I have a new (not re-manufactured) 3.1L Vin D minivan engine (GM 12513152) and started to do the swap. I searched and found a couple of threads about the water bypass hole in the Fiero timing cover that needs to be filled or it will leak.

Here is the Fiero timing cover with the hole circled.


Here is the Fiero engine with the block hole circled.


Here is the 3.1L engine timing cover where the hole would be but it's just flat so the gasket which has the hole seals it.


What interesting is the next picture. This is the 3.1L engine but it has the bypass hole like the Fiero block.


This is a picture of the Fiero cover on the 3.1L block. The timing cover isn't screwed down but you can see how it mates in the area. I don't see any issue here.


I removed the gasket to show the mating surfaces together. Looks tight to me.


The in the block hole is exactly the same as the Fiero and would mate fine to the Fiero timing cover hole. I thought the 3.1L block was missing this hole and was somehow concave so if you didn't fill the hole in to cover it would leak. If this was true the gasket wouldn't seal the block either.

Note: The documentation with the engine says it's a 93 engine and to use 93 replacement parts.

Am is missing something here? I was thinking that either:

1. I am looking at the wrong hole, or;
2. There is something I am missing about that hole (I see nothing different), or;
3. The 93 engine is different than the 90-92 engines and they started using a more universal block, or;
4. I am crazy.

Anybody?

(Side note, the 3.1L D heads are the HO heads)

[This message has been edited by TK (edited 04-25-2008).]

its been a LONG time since ive messed with one of these swaps, but when i did mine, i used a 87-88 oil pan, and 87-88 timing cover, i dont ever remember there being a hole in the timing cover, even on the 85-86's i dont remember a hole being there.


also have you confirmed that the heads are the large valve heads?

i got a motor from a 1991 minivan that was a jasper remanufactured, and it had small valve heads, i replaced them with large valve heads from a fiero.

matthew

quote Originally posted by TK: I have a new (not re-manufactured) 3.1L Vin D minivan engine (GM 12513152) and started to do the swap. I searched and found a couple of threads about the water bypass hole in the Fiero timing cover that needs to be filled or it will leak. ...The in the block hole is exactly the same as the Fiero and would mate fine to the Fiero timing cover hole. I thought the 3.1L block was missing this hole and was somehow concave so if you didn't fill the hole in to cover it would leak. If this was true the gasket wouldn't seal the block either.

The 2.8 and 3.1 are the same block. It is the 3.4/3400 block that have nothing behind the timing cover hole for the coolant bypass. You need to plug the timing cover hole for those engine blocks.

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Thanks guys, the bottom line here is it looks like I am fine. The are a couple of threads on the forum about that area not sealing on their 3.1L D engines so they definitely can have the problem, but not all. Ed Park replied with the same info about closing the hole up.

The interesting thing is this is a brand new crate engine and not reman'd but it is the last of the engines for the U-Van so maybe they consolidated the parts. Who knows.

Yes, this one has the bigger valve heads.

Thanks for the info!

ps, since it's on the engine stand I will fill it up with water and pressurize it to make sure it doesn't leak 'cause I am one paranoid MF!