Mercruiser 4.3 - possibly blown up?

[NatedoggAZ]

4.3L2 V6
Serial Number: 0B847392
Engine model: 443S100AR


Hey All...

Well.... I spent nearly all summer restoring the stringers, flooring, and interior of my 1988 Sea Ray - and it looks beautiful.

Last summer I took the boat out 2 times with no issues - but this past weekend was the first time I could take it out due to the internal repairs.

Engine started up fine on the muffs in the driveway the night before.

Went to the lake the next day - drove it about 4 1/2 miles from boat launch to our beach area with no problems at all.

Got setup in our beach area then blew up the inflatables to go have some fun.

Boat started right up with no problems at all and I was towing away... but then the problem started.
Was about a half mile from our beach area when:

All of a sudden while towing.. the engine started knocking.
Started to see white smoke coming from the side vents.
I turned the engine off as fast as I could.
Opened up the compartment and a ton of smoke just billowed out.
The smoke was coming from both sides of the engine
I could see red embers around the valve cover gaskets.
The engine was snapping and popping - sounded like a camp fire... but there was no fire.

I checked the temp gauge and it was buried over 270 - or whatever is highest temp on the gauge.

...Had to get towed back to the marina but enjoyed the rest of the day on the beach.

When I pulled the plug in my driveway, about 3-4 gallons of milky/murky water was in the boat.

I think its screwed...but have no idea what happened or why...??

Thanks!

ND

 

[Bondo]

Ayuh,...... You over-heated it in an extreme way,......

Replace the raw water pump, fire it up, 'n access what the damage is,......

 

[Scott Danforth]

You seriously overheated. Most likely the raw water pump impeller failed

You should be glancing at your gauges between every 5-7 seconds

Do a compression test. All cylinders should be between 135-150 psi

if all is good, then replace all rubber parta in your exhaust because you burned all that up. Then pull the drive and replace the raw water pump.

 

[NatedoggAZ]

OK - so not the impeller in the outdrive (only been used 2 times since replaced)

and not the circulating water pump on the front of the engine...

...but the RAW water pump?

ND

 

[Tycer]

The impeller is part of the raw water pump.
Sorry for your impending tasks.

 

[Bondo]

OK - so not the impeller in the outdrive (only been used 2 times since replaced)

Ayuh,..... The pump in the drive,.... Yes,....

 

[NatedoggAZ]

AH - so this whole thing... not just the rubber impeller part?
https://www.iboats.com/shop/sierra-18-3320-water-pump-kit.html

 

[Lou C]

Even if the engine has close to normal compression...and doesn't have water in the oil...be aware that there is likely damage...in cracked cyl heads...and weakened head gaskets...I had the same thing happen back in '13...checked everything...seemed fine...then blew both HGs in the end of '16 and when I took it apart...both cyl heads had cracks in the exhaust valve seat areas...so I installed a pair of re-man heads and put it back together....

when mine overheated...the raw water hose at the transom mount popped off the PS cooler...and flooded the bilge with salt water...and at first I did not know where the water was coming in from...so waited for a tow...and just for fun...took out my IR temp gun and checked the manifolds and engine....the manifolds were at 375*, engine...about 240*….
I took those one piece batwings off and checked them for leaks with acetone...and neither one leaked!

 

[Bondo]

AH - so this whole thing... not just the rubber impeller part?
https://www.iboats.com/shop/sierra-18-3320-water-pump-kit.html

Ayuh,...... Correct,.......

As Scott, 'n lou have mentioned,..... There's no doubt more burnt up parts,.....

Burnt up exhaust rubber stuff, for Sure,.....
Cracked heads are very possible too,.... they may survive,................ or not,.......

 

[Lou C]

other burnt up stuff
exhaust flappers
in the drive...the water tube grommets can get burnt up depending on how exhaust water flows through the drive...

 

[NatedoggAZ]

crap... ya.. plus that knocking noise I heard really concerns me as well...

My buddy who works at a supplier said he sells the 4.3L all the time to people who get them for boats...
said he could get me a new 4.3 for $1600 with all the gaskets

He said he just needs the block and head casting numbers to match it up with the right one - which I don't know where they are at...

Maybe I will just go that route....

 

[Bondo]

He said he just needs the block and head casting numbers to match it up with the right one - which I don't know where they are at...

Ayuh,...... The block castin' number is on the aft flange, where the flywheel cover bolts too,......

On the top, 'bout center, to the portside,....

The head numbers are under the valve covers, but shouldn't really matter,....
They're either Vortec, or not,.,....
'n if they ain't,.... Now is the perfect time to update to 'em,.......

 

[achris]

Being 1988 you'll have a plastic water pocket cover. Concrete guarantee that will be damaged... (Up inside the exhaust cavity in the drive)...

Chris....

 

[Scott Danforth]

crap... ya.. plus that knocking noise I heard really concerns me as well...

My buddy who works at a supplier said he sells the 4.3L all the time to people who get them for boats...
said he could get me a new 4.3 for $1600 with all the gaskets

He said he just needs the block and head casting numbers to match it up with the right one - which I don't know where they are at...

Maybe I will just go that route....

you need to make a job selling 4.3's..... My guess is that is either a budget reman or the price is $2600. Brandy new 4.3 GM motors in a crate are about $3k this year.

 

[NatedoggAZ]

you need to make a job selling 4.3's..... My guess is that is either a budget reman or the price is $2600. Brandy new 4.3 GM motors in a crate are about $3k this year.

I don't think it is BRAND new.. but would be new to me.. It is probably a reman/rebuilt with a warranty.
Will get more details from my buddy once I give him the block/casting numbers.

 

[Scott Danforth]

Get a waranty

 

[Pzilly]

When you pull,it apart check the flappers, if missing as they are probably burned off pull the drive and look for it before reassembling, if you don't see it put a camera down the y pipe before putting things back on.

does your boat have n oil cooler? If so check that as it could also explain the milky water in bilge if you don't find another source.

 

[NatedoggAZ]

All I saw when looking for the block casting number was this stamp.
It says GM with 4.3 LG
then the "SGI"

...maybe I am looking in the wrong place?

 

[Ncherry84]

Where did you find that?

Only asking because for your year of boat ASSUMING the motor is the original you should be looking for 3 digits

011
867
553
863

Are you looking from the top of the motor down on top of where the starter is?

 

[NatedoggAZ]

It was mentioned to look on the port side by where the engine meets up with the flywheel...?
This is the original motor as far as I know.

The starter is on the starboard side of the motor... maybe I am just looking in the wrong place.

It is pretty hard to see back there and it is a very tight spot - I had to blindly take a video and pull that image from the video...

guess I will have to go back and look again

ND