GM 454 Crusader engine preventive maintenance, **New Owner**

Welcome to YF Beauregard. I'll leave 1 & 2 to the mechanics here to give you better answers. What I will address is that you have scary low hours on those motors unless they're replacements. Motors don't like to sit idle. Sure that's not since major overhaul (SMOH)? The other thing is that temp. It could be something as simple as the sensor or a bad thermostat, even a clogged sea strainer or bad impeller. It's only a few degrees high (one generally runs about 5* above the other). Did the surveyor check the temperature at your motor or did he go by the helm gauges? Does it hold at that temperature? If so any problem should be small. A real saving grace is that she's a fresh water boat, although some fresh water areas have a snail problem.

I would pull and replace the risers.
You cant tell when they are going to go from looking at the outside.

When they do fail you suck water into the engine through the valves when you shut down, that usually means the engine is toast unless you get the water out right away and don't bend valves, push rods, or piston rods.

I recommend boiling the risers out every two years and replacing every 4-5 years.

the 8inch risers cost around $200 each, you need 4 of them, plus gaskets, throw in a few hose clamps and hoses if needed and you are upto $1000 DIY project every couple of years.

The 454 is a great engine, that is simple to work on and there are still lots of parts available.

You will be happy with 454 Crusaders.

change the oil, keep them tuned, cool and clean and they will last a long time.


AS far as one engine at 165 and the other at 180 that could be just about anything from a faulty gauge, to different thermostats, to a warped head;

a few other things to consider, sometimes one engine is used to heat domestic water and that engine will usually show a cooler temp.

were both engines operating the same wot RMPs, could be one prop is fouled.

Other reasons why one engine could run hot and not the other, raw water pump or impeller, raw water flow, coolant, heat exchanger, also those engines have a trans and oil cooler that can catch be blocked with pieces of the impeller.

Does this boat also have a bad vibration

and an obnoxious fume detector?

1. do you have reciepts from the prior owner with the date on when they were changed? If you're going to take them off, you inspect the water passages for corrossion, scaling and blockage. I have never had risers boiled out, nor know anyone that has that done down here. I replace the risers every 5 years, you can also hit them with a heat gun at cruise speed and measure temperatures between them all. Usually you can tell a hot one that is clogged up doing this......

2. Crusader exhaust manifolds are fresh water cooled, so no saltwater, just the risers.

3. Check raw water impellor first, then go for the heat exchanger if the raw water impellor looks good....They should be changed every 2 years (impellors.)

The manifolds are cooled by antifreeze. Salt water runs through the heat exchanger then dumps out through the riser/elbow. The engine running 165 is actually on the cool side for a heat exchanger cooled motor. A little vibration at wot is nothing to get too excited about. Check the engine alignment. If it's ok have the props checked.