Oil Residue on cylinder wall

[jerry598]

The picture below shows black oil residue deposits on the #4 cylinder wall after hand turning the crank to look for cylinder wall problems. The heads were removed to change the gaskets and the engine was still in the truck.

Some of the other cylinders had oil deposits on the walls also, but not as much as this one.

Are these oil deposits normally seen after the truck has been idle and the engine is turned over by hand? Or does this mean a ring job is needed? Could this just be residual oil pooling behind the rings and seeping out over the top of the upper ring while the truck was idle?? The truck ran really good before it was torn down. I never noticed any blue smoke out the exhaust.

However, that said, it always did use alot of oil (1 qt every 400 miles). I just thought it was leaking it out the oil cooler lines that were finally replaced 2k miles ago. I didn't keep good records after that.

An oil analysis done 2K miles ago showed all readings were OK but the oil only had 1400 miles on it. The truck started well, even in cold weather after new injectors and glow plugs were installed.

Aside from that, the cylinders were smooth and appeared OK. Some coolant drip stains were evident on the #7 cylinder wall where I think the head gasket was leaking. I suspect the coolant seeped back into the cylinder when the truck was turned off, causing those stains.

Any feedback would be welcome.
Jerry
95 6.5 turbo, 124 K miles, 929 block

[jerry598]

Tore the engine down for a rebuild and found three pistons with stuck center rings. Didn't pay attention to which cylinder they came from but I'm sure this was probably the cause of the thick oil smudges.

[Robyn]

Good bet that with a quart in 400 mile oil consumption that therin lies the issue.

Was the cooling system getting overpressureed and blowing out the overflow???

Clean things up good and lightly hone the cylinders and install new rings.

Check the bottom end for cracks in the outer bolt holes on the center 3 main webs
(These are repairable if not to large)

Keep us posted

Robyn

[More Power]

Do you know how often the oil was changed in this engine and what oil was used?

Jim

[jerry598]

This is lengthy and somewhat verbose but documents most of my problems on this rebuild.

1. Yes, the truck was running great except for the pressurized cooling system (hard hoses almost immediately after startup and burping coolant on any short trip). Figured it was a head gasket and sure enough the LH gasket had a crack in the 3:00oclock position to the coolant passage.

2. The heads also had minor cracks between valves but my local machinist did not want to attempt a repair. Should have found someone else to sleeve those passages and might have saved a couple hundred bucks, but have now ordered new heads from Clearwater Florida ($650).

3. Considering the oil smudges that I found on the cylinder walls (due to stuck rings) and slight ring ridges in at least 2 cylinders, and concern about crack issues in the bottom end I opted to pull the engine and rebuild whatever needed it. One minor crack was discovered along one outer bolt hole in the #4 main (completely repairable with one L&S insert ($40). So......went to a machine shop 150 miles away that could do L&S inserts. Based on your (Robyn's) feedback I had them do inserts in all six outer holes in the 3 inner webs (they were reluctant to do that because they had only installed one L&S insert once before, but they said it never came back to them - they suggested I find another uncracked block instead). I told them to install all six bolt hole inserts anyway (didn't want more hassle with finding another block) and I would just eat it if one of them failed.

4. I let them talk me into boring all cylinders to .040 oversize (probably didn't need it and just incurred extra cost) and also polish the crank (there was virtually no serious wear on main bearings, rod bearings or camshaft bearings. I let them sell me new oversize pistons, rings and bearings. They supplied standard bearings which after doing the plastigauge proceedure at only half the torque value, and with dry threads, the oil clearance seems to be too high .004-.005 (see separate thread). I'm going to recheck once more with oiled bolt threads and full torque values. Don't know about the rod bearing clearance yet, I figured I have to install the crank properly first.

5. Everything was returned to me from the shop unassembled (good) except that they did install the new pistons on the rods and the new rings on the pistons, but I have my doubts that they checked the ring gap or even miked the pistons. Didn't get a box for the rings so don't have a size listing for them.

6. If the bearings still check out with toooo.... much clearance, I will call the shop about exchanging the standard main bearings for undersize ones. I'd have to get .050mm undersize bearings (as listed in the catalog) to tighten the clearance to .002-.003. I was considerable confused about bearing size terminology. Seems that undersize bearings (inside diameter less than standard) decrease clearance between the two surfaces, while oversize bearings (larger ID than standard) increase clearance. Most bearings listed in the online catalogs I've checked list undersize bearings in several sizes.

7. Is the plastiguage proceedure accurate enough?. If I go to .025mm undersize bearings that would equal about .001 closer clearance than the .004-.005" on my first check. I'd like to make it right and go to .050mm undersize bearings to get the .002-.003 clearance, but am I safe to do that by just relying on plastiguage?

7. When I checked the clearance, I only torqued to half the specified value of 100 and 110 with dry bolts. Should I oil the bolts and torque them to near full value to ensure that the plastigauge is smashed well enough?

8. Next, I suppose I should have the cylinder bores miked and the pistons miked to make sure they match, right?

9. In addition, should I remove the new rings and fit them into the cylinders myself to check ring gap? I doubt the machine shop did this.

10. I would also like to inspect/replace the oil cooler and oil filter valves in the block. I see no evidence that the shop took them out or replaced them, but I'm not sure yet how to go about that.

10. The shop charged me $1800 for the above work and parts, which of course included the 6 L&S inserts ($240). Now I'm looking at a total rebuild cost of about $3K with the heads, bolts and all other misc. parts, $3.5k after I purchase a new fluid damper. I'm thinking I would have been better off to buy a new/rebuilt long block which would have only? cost about $5500 with freight and exchange, and including the fluid damper. Then I would have had a professionally balanced rotating assembly, stud girdle, and ceramic coatings, but no L&S inserts that could be a better way to strengthen the block than even a stud girdle.And I would not have had to do any of this internal work myself.

If it wasn't that the truck body is in great shape (K3500 black new paint) and the fact that I've already sprung for a rebuilt NV4500 and all the other stuff listed below, I might have long ago given up on this project - But I love my truck, like all of us do.

I will post this entire response under another thread titled "Some hassles of a do-it-yourself novice rebuild" - it might give some other novices like me more of an idea of what to expect if they wand to try this.

That's where I am now, checking bearings, waiting on new heads and other parts (timing chain, new oil pressure switch, newer '98 higher pressure oil pump and other stuff.

[jerry598]

Jim,
Don't know about oil history prior to buying the truck at 94K miles. I've changed the oil religiously at 2500 mile intervals using 15-40 turbo rated oil. It always used too much oil. Pulled the heads and found the smudges and stuck rings at 126K miles.

[Robyn]

The bearings are/were a select fit on these engines and it was entirely possible to find .001 undersize on one shell and the other half be standard. Or you can find .0005" (Half a Thou under on one and one thou on the other half in order to get the clearances right)

Its a mix and match mess.
I much prefer to see the clearance on these engines at the middle to slightly over middle of the clearance specs.
The bottom spec (TIGHT) is just not what makes me warm and fuzzy. .002-.003 is very good. .0025" is perfect.



My burb had a bunch of stuff in it but I averaged it all out and a set of STD rods and mains put things in the upper end of Normal at about .003-.0035 so it was a go.

Piston clearance should be .004" on cyls 1 through 6 and .0045" on 7 and 8 due to extra heat back there.

Now if you go to the 6.2/6.5 Tech forum, I posted a thread on build tips for these engines with lots of of pix and much good info.

Have a look there, I think you will find it useful

I really wonder why you are seeing so much clearance on the bearings, I have never seen one of these that even if you installed STD Bearings would have .004 or more

Plastigage needs to be used with near full torque to be accurate.

Place the Plastigage strip (1/2" long piece) on the crank laying across the width of the bearing, lightly oil (very little swipe of oil on the bearing over the Plastigage I mean tiny bit**) so the gage piece will stay stuck to the crank.

Torque the cap then remove, the gage piece will be stuck to the crank shaft journal.

Use the inch side gage chart to check the reading. Proper reading will see the smashed gage piece about 1/8th of an inch wide IIRC.

The stuff is very accurate if used properly. *** I have used the stuff for years. (Never leave home without it )

You should be using the GREEN stuff. IIRC it comes in green red and blue for the different clearance values.

GREEN IS GOOD

Just be sure to use the Inch side chart to check the stuff after smashing it.

Keep us informed

Robyn

[jerry598]

Thanks Robyn! You were right. I rechecked the bearing clearance with the green plastiguage and torqued all the bolts (after oiling them) to full specs. 3 out of 5 came in right at .002" The #2 and the #4 came in just under .002" (but the smashed stripe was not as wide as the .0015 guage stripe).

Thought maybe my oil smudge was too thick on # 2 & 4, so dryed the journal off and rechecked those two again. Same result - Less than .002". Checked again after lifting and turning the crank to a different position. Same result - slightly less than .002". My Haynes book says .0018 is minimum.

Decided to try the red plastiguage where the lower limit is .002". Results were now different. Both the #2 and #4 bearing clearances came out at or slightly greater than .002", but not less than .002", according to the red guage.

Do you think there is any chance that they might too tight? My guess is that they're OK.

Soon as Rock auto gets me the rear main seal, I'll be ready to coat those bearings with lubriplate and cap that crank for good - then mike the pistons, install and check the rod bearings.