engine rebuild Engine tear-down for rebuild- 660cc Vivio

[Bdamit]

Hi all

I know there are few (or none) Vivio owners on this forum, but as it is a full-fledged Subaru I hope some of us may find this interesting.

I am in the middle of an engine rebuild for the tiny 4WD, and so far so good (tearing down is the easy bit). This is my first full engine job.

After my little spark plug worry I have since stripped down the head and block, and given the clutch housing a good clean inside and out. It has been accumulating a lot of leaked oil inside, apparently from some bad head seals. 

The pistons are in good condition, except number 2 which has some minor damage from the spark plug insulation which had broken off.

The cylinder bores are fine, as is the crank, but I have the **flywheel-end** main bearing with some wear through to the copper. This one is furthest from the oil pump. I am guessing that a new set is on the cards.  

**my bad- it's not the flywheel end, it's the other end, closest to the pump!! Go figure.

I shall plastigage the caps to see if I need undersize bearings, but judging by the condition of the majority of the bearings I imagine not.

The bores shall be lightly honed, new rings installed,  and perhaps I should check the oil pump too while everything is off.

Fingers crossed, thanks!!

Block out and cleaned up:

 

Gear box spruced up:

 

That worn bearing :/

 

The rest look like this:

 

Edited July 9, 2018 by Bdamit
** bearing location

[GeneralDisorder]

Don't hone it:

http://www.snowvalley.20m.com/bikes/dnthone.htm

[el_freddo]

Definitely service the oil pump. If that fails you kiss your efforts goodbye

Very interesting read GD!

Cheers

Bennie

[GeneralDisorder]

I never hone any engine except as the final step to an over-bore. If the bores are bad it needs to be oversized or have sleeves installed. Honing will not fix out of round, hourglassed or tapered (or all three) bores. And it isn't required for ring seating. So it serves absolutely no purpose. 

GD

[Bdamit]

Thank you for your comments, gents.

El Freddo - I'll certainly be checking that pump thoroughly, I have a Subaru Sambar service manual which I use for engine work- it is the same engine as far as the major components are concerned. I have all the new seals too.

 

General disorder- That article is really useful, thank you; I was concerned about the honing part, especially as it would likely be done inaccurately with a hand drill as I have seen and read all over the internet. Doesn't seem the most professional method for these Japanese motors.... it scares me a bit!

Additionally, the bores actually look really good, and I was secretly hoping that a good reason NOT to hone the bores would crop up. And it is totally intuitive that a well 'finished' shiny not worn cylinder is what is needed.

Four bores like this; excuse the shop-rag residues:

 

There are even traces of the factory honing on all bores:

 

The pistons show a light polishing on the pin sides of the skirt, but no 'rubbing'.

I am installing brand new Subaru rings, though the originals look quite good too. (I snapped one stupidly while giving the piston a preliminary clean, damn they're fragile) .  Something to clean the grooves with!

I am waiting for some parts, which gives me time  to check and clean, and I'll post my progress and countless questions.

 

Thanks again!

 

 

[Bdamit]

Hello again

its been a little while, juggling a few hours here and there to finally get the little engine back together again.

so we have installed new piston rings, main bearings, conn rod bearings, seals for crank, cam, valve stems, water and oil pumps, and the belts. Everything has been deep cleaned, there’s a new clutch kit, and hey, it started on the key as if nothing had happened!

no smoke, no rattles, and it doesn’t miss a beat. Now the tricky part is treating it gently whilst we run her in. 

Taking General disorder’s advice, I did not touch the decent bores, letting the piston rings do their job with some SAE 30, now changed after 30 miles of run-in.

Running in:

First start I disconnected the fuel system fuse, letting the engine crank on the starter until we reached oil pressure. Then with everything connected I started the engine and gently played with the revs (2-3k) with gears in neutral for about 20 minutes.

all good, so onto the road run; a good 30 mile drive, gently building engine speed then deccelerating in gear. No problems.

fresh oil and filter, and now I shall accumulate another 500 miles of gentle highway before a further oil change. Then 1500, then every 3-4000 miles as usual.

so i’m a happy bunny, time to give the forester it’s service.