confused, IL6 runs dandy & probably shouldn't

[ziggy]

hi folks, boat listed below. 1st, the classic statement of my boat runs fine (ya, right). it starts like turn key starting. 1st time every time. idles at 600, perhaps a little ruff but can idle all day long. has nice throttle response and comes up on plane ok too even at half throttle applied (w/o the whale tail, it's gone for good). wot at 4300 trimmed up, bout 3900 trimmed down. stays nice and cool. no overheating. now for my question. i got some compression readings. 4-6 is 140-125 or so. #2 is a bit lower at 120 or so and then there's #1. 1st reading of the year was 90. few weeks later is at 60, still at 60. this is after several outings. when it was at 90 i did the oil squirt thing and came up to 105. now last time is did the compression test, at 60, the oil test didn't bring it up. also vac. readings are at about 11 (a shade low i think)inches with a slow variance of maybe one inch. havent done a leakdown test. i'm suppose that would be recommeded. guess all things so far lead me to believe i got ring problems on #1. but why does it seem to run ok? what will the consiqueses be for running it like this? a toasty motor after it fails catistophicly? i inherited the boat and for all i know i've been running like this (one low cyl.)since i got it last year and it's seen many hours since then. should i be preping for a rebuild this winter. gonna have to sell the ski if i do that..(oh well, i like boating better anyways) got no bread left after a few other repairs this summer. any opinions on this one low cyl. and where it's takin me?<br />only other thing i can say is that i don't do a lot of wot runs. mostly cruisein at 2500- 3k as i think i'm on thin ice, so to speak.........

 

[ziggy]

Re: confused, IL6 runs dandy & probably shouldn't

one more note. spark plugs are pretty much normal looking i think, tan in color with a bit of white on them. and i also have no oil consumption.

 

[olbuddyjack]

Re: confused, IL6 runs dandy & probably shouldn't

guess all things so far lead me to believe i got ring problems on #1.

I disagree.<br />

last time is did the compression test, at 60, the oil test didn't bring it up.

Oil test should bring it up if its rings. I'd bet its a leaking exaust valve on no.1 or a head gasket leaking between 1 and 2. Yank the head when you lay it up for the season and have the valves done. She'll be all ready to go for next season. Them ol Jimmys will run till you shoot em.

 

[weslacey]

Re: confused, IL6 runs dandy & probably shouldn't

Them ol Jimmys will run till you shoot em.

That's the truth. I have a '78 Caravelle with the Mercruiser IL6 165. It's been run hard every summer since new and even sunk. NO engine work what-so-ever(except flush after sinking) and she still runs like the day we bought her new in '78. Good luck with yours!

 

[Haut Medoc]

Re: confused, IL6 runs dandy & probably shouldn't

I agree with olbuddyjack, and running on 5.5 cylinders won't show that much power loss. If you do the work yourself, and send the head out to be redone, it should't empty your wallet.....JK

 

[DJ]

Re: confused, IL6 runs dandy & probably shouldn't

Zig,<br /><br />4300 is TOPS for that engine.<br /><br />I sugeest you run some Sea Foam (NAPA), or, GM TOP ENGINE CLEANER (dealer) through it to loosen up any stuck rings or valve deposits.

 

[ziggy]

Re: confused, IL6 runs dandy & probably shouldn't

thanks for the input folks. that would be good news if it is only the head that needs work. reason i'm confused is that, on one test the compression came up with the oil added, one time it didn't. the sea foam sounds like a good idea perhaps. think i will do one more compression test and make sure that the 3 squirts of oil don't bring it up for sure before i do any work to it. thanks for the reassurance that it is a hard to destroy engine. thanks for the ideas. i reckon i will be doing something to it and will be writing in soon about what i decide to do......thanks.