June 23, 2018, 04:39:45 PM

Author Topic: GMC 4104 head rebuild question (machine shop mistake?) Any mechanics out there?  (Read 12346 times)

Offline irstaxhelp

  • 1960 GMC 4104
  • Newbie
  • *
  • Posts: 47
  • 1960 GMC 4104
    • San Diego Down Syndrome
Mobile mechanic R&R head and two of the fixed studs not sure of the exact name but they are on the rockers and have no threads but pressed in.  After installing the head one broke off when tightening the rockers and the other rocker got stuck .  I am not a mechanic so the names of the parts might be wrong but I can post a picture if it helps. 

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19424
If you have over a 1/2 of stud showing DD has a tool to remove those if not they have to be drilled out,2 valve head or 4 valve ?


good lick
Life is short drink the good wine first

Offline zubzub

  • Hero Member
  • *****
  • Posts: 1212
  • '53 4104. Roadworthy but rough around the edges.
    • pics of my bus etc....
well luvrbus has been around these old 2 strokes way longer than I have so I'll have to take his word for it.  Next time I have the valve cover off I'll give it a lick.

Offline irstaxhelp

  • 1960 GMC 4104
  • Newbie
  • *
  • Posts: 47
  • 1960 GMC 4104
    • San Diego Down Syndrome


So it is the new oversize stid put in with the locktite all over it.  Two were bad.  Shouldn't the head shop caught this?  Two of them were bad on broke when tightning the rocker and the other jammed when the bus was started up

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19424
How did you break a bridge stud those are set off the engine and before you install the rocker arms ?

good luck
« Last Edit: April 13, 2011, 09:13:47 AM by luvrbus »
Life is short drink the good wine first

Offline irstaxhelp

  • 1960 GMC 4104
  • Newbie
  • *
  • Posts: 47
  • 1960 GMC 4104
    • San Diego Down Syndrome
The mechanic installed the head then when tightning the rocker arm one broke and then after fixing the one they started the engine and the other one broke.  Shouldn't these have been checked or replaced when they rebuilt the head?   Why would these break?

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19424
I cannot answer why they broke I have never broken one but have removed and replaced a few for wear but not that way, are you sure the injector is going to tighten down with that setup looks close to me fwiw shops just replace those because of wear that looks like work to me drilling and tapping to replace one lol me I think your guy screwed up 

good luck
Life is short drink the good wine first

Offline irstaxhelp

  • 1960 GMC 4104
  • Newbie
  • *
  • Posts: 47
  • 1960 GMC 4104
    • San Diego Down Syndrome
That's what I was thinking.  He could not get the remaining pieces out so had to drill the hole out and buy the oversize and tap in.  I have not received a bill yet but when I do I am not sure, if he charges me for the stud replacement, that I should have to pay...  If I do not pay I would like to tell him why.  That is why I am seeking clarification here.   Good luck...   huh!  LOL

Offline eagle19952

  • Hero Member
  • *****
  • Posts: 3716
Correct me if I am wrong.....and i hope I am...but your photo seems to show some SERIOUS shop dirt dust OR what ?
We're talking engine killer.
were I you I would either eat it or STOP until you sort out the reasons.this could perpetuate at a very unfortunate time.
Those valve bridge studs would have to be SERIOUSLY worn to warrant any attention/change.
I carry my 30 year old Kent Moore rack/gov adj tools and I have NEVER seen what you got.
If one broke when they started it......well use your imagination.
Somethings are bent,how or why they would be telling me.
and really ReliBilt are cheaper.
Think about it. eopoxy does not take well to heat.....




So it is the new oversize stid put in with the locktite all over it.  Two were bad.  Shouldn't the head shop caught this?  Two of them were bad on broke when tightning the rocker and the other jammed when the bus was started up
Donald PH
1978 Model 05 Eagle w/Torsilastic Suspension,8V71 N, DD, Allison on 24.5's 12kw Kubota.

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19424
I really feel bad for but I don't think your guy knows how to adjust the bridges those need the same clearance on both valves they can be a pain then you adjust the valve clearence after they are set.
I would not be afraid to say you probably have bent valves now and I have never saw a bridge stud screwed in to the head I question that repair may work may not just not the right way to do one JMO and now he has over sized the hole by tapping I hope it works out for you

good luck
Life is short drink the good wine first

Offline JohnEd

  • Hero Member
  • *****
  • Posts: 4571
Listen to what you are being told by a couple hundred years of experience.  They are being kind and patient in their tone but the news seems to certainly be grim.

STOP ALL WORK!  When the likes of LUVRBUS says he has "never seen....".   That is the worst news possible.  You need to find out where you are in this.

GET YOUR STUFF TO A SAFE LOCATION.

Disassociate yourself from that mechanic.  You cannot afford to allow him any further involvement.  He seems dishonest at best.  His workmanship is deplorable in the pics.  From what I read he has invented new ways to destroy your engine as this crew is hard to leave speechless.  Apparently, this man has misrepresented himself to you and that is a "lie".  When people lie to your face it is the worst of signs.

Get competent help to access "your" current position and that of your engine.  No matter what you have invested to date, you don't want to throw any more money at this thing if there is little or no hope of a satisfactory outcome.  I suggest you ask this board for recommendations of a mech in your area.  And where not to go as well.  I would suggest a small shop with an impeccable reputation such as Choo Choo Gar.

If you get a judgement against this bird for damages in "Small Claims" that should short circuit any claims he might have for lost wages or materials.  If what you say and show in pics is true then the Judge should go all weepy on your behalf.  The two "shoulds" in this para are operative.  Just spit ball'n here.

If the engine was started with dirt and debris in the oil lines you are probably looking at a bad engine.  I would not put another dime in that Puppy till I pulled a bearing and checked for "crap" imbedded in the bearing surface that would acts as a cutting tool on your crank.

I wish I had better feelings about this.....I don't.  prepare to open your wallet for repairs.  When the guys here say "Good Luck with this" it means something like "abandon all hope" as far as I have been able to tell.  That doesn't mean there is no solution....it means that, like so many others before you, in all probability, you are about to make decisions that will haunt you.  Beware the "solution" that involves a "compromise" with the mech that allows him to recover all charges and get a BONUS and a letter from you that thanks him for his professionalism and skill....you know....a COMPROMISE that considers the expense of being in business and all the hidden costs of serving the public and ....wretch....wretch....puke.

Timidly,

John
"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla

Offline irstaxhelp

  • 1960 GMC 4104
  • Newbie
  • *
  • Posts: 47
  • 1960 GMC 4104
    • San Diego Down Syndrome
Okay so sounds like I need to know of a good mechanic in the San Diego area.  Anyone know of one.

they did clean out the head after the picture was taken.  They used a magnet and blew it out the best they could. 

Offline luvrbus

  • Hero Member
  • *****
  • Posts: 19424
JohnEd, just because I never saw a stud installed using that method does not make it gospel 

good luck
Life is short drink the good wine first

Offline Geoff

  • Hero Member
  • *****
  • Posts: 1458
    • Geoff & Sherry's RTS Conversion Pics
I have seen replacement screw-in bridge studs, but if the mechanic was tightening the bridges without holding them in a fixture or with another wrench then I understand how he broke them off.  And like Cliffford says he likely bent the valve stems.  Not only that, but if he is doing stupid stuff like that I would not trust his bridge adjustments which in turn can lead to sucking a valve when the keepers come flying off.
Geoff
'82 RTS AZ

Offline JohnEd

  • Hero Member
  • *****
  • Posts: 4571
JohnEd, just because I never saw a stud installed using that method does not make it gospel 

good luck

That isn't the way I "see" it, Clifford.  Trust me on this....Please. ??? ::) ;D

John
"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla