what to check with twin 1988 merc. 305's and Alpha ones

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heatz1express

Petty Officer 2nd Class
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Jun 23, 2004
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hi folks. I'm in the middle of a boat purchase pending survey and sea trial. 1988 Boat is 35 ft. w/twin 305 merc's and alpha ones. Just wondered if someone might be able to tell me what W.O.T. should be on these engines? Also, appropriate temp. and oil pressure readings at idle, cruise and W.O.T. ?
Anything else I should be mindful of?
 
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Bumperlt12

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Mar 17, 2012
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Re: what to check with twin 1988 merc. 305's and Alpha ones

I think... think, 4800-5200

Mine sits at about 170 degress, and center of the oil gauge... just dunno what the psi level is.
 
Don S

Don S

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Re: what to check with twin 1988 merc. 305's and Alpha ones

I think... think, 4800-5200
Click to expand...

Not even close. You are 1000 rpm too high.

3800 to 4200 per the manual, unless it's an LX.

specs.jpg
 
F

four winns 214

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Re: what to check with twin 1988 merc. 305's and Alpha ones

heatz1express said:
hi folks. I'm in the middle of a boat purchase pending survey and sea trial. 1988 Boat is 35 ft. w/twin 305 merc's and alpha ones. Just wondered if someone might be able to tell me what W.O.T. should be on these engines? Also, appropriate temp. and oil pressure readings at idle, cruise and W.O.T. ?
Anything else I should be mindful of?
Click to expand...
There should be documentation on the vessel specifying that value and others for your particular engine. The WOT throttle range specified by the original Merc documentation for my 305 and Alpha 1 (MR-1, actually) installed in my 1984 Sea Ray cuddy is 4200-4600.
 
Bondo

Bondo

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Re: what to check with twin 1988 merc. 305's and Alpha ones

heatz1express said:
hi folks. I'm in the middle of a boat purchase pending survey and sea trial. 1988 Boat is 35 ft. w/twin 305 merc's and alpha ones.
Just wondered if someone might be able to tell me what W.O.T. should be on these engines?
In the neighborhood of 4600 rpms...
Also, appropriate temp. and oil pressure readings at idle, cruise and W.O.T. ?
Temps of 160? or 170? would be expected, the rule of thumb on OP is 10 psi per 1000 rpms...
Anything else I should be mindful of?
Just like any other hull of that vintage, Rotten wood, stringers, 'n transom Especially...
Click to expand...

Ayuh,.... Good luck with it,...

A compression test oughta yield 'bout 140 psi to 160 psi across all the cylinders, with less than 10% variation...
 
H

heatz1express

Petty Officer 2nd Class
Joined
Jun 23, 2004
Messages
115
Re: what to check with twin 1988 merc. 305's and Alpha ones

thanks guys. Bond-o you are right to mention wood, stringers and transom. On-land survey just completed and some issues in these areas were identified. Now I have to decide whether I want to even bother with the sea trial or if I should let the deal go down the tubes.
 
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