Checking Compression

Hi everyone. I'm purchasing a 1992 Ski Nautique with the 5.7 H.O 351. The boat is all original and is in very nice shape. I'm planning on doing a compression test before finalizing the sale. I have a few questions on the procedure.

1) Will pulling the circuit breaker labeled ignition be sufficient to protect the electrical system while cranking over the engine with the key? Looks to have electronic ignition. Coils at the back under the plastic cover and some type of engine management hardware at the front of the engine.

2) Will the impeller pump get damaged from cranking dry, 5 strokes on 8 cylinders

3) Is there a way to shutoff fuel? This motor is carb'd

Planning to warm the engine, pull the plugs, crank at WOT, and give the starter some time to cool off.

Any other advice on how to safely run the test?

Also is there an easy way to tell if the stringers are wood or composite? The owner said the boat was a demo model he bought from a skier in 94. He was told when he bought it from him that it had composite stringers. I read that there were a few boats from 92 with composite but most had wood.

Thanks,

Dave

As far as the stringers, I'd remove one of the bolts holding the cradle to the stringers and see what's down in that hole.

Maybe you'll find wood, maybe you'll find foam down in the hole.

morpheus122 wrote: Keno, If the stringers end up being wood, do I need to put some kind of sealant back in with the bolt so moisture doesn't penetrate the stringer? I'll pull the connector from the interruptor. That manual is a great resource. On these Holly carbs can you just hold the choke and throttle open with your hand at the engine while someone cranks with the key?

Put the throttle lever at full throttle with the neutral button pulled out. You may have to do this in reverse because in forward with the button out you probablycan't move the lever to full throttle.

You can use a screwdriver lightly "wedged" in the air horn to hold the choke open.

Lots of different sealers out there, I'd use something to seal it.

3M 5200 seems too strong. I guess I'll check the Home Depot for alternatives. Still haven't pulled any bolts but if it ends up being wood I want the sealant to last a long time.

morpheus122 wrote: Has anyone tried Amazing Goop Marine Adhesive from True Value?

Silicone with a different name and a jacked up price!

morpheus122 wrote: 3M 5200 seems too strong. I guess I'll check the Home Depot for alternatives. Still haven't pulled any bolts but if it ends up being wood I want the sealant to last a long time.

Go for 4200 sealant.

SNobsessed wrote: I have used amazing goop & it is not is same league as 3m products at all. Adhesion was very marginal.

As with all silicones. I hate silicone!!

Duane,
Sashco makes some great stuff. Yes, I've used the Lexel with excellent results. I've also used plenty of Sashco's Big Stretch. I've got 4 tubes of different colors in the cabinet now! I wouldn't use it for a marine application where it would be subjected to lots of water.

Not me I think it's one of the greatest inventions of modern life!

I'd just be so curious right now about whether I got a "special" boat with composite stringers or maybe got a "special" sales pitch from the previous owner, that I'd have to pull one of the screws holding the cradle to a stringer to see what I had

Do you mean a squirt from a bottle in your hand or a squirt from the accelerator pump?

morpheus122 wrote: I was about to pull a bolt but felt bad about wasting a tube of 4000 for just one bolt. I'll probably do it next time I go work on the boat. When using 4000 do I loosely tighten the bolt, then come back after it cures and sinch it to finally torque?

4200 and 5200 is available in the 1oz. size.



Torque the bolt down just like you would without any sealant.

KENO wrote: morpheus122 wrote: I have to open the throttle and keep the idle raised a bit during starting. It doesn't seem to want to start at idle position. Nothing wrong with that if that's what works for you You'll hear 13 different ways to start your boat from 12 different people

Roger that. I need to take it out and lower the idle to spec. It was right around 1000rpm or so. Is it normal to hear a whirl sound when giving it power in reverse? It’s a different sound that when in forward.

You can click on this link for a manual for a PCM transmission It's a free download from the SkiDim website. Pretty nice on their part.

trans manual