Lost compression - How much on a rebuild kit?

[jezza2011]

Every start of the season I always run the motor with the oil injection and 50:1 in the tank.

looking a the piccys a rebore should do the trick.

I had minor oil leak due to broken clear feed pipes and running with a little oil in the fuel tank saved my obm!!

always pop a little oil in the fuel tank on my 21 year old motor just in case.

[nugent]

Check out coventry boring
They have machined 3 x merc blocks for me In the last two years v6 over bore +30 thou £130. V6 hone 6 and replace liner £140.
Excellent service and knows out boards inside out

http://www.coventryboring.co.uk/boringhoning/4537933479

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[nugent]

I know of aftermarket parts at. A good price ticket marine excellent service to hoot


http://www.tmp-murcury-mariner.co.uk...nalengine.html

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[buzzin hornet]

Originally Posted by 9D280

I thought I might have been in a similar situation when mine died. I decided on the rebuild route becuase I now have a known quantity as opposed to a secondhand unknown quantity of unknown history for the same cost that may or may not go bang.....

Mallory Pistons as you say - cheap as chips. I assume yours is a standard merc +0.015" +0.030" bores for the standard pistons. I found somewhere that would do a +0.045" for Mercs, at not much more than the standard oversise price.

If your man can't get his cutting device far enough in*, there is a place up here does have one that will reach. Did all three of mine for £200 odd, including skimming the back face to make sure it was all perpendicular. Will need to look the number out, so let me know if you want to go this route & are stuck.


Disconnecting the autolube: Remove the pump, plug the oil inlet holes, then divide by 50 when you fill the tank! It'll smoke a bit more at idle, but that's about the down side of it unless you do a lot of pottering at low speeds.

* a vague attempt to prevent it all going bilge-ward

Thankyou, will be looking into this!!!!!!!

[mctaggart]

Typical i send my engine block off to to rebored and then someone offers me a standard power head, piston and gasket set for £350!

Bah! now my block is with FJ Payne and son, I guess i will at least have a spare power head, not that i want to strip this thing again

[uncle al]

just look on the bright side think of all that experiance you are getting!

[paddlers]

Originally Posted by 9D280

No pics! is the autolube one of these ones that injects into the air / fuel flow downstream of the carb, or does it bulk mix with the fuel beforehand?

I'm guessing what your pics show, but is the missing bit of piston on the exhaust side? Another Clamshell issue was the early ones had a precariously close to destruction spark advance - it didn't take much error to be sparking too soon, resulting in more fuel on the inlet side of the piston "dam" than the exhaust when it sparked. Net result when it went bang, because of the asymetry of the explosive mixture the piston was forced sideways into the exhaust port.... My engine stopped because the resulting shards shorted the plug! The "factory" cure was to retard the spark, which then was compensated for with a slightly lighter piston to allow it to spin faster & regain the lost gee gees.



I'll second DaveJ on the oils - much to my amazement I had a remarkably un-smokey engine after crawling up the Forth at canal boat speed for 2 hrs.....

Hi, currently having an issue with a marine service centre!!
1993 Mariner 115 went in for a service, everything fine until they set about adjusting the timing then rang me to say the engine had gone bang. Turns out the piston had caught a port & damaged the bore. Sounds like the symptons you describe. How would I find this imformation as they're denying liability?
Thanks, Tony.

[9D280]

I guess if you look at the spark advance screw, if it hadn't been moved since 1993 I would expect to see dirt caught in the screw / hole interface (and probably the slot / phillips / allen hole as well). Likewise the locknut.

It should be obvious if the adjuster has been moved recently, unless you steam clean under your cowl every other weekend!

[Turbodiesel]

Just to throw something else in..... Number 2 piston is usually the one that fails due to an overheat (it runs hotter as its in the middle) The oil is fed through the fuel system/carbs so if you have a loss of oil it usually seen on all the cylinders/pistons. Also the piston is dry could be because it has overheated. What dose the crank look like and con rods? any signs of colour change?
Just a though as everyone keeps going on about oil pump problems!!