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a couple of motor rebuild questions. ...

O

outlander

NAXJA Forum User
Location
Columbus,Ohio
The search function isnt working right because im using a phone.(im sure this has been covered before)

Its been a lot of years since I rebuilt a motor and im in the process of putting together a 97 4.0 that came outta my 97 grand cherokee

I need to know if head bolts are torqued dry or do they get lubed?

Do main and rod bolts get torqued dry or lubed?

Someone care to explain how to seat the main thrust bearing....my chilton mentions some kind of procedure that involves prying back and forth on the crank?

Thanks for your replies.
 
I just reviewed my Haynes. What I am getting from the text, is the bolts (head and crank/rods) are spec'd for dry torque, except for #11 head bolt, which needs sealer and takes less torque.

Prying back and forth on the crank is to check the crankshaft end play.
 
I've a stroked engine and #11 wasn't torqued to spec. Cool-ant anti-freeze tickled out at the intake exhaust manifold stud-nut #6 in the tighten/remove process. I coated the #11 bolt threads with sealant PTFE and in doing so stopped the coolant leak.
 
Loctite makes a head bolt assembly sealant. Regular Loctite doesn't require any torque changes, I'm not sure about the head bolt sealant (E-mail?). Henkel (Loctite) in my experience performs as advertised. The sealant is good to around 570 F.

I can't remember a bolt I've installed without Loctite in a very long time, I always torque to spec, no problems so far.

The only downside I can see to using the sealant is, re-torque is recommended on many head bolts. I've never done that (except once).

I Loctite main and rod bolts. Ever since replacing bearings and finding loose bolts and once a bolt that actually fell out (no kidding). Off topic, but I once found an engine with two number three rod caps with around 200,000 miles on it.

I've never reduced torque on anything. One thing I do on a regular basis is take two torque wrenches and put one in a vise. I then try a few torque values and see if the two torque wrenches pop at the same time or really close anyways. Torque wrenches tend to screw up at the most critical times.
 
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mechbullxj said:
I've a stroked engine and #11 wasn't torqued to spec. Cool-ant anti-freeze tickled out at the intake exhaust manifold stud-nut #6 in the tighten/remove process. I coated the #11 bolt threads with sealant PTFE and in doing so stopped the coolant leak.
Click to expand...

Maybe they reduced the torque value because that hole has fewer threads than the others?
 
8Mud said:
Maybe they reduced the torque value because that hole has fewer threads than the others?
Click to expand...

Head bolt number 11 screws into a water passage and will leak coolant into the #1 exhaust, if not sealed.
The FSM call for sealant to be applied to the threads of bolt 11 and to use a slightly lower torque.
It's all in the good book.
 
lazyxj said:
Head bolt number 11 screws into a water passage and will leak coolant into the #1 exhaust, if not sealed.
The FSM call for sealant to be applied to the threads of bolt 11 and to use a slightly lower torque.
It's all in the good book.
Click to expand...

I'm not saying I disagree, it is in the book. I was just thinking maybe the lower torque is because the hole has fewer threads and not because of using the sealer and it's lubricating properties.

These are the same guys who put the crappy end studs in the manifold, that may or may not torque to spec. more than once. Just saying.

I Loctite all the manifold bolts. They have a habit of backing out, all those heat up and cool down cycles.

I replaced my end studs with M 12 bolts, drilled out the standard stress/cone washers. Those washers are made of some hard stuff. I think at one time I had maybe two end studs in three XJ's. I'm now down to three in two XJ's.
I'll let you know how the M 12's hold up, they have only been in there for a year so far. I've learned to lower the torque on the end studs, if you have any hope of keeping them from snapping off.

Even the good book has it's flaws.
 
Don't the I-E manifold studs have a unthreaded portion in mid stud? I thought I used the opposite side nut to friction lock it so as to thread it in to that un threaded portion. Then break the friction lock and replace each retaining cone and nut.
 
mechbullxj said:
Don't the I-E manifold studs have a unthreaded portion in mid stud? I thought I used the opposite side nut to friction lock it so as to thread it in to that un threaded portion. Then break the friction lock and replace each retaining cone and nut.
Click to expand...

I guess we are hijacking the guys thread. I've backed those studs out before trying to remove the nut. which is good. I then had a chance to replace the stud. Most times the studs are pretty corroded and may even bond to the nut from electrolysis (maybe). The studs sure tend to bond to the block for sure and become weaker with age, either from corrosion, temper/heat or they are just plan too small in diameter. Getting the broken stud out of the block, most times, is borderline impossible. Heck even on my newer XJ, it has still been in there for nearly twenty years. Anyway, at a minimum, wire brush the threads and use penetrating oil. Th blank spot you are talking about could be a stud that partially backed out. I have a mental image of the threads going all the way to the deck or darned close, I may be wrong.

About 50/50 when they snapped off, sometimes they snapped during use (normal duty cycle) from heat/cool cycles or sometimes during disassembly or reassembly. I think I've only snapped one trying to remove the nut, the rest (non normal duty cycle) where trying to torque them back down.
 
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8Mud said:
I'm not saying I disagree, it is in the book. I was just thinking maybe the lower torque is because the hole has fewer threads and not because of using the sealer and it's lubricating properties.
QUOTE]
The FSM calls coating the threads of #11 with Loctite 592 sealant with PTFE (better known as Teflon).
Would imagine that has an effect the friction and torque settings.
My experience with 592 sealing plumbing fittings show it does a good job of lubricating threads. YMMV
Click to expand...
 
lazyxj said:
8Mud said:
I'm not saying I disagree, it is in the book. I was just thinking maybe the lower torque is because the hole has fewer threads and not because of using the sealer and it's lubricating properties.
QUOTE]
The FSM calls coating the threads of #11 with Loctite 592 sealant with PTFE (better known as Teflon).
Would imagine that has an effect the friction and torque settings.
My experience with 592 sealing plumbing fittings show it does a good job of lubricating threads. YMMV
Click to expand...

Could be, seems likely, but I do seem to remember fewer threads in the block for the bolt to pull against in that hole. Just supposition on my part.

The object is to not over or under stretch the bolt. I tend to favor over a bit more than under, I've had more issues with under than over, in most cases.

Many/most torque wrenches haven't been tested in ages or you just have to take the manufacturers word for there accuracy. There is likely to be some margin for error.

The FSM isn't the Ten Commandments, Ooops sorry I forgot the Ten Commandments are irrelevant now on days.:) In the FSM I'm most familiar with, I remember no mention of Loctite.
Click to expand...
 
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All hijackings aside, I've an impossible to remove stud from a 2nd. 4.0l l6. It is the fastener on a passengers side, holding bracket for the oil dip. Sometime it'll be a hack and tap for moi. Dang and shoot.:gee:
 
mechbullxj said:
All hijackings aside, I've an impossible to remove stud from a 2nd. 4.0l l6. It is the fastener on a passengers side, holding bracket for the oil dip. Sometime it'll be a hack and tap for moi. Dang and shoot.:gee:
Click to expand...

There are some unused holes down there. If it is the typical ground stud issue, move the whole works to a new hole.

Time for bed, I work late shift.
 
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Im aware of that #11 bolt and have the appropriate sealer in the garage..
..
So i gather that head bolts get torqued dry and the rod and mains also?

I need a FSM...
anyone have a fsm and care to clear up any confusion?

I dont believe anything that is printed in a haynes manual....I actually feel they should be sued.
 
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IMO disagree with previous reply. Like a boat propeller, aircraft propeller, or Archimedes screw, fluid is displaced when torque is applied. A fluid in a tapped hole will be displaced, once a fastener is twisted into it. It seems that that fluid would move outward towards the opening, and not have a significant effect on the bolt/screw itself. To reduce a fastener torque value x 1/3rd. doesn't make sense to me. I'll have to snap a few bolts/screws, only I'll do it later.
 
mechbullxj said:
IMO disagree with previous reply. ..
To reduce a fastener torque value x 1/3rd. doesn't make sense to me. I'll have to snap a few bolts/screws, only I'll do it later.
Click to expand...


Gosh, I guess they didn't teach me the correct methods in trade school many decades ago. Every piece of automotive literature I have ever read indicates that torque ratings are for dry bolts, unless indicated otherwise.
My standard reference is the Engineers Handbook, the industries standard reference for the last century or so. It list the dry ratings
http://www.engineershandbook.com/Tables/torque.htm

Even the sealant, used on #11, has an lubricating effect, lowering the torque by 10ft.lbs. Remember, it's the bolt stretch that we are concerned about, not the absolute tightness. Anything that reduces friction in the threads is going to lead to greater stretch, at a given torque.
 
Even the sealant, used on #11, has an lubricating effect, lowering the torque by 10ft.lbs. Remember, it's the bolt stretch that we are concerned about, not the absolute tightness. Anything that reduces friction in the threads is going to lead to greater stretch, at a given torque.[/QUOTE]


Alright when turning a fastener to a given torque value I'll keep in mind that, it is based upon being dry. Also being metal to metal contact. I've no idea what, fastener "stretch" is in relation. Metal will expand and contract with changes in temperature, and or pressure. How about dissimilar metals, from a tapped hole and threaded bolt? What torque will apply when two dissimilar metals are joined together, with differing properties?
 
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