Balls! Mi Oval Rod After Re-build

[SweetBadger 94]

Really getting pissed off with this car... One bloody thing after another!

 

Anyway, I managed to swap my old knackered MI (engine #3!) with the MI lump I've just rebuilt (just about renewed everything) over 3 days at easter when it wasn't raining!

 

I've run it for 150 miles and it soon developed a tapping noise - more high pitched, so at first I thought it was coming from the head. Unfortunately the noise is loudest at 3000-4000 rpm on light throttle which suggests the bottom sodding end. I had the crank re-ground (mains and big ends) and the oil pressure is ok showing 3/4 when cold at idle going to the top of the gauge when revved, and sitting at 1/2 way on the gauge @ 4000 rpm with hot oil so with no real clues as to where the noise was coming from I've pulled the sump off and had a look at all of the mains/big end shells and journels.

 

Everything looks ok with regards to the crank but I noticed that #1 big end shells looked more 'polished/shiney' than the rest, and then when trying to refit #1 rod I couldn't get the cap back on! I also tried the cap on another journel and it simply won't push on by hand, so I'm guessing the rod was ovaled when I installed it. Can't beleive I missed it, but it went on much easier when I was building the engine and the crank turned without a problem... Anyway got a few questions about this...

 

Would this have caused the symptoms I described above ?(I would have expected more of a knocking sound)

 

And also seeing as I'm going to have to take the head off to change the sodding rod can I re-use the head gasket and head bolts as they've only done 150 miles?

 

What about the rings bedding into the liners (new) - if I remove the pistons, the rings will rotate, does that mean that they will have to bed in again and I'll need a cylinder re-hone and new rings? Would I be better off removing the whole liner and piston as one then fitting a new rod without removing the piston from the liner completely.

 

Thanks,

 

Alex.

[pug_ham 244 3 Cars]

Thats damned unlucky, unfortuately if the crank has previously spun a bearing it is more than likely the rod will also be dead & you are lucky if the crank isn't bent.

 

AFAIK you'll have to remove the piston from the liner to make removing the rod easier (if you disturb the liner you'll need a new seal) but if the rings do move slightly all you need to do is realign them at the correct spacings & they should be fine, no liner hoe needed or anything. I did this on my engine when I rebuilt it & it doesn't use any oil.

 

Head gasket & bolts are best replaced, head gasket is a definate but bolts aren't really worth the risk, if one snaps in the block removing the remains will really cause you to be peed off.

 

Graham.

[SweetBadger 94]

Thats damned unlucky, unfortuately if the crank has previously spun a bearing it is more than likely the rod will also be dead & you are lucky if the crank isn't bent.

 

AFAIK you'll have to remove the piston from the liner to make removing the rod easier (if you disturb the liner you'll need a new seal) but if the rings do move slightly all you need to do is realign them at the correct spacings & they should be fine, no liner hoe needed or anything. I did this on my engine when I rebuilt it & it doesn't use any oil.

 

Head gasket & bolts are best replaced, head gasket is a definate but bolts aren't really worth the risk, if one snaps in the block removing the remains will really cause you to be peed off.

 

Graham.

 

Ok thanks for the advice, I've managed to secure another rod and I'll go for the new head bolts and gasket, as the way this project's been going if something can go wrong it will!

 

You've worried me a bit about the crank possibly being bent! It was in quite a state when it came out if the engine with scoring on every journel, but I sent it off for a check and regrind and it came back with a clean bill of health... but this is from the same company that skimmed too much off my head and made a bit of a pigs ear of the finish, hmm. All of the journels look fine and measure up ok so they've done a good job of that at least, would it even be possible to regrind a bent crank?

[ALEX 98 1 Cars]

would it even be possible to regrind a bent crank?

 

I doubt it.

Though I've never seen a bent crank before.

I had an 8valve crank with an oval journal (spun shell) the crank was destroyed and had to be scrapped.

Your local engineer should be able to tell you if it can be repaired or not.

If the piston liner seals were done in the rebuild 150 miles ago I wouldn't worry about disturbing the liners as the rubber should still be flexible. unless you fitted paper ones.

[SweetBadger 94]

I doubt it.

Though I've never seen a bent crank before.

I had an 8valve crank with an oval journal (spun shell) the crank was destroyed and had to be scrapped.

Your local engineer should be able to tell you if it can be repaired or not.

If the piston liner seals were done in the rebuild 150 miles ago I wouldn't worry about disturbing the liners as the rubber should still be flexible. unless you fitted paper ones.

 

Ok, well that's good news because the crank was reground before going in and I found the problem with the rod before the shells spun or caused any ovaling to the journel (measured @ 49.71 /49.72 mm with my verniers), in fact the shells still look in good nic, but i'm goint to replace em just to be on the safe side - another 40quid for 2 shells as they only come in full sets bugger!. I've got some spare liner seals anyway as I got 4 with the bottom end gasket set and then 4 with the liners, so I'm not too worried about disturbing the liners...

[pug_ham 244 3 Cars]

You can re-grind a bent crank but it will still be bent & catch the bearings causing another spunbig end.

 

If you are taking it out again to do the rod etc, I'd get it checked by an engineer to see if it is bent rather than just risking it again.

 

Graham.

[SweetBadger 94]

You can re-grind a bent crank but it will still be bent & catch the bearings causing another spunbig end.

 

If you are taking it out again to do the rod etc, I'd get it checked by an engineer to see if it is bent rather than just risking it again.

 

Graham.

 

Hmm, blimey, dilema time... I was not planning to take the crank out again, and I can't afford the cost of another 2 weekends of hiring an engine hoist to take out/replace the engine.

 

The company that reground the crank are members of the FER (Federation of Engine Re-Manufacturers), which apparantly means their work should be guaranteed for 12 mts, and with this being the case I would have thought that they should notice whether a crank is bent before they regrind it...

 

If the crank was bent surely it would have been more obvious with regards to damage to the shells - one side being worn or the shells out of shape? Also the tapping noise only occurred when the oil warmed up - with a bent crank would this not have hapened all the time.

 

I guess you can speculate all day long but I think i'm going to stick a new rod in and give it a try (i'm due some good luck on this project). I'll keep a close eye on it and if there's still a problem I'll get the crank checked else where and deal with it from there on.

[pug_ham 244 3 Cars]

The company that reground the crank are members of the FER (Federation of Engine Re-Manufacturers), which apparantly means their work should be guaranteed for 12 mts, and with this being the case I would have thought that they should notice whether a crank is bent before they regrind it...

They might've checked to see if it was bent but ring them up & ask to make sure.

If the crank was bent surely it would have been more obvious with regards to damage to the shells - one side being worn or the shells out of shape? Also the tapping noise only occurred when the oil warmed up - with a bent crank would this not have hapened all the time.

Not afaik, even when they are bent it isn't easily visable to the naked eye.

 

Graham.

[smckeown 1]

I can't afford the cost of another 2 weekends of hiring an engine hoist to take out/replace the engine.

 

I have an engine hoist you can borrow

Edited April 22, 2006 by smckeown

[SweetBadger 94]

I have an engine hoist you can borrow

 

Thanks, that'd be great - I may well take you up on that but I'm going to try a decent rod first.

 

My circumstances at the moment mean that pulling the engine out again really will have to be a last resort - i'm living with my girlfriend and her parents, just while we get on our feet after finishing uni and the only place I have to work on the car is in a very cramped shed or their driveway which I already took over for the whole easter weekend... Although they have been really good about my car shenanigans I don't want to push my luck! It really sucks not having a decent space to work!

 

The way I figure it, if the crank is bent it's scrap anyway and I'll have to take the engine out to replace it. It's preety easy to get the head and sump on and of in the car, in fact I've got the head off and the offending rod out already (just removed the piston and liner complete and kept the rings in place) so I might aswell try it seeing as it didn't spin a shell the first time (and when i though it was a tappet I did get carried away and take it to about 6500rpm a couple of times with out any drama). If I have the same problems all I have to do is remove the crank and re-grind the one out of my old MI. I should be able to leave the top end alone... I'll definately give the company who re-ground it a call to see whether the checked it first - they might be able to give me peace of mind!

 

Talking about having nowhere to work on it - when taking the spring clip out from the side of the piston to remove the rod (on the side of the road!) I forgot just how springy they are and it pinged and flew in the air for a few seconds before landing in a bush in the front garden! Bugger! Can't see any sign of it now...

 

Does anyone have a spare they are willing to part with?

 

Thanks,

Alex.