1980 Mercruiser MIE 330: Advice/Suggestions Wanted

[1980Coronado]

I'm now in the acceptance/action stage of stringer replacement in my 1980 Century Coronado. I've been battling a vibration issue since I bought it in 2010.....final diagnosis is bad stringers. I've realigned the engine 3x this summer and the vibration goes away and then comes back slowly over the next several hours of operation. So....the engine has to come out. I know the engine is the original and the hour meter indicates 1140+ hrs. A compression check was done last summer with good results....from memory they were all in the 130-140 psi range. #8 might have been a little low on compression but I believe it was from cranking the engine. It was the last one we checked and I don't think I got an accurate reading....something to check again for sure. The bottom line here is that the engine runs and performs well but has quite a few hrs on it.

My question is this. Since it has to come out for the stringer replacement, what recommendations can you provide regarding the engine? What should I do as a minimum while it's out? I plan on keeping the boat so this isn't a fix it to sell it thing. What would you do if it was your boat?

I'll definitely be posting in the restore thread for help with the stringers. Dis-assembly begins this weekend hopefully.

 

[Bondo]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

I'm now in the acceptance/action stage of stringer replacement in my 1980 Century Coronado. I've been battling a vibration issue since I bought it in 2010.....final diagnosis is bad stringers. I've realigned the engine 3x this summer and the vibration goes away and then comes back slowly over the next several hours of operation. So....the engine has to come out. I know the engine is the original and the hour meter indicates 1140+ hrs. A compression check was done last summer with good results....from memory they were all in the 130-140 psi range. #8 might have been a little low on compression but I believe it was from cranking the engine. It was the last one we checked and I don't think I got an accurate reading....something to check again for sure. The bottom line here is that the engine runs and performs well but has quite a few hrs on it.

My question is this. Since it has to come out for the stringer replacement, what recommendations can you provide regarding the engine? What should I do as a minimum while it's out? I plan on keeping the boat so this isn't a fix it to sell it thing. What would you do if it was your boat?

I'll definitely be posting in the restore thread for help with the stringers. Dis-assembly begins this weekend hopefully.

Ayuh,... I'd do another compression test, 'n do it right, if ya didn't before,...

1100 hours is only maybe 20% of it's expected service...

but a good solid set of numbers is a better indicator of it's health...

If their even across the board,... clean it up, 'n paint it, then call it a day...

 

[1980Coronado]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Okay, I will recheck compression before removal. If 1100 hrs is 20% of the service life that means this engine has an expected service life of 5500 hrs? I had no idea it was that much. I had heard somewhere that the inboard ski boats (usually with the small block v8's), were at the end of their expected life at roughly 1000 hrs. I know this is a Big Block, but I never guessed it was supposed to go over 5000 hrs.

My concern was more with the 32 years of age. I thought that maybe I should replace seals and gaskets, along with hoses belts etc. while I had it out and accessible. Maybe rebuild the carb as a preventative? My neighbor was a good car mechanic in his previous life....he basically said the same thing...."if it's running good why touch it...you act like it's a big deal to take the engine out". The two of you seem to agree.

 

[Bondo]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Okay, I will recheck compression before removal. If 1100 hrs is 20% of the service life that means this engine has an expected service life of 5500 hrs? I had no idea it was that much. I had heard somewhere that the inboard ski boats (usually with the small block v8's), were at the end of their expected life at roughly 1000 hrs. I know this is a Big Block, but I never guessed it was supposed to go over 5000 hrs.

My concern was more with the 32 years of age. I thought that maybe I should replace seals and gaskets, along with hoses belts etc. while I had it out and accessible. Maybe rebuild the carb as a preventative? My neighbor was a good car mechanic in his previous life....he basically said the same thing...."if it's running good why touch it...you act like it's a big deal to take the engine out". The two of you seem to agree.

Ayuh,.... Most motors are Killed by their Owners, at well under 1000 hours,...
Many in under 100 hours,..

5000 + hours is no big deal for a Well Maintained motor,...

A diesel will easily go Twice that...

My little ole 4.3l was a band-aid build, by me, something over 1200 hours ago, 'n she still shows solid even compression numbers,...

Btw,.... I like yer neighbor, already,... pretty smart guy,...

 

[1980Coronado]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Yes my "beer buddy" DeWayne is one of the good mechanics.......he is one of those hard working school of hard knocks guys that never went to College but is probably smarter than most who did (including me at times)....you'd probably get along with him just fine. He buys broken down cars for $500 and sells them after he fixes them. I keep trying to get him to do a couple of boats, but he won't do it.

The entire boat seems to be well maintained for a 32 year old boat but I have no idea what the engine maintenance has been like. I'm the third owner so who knows. I just know it runs too smooth to have any serious issues. The only problem I've had with it is when you shut down in the middle of the lake to swim for 15 minutes and then start it back up, it will stumble and die when you accelerate. It's acting as though it doesn't have enough fuel because if you pump the throttle you can keep it from dieing and it will come out of it. I suspect that fuel is evaporating from the bowl when the engine is hot and then it has to "catch up". It doesn't happen every time and is more likely to happen if you've been pulling a skier or working the engine hard and then shut it down for 10-15 min and start back up again. It has the Quadrajet carb, and I've been told they have a tendency to leak fuel out of the cross drilled hole plugs in the base, but I don't believe I have this problem.

The stringers are bad due to age not neglect, and it's not like they are rotten mush........just soft enough that the motor is sinking enough to cause vibration. As you know it only takes about .010" of movement to cause it to vibrate terribly, and you can feel it wobble when it's only .005" off. It's time to fix it. Interior has already been removed. Compression check will be done this weekend and I'll write the numbers down this time and post here.

 

[Bondo]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

I suspect that fuel is evaporating from the bowl when the engine is hot and then it has to "catch up". It doesn't happen every time and is more likely to happen if you've been pulling a skier or working the engine hard and then shut it down for 10-15 min and start back up again. It has the Quadrajet carb, and I've been told they have a tendency to leak fuel out of the cross drilled hole plugs in the base, but I don't believe I have this problem.

Ayuh,.... I'd sooner think it IS yer problem,....

Gasoline don't evaporate like that...

 

[1980Coronado]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

hmmm.....ok then. I guess the carb needs to come off and be looked at. What other symptoms might indicate this problem?

 

[1980Coronado]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Ok Bond-o...here are the compression numbers

warmed engine up, removed spark plugs, opened carb to full throttle.

readings in order of check

#8 140 psi
#6 140 psi
#4 140 psi
#2 140 psi
#1 144 psi
#3 143 psi
#5 146 psi
#7 145 psi


all cylinders had a maximum pressure reading that was approximately 5 psi higher while cranking. When stopped the pressure reduced and held at the numbers posted above.


The service manual specifies a compression of 150 psi for the MIE 330....so what do you think? At 140 psi I'm over 6% off the factory specification after cranking stops...while cranking the lowest number would be 145 psi and we did see 150 psi while cranking on several of them. so what's your verdict Bond-O...rebuild the carb and check the cross drilled ports in the base for leakage? Then clean it up, paint it and call it good?

 

[Bondo]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Ok Bond-o...here are the compression numbers

warmed engine up, removed spark plugs, opened carb to full throttle.

readings in order of check

#8 140 psi
#6 140 psi
#4 140 psi
#2 140 psi
#1 144 psi
#3 143 psi
#5 146 psi
#7 145 psi


all cylinders had a maximum pressure reading that was approximately 5 psi higher while cranking. When stopped the pressure reduced and held at the numbers posted above.


The service manual specifies a compression of 150 psi for the MIE 330....so what do you think? At 140 psi I'm over 6% off the factory specification after cranking stops...while cranking the lowest number would be 145 psi and we did see 150 psi while cranking on several of them. so what's your verdict Bond-O...rebuild the carb and check the cross drilled ports in the base for leakage? Then clean it up, paint it and call it good?

Ayuh,.... Sounds like a rock solid long block motor to me,....

Either fix/ rebuild/ reman the carb, or splurge, 'n drop on an Edlebrock 1410....

The droppin' pressure is probably yer gauge,...

Mine the needle only goes Up, til I push the release button...

 

[1980Coronado]

Re: 1980 Mercruiser MIE 330: Advice/Suggestions Wanted

Ayuh,.... Sounds like a rock solid long block motor to me,....

Either fix/ rebuild/ reman the carb, or splurge, 'n drop on an Edlebrock 1410....

The droppin' pressure is probably yer gauge,...

Mine the needle only goes Up, til I push the release button...

I wondered about the gauge. It holds pressure until you hit the release button, but if you watch the gauge while cranking it spikes a little higher than where is settles when you stop. It's not a "high-end" liquid filled gauge...just your run of the mill off the shelf at the auto parts store type. Probably not what a guy would buy if he was doing this for a living. It is the type that threads into the spark-plug hole so it's a little better than the type with the rubber tip you push into the hole and hold.

Thanks for the feedback. I'll look into the Edelbrock.