98-99 4.3 bare block/short block interchange

[lintmann]

Ok so my 99 Regal has a 98(cast June of 98) 4.3 with a block casting number of 14099090. It is cracked from freezing and needs to be replaced. Heads look okay.

I have found a supposedly running 99(cast Feb of 99) with a block casting number of 14099090M from a S10/Sonoma.

My question is, does anyone now for certain if I can use this later "M" version bare block or short block?

I've done a lot of research so far and it seems that the difference is that the "M" has metric threads for starter, bell housing and engine mounts so I could probably accept that. One site says the oil pan has a different number of holes between the two castings so I won't deal with that.

A lot of the info I have found on various sites has been copied and pasted so now I'm finding the same info over and over. I found some really good info on the 4.3 with casting numbers and all but it stops at 98... I think that original article was printed in the early 2000's.

Anyways, has anyone used the later 14099090M block casting in place of the 14099090 and if so what all did you have to do, if anything?

Thanks, any advice is much appreciated!

 

[Scott Danforth]

1996-2003 blocks same. The Metric blocks will need different fasteners, but that's it

 

[Lou C]

Check those heads carefully because if the block cracked it’s pretty likely that the heads, intake manifold and exhaust manifolds could be cracked too…

 

[Lou C]

All these threads about cracked blocks goes to show you..you put in a new or re-man or a salvage from a truck motor do yourself a big favor and either add closed cooling or at least make your engine easier to winterize…I thought up a way to extend the block drains without the draw backs of Merc’s single point drain system. This will enable me to drain the motor without having to pull out the rear seats to get at the block drains. That & a remote oil filter mount will make my boat maintenance easier on my old(er) self lol….

So the idea for the block drains….
You know the drains with the brass fitting that screws into the block with the t handle plus that then screws into that? Remove those t handle plugs. Then get about 12” of hose that fits tightly on those fittings & clamp them in place with hose clamps. Then get garden hose fitting with the screw on caps to seal the open end. This way you can easily reach the hose without taking half the boat apart and, you could still rod them out with a long piece of coat hanger wire. I got this idea from seeing a similar system on a VP engine but both drains were connected with a Y fitting. I’d keep ‘em separate so you can rod em out….

 

[lintmann]

Thanks guys.

Scott thanks for the clear concise answer!

Lou, thanks for the tip on the drains. I've never winterized this boat so I'll take your advice on the remote drains. Our first boat has a 3L Volvo Penta and the drains are easy to get and as you know, you do need to make sure a good stream of liquid comes out of each one and not just crack them open and figure you've drained it.
I'm pretty sure that a plugged drain is what caused this 4.3 of mine to crack because the guy I bought it from said that he drained and ran antifreeze though it but it still cracked on his second winter. While looking at it once it was out of the boat I could clearly see that one of the block drains is plugged...