Repowering a 280 (4.3's)

T

themikehyde

New Member
Nov 6, 2009
629
Potomac River - Colonial Beach
Boat Info
2001 280 Sundancer
Engines
Twin 4.3's
Well, after a compression test last night indicating 2 cylinders down (1: 160, 2: 160, 3: 150, 4:20, 5: 0, 6:160) I believe I am looking at some replacements (Long Blocks). The replacement for my last boat came from ebasicpower.com. That engine gave me 6 years of awesome performance before moving up to the 280. I found usengines.us that appears to have several upgrade options (50 more hp?). Has anyone purchased from them, or have any other recommended sources?
Thanks,
Mike
 
Are you sure the engine is shot - my friends boat had the same issue and it was a blown head gasket.
 
Since you are talking about a possible replacement with significantly more horsepower, it sounds like you are contemplating replacing both engines. Low compression in two cylinders can mean a lot of bad things, but as Scott said it could also be a bad head gasket, or bad valves, items that are far cheaper than two long blocks. There is probably enough room to pull the head with the engine in place and it would be short money even if it turns out to be something worse.

Henry
 
oops. Apparently the usengines have a few sites with conflicting prices. I just talked to them and their current site is www.usenginesinc.com.
@skolbe - I have not pulled it down yet, but since the low cylinders are on separate banks, I am thinking I have 2 different problems. I am going to try a leak down this evening. Yes, a head gasket woul dbe any easy fix, but I am not usually that lucky.
@Henry - I would definately replace both motors. This Spring when I replaced my manifolds, I replaced all 4, instead of just the 1 I thought was leaking. WE like taking cruises and I usually figure if something breaks, other like items are not far behind.
Mike
 
I purchased two new 4.3's and legs from Mercruiser this year through my local dealer. Warranty and peice of mind came foc.
They replaced very unreliable and for some reason underpowered 4.3's etc (previous owner issues, long story blah blah). The difference is amazing, we are a family of 4 and carry all the associated 'stuff' a family would and she simply leaps out of the hole and planes in a metter of seconds. Time and choice over again I'd pick 4.3 and bravo 1's again. My 2c
 
I am hearing from quite a few that replacing the 4.3 with upgraded 4.3's really seems to make an improvement. I am going to try one last effort and do a leak down to test for something simple (if you can call head gaskets simple?) before I start yanking it apart. I just know once I start repowering I am going to want to do all sort sof other upgrades while in the bilge. I am just not ready for the boatring season to be over so if I can get by the rest of theseason then repower over the winter, my wife will be much happier!
 
I feel your Pain Mike I had to repower earlier in the season. Good luck with the leak down test!
 
I repowered my 270 this winter and used Center State Engine from ebay. Long block 4.3s with new flywheel, refinished manifolds, starter and performance upgrades (now rated at 235hp) were $2500 each shipped. I had previously changed out the original Weber carbs to Edelbrock 1409s and replaced the exhaust on both engines. With the new engines, I also changed out alternators, batteries and all tune up items. Only the wiring harness and sensors (temp and oil pressure) and distributors were reused. I'd use them again - engines have both been fantastic and the difference in getting on plane is fantastic. I'm sure he has EFI versions available if you need it.
 
Well, I pulled the heads Thursday night and found two Tupi Ed exhaust valves. Dropped them off at the machine shop. He called and said all the seats had sunk so he was going to replace all of them and I can pick them up Tuesday. He said I should check the other engine also. I am hoping that that can hold off till layup. Not sure what caused the issue? Will give an update when I get her back together.
 
Just a thought before you run it again you might want to find out what caused the valves to tulip it's not normal wear in my opinion that engine either got overheated or could be running lean would definitely check the other engine and fuel for moisture.
 
What's the best way to check for moisture in the fuel other than to pull the separator and dump it into a clear glass bowl, let it sit and look for separation? I just filled it up 20 minutes before the engine started loosing power and I I had to shut it down. The other seems fine and they both pull from the same tank. I am planning on pulling the other one down this fall so I can chec that one also.
Thanks
 
At least they are not 454 heads,very heavy!!!


themikehyde said:
Well, I pulled the heads Thursday night and found two Tupi Ed exhaust valves. Dropped them off at the machine shop. He called and said all the seats had sunk so he was going to replace all of them and I can pick them up Tuesday. He said I should check the other engine also. I am hoping that that can hold off till layup. Not sure what caused the issue? Will give an update when I get her back together.
Click to expand...
 
Yes, the 4.3's are not very heavy. Since I had just replaced the manifolds/risers the spring, with bolts instead of studs, I was able to remove the risers, then the manifolds. Makes it much easier to lift them out.
 
Well, more bad news. Machine shop found both heads cracked. Back to the big decision of spending 1200+ for heads, or 1800 + freight for new long block. Of course, times 2. I think I know which way I'm headed!
 
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