04-19-06, 09:23 AM
I just tore down an 03 SLS with 37,000 miles for a breeched head gasket. I'm going to drill my own block for inserts and I have several questions that you pros can help me with:
1. How do I get the upper corner dowels out for drilling?
2. I'm still a bit fuzzy on cam timing and I have a little wear I'm concerned with on one of the tensioners.
3. The oil pump drive chain seems really slacky . . . .?
4. One of the little plastic snap rings came off of an injector and snaped right back on but is now looser than the others . . . .concern?
Thanks so much . . . . what a great forum!!!!!!
04-19-06, 10:37 AM
1) Cut them out. You'll have to replace them.
2) This has been posted multiple times. You should be able to find it with a search. If not maybe someone saved it. You really should have an FSM but it can be done without.
3) Hard to judge without seeing it. How slack is slacky? Easy to change if you think it's stretched.
4) It's probably OK but again, we can't see it.
04-19-06, 10:54 AM
Is the chain tensioner working on that lower chain?
04-19-06, 11:27 AM
Crush the dowels with pliers or visegrips and twist them to remove. They cannot be reused. Get new ones as the old ones will have to be destroyed to remove them. If they are really tough you can thread a tap into the ID of the dowels and use a slide hammer on the tap to remove them.
I assume you are using the correct timesert inserts specifically made for the Northstar head bolt holes? If not, then acquire and use the timesert inserts. Others will fail since they are not long enough and are (sometimes) not a solid insert design. The timesert kit for the Northstar is absolutely critical to making a good repair.
There is no "oil pump" drive chain. The oil pump is on the crank shaft itself. The short chain from the crank is to the intermediate shaft sprockets as there is a stepped chain drive on the Northstar. There is a tensioner on each chain that is hydraulically tensioned by oil pressure. There is a rachet on the tensioners that stop it from fully retracting but it can be "between teeth" on the rachet mechanism making the chain slightly loose when the engine is not running. Normal. Take the tensioner off and make sure the rachet it working. You release the rachet with the small link on the tensioner and can lock it with the link in the other direction. If the rachet works then it is ok.
If the "wear" on the guides and tensioner shoes is just the marking of the material by the side links it is perfectly normal.. Those guides will run for several hundred thousand miles without wearing out. The normal look is two parallell tracks on the wear surface from the side links that are about .030 deep. They mark like that very early in the life of the guides and stay that way as soon as the rollers slide along the guides.
04-19-06, 01:18 PM
Be careful not to scratch the top of the block! I do not recomend crushing the dowel as this can cause it to deform and further bind in the hole and even deform the hole. Instead find a rigid metal rod, socket or extension that fit snugly inside the dowel this will prevent it from deforming. Use a vise grip with sharp teeth (new with curved gaws) works great. Tighten the vise grips down very tight and rotate the dowel and then add an upwards pull without letting the gaws touch the top of the block. If necessary heat up the block around the dowel and cool the dowel to get it more clearance. If all else fails the dowel can be weaken and cut lengthwise with a dremel tool (use carbite file bit for cutting tile).
A more professional method is to cut threads into the inside of the dowel, install a matching bolt attached to a slide hamer and with a few hits out it comes. Get new dowels
04-19-06, 03:02 PM
You are exactly right on!
Thank you so much!!!!!