Engine Identification

GirlyGirl1999

GirlyGirl1999

Well-Known Member
SILVER Sponsor
Apr 10, 2021
997
Lake Norman NC
Boat Info
1999 Sea Ray 290 DA
Engines
Twin 4.3 with Alpha 1 Gen 2 drives
Hey Group, hope everyone is getting ready for spring. Sorry if this has been covered before but I couldn’t find what I was looking for. My boat came to me with very little documentation. But I was “told” the engines had been replaced sometime in 2015. I believe at least one has been changed as the starboard engine has wet risers and the port has dry. Yes I know the starboard is rusty in the picture, it’s an old picture from 2021. I have removed the the risers and had them inspected and repainted. New manifolds and risers are on the list for this season. I’m going down tomorrow for some unrelated work but wanted to pick your brains on how to ID the 4.3’s there are no serial numbers on the flame arrestors. From reading here and watching some youtube stuff, if they are true Mercruiser engines there should be a tag on the lower left (as your looking at the engine from bow to stern) with a serial number. So if there is no tag then where would the casting number be and can the origin of the engine be looked up with this number? In my old gear head days SB chevys were on the top left behind the intake. Thanks in advance for any and all comments.
Jon
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@GirlyGirl1999 Jon, the chevy location for the engine block serial number is on the block, on a casted tab where the head meets the block on the front of the engine. Front right side looking at the front of the engine. That is standard for all SB 350's and possibly the same for you.
 
the casting number is located at the rear of the block just behind cylinder 7. ID code is where it was described above.
 
scoflaw said:
the casting number is located at the rear of the block just behind cylinder 7. ID code is where it was described above.
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l’ll have to look for that #7 cylinder, sorry couldn’t resist being a smart ass.
 
SKybolt said:
@GirlyGirl1999 Jon, the chevy location for the engine block serial number is on the block, on a casted tab where the head meets the block on the front of the engine. Front right side looking at the front of the engine. That is standard for all SB 350's and possibly the same for you.
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Correct, I remember now. Those are stamped not cast correct? I’ll look tomorrow.
 
Might have a hard time looking behind #7 on a 6 cylinder. LOL
Never noticed any stamping on a Merc block, never looked that hard either. Obviously no VIN.
 
Correct me if I'm wrong here... the more important number is going to be the Mercruiser serial number since that tells him the specifics of THAT particular Chevy 4.3 block and when it became a "Mercruiser". THAT serial number is the one on the little metal tag on the engine's stbd side - above the starter.

Try using your phone - put it on a stick if you have to :)
 
scoflaw said:
Might have a hard time looking behind #7 on a 6 cylinder. LOL
Never noticed any stamping on a Merc block, never looked that hard either. Obviously no VIN.
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LOL, yeah was going to leave that alone. But the serial number is part of a cars vin, obviously not a boats HIN. That posting was just a reference as to it's location.

But yeah, all SB Chevy's have it stamped in. The casting number is on the rear but the serial is stamped on the front. Strange why the change the location of the v6. On my 80' C3 it's on on the right front by the water pump top bolt in front of #2 cylinder.
 
Lazy Daze said:
Correct me if I'm wrong here... the more important number is going to be the Mercruiser serial number since that tells him the specifics of THAT particular Chevy 4.3 block and when it became a "Mercruiser". THAT serial number is the one on the little metal tag on the engine's stbd side - above the starter.

Try using your phone - put it on a stick if you have to :)
Click to expand...

Aren't they the same? The Merc number includes the engine serial number? Could be wrong on the V6's, the earlier V8's were that way.
 
Lazy Daze said:
Correct me if I'm wrong here... the more important number is going to be the Mercruiser serial number since that tells him the specifics of THAT particular Chevy 4.3 block and when it became a "Mercruiser". THAT serial number is the one on the little metal tag on the engine's stbd side - above the starter.

Try using your phone - put it on a stick if you have to :)
Click to expand...
Agreed, however my poor Frankensteined boat may have engines from somewhere else, as posted and in the pictures one is wet riser and one dry, super electrician had to trace and splice the starboard engine for a no start condition and commented that when it (starboard) engine was replaced the “professional” mechanics simply cut the connector plug off and spliced it back together (poorly), that has since been completely repaired by him and warrantied for as long as I own the boat. Point is he said the Thunderbolt ignition on the port engine (dry riser) is newer than the starboard. Both have the “Vortec” valve covers and the correct 8 bolt intake manifolds. So we will see if they have Mercruiser tags or not tomorrow. As for the phone on a stick thing maybe I can convince one of the marina girls to climb in and look for me, that reminds me, I need to stop and get more money. :rolleyes: The plot thickens.
 
GirlyGirl1999 said:
Agreed, however my poor Frankensteined boat may have engines from somewhere else, as posted and in the pictures one is wet riser and one dry, super electrician had to trace and splice the starboard engine for a no start condition and commented that when it (starboard) engine was replaced the “professional” mechanics simply cut the connector plug off and spliced it back together (poorly), that has since been completely repaired by him and warrantied for as long as I own the boat. Point is he said the Thunderbolt ignition on the port engine (dry riser) is newer than the starboard. Both have the “Vortec” valve covers and the correct 8 bolt intake manifolds. So we will see if they have Mercruiser tags or not tomorrow. As for the phone on a stick thing maybe I can convince one of the marina girls to climb in and look for me, that reminds me, I need to stop and get more money. :rolleyes: The plot thickens.
Click to expand...

So if that is the case, you can get the engine year from the serial number stamp and from that year you can track down roughly what the Merc number is by looking up parts. Here is an example, if you look at the years this will narrow down he possible numbers and with a little more investigation you can nail it.

example site: https://www.crowleymarine.com/mercruiser/oem-parts/stern-drive/serial-range

That is if you get stuck and can't read the Merc number.
 
Phil S said:
Ok, lost interest in the vin tag. Let's hear more about these marina girls :cool:
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I’ll have to ask if they would like their faces on our world wide site. Won’t be bikini thread worthy but they are real, maybe the HMFIC will let me take her pic, everyone says she’s a complete bitch but she runs a tight ship and her and I get along great. Tomorrow should be fun. ;)
 
SKybolt said:
Aren't they the same? The Merc number includes the engine serial number? Could be wrong on the V6's, the earlier V8's were that way.
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You know, I've never thought about that. I don't think I have ever even looked at the block's (GM) serial number and compared it to the Merc serial number before, either.

I'm thinking "no", though? The Merc serial number will start with something like a "0W" or 0M" (or something like that) and then there would be 6 digits after that. Those 6 digits tend to go, pretty much, in order, too. I doubt that the block's serial number would match up with those 6 digits - Merc would have to buy many, MANY blocks all at the same time - and do that year after year.

I'm curious, now!

V6 vs V8 should be the same, though.
 
Lazy Daze said:
You know, I've never thought about that. I don't think I have ever even looked at the block's (GM) serial number and compared it to the Merc serial number before, either.

I'm thinking "no", though? The Merc serial number will start with something like a "0W" or 0M" (or something like that) and then there would be 6 digits after that. Those 6 digits tend to go, pretty much, in order, too. I doubt that the block's serial number would match up with those 6 digits - Merc would have to buy many, MANY blocks all at the same time - and do that year after year.

I'm curious, now!

V6 vs V8 should be the same, though.
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I thought the last 4-6 were the same, possibly? Like VIN numbers are.

Didn't follow having to buy too many blocks. I would think they would make the tags to match the build.
 
SKybolt said:
I thought the last 4-6 were the same, possibly? Like VIN numbers are.

Didn't follow having to buy too many blocks. I would think they would make the tags to match the build.
Click to expand...
No, all 6 numbers (the last 6 digits) are unique. The first two "0M" or "0W" or "1A" stay the same for a long time while the last 6 continually change.

The Merc serial numbers go in order... 0M300000... 0M300001... 0M300002... etc. So if Merc was using a block's number as the basis for the Merc serial number, it would stand to reason that Merc would have to buy thousands and thousands and thousands of blocks at a time in order for the final Merc number to be "in order". It would also mean that no other vendor could buy blocks while Merc was buying otherwise the numbers would get out of order. And that doesn't seem to make sense.
 
Lazy Daze said:
No, all 6 numbers (the last 6 digits) are unique. The first two "0M" or "0W" or "1A" stay the same for a long time while the last 6 continually change.

The Merc serial numbers go in order... 0M300000... 0M300001... 0M300002... etc. So if Merc was using a block's number as the basis for the Merc serial number, it would stand to reason that Merc would have to buy thousands and thousands and thousands of blocks at a time in order for the final Merc number to be "in order". It would also mean that no other vendor could buy blocks while Merc was buying otherwise the numbers would get out of order. And that doesn't seem to make sense.
Click to expand...

Yeah I re-thought that one and that makes sense and why the serial tag is in three different spots on the engine.
 
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