Test Run Issues HELP!!!!!!!!

[matty8468]

So i have a 1984 Cruisers 23 ft, it has a 228 mercruiser with a MC1 alpha outdrive. I am running a 1.64 ratio outdrive with a 15 inch prop. So I took it out yesterday and I found the following issues, I am leaking oil from both the front and back of the intake gasket (gaskets will be changed) It is a FWC Boat as well. When running at idle she?s at 140-150 degrees and at 3000 rpms it?s about 180 degrees. I only brought her up to about 3200 rpms which gave me a temp of about 200 lower the rpms and the gauge drops almost very quickly. I have run the boat in the yard and it pushes water threw very well. At 2800rpms I?m running 18-20mph. At 3200 rpms 22mph.So a few questions,
Is this normal operating temp?
Why does she seem not to accelerate that much when given more power?
What pitch prop does anyone recommend I don?t care much about shooting out of the hole but I would love to get my cruising speed about 24 mph?
What rpms should be cruising speed?

 

[90stingray]

Re: Test Run Issues HELP!!!!!!!!

Can't tell much about prop and engine... need to see what boat will do wot and trimmed out. Then you can see if you need to re prop. Or see if its an engine problem. Temps are too high. Maybe time for an impeller? But most likely you have a blockage of some sort in the cooling system.

 

[EddiePetty]

Re: Test Run Issues HELP!!!!!!!!

To continue Stingray's thoughts, I, too, would consider an exhaust passage blockage, possibly a clogged riser, obstructed exhaust by old flapper. You stated 'FWC' so I believe you are saying the engine is a closed cooling system engine, if so, remove the end caps from the heat exchanger and inspect for obstructions (pieces of former impellers, marine/aquatic debris, etc.)
The engine speed doesn't make good sense...scrib a line across the propeller hub and check for hub slippage or even a coupler heading south (usually indicated by black dust in the bell housing area and a hot rubber smell.

 

[Don S]

Re: Test Run Issues HELP!!!!!!!!

If you had a prop hub, or a coupler hub problem, you wouldn't be under load at 3200 rpm and doing 22 mph. You would here it start slipping and no speed over about 1500 rpm and 2 mph.

The first thing you have to do is get the temp problem fixed, then run at WOT and see what the max rpm is.
The impeller is the FIRST thing you check with any overheat problem. An old impeller that the vanes are all bent over and will not straighten out may pump fine at low rpm but less at higher rpm.
Since the engine has a closed cooling system, it's probably a salt water boat. If that is the case, then have a certified Mercruiser shop pull the exhaust risers and check for clogging in the riser or the manifold if the impeller doesn't fix the problem.
Obviously the seller knew about the overheat, he probably knows something you don't, and decided to sell instead of putting a bunch of money into the boat.