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Author Topic:   engine problems / repower?
JOHN W MAYO posted 08-10-2002 09:59 AM ET (US)   Profile for JOHN W MAYO   Send Email to JOHN W MAYO  
On my 19 Revenge, I have a Mercury 150 1500 inline 6 cyc probably a 1976 model.

It runs, but badly. Compression is 60 /125 / 120 / 120 /15 /#6 I was unable to check because of location.

#1 cilinder with 60psi has shiney metal on the plug after about 30 miles of use. the engine also shuts down if you run it full throttle after about 1 mile.

Any idears???
IF i repower would a 175 or 200 work ok on the whaler?

DIVE 1 posted 08-10-2002 09:12 PM ET (US)     Profile for DIVE 1    
Shiney metal on a spark plug usually indicates a piston is melting. This is caused from a lean fuel condition. Two things will cause the lean condition: carburetor jets plugged or a bad crankshaft seal that alters the air to fuel ratio.
JOHN W MAYO posted 08-11-2002 02:44 AM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
I just got the revenge 19 a month ago and the previous owner said he at just had it in the shop have the carburators worked on.

I just got back from a 12 mile run with the whaler and after adjusting the top carb 1/2 turn richer, it did not shut down, and ran about the same or maybe a little better. I did not push the speed, only 10 to 26 mph. jim
The compression has me really worried and from what you say of the piston........not good news.

How difficult is it to rebuid one of those engines? (I have rebuilt several car motors)
any idea of cost? This may be the wrong forum for that question, but not sure where to go.

DIVE 1 posted 08-11-2002 07:26 AM ET (US)     Profile for DIVE 1    
It's been 20 years since I worked on an inline merc. It depends on how many special factory tools are required. The first thing that you should do is to pull the cylinder head and look at the bad piston and cylinder and then decide if a rebuild is cost effective or possible(depending on the cylinder). I have no idea on parts cost-sorry.
shoctor posted 08-12-2002 09:23 AM ET (US)     Profile for shoctor  Send Email to shoctor     
John I recently helped a friend with a similar situation he had an old 115 merc that inhaled a garbage bag for a few miles. We caught the problem half a miles to late and beyond overheated the motor and burned a few pistons. After removing the head and checking the extent of the damage we decided to replace. Not wanting to spend the 4-7 grand to replace we looked in local papers and want ads for a newer used motor. Found a freshwater 115 yamaha in awesome shape with 300 hours for 2000. Bolted on and ran it. There are plenty of used motors in good shape for significantly less than the price of a rebuild. looked to rebuild a 200 evinrude. rebuild kit was slightly more than 800 and you still have all of the machining costs on top of that. The merc you have is a 76 (26 yrs old) Parts are far and few between and $$$$$$. Just my .02
JOHN W MAYO posted 08-12-2002 11:36 AM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
Thanks for the info. I am thinking more and more about maybe running it till it just quites.
The 150 Merc would probably not be worth it as you said. I took the whaler out for the yesterday and enriched the #1 carb 1/2 turn, to maybe make it run cooler. I went about 30 miles with no shut downs.(I did not run it hard)..maybe it will last the summer. I just won't take it back to sea with that engine.
I will check the papers. Thanks
Clark Roberts posted 08-12-2002 12:38 PM ET (US)     Profile for Clark Roberts  Send Email to Clark Roberts     
Reference to "removing the head" on in-line six Merc... comment.. there is no removeable head since block is blind bore (pistons go in from crank side). The plate that resembles a removeable head is in reality a water jacket cover. Almost all mercs are blind bore and most notable exception are the V6's... happy Wrench Twistin'... Clark.. Spruce Creek Navy
Bigshot posted 08-12-2002 01:44 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ditto! I would be more worried about the cyl with 15lbs or was that a mistake? Run it till it pukes or replace it. You can not rebuild one yourself unless you have a boatload of ring compressors, etc. These engines are a strange design and not conventional at all. If you remove the exhaust plate, you might get a good look at the cyl wall but I would not even bother with compression numbers like you have.

Are you sure it is metal on the plug and not just clean from water ingestion?

DIVE 1 posted 08-12-2002 05:58 PM ET (US)     Profile for DIVE 1    
Thanks for catching my mistake about the cylinder head, I guess I have been working on the OMC V-6s too long.
JOHN W MAYO posted 08-12-2002 09:12 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
I have the ring squeezers etc for automotive work, but not sure of the extra tools for the Merc inline 6 cyl 1500

The plug did appear white metal as I removed it and the plug was cleaned

Yes, that compression was 15 on one plug, surprisenly the plug was pretty good on that was the cylinder with 60 psi, that I get the thin metal.

I squirted oil in the clyinders and all went up to 125 to it sounds like shot rings to me

shoctor posted 08-13-2002 11:53 AM ET (US)     Profile for shoctor  Send Email to shoctor     
John run it till she craps out big time just wouldn't venture too far from shore and the renewal of the sea tow membership may be a good idea for the free tow back in. Good luck with the search. If you live within a few hours of freshwater lakes I would call around up there to find a nice freshwater unit.
JOHN W MAYO posted 08-19-2002 08:57 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
Thanks, just renewed the sea-tow just in case. I am trying to add a little extra oil to try and keep it cooler...40-1 or more, maybe better lubrication will to make it last a little longer.

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