Difficulty installing last main cap in L28

[Hype]

Rebuilding an L28 and that last main cap (the one with the rear main seal) is giving me grief. It's near impossible to tap it in with a mallet and it always ends up moving in its register. I resorted to using old head bolts threaded into the block as guides to get it reasonably straight, but when I finally got it installed it wasn't quite flush with the block and of course, the was crank seized completely.

I'm hesitant to remove any material from the cap because of the side oil seals. Any ideas? Thanks.

[hr369]

Rebuilding an L28 and that last main cap (the one with the rear main seal) is giving me grief. It's near impossible to tap it in with a mallet and it always ends up moving in its register. I resorted to using old head bolts threaded into the block as guides to get it reasonably straight, but when I finally got it installed it wasn't quite flush with the block and of course, the was crank seized completely.

I'm hesitant to remove any material from the cap because of the side oil seals. Any ideas? Thanks.

Is that a factory nissan seal or aftermarket?

I have never had this problem myself but others have commented on the problem. This is from another website.

"If the mating surface on the crank is grooved, you can adjust the depth of the new seal.

Instead of bottoming out the seal where it rubs on the grooves, it can be positioned slightly rearward so that it seals on a fresh ungrooved area of the crank. As long as it is square to the crank and inserted into the block far enough, it will still seal."

[ozconnection]

Put the cap in the freezer and heat the block with a heat gun. That should allow you some time to get the cap in position before the clearances close up.

[Diseazd]

Under no circumstances should you remove any metal.......your idea with the head bolts is tried and true. With the head bolts installed,tap it down close enough to install main cap bolts, then torque them down to about a half inch from bottoming......install the side seals all the way down, then torque the caps all the way down. This seats your side seals.......make sure you apply sealant for seals as per FSM.

Edited November 18, 2012 by Diseazd

[Wade Nelson]

JEsus Christ in a chicken basket, take it ALL to an automotive machine shop and ask THEM what's going on and how to fix it!!! They may need to line bore your block!

[Ben's Z]

Make sure you have your bearings in the right order. #1 and #7 are wider than all the others. I recently torqued my main bolts to 40 ft lbs. Did this thing turn over before it went to the shop? Does it spin freely with the rear cap loose? My rear oil seal was in there crooked and I had to take the cap off and reposition. Mine was a little tight and went in awkward too, but I was able to tap it straight. If you think that sucks wait until you have to put in the side seals and nails. I had to LIGHTLY take a razor blade and shave just a little off of the tops of the "U" side of the seals. I'd put the rear saddle in a freezer and use a torch or heat gun on the block. Good luck.

[AlexS13]

I remember doing this when building my motor aswell. It is a very tight fit so you have to be patient and take your time. Also don't forget about the sealant this is very important! When the crank is in and torqued down it should spin over with very minimal effort (no rods/pistons connected) if you feel like its binding or resisting you have a problem.

[Zed Head]

Rebuilding an L28 and that last main cap (the one with the rear main seal)...

I don't really know if this would make a difference, but it might. The "How to Rebuild..." book by Monroe says to install the rear main cap first. Your statement above suggests that you are installing it last, unless by "last" you mean last in line from front to back.

[Hype]

Put the cap in the freezer and heat the block with a heat gun. That should allow you some time to get the cap in position before the clearances close up.

Ohh good one, totally forgot about that trick.

Make sure you have your bearings in the right order. #1 and #7 are wider than all the others. I recently torqued my main bolts to 40 ft lbs. Did this thing turn over before it went to the shop? Does it spin freely with the rear cap loose? My rear oil seal was in there crooked and I had to take the cap off and reposition. Mine was a little tight and went in awkward too' date=' but I was able to tap it straight. If you think that sucks wait until you have to put in the side seals and nails. I had to LIGHTLY take a razor blade and shave just a little off of the tops of the "U" side of the seals. I'd put the rear saddle in a freezer and use a torch or heat gun on the block. Good luck.[/quote']

Yes I'm certain I have the correct bearing for this cap. It spins if I back off the torque on the bolts for ONLY this cap, so I suspect the orientation of this cap isn't quite right.

I remember doing this when building my motor aswell. It is a very tight fit so you have to be patient and take your time.

Will do! Surprised I haven't found any other threads on fitting the cap, only issues installing the seals. The seals installed fine, but they're ruined because I had to pull it all apart again. :stupid: I'll pick up a replacement seal kit as soon as I get this install sorted out. Curiously, the Stone gasket set I got uses side seals that have the "nail" integral to the rubber so it's all one piece. They installed easy enough.

I don't really know if this would make a difference, but it might. The "How to Rebuild..." book by Monroe says to install the rear main cap first. Your statement above suggests that you are installing it last, unless by "last" you mean last in line from front to back.

Negative - I meant it's the last cap as in #7 main. That's why I specified that it's the cap with the rear main seal. I'm following the book, and it suggests to lightly file the bottoms of the caps, but my issue is with the sides of the cap. All the other caps tapped in just as the "How to Rebuild" books suggest, but I was stopped dead in my tracks when I tried to turn the crank after torquing all the mains.

[EuroDat]

You mention problems with the last bearing cap, but you didn't mention what has been done to it. What work did the shop do to crank? Do you have new bearings or undersized crank with new bearing?

Don't file anything off the cap. It was fitted once before you dismantled it so it will fit again. The freezer trick can help a lot, but I think you have a problem with alignment. Are the bearing shells fitted snugly in place, both in the cap and block?

Can you fit the cap without the crank? Then it would be an alignment problem.

Chas

[Hype]

You mention problems with the last bearing cap, but you didn't mention what has been done to it. What work did the shop do to crank? Do you have new bearings or undersized crank with new bearing?

Don't file anything off the cap. It was fitted once before you dismantled it so it will fit again. The freezer trick can help a lot, but I think you have a problem with alignment. Are the bearing shells fitted snugly in place, both in the cap and block?

Can you fit the cap without the crank? Then it would be an alignment problem.

Chas

The difficulty is in installing the cap, even without the crank. I took 5 minutes of out my day today to try the fitment again after freezing the cap and it was significantly easier. Next chance I get, I'll heat the block as suggested above.

Thanks for all the suggestions. I'll follow up when I try again.