1978 INLINE 6 MERC 150HP - BAD COMPRESSION

[JJ JOHNSON]

I've got 120 to 125psi on 6 cylinders except on #3 I've got 30psi. How bad is this ?<br />Spark plug on #3 had tiny aluminum shavings.<br />Any idea on cost to get repaired ? Only have $1,500 in the rig & don't want to throw good money after bad. Is this old inline worth<br />it ? Thanks

 

[trevorcday]

Re: 1978 INLINE 6 MERC 150HP - BAD COMPRESSION

You will find the piston crown of the #3 cylinder is melted. The powerhead will need to come apart and the cylinder re-bored etc. This will not be an inexpensive repair but probably worth doing considering the likely resale value of the motor in working condition vs. its current state. The real problem is that you MUST figure out why the piston melted in the first place. The melted piston is only a symptom of another problem which must be corrected or the probelm will recurr.

 

[what200]

Re: 1978 INLINE 6 MERC 150HP - BAD COMPRESSION

I sould say that fair value of a running 70's inline would be around $1000. I bought a 1500 a couple of months ago for $800.