3 Bad Pistons in 85 150 hp, Do I need to replace All

[Mik]

I've got an 1985 Evinrude 150 hp powerhead that had a broken ring in the #1 cylinder, and several others are scored (rings are stuck).<br /><br />Can I replace the 3 bad ones with .030 oversize, or do I need to replace all of them? If I do just replace 3, will I need to rebalance them?<br /><br />Also, there are a few dings in the head (not terribly bad), can I smooth out the worst of it and still use it, or is this an absolute "no-no"?<br /><br />Mik

 

[DHPMARINE]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

Mik,good question,got me thinking here.The head dings may be livable but I wonder about 3, .030 pistons and 3 std.Maybe some one can advise as to where in the firing order they should not be.A v-6 should be smooth and not go cachug.<br /> Can you find a remanufacted engine with a gaurantee?I think that's a better bet.<br />DHP

 

[marinemech]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

best bet replace all six <br />what caused three to fail?<br />changing one or more pistons is acceptible if using omc/bombardier piston but best to replace all six, pins and crank bearings

 

[Mik]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

Thanks for the replies,<br /><br />The more that I look at the block, the more that I'm convinced to replace all 6. When I run my fingers around the base of the jugs, I keep feeling some minor ridges. I'll replace all 6 with .030 over pistons.<br /><br />Like I mentioned, several of the rings were stuck, which is why the thing failed.<br /><br />The bearings really seem OK, no play in them at all. Other's I have talked to said that it's not necessary to replace the bearings.

 

[DJ]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

I don't like the idea of the dings in the head(s).<br /><br />They can cuase hot spots. If you keep the heads make darn sure they are smooth.<br /><br />You really need to find out what aused the failure, or you'll get to do it again.<br /><br />I cn tell you that it wasn't the oil injection. It can't be cylinder selective.

 

[Mik]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

I know what caused the failure. A number of the rings are stuck and also the ports are somewhat sharp (coking?). The ring broke.<br /><br />Mik

 

[james roach]

Re: 3 Bad Pistons in 85 150 hp, Do I need to replace All

Dont worry about different sized pistons. When i replaced the head gaskets on my 1987 200 Johnson the other winter boy did I get a suprise. I was bored .06, 3 were .03, and 2 were .02. The motor runs great however. I would be concerned with the imperfect head covers.