S50 Dissasembled. Have some Q's.

[golde30]

okay, so my mechanic and I pulled the head on my s50 today, and it looks like it had a blown headgasket. the head is being sent off to the machine shop to be measured for straightness, and if its ok, the valve guides will be replaced.

NOW, the block is at TDC, with #6+1 pistons at the top. the Question I have is, how much should i be able to rock the #1 pistons side to side? should they move at all? i am able to get them to rock about 1mm maybe, like in a teetering motion(center in same place, sides moving up and down) also, are the s50 pistons forged?

im tryn to decide whether or not the piston rings need to be changed. i would rather not pay my mechanic to do anymore work that he is already doing, as my budget is totally shot as is, but i gotta do whats gotta be done rite? thanks for any information!

[dougsic]

The pistons will rock in their bores and 1mm is normal.

[325Projectz]

if you go to replace the rings, you might as well rebuild the bottom end. new main bearings, rod bearings, you need to have the block cross-hatched/honed and i would have them deck it too. no more then $200 for the block labor. parts are going to vary, depends on your hookups.

how many miles are on the motor? how does the factory cross-hatch look? any worn spots?

[RVA e30]

1mm rock is normal.

if you start to pull apart the bottom end, like 325projectz said, you might as well rebuild the whole bottom end.

were there any known problems with the bottom end?

[static]

hmm , my mechanic told me he could replace rings with just the head off (no bottom end disassembling) - or maybe i misunderstood him

to OP: change retainers for later style if still haven't!

Alex

[LINUS]

hmm , my mechanic told me he could replace rings with just the head off (no bottom end disassembling) - or maybe i misunderstood him

to OP: change retainers for later style if still haven't!

Alex

"Can" & "Doing it right" aren't the same, if you're rings/bores are worn, then you probably need new rod bearings, etc. due to total wear on motor.

Just changing rings is like plugging a few holes in a vegetable strainer - it does a bit of good, but not like filling all the holes.


golde30 - If it helps at all, when I had my S52 apart, it had nearly the same rock and I had all my crosshatch on a 4xK motor, I just had to teardown mine since it had some grit down the intake ports since it shipped without a intake manifold.

[golde30]

to be honest, im totally out of money. so im going to do as little as possible on the block. the head is being rebuilt, but i think imma try and get away with just doing the rings and conrod bearings. the motor has 8XK on it, and after talking to my machinist, he also says that the lil bit of rocking is normal b/c the piston skirts are so short on this motor.

i have 6K into this swap as is, i was shooting for 5K, and im not even done buying other needed parts. machining/mechanic work in the SF bay area is really pricey, so im not just dealing with parts cost when it comes to rebuilding the motor. i guess the block will have to do with the rings and conrod bearings. thanks for the info!

[golde30]

my head pressure tested out OK. so its getting a valve job, 3angle etc etc. as for the block, the cross hatching is still visible, and i think imma just clean off all the carbon, check the surface for straightness, and re-assemble. if i had an extra $2K sitting around i would have done alot more, but for now imma have to make due with my budget.

motor is gonna be assembled this week, then my car goes into the shop to get that old m20 out and some major cleaning will go down on the engine bay. then the z3 2.7 rack goes in, along with braking system, then the motor next week!!

[m42technic]

With only 80k miles, the bottom end should be fine.

[Jean]

Good luck man! Is there a way to clean the bottom end w/o taking it all completely apart ?

[m42technic]

Good luck man! Is there a way to clean the bottom end w/o taking it all completely apart ?

Yeah, change the oil on a regular basis.

[Jean]

Yeah, change the oil on a regular basis.

Helpful, let me find the PO and ask him to change the oil on the removed block

[FredK]

why, is there a lot of gunk in there?

[Jean]

why, is there a lot of gunk in there?

Not to hijack the thread, it was more of a theoretical question. Was just thinking it might be a good info to know..

[golde30]

Good luck man! Is there a way to clean the bottom end w/o taking it all completely apart ?

drive hard and change oil is my policy. has worked quite well with my m20. when i opened my m20 up, it was pretty damn clean.