just wanted to know peoples opinions or ideas on getting this rust off. yes it is rust definitely not old gasket. id prefer not to strip the bottom end but if i have then i guess i have to.

if i need to get the block decked what would something like that cost with hot tanking and a cylinder hone?

and if the bottom end does have to come out is it ok to use the existing pistons and rods? obviously id change the rings and all the bearings.

thanks all

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That's normal. All you neeed to do is scrape it with a scraper tool, then use fine sandpaper and a block of wood and sand it

For the bottom end, reusing the rods and pistons is normal for a rebuild. "Remanufacured" engines will often have new pistons, but still use the old rods. Since the pistons last at least 500,000 miles, replace them only if damaged or worn

Wouldn't sanding possibly get material into the engine and possibly ruin the bearings. Obviously trying your hardest to block everything off so it doesn't get into the engine but I'm worried there's that possibility.

And the sanding wouldn't that leave high and low spots and not make the deck flat?

Good questions

1. You're going to replace the bearings, so it doesn't matter. What do you think happens when the cylinders are honed for new rings? Honing is a type of rotary sanding. After honing you clean the cylinders with soap & water to remove the residues. With sanding, mechanics put clean rags in the the cylinders to catch any residues

2. To prevent high and low spots, use a flat block of wood with the sandpaper, block of wood wider than the deck. One could also use a purpose-made block sander but a piece of wood works as well

Yes I know that but my q's was is there anyway of doing it without taking the bottom end out? If everything came out then no problem. But I don't wanna have to pull it apart because everything is fine.

But like I said if there's no any other way then yes I will pull out the bottom end.

If you're going to to replace the bearings, the bottom (the crankshaft) should come out. I don't recommend replacing the bearings with the crank in, because they bearing bores are supposed to be wiped clean. It is possible to do, for example dropping the crank 3mm and using spray ether to clean the bearing bores, but a quality job is much easier to ensure after removing the crank

If I was overhauling the engine, I would measure the bearings and only replace them if worn. Some A-engines still have bearings in specification even after 150,000 miles (there is a new install spec, and a service spec, those still in install spec don't need to be replaced), However if the oil pressure was low of the engine made knocking or tapping sounds, then the bearings probably are worn

To measure the bearings, the oil pan must be removed, there's no way around it

I'm talking about taking the rust off. Anyway of doing that without pulling the bottom end out.

Taking the rust off the block deck does not require pulling the bottom end out

More on the sanding: plug the oil feed hole and head bolt holes with grease before sanding, and plug the pushrod holes and oil return grooves (in bewteen the pushrod holes) in the same way. Use only enough grease to cover the hole, as it will need to come back out. Any oil or grease left in the head bolt holes can cause head gasket failure. After sanding you can carefully remove the grease and any shavings it caught, get the head bolt holes clean and dry so the bolts will torque down properly

A traditional hot-tanking is not recommended by Nissan. If you do go this route, you must fit new cam bearings and have them line-honed. Since they normally last the life of the block it is a needless expense.

Better to use a shop that uses a gentler tanking method. But I wouldn't bother. After honing, the block needs hand-scrubbing anyways (detergent cleaner works best to clean the cylinders), then after assembly you can flush the cooling system to remove the surface rust in the water passages before reconnecting the radiator and starting the engine. Use a garden hose and run it until the water comes out clean. If you want you can also use a chemical flush agent from the local auto parts shop, although again I wouldn't bother unless there was baked in oil contamination

On the deck, use #400 sandpaper or equivalent scotchbrite for a nice finish. Some say to use a flat stone instead of sandpaper, but either way it ends up with some stone/sanding residue, which must be cleaned up. The goal is not to get a mirror-finish surface, but is to get it oil-free, gasket traces removed, and let the flatness of the cast iron deck stand out. Then the head gasket will last. Use light pressure and only do it enough to clean it up. Some say a mirror-finish can cause head gasket failure

Here's a properly prepped block deck



Before:

Great. That's exactly what I needed to know. Thanks again.