1987 OMC 7.5 popping and not reaching higher rpm range.

[JerryRigged]

Re: 1987 OMC 7.5 popping and not reaching higher rpm range.

I talked to a guy who has been rebuilding engines for thirty years.

He said that the former owner who built the engine should have installed an MSD distributor with the adjustable MSD ignition system.

He said he bet money that the advance was not set properly thereby setting the timing off when under load.

He said he'd also avoid using aluminum rods in a boat engine since they have a short lifespan.

Looks like I have a couple of options here.

Yank it and rebuild. Boats in great shape, Outdrive has only 40 hours since rebuild. Update the distributor, replace rings, and rods and whatever damage the pistons may have.

Dismantle the boat and sell the parts.

Gil marine aluminum racing Exhauast: 2400.00
Engine rebuilt for street use: 9000.00 minus 3000.00 for rebuild, net 6000.00
Outdrive: 2800.00
Other OMC drive components: 1200.00
Other Liberator stuff parted out: 3000.00 or more
trailer 800.00

All worth more than the boat itself now as a whole

 

[HT32BSX115]

Re: 1987 OMC 7.5 popping and not reaching higher rpm range.

Gil marine aluminum racing Exhauast: 2400.00
Engine rebuilt for street use: 9000.00 minus 3000.00 for rebuild, net 6000.00
Outdrive: 2800.00
Other OMC drive components: 1200.00
Other Liberator stuff parted out: 3000.00 or more
trailer 800.00

All worth more than the boat itself now as a whole

If you could get that much for the engine, drive and other engine and exhaust parts, I would go for it!

In 2006, I bought a complete 1997(120hrs since new) 454/Bravo III package for $5000. It posted on Craigslist from a 1998 24ft Bayliner that had a tree fall on it for. After selling all my OMC "junk" for $3500+ it turned out to be a pretty good swap!


After I bought the engine and drive, I spoke to a Mercruiser dealer and he told me that he would have sold+installed the above package in my boat for about $13000 !

A few months later, someone posted a 2008 (80hrs) 496HO + Bravo III on Craigslist for approx $8000! I would have bought it if I hadn't already installed the first one!

There's always deals like this that pop up from time to time on Craigslist, EBAY etc......

I also looked for Volvo BBC/DP packages but boats with Volvos in them don't ever seem to get damaged!! (I suspect that, for every Volvo sold, Merc sells 10!!)

When I was doing this project, I saw an 87 Liberator on EBAY in very nice condition with a trailer (NO-ENGINE) starting at $1500 with no reserve. The auction expired with NO bids on it at all!

The good thing about an 87 boat with an upgraded/newer engine etc, is that the yearly costs are very low! My yearly registration is only $25! There's no personal property tax in Wa but if there was, it'd be pretty low too on a 26 year old boat!!

The insurance is really low too.

 

[JerryRigged]

Re: 1987 OMC 7.5 popping and not reaching higher rpm range.

If you could get that much for the engine, drive and other engine and exhaust parts, I would go for it!

In 2006, I bought a complete 1997(120hrs since new) 454/Bravo III package for $5000. It posted on Craigslist from a 1998 24ft Bayliner that had a tree fall on it for. After selling all my OMC "junk" for $3500+ it turned out to be a pretty good swap!


After I bought the engine and drive, I spoke to a Mercruiser dealer and he told me that he would have sold+installed the above package in my boat for about $13000 !

A few months later, someone posted a 2008 (80hrs) 496HO + Bravo III on Craigslist for approx $8000! I would have bought it if I hadn't already installed the first one!

There's always deals like this that pop up from time to time on Craigslist, EBAY etc......

I also looked for Volvo BBC/DP packages but boats with Volvos in them don't ever seem to get damaged!! (I suspect that, for every Volvo sold, Merc sells 10!!)

When I was doing this project, I saw an 87 Liberator on EBAY in very nice condition with a trailer (NO-ENGINE) starting at $1500 with no reserve. The auction expired with NO bids on it at all!

The good thing about an 87 boat with an upgraded/newer engine etc, is that the yearly costs are very low! My yearly registration is only $25! There's no personal property tax in Wa but if there was, it'd be pretty low too on a 26 year old boat!!

The insurance is really low too.

Yeah, I think I'm going that route

 

[JerryRigged]

Re: 1987 OMC 7.5 popping and not reaching higher rpm range.

What type of fouling did the sparkplugs show? Wet fouling? (spark problem) Sludgy deposits clogging the gap? (extreme oil fouling exaceratbing potential spark problem)

Got any pics of the sparkplugs?

They were wet with what appeared to be gas, but it could have been oil too. I was running Royal Purple full synth. which is really light and thin. less than one hour on plugs and oil too.