OMC compression ratio

[Glen Mar]

I am considering buying a boat that has a 1989 OMC V-6 3.0 Litre 225hp Outboard. The compession test read 80 lbs. straight across all cylinders. The leak down test showed 5%. The hour meter reads 270 hrs. Is this an acceptable read or is it time for a rebuild. It'll be pushing a 26' Olympic. Weight 4300 lbs. Do You think I would be safe buying it or should I pass due to a weak motor?

 

[rodbolt]

Re: OMC compression ratio

hello<br /> wow. thats right on the money. and only 5% is great. 80 psi is normal for that engine. test the gearcase for water or metal . I would change the water pump and t-stats and diaphrams. flush the carbs and change the water seperator and go ply <br /> good luck and keep posting

 

[Glen Mar]

Re: OMC compression ratio

Thanks for the reply Rodbolt, I've spoken with 6 different boat shops and 5 say it should be over 100-150 lbs. per cyl.. The other two say it's fine and it's the leak down test that really matters. Maybe someone with a manual will post a reply.1989 OMC V-6 3litre 225hp Sea Drive

 

[walleyehed]

Re: OMC compression ratio

sturg-on, you got the best reply from an experienced mechanic-not a part-timer. <br />I will also tell you 80-90psi on that engine is good-real good.<br /> the 5% leak-down is near perfect, not knowing how the test was done...cold/hot.<br />The compression on that engine is only 6:1, maybe 5.5:1.<br />There are alot of guys on this forum that ARE dealers, and some of them, high-tech guru's with 30+ years behind the wheels......... <br /> I can't help but say as well, the manual will give certain specs, but will not compensate for altitude, ambient air temp, or the manner in which you test your engine....It's simple, and yet there are things the inexperienced eye will miss..........

 

[Glen Mar]

Re: OMC compression ratio

Walleyehed,<br /> I finally feel confident enough to purchase the boat and feel great about it! I'm gonna buy it tomorrow and hopefully fish it on Wednesday. I now realize that everyone I talked to on the phone was in business to make money. On the other hand you guys are helping out of the goodness of your heart. I'll not forget it. Hopefully I can help someone else out in the future.(after I learn a little about boating as a canoe is my other boat!) <br /> Sturg-On!

 

[rodbolt]

Re: OMC compression ratio

Hello<br /> I am not a guru or anything. however I am currently or have been certified in yamaha,suzuki,force merc mercruiser and volvo-penta, my spelling gets lazy and my keyboarding skills bite but I have been doing this over 30 years. I have owned my own repair business since 1994. I was also in the Navy's advanced electronics field and used to program and set up CNC lathes and Mills for an explosive plant in texas. most my work is J/E. up until the bombariar engines. I dont see many of them as most the OMC dealers in my area gave them up and went yamaha. what I will advise is that you hire a marine surveyor to look over the hull and electronics. and hire a professional to water test the boat with you. if you have any doubts, ask. I am rebuilding a 98 model 225 now that had a leanout from a dirty carb. it ran well just lean on #1. all the other 5 cyl's still show hone marks. most of #1 piston is missing. the sad news was the guy had just bought it. 270 hours on a 1989 shows that it sat a lot. also make sure the lower unit will actually seperate from the upper. I had a pair of good running 87 225's OMC's last summer that both shafts were stuck in the cranks.and with only 270 hours I will bet any amount that no cooling system maint was ever done. so do the carbs and fuel system. do the entire cooling system and enjoy the ride <br /> good luck and keep posting