: To hone? or not to hone



buggin123
12-03-09, 06:43 PM
I hope I don't sound too ignorant here, I have my 1997 seville in a million bits and pieces in my work shop and I figured if I was going to the trouble of pullling engine to redo heads I would freshen up lower end with rings and rod bearings, The GM bullitens I read about replacing rings due to oil consumption state not to hone cylinders what do the experts think? tHANKS again

Douglass Harroun
12-03-09, 09:15 PM
Could you quote the source on not honing more specifically? Date/ page/author, or however they are categorized?
I recall our old "guru" Bbob advised not honing on rebuild. He was on the power-train team that designed the Northstar and rebuilt them. I've seen some posts from time to time that make me think someone saved at least some of his posts. Maybe somebody can re-post what he said about that. All his posts got taken off the site for legal reasons or something. I recall his dept had a comparison with a major commercial rebuilder "their way" vs his way and the other guys didn't do as well. It may have had to do with the companynot rolling the crank journals. Maybe also honing vs not honing. I've got definate ideas on the subject which I stated recently, others disagree. I'm sure they will be along shortly and tell you.
Doug

Ranger
12-03-09, 09:54 PM
Don't even touch the bottom end unless it is leaking and you are trying to solve that. The lower end is practically bullet proof. Our old Guru said that they took down 250,000 mile limo engines and the factory crosshatch hone marks where still visible.

Douglass Harroun
12-03-09, 09:59 PM
Was this the info you saw? It says it is important to NOT hone
Doug


Bulletin 02-06-01-009C Oil Economy
This bulletin addresses NorthstarŽ oil economy only. The cleaning procedure in this bulletin should be done first and the oil economy evaluated. In most cases, cleaning the cylinders per bulletin 02-06-01-009C will restore the function of the rings to wipe the oil down the bore. If the oil economy after cleaning is still not satisfactory, then the revised piston rings should be installed. For an oil consumption concern, it is not necessary to replace pistons. The original pistons can be cleaned. The critical part of the cleaning process it to remove all the carbon deposits from the piston ring groves.

Important: The cylinder bore surface does not require any preparation when installing new rings. The repair would be ineffective if any honing is done to the bore surface.

buggin123
12-03-09, 10:06 PM
This is the GM service bulletin I was referring to, Any Thoughts? This engine doesn't have excessive oil consumption, I just figured when is the next time the engine will be out? So for a couple hundred bucks rings and rod bearings are cheap peace of mind. I just don't know if I should hone cylinder walls? they look fine, (factory cross hatching mostly).


Document ID# 1368396

4.6L LD8 , L37 Engines Oil Consumption Greater than 1 Qt. in 2,000 Miles - cylinder economy #PI00606A - (Aug 13, 2003)
4.6L LD8, L37 Engines Oil Consumption Greater Than 1 Qt. in 2,000 Miles
.

When servicing the vehicle with the VIN you entered, the following diagnosis might be helpful if the vehicle exhibits the described symptoms.

Condition/Concern:
Oil consumption greater than 1 quart in 2,000 miles on 96 -99 Cadillac Seville, Deville, Eldorado with 4.6L (LD8/L37) engines.

Recommendation/Instructions:
Be sure to note all the possible factors for oil consumption. Perform suggested checks and the oil economy test to determine if the engine is consuming more than 1 quart of oil in 2,000 miles.

Before performing the oil economy test on 4.6L Northstar engines:

Verify correct oil level on dip stick after oil change fill.
Verify the presence of the cam cover baffle through PCV hole.
Verify the PCV valve is functioning correctly. If the valve is in question, replace the PCV valve prior to the oil economy test.
Perform the 4.6L (LD8, L37) piston ring cleaning procedures in Bulletin 02-06-01-009.
An oil economy test should be performed after the cleaning process is completed. Before starting this test, the full oil level on the dip stick should be noted and shown to the customer. The correct oil fill is 7.1L (7 ˝ qts) with a filter. The dipstick should not be read for least 15 minutes after the engine has been shut off for an accurate reading.
Verify when the vehicle returns after the oil economy test that the oil level is checked in the same exact manner in which the initial check was performed. If it is determined by the oil economy test that the engine is consuming more then 1 quart of oil in 1,000 miles, it is important that proper diagnosis be performed before any major engine disassembly. Perform the following additional checks/steps:
Check misfire history counters if available. High counts indicate suspect cylinder.
Check each bank heated oxygen sensor (h02s) for signs of oil burning, indicating suspect cylinder bank.
Check for oil fouled spark plugs, indicating suspect cylinder.
Perform cylinder compression tests dry, wet and leak down (listen for leak down at intake, exhaust, oil fill). Any cylinder compression or leak down numbers outside of the range of the other cylinders would indicate suspect cylinder.
Remove intake and check for excessive oil present on back of intake valves, indicating valve guide scoring.
Check valve guide seals.
Check for missing/upside-down rings
Check for possible ring end gap alignment.
Check for cylinder wall irregularities.
SPECIAL NOTE: The 1996 through and including the 1999 service information manuals contain incorrect engine specification values. the service information manuals list values that are for production, and should not be used for service specifications.

THE CORRECT ENGINE SERVICE SPECIFICATIONS ARE AS FOLLOWS:

Cylinder bore diameter: 93 mm or 3.661 inches

Cylinder bore taper (MAXIMUM) is 0.100 mm or 0.004 inch.

Cylinder bore out of round (MAXIMUM) is 0.100 mm or 0.004 inch.

The piston to bore clearance @ 50 mm from top of piston (MAXIMUM) - 0.004 inch.

Now that you have completed the above diagnostics for an engine oil consumption with no trouble found, install the updated piston rings P/N 89017431. Note: This part number consists of a ring pack that only services ONE cylinder.

Special Note: The cylinder walls should inspected for any damage. The cylinder walls do not require any surface conditioning. (no honing necessary). Also the 2nd ring should be installed with the notch side down in the cylinder bore and finally, be sure to use the reduced cylinder head bolt torques when reassembling the 96 -99 4.6L (LD8/L37) engine.


Models:
(96, 97, 98, 99 Cadillac Deville, 4.6L LD8 Engine) and (96, 97, 98, 99 Cadillac Eldorado, 4.6L LD8, L37 Engine) and (96, 97, 98, 99 Cadillac Seville 4.6L LD8, L37 Engine)

97EldoCoupe
12-03-09, 11:20 PM
Correct. 02-06-01-009C.


This bulletin addreses Northstar oil economy only. The cleaning procedure in this bulletin should be done first and the oil economy evaluated. In most cases, cleaning the cylinders per Bulletin 02-06-01-009C will restore the function of the rings to wipe the oil down the bore. If the oil economy after cleaning is still not satisfactory, then the revised piston rings should be installed. For an oil consumption concern, it is not necessary to replace pistons. The original pistons can be cleaned. The critical part of the cleaning process is to remove all the carbon deposits from the piston ring grooves.

Important: The cylinder bore surface does not require any preparation when installing new rings. The repair would be ineffective if any honing is done to the bore surface.

97EldoCoupe
12-03-09, 11:24 PM
Bulletin No: 04-06-01-032 Nov. 2004


Important: Light vertical scratches that are not deep enough to catch a finernail are acceptable. If any of the cylinder bores are scored, that is not acceptable and the engine will have to be replaced.

buggin123
12-04-09, 09:34 AM
I really appreciate the feedback, I guess I'll scrape the carbon out of the ring grooves, put new rings on, oil and install. Thanks a lot!!!

codewize
12-04-09, 06:03 PM
Traditionally speaking, having rebuild a few SBC in my life I would say if you feel the need or they're an obvious reason to replace the rings then you should hone.

Having never worked on a N* like that, I have to agree that if there's not a definite problem, don't touch the bottom end.

Submariner409
12-04-09, 06:30 PM
The ring type and hone pattern in a Northstar are a far cry from those in a SBC (or Olds 455 :lildevil:). For starters, the Northstar uses light tension rings.

If the bottom has been opened (the halfcase removed) then there's a procedure for getting it all back together and having it stay together. The halfcase is actually a stud girdle, 4-bolt main caps, and lower half of the block all in one piece, so there is little room for error when replacing it. There's NO gasket, per se. It's a silicone bead seal because there can be NO space in the mating surfaces as this clamping surface determines main bearing clearance. If the engine had good oil pressure and normal consumption, there is (was) no reason to go into the lower end/cylinders.

tateos
12-04-09, 07:52 PM
Yeah - unless you have a definite problem that you need to address, resist your urge and leave it alone

codewize
12-04-09, 09:08 PM
Oh that's right. I remember now. That was always the problem with rebuilding the N*, the honing patter was impossible or at least extremely very difficult to duplicate.

Having now been reminded of that I wouldn't touch a thing.


The ring type and hone pattern in a Northstar are a far cry from those in a SBC (or Olds 455 :lildevil:). For starters, the Northstar uses light tension rings.

If the bottom has been opened (the halfcase removed) then there's a procedure for getting it all back together and having it stay together. The halfcase is actually a stud girdle, 4-bolt main caps, and lower half of the block all in one piece, so there is little room for error when replacing it. There's NO gasket, per se. It's a silicone bead seal because there can be NO space in the mating surfaces as this clamping surface determines main bearing clearance. If the engine had good oil pressure and normal consumption, there is (was) no reason to go into the lower end/cylinders.

97EldoCoupe
12-04-09, 09:44 PM
I just checked the stock rings today on a '99 Northstar block- with about 120,000 miles. I placed the rings in a stock bore and squared it up, and checked end-gap. Still well within stock specs and no wear to really speak of- if any. The real cause of some of the oil consumption is the baked-on oil sludge around and behind the rings in the grooves. The rings get stuck, badly. There is no amount of top-end cleaning solution that will completely remove it. It may help, but removing the pistons and physically cleaning each ring groove and rings with carb cleaner will do a much better job. Carb cleaner contains xylene and that breaks up baked-on sludge better than anything else I've ever used.

ponyboyt
12-08-09, 01:36 PM
i have a VIN9 here with over 240,000 miles that doesnt blow smoke... i would like to see what it looks like inside... maybe ill hit a tree this winter?

tateos
12-08-09, 04:43 PM
I just checked the stock rings today on a '99 Northstar block- with about 120,000 miles. I placed the rings in a stock bore and squared it up, and checked end-gap. Still well within stock specs and no wear to really speak of- if any. The real cause of some of the oil consumption is the baked-on oil sludge around and behind the rings in the grooves. The rings get stuck, badly. There is no amount of top-end cleaning solution that will completely remove it. It may help, but removing the pistons and physically cleaning each ring groove and rings with carb cleaner will do a much better job. Carb cleaner contains xylene and that breaks up baked-on sludge better than anything else I've ever used.

I'll bet synthetic oil is better than dino for avoiding that problem, but I will also say that I have leased or owned 4 N* cars, and they all went about 1,500-2,000 miles per quart of oil, which is fine with me. The only one that has seen syn is the 2000 DTS; I first started using syn in it at 71K miles after my father sent it out to AZ - not even sure why I did that, because my '97 ETC has always been lubricated with the cheapest 10W-30 around that meets the requirements, be it Shell, Chevron, or Wal-mart brand, with no oil related issues, at least not yet. Anyway, I do think dino oil is fine, but depending on the severity of use, the syn might be a little better at not coking up in the ring lands.

dkozloski
12-08-09, 11:23 PM
GM uses diamond tooling for North* cylinder bore finishing that is not available in the field. Don't mess with it.

32vmonte
12-11-09, 01:56 AM
I had my block lightly honed. It had corrosion from dex-cool sitting in the cylinders over the winter while the car sat broke.

Also there where a few areas in the bore where you could feel a groove that would catch your fingernail. The machine shop said he has done it on dozens of N* blocks without an issue. So I did it and my motor runs great with no oil loss. I didn't want to put my motor together with all that junk on the walls so I said the hell with it hopefully it turns out ok and it did. The hone was so light you can still see the stains from the coolant but can't feel them anymore.

tateos
12-11-09, 11:12 PM
Yeah - under those circumstances, that's exactly what I would have done; If the bore is in good shape, it's best to leave it alone, but with your situation, you were more likely to improve your chances for a good result, plus with palpable grooves and visible corrosion, what did you really have to lose?

32vmonte
12-13-09, 01:41 AM
Yeah - under those circumstances, that's exactly what I would have done; If the bore is in good shape, it's best to leave it alone, but with your situation, you were more likely to improve your chances for a good result, plus with palpable grooves and visible corrosion, what did you really have to lose?

Yea thats what I thought exactly. I did it and it turned out perfect as far as i can tell. There was no way I was gonna assemble the motor with that junk on the cylinders :cookoo:

johnny kannapo
12-21-09, 11:14 AM
You are so far along. I have done the quick hone to an engine getting 350 mi. to the qt. fitted new rings, Light hone, Scrape the grooves out. That changed to 2000mi consumption for the 1st qt after 125 mi. break in. That all turned out well. I wouldn't hesitate if the consumption was that bad. You mention you have reasonable oil usage. In that case if upper ring has cut a ridge at the top, you then have significant wear. The ring gaps will be out of spec. Piston skirts out of spec, that alone is not the end of the world. It would be a shame not to do something to address the wear or at least the carbon in the grooves at this advanced state of disassembly. The block is so simple compared dealing with a dohc head it silly to think you would be forbidden to deal with it at this point be cause "its bulletproof" Bull sh t. You could bring this block to a engine machinist and get a ridge removed, light hone with a TQ plate, 0.003 over rings fitted. under $300 and they would do a nice cleaning. Better yet if you considered getting new pistons fitted it would be all like new. That would bring the cost up to about $700 to $800. I think it would also be important to take a peek in the head ports and see if there is buildup on the backside of the valve heads that would warrant valve removal, cleaning & lapping. The engine would perform as new mechanically. If you want to do extra now is the time. You don't want to do any of this labor twice. You will need some special tools to deal with the valve springs & the re builder will assemble the rotating assembly in the block for you.

KHE
12-22-09, 09:18 PM
You are so far along. I have done the quick hone to an engine getting 350 mi. to the qt. fitted new rings, Light hone, Scrape the grooves out. That changed to 2000mi consumption for the 1st qt after 125 mi. break in. That all turned out well. I wouldn't hesitate if the consumption was that bad. You mention you have reasonable oil usage. In that case if upper ring has cut a ridge at the top, you then have significant wear. The ring gaps will be out of spec. Piston skirts out of spec, that alone is not the end of the world. It would be a shame not to do something to address the wear or at least the carbon in the grooves at this advanced state of disassembly. The block is so simple compared dealing with a dohc head it silly to think you would be forbidden to deal with it at this point be cause "its bulletproof" Bull sh t. You could bring this block to a engine machinist and get a ridge removed, light hone with a TQ plate, 0.003 over rings fitted. under $300 and they would do a nice cleaning. Better yet if you considered getting new pistons fitted it would be all like new. That would bring the cost up to about $700 to $800. I think it would also be important to take a peek in the head ports and see if there is buildup on the backside of the valve heads that would warrant valve removal, cleaning & lapping. The engine would perform as new mechanically. If you want to do extra now is the time. You don't want to do any of this labor twice. You will need some special tools to deal with the valve springs & the re builder will assemble the rotating assembly in the block for you.

Northstar engines will not have a ridge that needs to be removed. If the engine is burning 1 qt every 350 miles, then a hone to deglaze the cylinders and new rings should cure the problem. Just be sure the shop honing the engine has an automated machine capabile of providing a finish hone with a Ra 0.2-0.4mm. The cross hatch pattern should be 40-60 degrees included angle relative to the deck surface and the finish must be multidirectional.

I am in the process of rebuilding a junkyard Northstar from a '98 Deville engine. One of the cylinders had some minor surface corrosion and all the cylinders appeared to be glazed. The shop I'm using has a machine that can duplicate the factory pattern. You DON'T want someone with a handheld hone in a drill motor working on these engines.