop (only one of which is calibrated) and read three different pressure readings between them.
 
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