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1999 4.3 with cracked block or head

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mike.l

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Hi I have just purchased a 18 ft larson with a 4.3 mercury engine. Stern drive is in excellent condition, engine is in a sorry state i would like to remove the engine to work on it through the winter. How to attack this is just a little unsure i will need to purchase a workshop manual that will cover this> But would like it to go into a little depth on every step, am i right in understanding that the stern drive must be removed first , so would the same manual cover that as well . I am very confident in engine rebuild etc but never in marine situations Thanks for all help mike
 
the only difference in the marine application is the gaskets and the expansion (feeze out) plugs. the cam is a marine or truck cam. other than that it is a simple gm 4.3
 
they are "core plugs" they have nothing to do with freezing.Sometimes they will pop out ,most times not and crack the block
 
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mike.l said:
................. am i right in understanding that the stern drive must be removed first ,
For pulling the engine, it isn't completely necessary to remove the stern drive. You would need to slide the engine forward enough to disengage the input shaft from the drive coupler splines.

For going back in, yes... you will want the drive removed as to not be fighting the alignment of the shaft and coupler!

Once the fresh engine is re-installed, you will want to check/adjust the drive coupler alignment..... aka engine alignment!
There is an alignment tool for this that you can rent, borrow or buy!

I am very confident in engine rebuild etc but never in marine situations
If raw water cooled, you will want to use the Marine head gasket set and the brass casting core plugs.... aka Welch plugs!

If fitted with a Closed Cooling System, you can use a high grade automotive head gasket set.


If your 1999 4.3L was equipped with a Marine roller cam and roller followers, you may be able to re-use them. Examine everything closely..... most often they can be re-used (unlike a flat tappet system).
Click to expand...

NOTE:
My first image is as though you are viewing these components from the Port side.
My second image is as though you are viewing these components from the Stdb side.
 

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Hi thanks for the replies guys . i am well on my way to removing the engine removed the stern drive with no problem engine was a bit more of a challenge but its all loose now ready for a lift on monday morning had to remove the exhaust manifolds first so i could see under the engine at the rear. This afternoon i removed the centre head for curiosity and yes the block is cracked both sides and the centre head is cracked as well. I am not having a lot of luck with finding the block casting # as it has a balance shaft merc 2 barrel carb and thunderbolt ign seems its right in the change over to fuel injection so not sure if the blocks are all the same have found a few 2003 blocks in chevy pickup anyone know if they would be the same thanks mike
 
The 4.3L GM is an "even-fire" engine.... I.E., 90 degree apposing cylinder banks.
Instead of firing at 90 degrees separation as the V-8's do, the 4.3L cylinders fire at a 120 degree separation, of which does not allow this engine to operate as smoothly as it's V-8 counter-part.
The 4.3L counter balance shaft has become necessary in order to smooth this engine out!


Are you looking for cylinder block and cylinder head castings that you yourself will be putting together, or are you looking for a complete ready-to-go 4.3L engine?

You should be able to find the casting numbers on your parts. It would be best to match these.


FYI: a complete car/truck engine will be set up with head gaskets that will not be compatible with Raw Water cooling.
If Raw Water cooled, these would need to be changed to the Marine version head gaskets.

If you were to add a Closed Cooling System, the automotive set will be OK!
 
Hi thanks for the replies i read and hear what you guys are saying , ,but remember i have no overhead costs no labour costs and the engine i have is complete with a small amount of hours on it so i will take it apart and check the condition of the internals and the wear on things like the crank and mains then i will decide as to the best coarse of action this will be my winter project with no time line as to when it has to be finished .But i would like to put it in the water next year I will use the casting number to find a block. someone local has a few bare blocks that have been cleaned and tested by a local machine shop they are supposed to be marine blocks?????
i will take a few pictures of the engine and internals when i have it apart and have it measured as a picture is worth a thousand words and a few extra eyes might spot something i have missed thanks Mike
 
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HI engine all back together total rebuild bored block new pistons regrind valves all bearings and seals replaced new head centre inlet purchased total cost to me
$1000 so guess it was not a bad exercise will install in the boat when it gets a little warmer I have one part that i cannot find the home for took pictures of it when i removed it as you can see from the grease on it but i am lost as to what it does any help please guess picture got lost will have to try again
 
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Hi Rick I have tried several times to get the picture i go to advanced upload picture which it does as the percentage always reaches 100 but then it never appears in the window so i cannot drag it to my post that would be the same with a link only thing i could do is send it email to you and you could reply or direct me to where this piece of plastic shaped like a c, rubber mounted with a part number of 807456 should fit i spent a hour with the old block and oil pan trying to find a home for it but no luck yet
i did do a no-no i sent you a pm thanks for your help mike
 
Hi Well i have achieved something today i managed to get a picture of the part on the forum. yes i had found the parts diagram posted and it looks like it attaches to the block under the flywheel, but there are no bolt holes of that pattern . i stood the old block on end and the spare oil pan and old oil seal it just doesn't fit anywhere hope someone will point me in the correct direction thanks for help Rick mike
 
It looks a two piece shield, that part fits around the starter. It would bolt to the larger cover Item 10 not the block
 
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kghost said:
It looks a two piece shield, that part fits around the starter. It would bolt to the larger cover Item 10 not the block
Click to expand...

Hi i pulled that cover off yesterday and found no place to fit the thing. i do believe it comes from around the starter it looks like that shape its such a simple thing , but i cannot find a home for it you would think i could find the 2 1/4 " bolt holes easy mike
 
Hi no its like part #1 in the link above will remove the starter in next few days to see if it bolts on before starter is installed Mike
 
I believe it does!!

You or anyone else would not want to have to remove that before removing the starter...............That would suck!
 
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