? on HG replacement

[nicksr]

So, I got a call last friday from the mechanic working on my timing chain slipper & HG.

He said when he was tightening the HG bolts that 3 of them went "soft".

He gave me some options.

1. leave them as it stands now, he thinks there is only a very small chance of failure

2. get all new bolts and a new hg and redo it.

He says i would need a new HG because they are "crush once" and if he pulls all the bolts, he would need to put a new HG.

What I am wondering is. Can't he just back out each of the 3 bad bolts, one at a time and replace them one at a time while the remaining bolts stay torqued? He says they 3 bad ones are spaced evenly out over all the bolts.

Appreciate any help from those that have way more experience at this.

Also, the engine has not been completed and started yet, so keep that in mind. He stopped and is waiting for my response because I need to get the parts. Not paying his "retail" price for parts when I can get them from Cdan.

 

[91Cruizer]

I would say replace them. Nothing worse that constantly thinking about it breaking.

 

[elhombre]

If you had the timing chain guides replaced, then you are well into the engine. The extra cost for the new bolts (3) is chump change compared to what you have already spent. Don't get cheap all of a sudden. Go out and sell another unit of plasma and replace those bolts. The cost for a new gasket and the three bolts is way less than doing it again due to a warped head. I cannot speak to your question about removing the 3 bolts with the others torqued all the way down from experience, but my bet is that it would not cause problems changing out one at a time.

 

[Land Speeder]

hmmm... mines actually torn down as of today, so I know what your mechanic is facing... not fun. If he ain't using an OEM gasket then have him replace it with one, and he can replace the bad bolts as he's replacing the gasket. a non-oem gasket will fail a lot sooner than oem.
Surely he mic'd the bolts before re-using them. I'll be mic'ing mine tomorrow to ensure they are still in spec. if not then new oem bolts for me...

 

[mainemike]

It saves money and headaches to buy the whole HG kit from CDan, but at this point sourcing just a HG and 3 bolts from your local dealer might make more sense. No shipping from a dealer and they can often get parts the next day, and as elhombre said this is chump change. I'd let the mechanic fix it the way he feels is best - sounds like an honest and competent guy. Why not get all new bolts?

 

[Land Speeder]

Why not get all new bolts?

Because if they're "in spec" then they're fine... and the fact that they're like $15/ea..... at 14 bolts... it's a pricey item if you can re-use the old ones that are still "in spec"....

 

[OGBeno]

A new set of head bolts at the smart shopper price is about $150 or so. Of course, they can be had individually as well.

 

[nicksr]

Well, you all make good points.

I am not sure I was perfectly clear in my first post.

The new HG from the kit I purchased from Cdan was being installed at the time the bolts went bad.

The real question is. Can I just back out the bad bolts and replace them one at a time with new? If so, that is the best way to go.

Someone mentioned my mechanic knows best. I am not sure he does. Why would he recommend replacing all 14 bolts if only 3 are bad? And for the record, he told me there are 12 so I have some concerns about that as well now.

The other thing is that he wants to charge me for an extra 1.5hrs labor to remove all the bolts and put the HG in. He quoted me all of $600 to remove all the old bolts and replace them with new and another new HG. Cdan did leave me a message that he could special order me just the HG if I needed it.

 

[Chaldaean]

The real question is. Can I just back out the bad bolts and replace them one at a time with new? If so, that is the best way to go.

When I did my HG, a couple of my bolts felt "soft" when torquing them down. I got nervous and a MUD search revealed that others had experienced this as well (I can't find the posts now though...).

I took ALL the bolts out and put the micrometer to them (they were all still within spec) and reinstalled. Everything felt fine the second time around.

I would have three suggestions:

(1) I'm not sure how good replacing just the bad bolts would be (while the others are fully torqued). The initial torque on the bolt (before the 90 degree final turns) is partially governed by the load on the other head bolts. I'd take them all out, check them with a micrometer and reinstall in the proper torquing sequence. With all the time invested in the HG replacement, starting from scratch in the torque sequence is chump change.

(2) I don't think it's necessary to replace the newly installed HG just because you've crushed it once. I think I've read here on MUD that this is not a concern (search for confidence).

(3) Put a very light coating of oil on the head bolt threads before install.

 

[jlg32281]

Buy a set of ARP head studs or bolts. They probably aren't any more expensive than the OEM bolts and they're re-usable and will yeild a better torque reading.