80 replies to this topic

[AndyMiniMad.]

When you put the caps on. put the locating lugs for the bearings on the same side. so long as you have the correct cap on the correct rod it should move fine. But do them one at a time and turn the crank each time to be sure!

[ACDodd]

Dry build without rings fitted. This way you can see if the assembly if free to turn after each cap is fitted.

 

AC

[johnnyblaze]

like AC has said , fit 1 piston at a time , thats fit into the bore -onto the crank cap on and torque, spin the crank over if its smooth and good do the next piston, this way of 1 at a time is best because if you put 2 in and they are sweet then the 3rd goes in and is tight or locks up then you know straight away where the issue is,

[maieth]

Yeah, that would have been a much better way to go through it. May need to strip back down and start again.
I tried removing all caps and testing the first one both ways round. Locked up both times. Took it off again and inspected bearing and it looks unpleasantly scored. Beginning to think that first machinist might have mixed up the caps completely. Wish I'd marked them up myself so much now.

Pictures if crank journal on #1 piston, and bearing surfaces on the caps for #1 and #4:

[maieth]

NBC: black goo is graphene, not oil.

[maieth]

Extra question as well - how much resistance/ freedom of movement am I looking for. I've removed all but one piston and torqued the cap down. Crank turns freely but takes some effort getting the piston past tdc. If all 4 grip this tightly it's no wonder I can't turn it (I'm no Johnny bravo), but is that too much for the engine?

[maieth]

Sorry to repeat post so much.
Some progress though. Removed all 4 pistons and started one at a time, beginning with number 4. Each one got fitted to crank pin and fully torqued down, then tested before taking apart again and removing the piston to try the next one.

Many thanks to Andy again, matching up the locating lugs on the bearings saved a lot of time on trial and error here.

4, 3 and 2 all turn very freely, very smoothly.
1 is definitely the problem. With cap the correct way round it turns okay when hand tight, but fully torqued down it locks right up and is extremely difficult to turn even a tiny distance.

EDIT:
Tried switching all caps now, the cap from piston #1 locks up no matter where you try it. Other caps used with con rod #1 allow crank to move.
Also, with caps fully torqued down on 2,3 and 4 all 3 move and turn fine. Problem is definitely the big end cap on number 1. Now I just need to figure out what's wrong and how to fix it. Any ideas?

Edited by maieth, 11 May 2013 - 04:08 PM.

[Jordie]

remove the bearing from the con rod cap.

 

get some 2000 grit wet n dry and lightly sand the face where the shell sits into. there may be something stopping the shell sitting fully home and causing issue. spec of dirt etc.

[maieth]

Good call jordie. I'm going to try swapping over another bearing and ill give it a quick once over with wet and dry 1st, if there's no differences I'll put some more elbow grease in.

[Fast Ivan]

You could remove the bearing, torque it up and measure the internal diameter to make sure its within tolerance

[Fast Ivan]

what condition was the bearing that came off when stripping the engine? this may yield some information

[maieth]

Good question. Out tonight but I'll have a look tomorrow.

[johnnyblaze]

please tell me you have the pistons in the correct way or that someone has not put a rod on backwards, remember that the rods need to be facing a certain way 

[maieth]

I kind of wish it was something that dumb by now. Another half hour on it tonight. Good news id im getting much better at taking pistons out and putting them back. Pistons are right way round. Referred to Haynes but they won't line up wrong way round anywho.

I've tried swapping a different bearing into the cap for number 1, and I've tried cleaning the faces of both cap and con rod with 2500 grit wet and dry. Combination of those two things has made a noticeable improvement, but it still feels exceptionally tight

[Fast Ivan]

you need to start measuring dude, what did the crank where no 1 big end was look like before the grind? and the bearing? you mention the big end journals needed regrinding