question about 8.1 mercs

[adams]

The boat I am looking at has 2004 8.1 merc horizons in it. It is the 370hp version not the HO. Does anyone have any experience with these motors in a 31? What is the cruise, top speed, respected rpms and fuel burn?

I tried doing some searching but found little actual applications in the 31. What I found was people asking the same thing I am, but the posts were a few yesrs old now. I think I saw something about the motors in a 33 and 35? Also I saw some posts about a guy who put the HOs in.

Also does anyone know anything about the reliabilty of the motors in general, or what to look out for? I also saw a post about someone mentioning someting about getting water in the cylinders?

Thanks again everyone!

[alano]

Going on 5 yrs, ~500 hours in my 35 - no major issues, lost a couple of weeks troubleshooting what turned out to be crappy AC spark plugs that cost like $10 a piece, will be replacing them with NGK this fall. A MAP sensor needed to be replaced, Rinda software ID'd the actual sensor, the Livorsi gauges ID'd a fault with warning, cleaned and retorqued a knock sensor after the same. I've got real concerns with (1) how to EVER replace a pump impellor, it's buried underneath and behind the motor mount/stringer and (2) ditto with the fuel cooler and (3) a manifold is in the $500 neighborhood (A as in (1) manifold)! They are really torque filled, put 1.5" pitch in the wheels and bounce the rev limiter when fresh off the hill and burn the same as the 454s. Fuel burn / speed is 22kts/32gal/hr @ 3400 and the ratio (.7) stays the same across 2800rpm thru 3700rpm. BR, Alan.

[Mike Moran]

what about gas tanks have they been replaced ?

[adams]

No the fuel tank is original, the aux tank is newer. How heavy is the 35? Anyone else with real world experience with the 8.1s in a 31? Thanks guys.

[adams]

anyone? can someone point me in the right direction. I tried to do searches on google as well and came up with nothing, as well as THT.

[In Memory Walter K]

If If it were a 31 and the fuel tank is the original, I'd tell you to run!

[adams]

Walter...the new motors have 200 problem free hours on them running from the original tank. I would plan on replacing the tank.

[dougl33]

Is ehtanol sold at marinas in GA? If not, why bother messing with the tank?

[adams]

The places I fuel up are ethanol free. I just sold my Boston Whaler Dauntless. There was a gas station close to the house that sold non-ethanol gas, 89 octane, for about the same as reg. unleaded. The thinking behind replacing the tank is that it is old. Replace it before something happens.

[In Memory Walter K]

Old doesn't matter, ethanol does. Without ethanol the Bertram fiberglass tanks are forever. You guys are lucky, no way in hell we can find non-ethanol fuel out our way unless you have an airport connection so you can get Avgas.

[adams]

Thanks for the info Walter. The boat is actually a NE boat and has had ethanol ran in it, and currently has ethanol fuel in it. The motors were installed in 2004 and have 200 hours on them. How long has ethanol been the main fuel up there?

[John F.]

Do on search on Scott Traenkle here. He put 8.1 HOs in his B31 last year or so, and posted some numbers. A friend of mine had a 2004 31 Tiara with the 8.1s, and they were great motors. No problems at all in the 900+ hours he put on them. I'm not sure of the fuel burn, but it was in the range of 1 nmpg.

If it were me, I'd get the Ethanol gas out of the boat, and run straight gas. Take a look at the plugs. I've heard too many bad stories about ethanol, motors, and Bertram tanks. I replaced my tank last year with an aluminum tank--we have E10 here in the Chesapeake--and the tank was about $2K. I have the original fiberglass tank that's never had ethanol in it and looks fine. You can have it if you need it for a donation to Capt. Pat.

Good luck.

John

[In Memory Walter K]

I am pretty sure we've had E-10 since about 2006. If you can, drain it out as it's at it's worst sitting there. Collects water, too. Technically called Phase Separation. The dissolved epoxy passes through the filters and settles in your carburetor, plugs, and worst of all on your valve seats. When your engine cools off and sits, the stuff hardens and unfortunately glues the closed valves down. When you crank her over, you bend your valve rods on those cylinders.

[Carl]

I am pretty sure we've had E-10 since about 2006. If you can, drain it out as it's at it's worst sitting there. Collects water, too. Technically called Phase Separation. The dissolved epoxy passes through the filters and settles in your carburetor, plugs, and worst of all on your valve seats. When your engine cools off and sits, the stuff hardens and unfortunately glues the closed valves down. When you crank her over, you bend your valve rods on those cylinders.

No joke, happened to me and many others. Not a good way to start with a new to you boat.

Pull a couple plugs and look for black caked on crap with a gooey residue at the tip. Kind of an early indicator

[adams]

Thanks for all the replies guys. About 2 years ago is when I found out about the problem with ethanol and boats. But my boat was already built with ethanol in mind so it didn't affect me besides letting the boat sit (separation) and I didn't do much more research on it. I know all about the phase seperation, the condensation that it will create in the tank, the ethanol basically cleaning the tank and sending all the junk to the filers and plugging them up etc.

Walter- I didn't know about the stuff passing through and then hardening, thank you for that. I was also told it has stabilizer in there. I haven't done any real searching on the stabilizer. Are there any products out there that actually work?

John- I did a search before on Scott Traenkle, but thank you for the heads up. The main difference is the boat I am looking at has the standard 370 hp. Also he was saying he was way under propped. I sent him a PM seeing if he had new props and new numbers but haven't heard back from him. And what size is that tank?! I just may take you up on that offer if the deal goes through!

Thanks guys.

[Carl]

the ethanol basically cleaning the tank and sending all the junk to the filers and plugging them up etc.

Walter- I didn't know about the stuff passing through and then hardening, thank you for that. I was also told it has stabilizer in there. I haven't done any real searching on the stabilizer. Are there any products out there that actually work?

Thanks guys.

Ethanol may clean out Alum, Steel, Stainless Steel and Fiberglass tanks...but aside from just cleaning the tars and varnish build up on some Fiberglass tanks... the Ethanol will DISSOLVE the tanks RESIN, yes it will eat away the tank itself. this is where the problem comes in. If it where just the Tars and Varnish... that could be filtered out...but the Resin goes into solution and passes right thru any filter you can find. Once in the motor it just glues everything it touchs. Stabilizers and additives just don't work for this. Aside from the motor being effected yo have to keep in mind the tank itself is being compromised...the Resin is the stuff holding it together.

If you have a fiberglass tank or other tank not effected by E10, then your lucky... just add the stabilizers so the alcohol level doesn't go higher with phase separation.

[John F.]

Adam-

I think the difference between the 8.1 375s and the 8.1 425s is that the HOs make the extra hp at higher rpms where a B31 won't really ever be. So, if you can get cruise numbers from Scott, they should give you a pretty good idea. I remember the underpropped thing. The tank is the older 175 gallon. I'd love to have a set of 8.1s in my boat.

John

[adams]

sim- thanks for explaining the ethanol and resin piece, I fully understand now.

John- Do you know anything about the motors in general? Are they reliable? Any common problems?

I am definitely going to have the boat surveyed, if and hopefully when it gets to that point. The seller seems to be a real good guy, and has seemed to be open and honest about everything. But this original tank with ethanol really has me worried. One of those you really never know type of things.

[Carl]

I don't mean to scare you..just go into it knowing the potential issues with fiberglass tanks and E-10. Without using E-10, the tank could last indefinitely from what I have been told. Some late model tanks could deal with E-10. I do not know which are which.

Just go into it knowing...

[John F.]

I don't know anything specific about the 496s. They have a rep. as really good motors (like 454s), and my friend had alot of trouble-free hours out them. His were Crusaders, not Mercs. I've never heard anything bad about them that was motor-related. CC had some problems that were install related.

[STraenkle]

Adam:

Sorry about not responding to the PM, but I have not changed the props so the info I posted is still true. I have to tell you though, the reason I got the 8.1 is the 454's fell victim to ethanol. The engines ran great, I had the old tank for the first year (it appeared in June) of ethanol and they seemed fine. I changed the tank that winter, but the next season was nothing but a nightmare. Both engines limped thru the year, but I could not trust it to go offshore. I got the HO's at a great deal from a reputable guy and that's how they ended up in the boat. Way too much power, but at cruise I am barely into the throttle. The only down side is it is very touchy and hard to sync. One little touch on the throttle and the engines change RPMs quite quickly.

I will tell you that if those engines have had ethanol run thru them with the old tank, expect to buy new engines soon. Not the fault of the engine, but that fiberglass resin hardening on the valves means they are dead. I pulled the heads on the old 454's that were perfect a year before, were caked after the ethanol and I exploded two lifters. I still would love to know who I could sue, but the "green party" types never looked at the whole picture, People with no food and engines blowing up. What an idea to subsidize corn farmers. I guess that might put this post on the politics page, but I am still irked about it all, $20,000 bucks tossed into the wind.

[Carl]

Adam:

but I am still irked about it all, $20,000 bucks tossed into the wind.

at least you got something for all the money you tossed to the wind. I spent a good portion of what you did to get right back to where I started. Talk about irked....

[In Memory Walter K]

Cost me $10,000+ on my 20. Bet Ethanol has cost this group alone over a million bucks and no one has even blinked. Try that on any other group and you'd be reading about it in the front page of the NY Times. I got us a story in the Wall Street Journal and no one did a thing. As I have said before, It's going to take a Congressman's or Senator's son blowing up from a distressed leaking boat tank before anyone does anything about Ethanol. Walter

[adams]

Scott- How do you like the engine so far? Any other issues besides the touchy throttles? I am sorry to hear about all the horror problems with ethanol. Like I said most marinas down here are ethanol free, or have ethanol free gas. Thanks again for all the help guys.