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leakdown test bad compression

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vedder2203

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so who can tell me the proper procedure for a leak down test on a 2000 150 xr6? # 2 & #5 cylinders are reading 60 and other all in at 110.. was going to pull the Heads but was told to do the leak down first if possible..
 
Did it overheat? If it did you may need to pull the heads as Merc. calls them or cylinder covers and check the gaskets but more important place a straight edge across the head mating surface to check for trueness. If questionable then send them to a machine shop for milling to true the surface.
 
guyjg said:
Did it overheat? If it did you may need to pull the heads as Merc. calls them or cylinder covers and check the gaskets but more important place a straight edge across the head mating surface to check for trueness. If questionable then send them to a machine shop for milling to true the surface.
Click to expand...

So it did overheat. Later inspection. I found the starboard side temp sensor wire was. Cut under the loom do to Ibelieve friction between the head cover and engine cover thus no alarm. So not sure if water pump or stat failed. Causing overheat. Thanx replies going to pull heads. Any idea on cost for mill job on heads
 
Local to me (Eastern Ontario), it runs 100'ish bucks to sand the head. Then 50 bucks a hole for a bore or hone. And with only 60 lbs in those two cylinders, I suspect that the pistons, rings, or both are toast in those two cylinders - but cross your fingers it's just a warped head or a bad gasket..

If you only have the two bad cylinders then you would be looking at about 400 bucks for parts - the pistons/rings (aftermarket GLM come as a set) go for about 100 bucks each (Merc wants 200 each for the pistons, and the rings, believe it or not, are 250 a set, for each piston) and almost 200 bucks for a powerhead gasket set - I would definitely look to the aftermarket for the piston/ring combo.

So, maybe 600'ish, plus the cost of correcting the original issue (waterpump, carb, whatever) - doing the work (less the bore/sand) yourself.

For the cost of 4 more piston/ring sets (another 400 bucks), I would certainly use the "eagle eye" on all the cylinders when you get a look.

1000-1200 bucks would be about "normal" for a "self" rebuild and you really don't want to tear it down twice by cheaping out on a couple pistons - especially if you are in there anyway (if the damage dictates a tear down)...

Food for thought.
 
Well, at least take a look - didn't want to scare you away from it, just be prepared for the worst and maybe you get a nice surprise..
 
No I really appreciate all the good info and advise, I am going to go through the steps you suggested and go from there.
i am thinking of pulling the motor off and working on it in the comfort of the garage, plus I can still go after some local tributary fall coho over the next month on my kicker...
That being said any ideas or info on a good way to yard that baby off and suggestions on motor racks? She weighs in around 400+.. Build your own.... Buy a hoist or motor jack of some sort.. worried about the shell , cover cowl ect....
 
The powerhead comes off probably easier than you think. You could pull it and leave the rest of the outboard mounted on the boat.

I have a portable electric hoist (picked up at a discount auto place) - just really a little electric motor that drives a couple pulleys (700lb max), which I use to pull heavier powerheads off the exhaust housing. I normally set up a tripod made of 2x6"'s, undo all the powerhead bolts, shift shaft, anything else attached to bottom cowl and lift the unit.

If you partially tear it down "in place" - remove the heads, take off the starter, flywheel, ignition etc (really strip it down) you can shed 50-75 quite quickly.

Without the "rest" of the outboard, while heavy, the powerhead is manageable (I can lift a partially stripped V4 myself) and then once you start tearing into it, it obviously gets easier to move around.

Some Do's -

Do follow a manual

Do take pictures (surprising what you forget after even a few days - ie, did the pink wire go to the top or bottom)

Label stuff with little pieces of tape - it's amazing how you can't remember what that "thingy" is or even where it came from.

Keep like things together (zip lock bag marked cylinder 1 gets the piston, bearings, rod etc - same with carbs - you can't mix them up on many models - carb 1/2 wont work on 3/4 or 5/6)

Some things like to rust quickly in the open air - spray the crankshaft with fogging oil or wd-40 and wrap it up in a clean rag/cloth/bedsheet and keep it in a dry location - don't want to end up pitting all the journals.

Just common sense stuff that sometimes we forget when taking on a big project...
 
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