1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

[Harritwo]

My exhaust manifold is the original manifold on the boat. I am going to replace it and would like some information and advice. I have been advised to replace it even though it is not showing any signs of failure since it is operated in Florida and has been since new and it is Brackish water where I am located.

1) Should i use a Mercruiser, Barrs, or Sierra manifold? My marine mechanic friend has told me to not ever use Sierra on a Mercury but i would like other opinions as to why or why not.

2) Since this manifold is 18 years old, Does any one have any tips on getting it off. Unless i am told something better, my intentions is to soak it with PB BLaster for two or three days, then bring it up to operating temp and try to take it off with an impact.

3) I intend to replace the manifold, riser, elbow, and hose as well as all plugs etc. Any other suggestions while i have it tore down. I have already replaced all the cooling hoses, t-stat, water pump impeller and bellows.

 

[Howard Sterndrive]

Re: 1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

I'd recommend a Mercruiser part for another 18 years of service.

Have a good look at the exhaust shutter and the pipe that runs down to the transom. Unfortunately, you have to pull the engine to change that pipe though, but better to check it now.

 

[fishrdan]

Re: 1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

I would either use the Mercruiser, or a Barr or Osco manifold. Buying a Sierra or other China made manifold is risky, "roll of the dice", it could work or it could not work. Not working could mean the engine gets filled with water, then you would be buying a new engine along with another manifold....

Check the shutters as Howard suggests, I would also replace the exhaust coupler. (I think you mentioned that as the "hose".)

For other suggestions, what maintenance been done on the boat in the past few years, any?

 

[tomdinwv]

Re: 1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

Be careful using an impact to remove the bolts. Really easy to snap exhaust manifold bolts.

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

Routine Maintenance is performed annually, Oil Change, Spark Plugs, Fuel & Water Filter, Fuel Filter, Lower unit oil change, repack wheel bearings annually, change every two years, and manufactured a bracket to place on the end of the starter after the outboard bolt broke off. It took me about 10 hours to get that bolt out and cost me over $100 in drill bits and an e-z out that snapped off. Left hand carbide bits are expensive. Last year the trim limit switch went out, so i had those changed, the water pump impeller, while i was in there i discovered the drive shaft was bad, and changed the drive shaft & Gimble bering, resealed the transmission because it showed signs of water intrusion, replaced the trim pump because it was blowing oil out the cap when trimming up to trailer mode, and replaced teh steering cable. Age had gotten the best of it. I have replaced all the cooling hoses, and the t-stat. The zincs still look good, but are 5 years old. Should they be replaced?

 

[wmk123]

Re: 1994 Mercruiser 3.0L Alpha 1 gen II Exhaust Manifold

Routine Maintenance is performed annually, Oil Change, Spark Plugs, Fuel & Water Filter, Fuel Filter, Lower unit oil change, repack wheel bearings annually, change every two years, and manufactured a bracket to place on the end of the starter after the outboard bolt broke off. It took me about 10 hours to get that bolt out and cost me over $100 in drill bits and an e-z out that snapped off. Left hand carbide bits are expensive. Last year the trim limit switch went out, so i had those changed, the water pump impeller, while i was in there i discovered the drive shaft was bad, and changed the drive shaft & Gimble bering, resealed the transmission because it showed signs of water intrusion, replaced the trim pump because it was blowing oil out the cap when trimming up to trailer mode, and replaced teh steering cable. Age had gotten the best of it. I have replaced all the cooling hoses, and the t-stat. The zincs still look good, but are 5 years old. Should they be replaced?

Can't believe it! It sounds almost like I was writing this post, WHEW. I am glad I did it all and its behind me.

Now for some boating!!

In addition to all you spoke of, I have put in 2 starters. Now I am told by my mechanic that I have to pull this new starter and lube the shaft where the pinion gear is, because its sticking. What a world, new should work?? NO??