Changing 454 Exhaust Elbows

[wake5150]

Guys,<br /> I have two(2) 1995 Mercruiser 454 XL Crusader INBOARDS (fresh water cooled). I'm changing all the Exhaust elbows. I've read the service manual, and have done this before on I/O Merc 3.0s<br /><br />Questions: <br />The service manual says to drain the elbows and manifold to prevent engine damage. Is this really necessary? Is removing the hose to the elbow sufficent?<br /><br />Also, any tips/comments on doing this work? It's a pretty easy thing to do, but I want to make sure I don't make any simple mistakes.<br /><br />Thanks for your help<br />Chris

 

[Don S]

Re: Changing 454 Exhaust Elbows

The service manual says to drain the elbows and manifold to prevent engine damage. Is this really necessary?

Yes it's necessary, otherwise water that is in the elbow will drain into the exhaust portion of the manifold and into the cylinders.<br />FOLLOW THE MANUAL, that's why they put that kind of information in there.

 

[yoced]

Re: Changing 454 Exhaust Elbows

D'oh. Don types faster than I do.<br /><br />Your riser is about 1/2 full of water (give or take) at rest. If you don't drain it, when you pull the riser some of that water is going to go into the exhaust passage of your manifold - that is what they are warning you about.<br /><br />Drain the riser, and this does not happen. <br /><br />Your call as to whether or not a cup of water sitting on your valves is worrysome....

 

[Bondo]

Re: Changing 454 Exhaust Elbows

but I want to make sure I don't make any simple mistakes.

The service manual says to drain the elbows and manifold to prevent engine damage. Is this really necessary? Is removing the hose to the elbow sufficent?<br />

As stated above,..............<br /><br />That's your 1st 1..........

 

[wake5150]

Re: Changing 454 Exhaust Elbows

Guys. Thanks for the quick responses. <br /><br />Being fairly knowledgable about (boat) engines, I was sure I would drain the Elbows. <br /><br />But, the Service Manual says drain the Manifolds also, and this is the part that confused me. <br /><br />Why do you need to drain the manifolds if you are simply removing the elbows? Did I misread the service manual?<br /><br />I know I should follow the service manual, but I don't like blindly following instructions either. <br /><br />Also, what's the best way to drain elbows? Just pull the hose? Any tricks here?<br /><br />Thanks again<br />--Chris

 

[Don S]

Re: Changing 454 Exhaust Elbows

The top surface of the exhaust manifold may not be the highest spot in the cooling system, then when you remove the elbow, any water that is above the hose to the riser is now going to go into the exhaust.<br />None of us here can see your engine, or how it is sitting or what the highest part is.<br />If you don't want to follow the manual, go ahead and do it your way, then you will know for sure if it was necessary. If you don't like blindly following instructions, then you better understand exactly everything about how, and why something works and why things are done that way.<br />I'm sure we will be able to give you some pointers on getting the water out of the cylinders.

 

[wake5150]

Re: Changing 454 Exhaust Elbows

Don,<br /> I think you nailed the problem in the head. I always need to understand exactly how everything works, and it gets me in trouble sometimes.<br /><br />The point you made about coolant levels throughout the engine is particularly poignant and something I hadn't considered. Thank you.<br /><br />Of course at this time, my plan is to follow the manual precisely. I generally like to dot my "i"s and cross my "t"s anyways.<br /><br />Don, I got a good chuckle out of the last line of your last response. Of course, lurking in this forum for the last few months, I'm quite familiar with the steps to clearing water from cylinders.<br /><br />Thanks again<br />Chris