150 black max odd sound ??!!

[Maximerc]

I just purchaced a black max 150 1984 with the oil injection removed. It appears that the power head has been apart at some time , though it looks like a good job not a mess. The engine runs great on the water on my 18 ft baja it will pull 52 or 53 with three in the boat. The engine just seems to have a odd sound to it .. Like a cracking .. if it were a 4 cycle I would suspect a intake valve would be burnt .... I took a compression reading and one cylinder is 15 or 20 below the others (130 and the low is about 110 ) I also could believe it to be a Exhaust manifold leaking ... I must profess I have had countless car engines apart but never a outboard power head .... Ideas and imput would be great thanks ,, BTW my dad sold mercs from 1961 till 1971 .. so its kinda in my blood ...

 

[merc16]

Re: 150 black max odd sound ??!!

maximerc give me a better descricption on how your engine is runnig and how it behaves then ill see if i can help you

 

[Maximerc]

Re: 150 black max odd sound ??!!

It runs fine , the sound is all the way through the power band. It may be just a touch rough all the way through or that may just be the sound of the engine making it seem that way .. It idles down fine . Starts pretty well. All the plugs look fine When running the 52 MPH it was not quite to redline but It was close ,, right where it should be in my mind with three people in the boat. I cant think of any thing else to add .. except that there is water squirting out the back ,, I think there is a hole in the Radiator..

 

[sharkcat]

Re: 150 black max odd sound ??!!

Try doing a decarb it might improve the compression on the low cylinder.Also try & go for a ride in another boat with the same engine on it & see how that sounds...could be the sound that this particular engine makes

 

[jdkzrt]

Re: 150 black max odd sound ??!!

Sounds like you may have a cracked / broken reed. Big job to check though, because they are on a plate behind the carbs on this engine.

 

[Outrage 19]

Re: 150 black max odd sound ??!!

Don’t let this happen to you. This is what a bent reed did in my 87 Merc 150. It’s worth the tare down time to check it out.

 

[jdkzrt]

Re: 150 black max odd sound ??!!

OR 19 - good point (I can't see you pic but I know what these factory reeds can do). I would always stay away from factory stainless reeds and use aftermarket plastic or fiberglass for sure.

 

[Maximerc]

Re: 150 black max odd sound ??!!

What are the best reeds ? cost ? any idea how many hours to pull off the carbs?

 

[Maximerc]

Re: 150 black max odd sound ??!!

where can I get these reeds ???????

 

[Mettaree]

Re: 150 black max odd sound ??!!

Maximerc: Try Boyesen.com for non-metallic reeds<br /><br />Fair Skys, Smooth water