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post #8 of (permalink) Old 8-13-10, 20:20 Thread Starter
chief tool

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Age: 47
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R2 engine differences

I have an old R2 engine block that I bought mainly to get the crankshaft, as I wanted it to build an FE3 stocker for one of my other cars.

However, the RF engine in my 626 seems to have a bit more bearing noise that i'd like....I would say it will probably need rebuilding if I plan to keep the car for any length of time.

Of course I could easily regrind the crank and replace the bearings.....Or I could build a frankenmotor with the R2 block and the RF head and gain an extra 10% capacity, and be able to build the block "offline" so to speak, and old pull the motor when the block is ready to use.

The R2 was never sold in FWD layouts until the most recent Mazda 6, so I would need to some modifications to make it all work....but thats another story for another thread.

Back to the R2 block.....the one I have has some seriously bad pitting at the top of all the bores.

I think the pitting might be caused when the engine starts to burn alot of oil, but I dont know for sure, I havent had much experience rebuilding diesel motors..
Note also that the R2 block that I have seems to have cylinder liners.

Something I didnt know either....some R2 (I would guess alot of the early ones), seem to have dry cylinder liners.
I guess Mazda figured that these engines might travel long distances being fitted to commercial vehicles, and made the liners replaceable.
In later engines they figured it was not necessary as the straight block motors seemed to last well enough.

So...can you get replacement liners....yes.. theyre about $500AUD/set.

I have no idea how much it would be cost to press out the old ones out and new ones in....I guess I'll get some quotes.

The advantage of motors with liners, is that spun cast iron liners can be alot harder alloy than the cast iron used in engine blocks, as you dont need to worry about how much wear it causes on the machining tools.
Spun liners dont need much machining, unlike a complete engine block.

The other advantage is that you dont need to replace the pistons with oversize ones....which is good as I acquired some new old stock std size ones very cheaply from a reseller closeout sale, my originals were badly scuffed.

The other thing I have been told is that liner motors need a different head gasket.
I want to find out what the difference is between that and the regular one.

I would say it has extra sealing arround where the liner joins the block....

I am still not sure its worthwhile doing from a cost point of view, we'll see.

update to come.

84 626 sedan FE SOHC turbo - Sold, no time to finish
84 626 sedan RF diesel - Sold, no time to work on it.
06 Mazda 6 MPS (Mazdaspeed) new fun car no mods yet
07 Mazda 6 MZR-CD 6sp manual - new DD
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