View Full Version : 19 LXR Manifold and Riser question

05-24-2011, 05:47 PM
New user here guys so please, be gentle. :wink:

I bought my first non-outboard boat last summer, a 1998 Donzi 19 LXR. 5.7 Mercruiser with an Alpha One drive.

The hull and interior are in fantastic shape and completely original. But the engine Im finally starting to have issues with.

I dropped the boat off at that shop yesterday to have some work done on the shift cable since it was not wanting to shift into forward gear.

Today I got a call to come up there and they found out the starter was shot and after pulling all the plugs, there was water coming out of the passenger side holes once the plugs were removed and the motor kicked over.

They are saying that the manifolds and risers are bad and quoted me $2000 to replace them. That seemed a bit high to me so I was wondering if that was in the ballpark.

I wouldnt be above changing them out myself, I havent messed with anything like that marine-wise before but it didnt look like too big a job.

They pretty much told me that if there were more issues with the cooling system (mine has a heat exchanger with a a fresh water pickup) that I could be looking at $3000 - $4000 total to fix it. They even suggested if I wasnt willing to do that, to just sell it for $2000 as a "mechanics special". I just bought the boat for 9K less than a year ago so I really want to fix it and not lose that kind of money on it, not to mention I love the boat!

Thanks in advance for any advice.

- a frustrated new Donzi owner

05-24-2011, 07:23 PM
Welcome to the forum.
Without looking at your engine it is a bit hard to tell exactly what is going on there~
Did you winterize your raw water cooling system half last fall ?
If you have cast-iron marine manifolds and they are over 6-7 years old you are most likely due for a new set.
It should cost you far less than $2000. for new replacment manifolds & riser elbows. Parts only~ You doing the installation labor.
Go with OSCO replacment cast-iron units.
I would also do a cylinder compression pressure test to check the engine's overall health & condition.
All cylinder compression pressures should be within 10% of each other or less.
Since you have freshwater heat exchanger engine cooling your engine should be in great shape cooling wise.
The only possible issue~ How long was that water sitting in those cylinders un-detected & did it cause any cylinder & valve area rust ?
Be sure to change the engine's oil before trying to start the engine.
If you are lucky you should be fixed-up fine with only new marine exhaust manifolds & riser elbows.

Good Luck

05-25-2011, 02:35 PM
Ebay link - Full kit (http://cgi.ebay.com/ebaymotors/MerCruiser-350-5-7-Center-Riser-Exhaust-manifold-Kit-/370269137710?pt=Boat_Parts_Accessories_Gear&hash=item5635c2ab2e) = $602.50 + ship
Since you would be going "like-for-like" the replacement should be pretty straight forward.

FWIW I recently replaced my 1998 big block manifolds and risers with new Stainless Marine and the old ones were in remarkably good shape.

05-25-2011, 04:50 PM
$2000 for manifolds and risers on a singe small block i/o? Sounds pretty crusty!

If you're at all handy it's not too hard a job and access should be pretty decent on your boat. You should be able to do it in a day even if it's your first time.

The big question of course is what damage did the water do in the cylinders? That could lead to all sorts of problems, up to complete engine replacement.

Step 1: retrieve boat from mechanic. he's taking you for a ride.
Step 2: check condition of oil - any signs of water?

Depending on how handy you are with a wrench, either do the following yourself, have a buddy give you a hand, or find a new mechanic to do the following:

Step 3: check compression. pay particular attention to the cylinders under the risers.
Step 4: If compression is good, replace manifolds, risers, and gaskets.

Where are you located? I'd bet somebody on the board could come lend you a hand if you had a cool refreshing beverage on stand-by one afternoon.

05-25-2011, 04:54 PM

More DIY parts sources....

Just wondering, did the mechanic give you a written estimate? I'd love to see his parts/labor break down.

Maybe I've been charging too little!:wink:

05-25-2011, 07:32 PM
Thanks for all of the responses guys! Its a big help and Im feeling a bit better about the whole situation now.

To answer a few questions, no they did not give me a written estimate at the time yesterday. He basically told me the riser kit would run about $1300 for parts and roughly 7 hours labor at $100/hr.

The water was only in the passenger side cylinders from what we could tell. And it couldnt have been there long since the boat was winterized and hasnt been run since November until we just pulled it out and fired it up on the hose.

The starter seems to have taken a nose dive during this whole fiasco somehow as well. It worked the other day when we fired it up on the hose fine, now the internals sound stripped.

Im having my dad help me replace the starter tomorrow (he's much more of a mechanic than I am) and then we are going to tackle replacing the manifolds and risers. He said he felt like he could do it with no problems after looking at it.

My only question would be about which ones to order. Nothing on this motor appears stock and this is the only 19LXR I have seen with huge through hull exhaust so Im not sure how to order the risers for that. I guess I would have to measure the exhaust outlet size?

I have attached a picture of the back of the boat where you can see the through hull exhaust.

BTW, Im in Jacksonville, FL and have *plenty* of cold <ahem> beverages... :wink:

05-26-2011, 12:31 AM
Post up a pic or two of the engines - we'll most likely be able to identify what you've got now and direct you to replacements.

The two links above are OEM Merc and aftermarket replicas for a few dollars less. Chances are either of those links would work.

Of course, you could get also go to some of the aftermarket performance manifolds like Stainless Marine, EMI, etc, but they'll cost more and won't really give you much/any performance gain. They'll typically save you some weight and they set the stage for future upgrades, but unless you plan to breath on the motor I would just stick with the stock replacement stuff.

Google Osco and Barr - you'll find plenty of vendors selling small block Merc gear.

I'd offer to come over and help you, but I'm on the other coast...if you want to tow it out here I'll be glad to lend a hand. :wink:

05-26-2011, 07:02 AM
Osco/Barr both decent products, go with a center riser setup over log style the give a slight performance boost.

05-26-2011, 08:58 AM
Thanks for the help zelatore. Im heading over to my parents where I store the boat this afternoon to pull the starter and do some assessment. I will snap a few pics while Im there and post them up tonight.

05-26-2011, 12:03 PM
I had water in my cylinders a couple years back, it was from a small crack on the exhaust manifold. I wound up replacing that one with an OSCO brand one. I have two manifolds and "logs" off my SBC, I'm not sure if they would work for your application or not, if they do, I'll sell them to you at a good price if interested. I'll take pics in a little while if you're interested.

05-26-2011, 12:41 PM
I find that Osco replacment manifolds & riser elbows have much thicker castings~
so they last longer.

They are also Made 100% In The USA .

Tom Cooper, OSCO's long-time owner lives five min. from my home. :bighug:

05-27-2011, 09:53 PM
Pulled the port side manifold off tonight and found this gooey gel like stuff inside the exhaust ports of the head and going into the manifold. Seemed like some of it was crystallizing as well. Not really sure what it is though.

The manifold was full of antifreeze. Im assuming thats normal on a freshwater cooled system.

Attaching a couple pics of the inside of the manifold ports that have some of the gel stuff in it.

05-27-2011, 11:03 PM
Your manifolds & elbow risers are long ovedue for replacment.
The gell you see is antifreeze that has partially dried-up.
Your manifold is leaking badly.

Replace BOTH exhaust manifolds & riser elbows.

We cannot really tell if you have a 1/2 freshwater cooling system that cooled the engine only ~~~
A FULL system that also cools the manifolds along with the engine with fresh water antifreeze?
Full systems are not very common.

Ths antifreeze we see here could be from winterizing the raw water side of this system which includes the manifolds & riser elbows.?

Buy a NEW complete system of OSCO marine replacment Cast Iron manifolds.

Also do an engine compression pressure test to make sure your engine is still OK, & was not damaged by water getting into it through the exhaust ports.

05-27-2011, 11:08 PM
Ah ok, that makes perfect sense. I figured it had something to do with antifreeze since some of it was green.

I found the right riser for mine but now Im trying to determine which gaskets I need to go between the riser and the manifold. There appears to be one with only the exhaust opening and another with the exhaust opening and 2 long thin openings on either side of that.

Im trying to find some information about this cooling system thats on it to see if that might help with identifying the gaskets needed for this setup.

Thanks again for the info! Its a big help!

05-27-2011, 11:18 PM
Take your riser ebow off this old manifold.
If there is only a gasket between the two castings you have a 1/2 fresh water cooling system and need the extra water passages style gasket.
The extra gaske holes allow the cooling water to run from the manifold to the riser elbow & out your tailpipe.

If there is also a Stainless Steel plate & two gaskets there you indeed have a FULL freshwater cooling system .

05-27-2011, 11:23 PM
Easy fast check~

Blow into the water fitting on the lower part of your manifold.

If air comes out the big exhaust riser tailpipe you need the gaskets WITH the extra holes.

Those extra holes allow the cooling water to travel from the manifold casting to the exhaust riser elbow casting & then out your tailpipe.

It's that simple.

05-28-2011, 07:26 AM
if it's in the ports, it's in the cylinders

no if's, and's, or but's about it

your in for more than a simple manifold repleacement

05-28-2011, 11:47 AM
if it's in the ports, it's in the cylinders

no if's, and's, or but's about it

your in for more than a simple manifold repleacement

This is what I fear also.
I suspect some rust in one , or more cylinders, or valve seats on that bad side.
This is why I keep telling him to do a cylinder presure compression check.
I fear some rust damage.

05-28-2011, 08:06 PM
On the positive side, doing a compression test with the manifolds off is about as easy as it gets...

And as stated, don't run out an buy manifolds yet - you really need to see what sort of damage may have been done to the cylinders.

05-28-2011, 08:20 PM
The fact that water blew out of the spark pug holes on that head has me concerned~~

How long was that water/antifreeze mixture in those cylinders ?
And what rust damage was done because of this water?
Was the starter damaged by the engine hydraulically locking because of that water in those affected cyliners ?
IF so~
What other possibe damage miht have been done ?
The boatyard guys may know more than they are telling you ?

I sure HOPE not ?