[DrGawn]

OK so I got my northstar shortblock out of the 01 caddy a few nights ago, and I am in the process of going over what needs to be done now. The entire engine is disassembled, heads off, pistons out, block fully disassembled. The engine had roughly 200k on it.

The bearings look excellent, I'd say they have 20k on them by the look of them. Pistons aren't noticeably cracked or scratched, so all good there.

The block has weird spider web cracks/lines on it and I don't know if it's normal or if it's bad, they look bad but I've never worked on an aluminum block before.

What I want to know is, what should be done and what should not? The crosshatch is still there on the cylinder walls, should they be honed regardless? I Will replace all the bearings, no matter how good they look. Rings, clean or replace?

What about the heads, I have a set of valve seals, should I have them installed, and the cams are a bit rusty because I've had the heads sitting on the side of my house for a few months. Im not sure if I need a valve job or if I should just have the valves lapped or if anything needs to be done at all to the valves.

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[CadillacLuke24]

Can you get a picture of the spiderweb lines? That may do the most good in diagnosing.

No hone. No hone. No hone. The factory crosshatch, as noted, is very durable, and should last the life of the engine IIRC. Rings should be ok with a cleaning, unless you suspect an issue. Bearings will depend on how they look, certain wear patterns can indicate the need for replacement.

Not sure on the vavles, we should have some of the gurus chiming in shortly.

Good on ya for rebuilding the ol' girl! Glad to see another staying in the game!

 

[Ranger]

:yeah: DO NOT hone the cylinders. :tisk:

As for the "cracks", I'd suspect casting marks that look like cracks. I seem to recall that being discussed before. Cracks are unlikely.

 

[Submariner409]

I would replace the timing chain tensioners and guide slippers.

New rings, no hone, stock size. Sealed Power ??? No cylinder bore allowed. The second compression ring is also an oil scraper - note the marks on the ring top side surface. Make sure all the piston skirt oil drain holes are clean.

If the cams have rust on the lobes, pray that it's only superficial - $$$. Given the head description you might want to do the valve seals - no real need to lap the valves. Max allowable cut on the heads is .004". I'll bet you need at least 6 new (flat tappet) cam followers. Use a good, trusted machine shop for the head work.

New crank/rod bearings will come at the original size - no crank journal grinding allowed. New front and rear crank oil seals. New torque converter, correct one for your SLS.

Special torques and procedures for main, rod, halfcase, oil pan bolts. New GM RTV seal procedure for halfcase and oil pan. Special procedure and torque for oil pump and harmonic balancer install.

Replace the water pump drive belt tensioner pulley...... yesterday.

New gaskets in the water crossover. New quick connect fitting for the heater outlet at the water crossover. Coolant purge line cleaning. New surge tank pressure cap.

500 mile break-in with 5W-30 engine oil, working up to full power acceleration runs.

Dremel tool cleanup of the extra pipe stuck into the manifold collector Y ..........

Subscribe the car to www.alldatadiy.com - the online GM/cadillac service manuals, and it's updated, unlike the DVD manuals from www.helminc.com.

 

[DrGawn]

You can see the "cracks" in this picture of the timing area, so those marks are fine?

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[CadillacLuke24]

I see nothing that would be cause for concern. I second Ranger's opinion.

 

[rodnok01]

Along with what the others have said, I would have heads reconditioned myself. My valve at 100k were rougher than I would have thought, guides were good but the seats were fairly rough and stem seals are a must.
If you want a good rebuild thread check out Bill Buttermore thread from a few years ago, he did a nice write up.

 

[Submariner409]

The "cracks" are the seam at the upper and lower crankcase halves. The lower halfcase is the main bearing girdle. Specially machined and sealed................have fun taking it all apart and getting it resealed. You might want to consider a main bearing stud kit from www.northstarperformance.com.

New main bearings go in at the original size. No crank grinding permitted. Special radius fillet journals.

Halfcase removal and replacement instructions in the Cadillac/GM service manuals or www.alldatadiy.com.

Click to enlarge, follow the prompts at the lower edge.

 

[DrGawn]

I am really considering a main stud kit, especially since 2 of my main bolts snapped upon removing them. I sent out the block halves to the machine shop today along with both heads. Just got off the phone and the heads are going to get reconditioned with a valve job, resurfacing, cam polish (rust), and he said all the hardware looks good for reuse. I also got an excellent deal, 200 for the pair! I still have a set of valve seals from my last rebuild so that's $$ saved. I am going to try and document the rebuild in this thread, although it will be slow, rebuilding a northstar working part time at $12/hr might take a bit of time.

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[Harry Yarnell]

I see no mention of headbolt thread repair....just sayin'.

 

[Submariner409]

Yep - you must insert or stud all 20 cylinder block head bolt holes, new gaskets - if inserted, use new GM head bolts using the new Northstar torque + degrees of twist to get final clamping pressure.

If studded, follow the manufacturer's recommended torque procedures.

https://www.cadillacforums.com/foru...345-1996-2003-northstar-head-bolt-torque.html

 

[DrGawn]

Oh don't worry, I already have all 20 holes drilled and ready to be studded

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[CadillacLuke24]

Good on ya! :thumbsup: