time for new manifolds

[bpmcl00]

Happy holidays everybody


So i bought my boat with cracked manifolds that had been JB welded back together. i have decided that this is too much of a risk to run due to the fact that a failure will result in waterlocked engine.

SOO, i will put on new manifolds, and use the stock risers. does anyone see a problem with this.

technically its the manifold that will do damage if it breaks and not the riser ... right?

 

[arks]

Re: time for new manifolds

Happy holidays everybody
...technically its the manifold that will do damage if it breaks and not the riser ... right?

Well, sort of.
Although not subjected to the extreme temperatures of the manifolds, the risers also circulate raw water. If you want to re-use them, make sure they're rodded out and pressure tested before installing them. Sometimes a hairline crack will not be visible because it's internal.
In addition- this should go without saying but- you need to use all new high quality gaskets as well.

 

[bpmcl00]

Re: time for new manifolds

thanks for the reply.

i started up the boat this weekend. the manifolds got hot to touch but risers were not the slightest bit warm.

but also impeller is way past due

i think i will take off the risers and inspect them and post some pictures to see what you guys here think.

 

[DJ]

Re: time for new manifolds

technically its the manifold that will do damage if it breaks and not the riser ... right?

NOPE! Both or either can hydrolock an engine.

 

[slasmith1]

Re: time for new manifolds

Usually when 1 goes the other will soon follow. if you have it apart better to replace manifold and riser at the same time. Labor costs the same and parts are only slightly more $$. "Do it right once and you wont need to do it again"

 

[HT32BSX115]

Re: time for new manifolds

Howdy,


I wouldn't replace manifolds without replacing the riser/elbows (unless they are fresh water and in VERY good condition)

Especially if you think they might be questionable.

If there's cracks in the risers they will allow water to run back into open exhaust valves right after you shut down the engine.

It's not a problem while running the engine.

Exhaust pressures will push any water out the exhaust. It's a problem right after shut down. (this is why it's important to prevent riser gasket leaks. The small amount of water above the riser gasket is enough to hydrolock an engine after shut down.

If you shut it down for en extended period of time, the water that enters the cyl thru the open exhaust valve will sit there until you start it again or it leaks past the rings.


This is the problem I had with my previous engine (OMC 460 ) In that case the riser gaskets were leaking.....every time I shut it down even for a few min, it would hydrolock briefly. At first I thought I had a bad starter or battery.



Regards,


Rick

 

[chiefalen]

Re: time for new manifolds

Any one tell you why they both cracked ?

And you have no cracks in the block ?

Could it be freeze damage ?

May i ask what sorta motor this is, cause for a half a grand you can have it all manifolds, risers, gaskets, the whole shebang. All in one nice box.

Now doesn't that just make you feel good all over.

 

[ziggy]

Re: time for new manifolds

i'd do both too. as important as they are. why play? then you'll have a known starting point for these items too.

 

[bpmcl00]

Re: time for new manifolds

Any one tell you why they both cracked ?

And you have no cracks in the block ?

Could it be freeze damage ?

May i ask what sorta motor this is, cause for a half a grand you can have it all manifolds, risers, gaskets, the whole shebang. All in one nice box.

Now doesn't that just make you feel good all over.

Hey chiefalen, Its a 4.3 lx mercruiser. the manifolds were cracked do to not properly winterizing 2 owners ago. The block is okay. but both manifolds were cracked. the last owner bought it like that and ran it last summer then i bought the boat fall. i have ran it a couple of times. but just stared to pay attention to the manifolds. they get warm to touch, but risers have no temp change in them at all. Boat has only seen Fresh water.

i know ebay has kits for like 500 shipped, but i only paid 850 for this boat. and i dont have too much cash to pour into it, being a college student full time.

my plan was to start with a new impeller and manifolds then eventually when i get the money put the risers on.

I plan on doing everything myself.

How do you guys feel about changing manifolds? Hard job??

 

[chiefalen]

Re: time for new manifolds

Ok easy job you need a torque wrench, follow the recommended torque value for the manifold bolts.

You did know the valley in the 4.3 heads are known to freeze also.

Your sure no other cracks, no water in the oil.

You ever do a compression check ?

Ok young man i understand money is tight, would you rather be buying a new motor also ?

Whats don say " why is there never time to do it right the first time ".

Oh well i wish you luck In all your endeavors.

 

[bpmcl00]

Re: time for new manifolds

Ok easy job you need a torque wrench, follow the recommended torque value for the manifold bolts.

You did know the valley in the 4.3 heads are known to freeze also.

Your sure no other cracks, no water in the oil.
Changed the oil saturday. black as night. no sign of milky/foamy/ anythign other then oil
You ever do a compression check ?
YES when i first bought the boat. 150 +/- 7psi

Ok young man i understand money is tight, would you rather be buying a new motor also ?
i understand neglect can result in complete destruction of the engine. i figured since manifolds are allready cracked go ahead and replace them..

i t
Whats don say " why is there never time to do it right the first time ".

Oh well i wish you luck In all your endeavors.

i figure i will take off risers and thuroughly inspect the inside and post pics here to get oppinions.

AS for the manifolds... thay will get replaced

 

[HT32BSX115]

Re: time for new manifolds

It's very unlikely that anyone can tell just by looking at the risers that's there's anything actually wrong with them.

They'll either leak or they won't.

The problem also is also that you might not know until it's too late. like when you put it away for the winter, etc.

Your best bet would be to get the whole exhaust "kit" so you put both the manifolds and riser/elbows in the same "time zone"


good luck with what ever you do!

 

[slasmith1]

Re: time for new manifolds

i know ebay has kits for like 500 shipped, but i only paid 850 for this boat. and i dont have too much cash to pour into it, being a college student full time.

my plan was to start with a new impeller and manifolds then eventually when i get the money put the risers on.

I plan on doing everything myself.

How do you guys feel about changing manifolds? Hard job??

Welcome to boating let me check my math but that sounds like 5 boat bucks to me.

 

[edjunior]

Re: time for new manifolds

Welcome to boating let me check my math but that sounds like 5 boat bucks to me.

Heh heh...5 "boat bucks". That' pretty funny. Funny true! Yikes!

 

[edjunior]

Re: time for new manifolds

Welcome to boating let me check my math but that sounds like 5 boat bucks to me.

Heh heh...5 "boat bucks". That' pretty funny. Funny true! Yikes!

As a new, and young, boater, he has obviously not been introduced to the two staple ideals of the boating world:

First the definition of "Boat". A hole in the water, surrounded by wood or fiberglass, into which you pour money.

And of course the breakout of the acronym BOAT: Bring Out Another Thousand

Are you learning yet??

 

[Gary H NC]

Re: time for new manifolds

You can get the complete kits,manifolds,risers gaskets and all for around 500...
http://bpi.ebasicpower.com/exhaust/index.php

 

[chiefalen]

Re: time for new manifolds

What i understand this site will match the price.

So keep it in the family and order from here.

 

[nimrod69]

Re: time for new manifolds

Stay away from GLM manifolds and risers!!!!!!
Made in china junk!!

 

[bpmcl00]

Re: time for new manifolds

thanks for the heads up nimrod69

 

[DJ]

Re: time for new manifolds

Replace both.


Anything is a "crap shoot".

"fools folly" in my book.