90 engine rebuild

[johnny928]

Ok, so I changed the caps on bearings 1,2 and 3. Since they all showed a little bit of wear on the bearings and now the crank turns smoothly with no effort. I guess the caps were no good. I am going to be doing the pistons tonight. I measured the gaps on the rings last night and they all checked out ok. I will let you guys know how that goes.

[libbybapa]

Okay, a bunch of red flags are going off in my head. What do you mean you changed bearing caps? Are you saying you swapped bearing caps with ones from another engine? If that's what you mean, that's a very bad idea. Those are align bored and specific to your engine. You can't even interchange the bearing caps within your engine. They are not interchangeable without getting them align bored after. They are numbered 1,2,3,etc. I was previously suggesting that you swap bearing shells, not bearing caps. I'm hoping that's actually what you did.

Was your engine align bored by the machine shop and oversize bearings fitted?

Was your crank ground by the machine shop or is it still standard size?

Andrew

[VW cat]

Hey Johny, we tell you that the caps must be on the right way, but it's not happening. Did you have them turned the right way in the first place? I can't remember what VW uses to indicate forward on these caps but generally the notched sides go together, the notch to prevent bearing rotation that is. Correct me if I'm wrong here guys. Johny, your bearings are going to show some light marking, the soft coating helps with break-in, I believe.

[johnny928]

Yeah so I was using the wrong bearing caps and pistons. I was using ones from another engine I had disassembled. So in short, I learned the hard way not to interchange parts unless you get them machined to fit. The problem I had with the pistons being to tight was resolved by putting pistons in designated for that engine. I did learn alot of stuff though on this screw up. I think I can put pistons in now 10X faster than when I started and know how to spec everything as well. I will let you guys know if I run into anymore problems and let u know once the engine is done. Thanks for all the help and info!

[johnny928]

If I want to change the wrist pins in the pistons with new ones should that be ok or would there be a problem with that??

[libbybapa]

Changing wrist pins should be fine, but be sure it is a good fit in the piston.

Pistons can be interchanged between different engines as long as the size stamped into the crown is the same between the replacement and original piston.

Andrew

[johnny928]

Just for fun I called VW to ask how much it is for rod bearings and wrist pins. Well, you can't get just the wrist pins they only come with the piston and at almost $700 a piston I think I will pass. Also, the rod bearings were $33 and I thought that was a decent price untill he said it was $33 for each half shell which would make it $264 for a set of bearings....I passed on that.

[Fatmobile]

I suppose if the wrist pins weigh the same and don't flop around in the rod bushings or the pistons, you would probably be OK.
The dealership doesn't always have the best price ... I'm sure Jack could get you the parts for much cheaper.

[VW cat]

That's a good point about the weight. Most never think of that. I don't remember seeing to many worn piston pins in my life compared to worn rod bushings; that fit is very important. That is something you could easily take in to a machine shop for a check. I believe it's just done by feel on the smaller engines.

[johnny928]

wouldn't the pins weigh the same if it came from the same kinda piston?? I didn't think they would use different weights for pins if it came from the same size and type of piston.

[sideburns]

I personally wouldnt bother swapping used pistons or pins from another engine, just because of the fact that if you go aftermarket (or other sources than the dealer) yyou can get really good deals, and the pins you are putting in have worn into a marriage with the piston, and the same goes with the piston head. once you swap em, you get a lot of wear right away as they grind away at the wear surfaces that are different, its just not really worth it to me.

[johnny928]

I ended up switching over one pin from another piston that I have. The one that I was going to put in seemed a little too sloppy for me. I put this one in and it felt better. There wasn't any real differences between the 2 from looking at them ie. wear marks. It felt better with this pin in the piston. I installed the 4 pistons last night and everything turns smoothly

[sideburns]

good to hear!

[johnny928]

... I finished the 90 1.6 engine rebuild and everything was running perfect for a year until I noticed an oil drip on the floor. Turns out the rear seal started leaking along with the seals on the tranny. So, I removed the tranny and replaced the rear seal and replaced the flange seals on the tranny and everything works again with no drips. Just a note to everyone, when changing the seals, only buy the german made ones, don't get the aftermarket ones to save a few bucks. it isn't worth it in the long run. The quality of the german made ones compared to the victor reinz ones that I originally used was night and day.

[Fatmobile]

Hey, thanks for the update.
Glad to hear you are still on the road.