Crankshaft conundrum

Post by **irish.david** » 01 Oct 2007, 13:49

I need to get a new set of main bearings for my crankshaft and have a choice of 2 sets from GSF. I don't know the age of my engine (donor) but the crankshaft has the red dot on it. I can get all the VW part numbers i need but all there is on the GSF site is a set of bearings for engines from 1985 to 1990 and another from 1990 onwards. Anyone know which age group the red crankshaft dot falls into?

On another slightly different note, when taking a stubborn gudgeon pin out i managed to mark the surface of a piston. The mark is just below the ring groove from the top compression ring. I given it the slightest of slight tickles with a file to make sure there are no raised edges so i can't see what damage it might do. With the new rings the compression should be ok but in Bentley and Haynes there are all sorts of scarey messages warning people not to sratch the pistons. Obviously it's not ideal but will it do any damage / seriously affect running?

Cheers

Dave

Post by **HOT 1200** » 01 Oct 2007, 14:12

Hi...firstly, what engine type........
(then someone can help with the crankshaft questions.....)

Second...
Any marks on pistons below the top ring do not affect compression ratio......Only modifications to the piston crown (area of metal above the top ring) can affect this......
That said, if its only a scratch that can just be felt with your finger nail, then you should be ok....
However, if its 'impact damage' from a subtle blow from a blunt instrument (what ever you drifing out your wrist pins with) you should check the ring-lands have not distorted ( the groove that holds the top ring.....make sure there are no tight spots ensuring the top ring is not being snaged by a 'burr' or heavey scuff....

Most importantly, make sure the ring lands are clean and free of any carbon deposits.....this will help the new rings to sit snuggly in their new homes !!!! DO NOT CLEAN THEM using old broken piston rings, CLEAN THEM using carb cleaner (soak them if needed) and use pipe cleaners for final clean up.........
One last thing, if your having trouble with tight wrist pins, warm up the pistons first, the wrist pin will simply push in using thumb pressure, always oil them and ensure plenty of oil is also on the small end bush. Take your time fitting the wrist pin retainers, check they locate correctly, then check again and again.....thrown clips make a real mess as your wrist pin eats its way out the side of the cylinder bore !!!
Good Luck....take your time and clean everything.......

Gav

Post by **irish.david** » 01 Oct 2007, 14:22

Ooops. I always roll my eyes when people ask engine questions without saying what engine type. Sooooo, engine is a 2.1 DJ.

When i was trying to get the gudgeon pin out i was heating it with a blowtorch for about 10 mins. I got an expanding bolt through it and was trying to pull it out by driving it out. Because of the lateral motion i was worried about the big ends so, stupidly, i put the head of a bolt between the piston and the crankcase. This has made a few slight indents on the pistons surface. The ring grooves are ok and the new rings can move and rotate without any sticking. I think it'll be ok, but i was wondering if there was anything that isn't obvious going on with the pistons or barrels in these engines.

Dave

Post by **HOT 1200** » 01 Oct 2007, 14:33

10 minutes it too long.........the piston would have disipated its heat into the writ pin......

Make sure you clean the wrist pin....they get a build up of cabon on the exposed section easily identified as two dark lines round around the pin. Because this part is exposed to the Crank Case and sits between the piston and the small end bush. Clean of the carbon deposits........this will be why the wrist pin was a pig to remove........

One thing worth checking on the 2.1 motors, small end bush wear...
Fit the pin into the small end (do not fit piston) now try to rock it side to side......feel it rocking........? then get new bushes fitted.....
GaV

Post by **toomanytoys** » 01 Oct 2007, 14:49

DONT reuse the big end bolts.....
and I would suggest you get the rods "resized" too.. any good vw machine shop will do this easy, your local should be able to as well..

You really ought to measure the crank... even ask your local machine shop to measure it for you.
ANd then ought to check the clearance with plastigauge when you get the bearings..

Post by **irish.david** » 01 Oct 2007, 15:45

When i say 10 mins, it was more a case of heating for about a min, then trying the pin and when it wouldn't shift, back to the blowtorch. Not going to do the big ends as they still feel ok, i don't want to start taking a perfectly good crankshaft apart and, most importantly, i'm out of cash. Small ends have been checked with a gudgeon pin and are still good. Pretty much the only thing stopping me from putting this thing back together are the main bearings. They're soo easy to change that it would be a waste not to put new ones in. I could get them from VW as i've got the VW part numbers for the red dot variety but GSF are a lot cheaper, if only i could figure out which year the dot changed from red to blue or vice versa....

Dave

Post by **HarryMann** » 01 Oct 2007, 16:01

Will see if ETKA says anything on re/blue dot yearchange later...

Piston no problem, you should see the way we used to run 2 strokes in, use a "bar-steward" file to remove seized high-spots, the grooves then retain the oil. Pistons are oval and not round below the gudgeon pin and large areas do not contact or play much part in supporting it, if you swaged it a bit, better remove more rather than less.

Post by **HOT 1200** » 01 Oct 2007, 16:04

Take a rod off........
The small ends will have part numbers stamped on the back of the shells....

You should use new rod bolts........but if you cant afford it, then use locktite and make sure you 'do not' overtighten the bolts/nuts....
Simply torq up to the correct figures....do not be tempted to 'sneak up' on the torq........

GaV

Post by **irish.david** » 01 Oct 2007, 16:23

I've checked the VW part numbers on Vagcat.com and even if you check the 1992 part numbers it still gives you different part numbers for red and blue dots. I think at this point it'll be easier for me to go into my local VW dealer with the part numbers and skip all this GSF stuff.

Dave

Post by **HarryMann** » 01 Oct 2007, 22:34

Yes, they won't be that much more (x 2) and I've had helluva job with shells from GSF before... admittedly I didn't know exactly what my engine was, but hey.... !