Compression on used motor

T

ttriebler

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Hi all,<br />Threw a rod on my 70's 115hp in-line 6 :-( so been looking around for a used motor. Have found an early 80's 150hp in-line 6. Can probably get it for $500-$700AUS ($400-$650US)<br /><br />It's been sitting for a little while but looks in reasonable shape. A quick compression test showed 110-120psi on all cylinders except #1 which had zero.<br /><br />A torch looking down hte bore of #1 showed the piston a bore looked good. Anyone know if the total lack of compresison could be from stuck reed valves/exhaust issues? And could it be simple to inspect by taking some of the side plates off?<br /><br />Is 110-120psi a decent amount of compression for one of these? My 115hp had around the same (but not so even) and it was a ***** to start.
 
OBJ

OBJ

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Re: Compression on used motor

Rings could be stuck Todd. 0 compression isn't good and usually signals bad news. Looking into the cylinder through the spark plug hole usually don't tell you the whole story. You could possibly remove the exhaust cover and get a good look from there or the fuel by-pass covers maybe easier.
 
rickdb1boat

rickdb1boat

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Re: Compression on used motor

110-120 is great! The one with no compression is not so good. Pass!! Nothing outside of a rebuild will cure "0" compression...
 
Clams Canino

Clams Canino

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Re: Compression on used motor

I'd say that's OK compression, though I've seen 140 / 145 on a really tight, just broken in 1500.<br /><br />#1 is an issue though.<br /><br />Aside from a set of rings and seals, the dead 115 could yeild all the parts you need to fix it assuming #1 don't have to go .015 over.<br /><br /><shrug><br /><br />-W
 
M

Mercury140-I6

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Re: Compression on used motor

Aside from the compression issues, who told you that the 150 inline 6 was an early 80's model? Late 70's was the end of the 150 inline 6 and the beginning of the 150 V-6. <br /><br />Thought you should know.<br /><br />Craig
 
T

ttriebler

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Re: Compression on used motor

Serial number is 8018589<br />I haven't checked the year out yet...the seller told me it's early eighties. I would have said 1980 at best.
 
A

andrewkafp

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Re: Compression on used motor

1500 (150,0) 3502806 - 3752619 1973 6 cyl inline <br />1500 (150,0) 3752620 - 4121434 1974 6 cyl inline <br />1500 (150,0) 4121435 - 4319879 1975 6 cyl inline <br />1500 (150,0) 4319880 - 4602011 1976 6 cyl inline <br />1500 (150,0) 4602012 - 4868997 1977 6 cyl inline <br />1500 (150,0) 4868998 - 1978 6 cyl inline <br />1500XS (150,0) 4868648 - 1978 6 cyl inline <br /><br />Reckon it's 1976 My Aust S/N 1981 is 8055*<br />I have a line-up chart that says USA 4357640 lines up with Aus 8030090 = points to 1976 ish :confused:
 
Clams Canino

Clams Canino

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Re: Compression on used motor

It's the year right before they renamed the 150 a 140. I think that makes it a 1977.<br /><br />-W
 
Clams Canino

Clams Canino

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Re: Compression on used motor

Yes confirmed. The "140" appeared in 1978. <br /><br />So you have a 1977 as yours falls into the serial year right before the 140.<br /><br />-W
 
A

andrewkafp

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Re: Compression on used motor

The distributer vanished in 1979 ? Correct me if I'm wrong Clams ???<br />So if it's got one it's not later than 1979..<br />1980 had light/dark blue bands, silver "Mercury" and red "150"<br />This is a 1979<br /> http://www.myfishingpictures.com/showphoto.php?photo=13002 <br />This is an 82<br /> http://www.myfishingpictures.com/watermark.php?file=527/141382_merc.jpg <br />This is an 81<br /> http://www.myfishingpictures.com/watermark.php?file=527/1413merc50b-med.jpg
 
T

ttriebler

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Re: Compression on used motor

It's got a distributor so can't be younger than 79. The cowling is different to the one in the photo though. It looks the same as my 76 115hp. Silver 'mercury' writing in italics. <br /><br />I think I'll let this motor go though. I've seen a 150hp 80's model with stainless prop advertised for $4000 that I can test on a boat. That sounds like less hassle (and more paychecks unfortunately).
 
A

andrewkafp

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Re: Compression on used motor

Don't be disuaded by the year...<br />If it has been looked after, a 70's motor is<br />as good as an 80's 150HP is 150HP after all..<br />But don't let the seller tell you it's something that it aint..
 
Clams Canino

Clams Canino

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Re: Compression on used motor

Yes, the distributor vanished sometime in 1979, presumably with the release of the 1980 models in late 1979. :) But knowing Mercury, you can never be quite sure. LOL<br /><br />(The classic example was 1972. The 140 appeared with the new base gasket, block painted black, etc etc. They all got the "new" blue stripe as opposed to the 1971 red. But the 115 got to use up the old silver blocks with the old base gasket, AND they apparantly started the season with red stripes, switching to blue when the red ones ran down.)<br /><br />Yes that '79 wrap looks like a '79, The early 80's ones confuse me. LOL<br /><br />-W
 
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