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  #1  
Old 04-07-2008, 06:32 PM
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560sel head bolts stripped

hey guys need some advice.i have some compression issues on the drivers side of the engine. the long head bolts that go on the outside of the cam that attaches those 4 bolts they are stripped in the block.my question is this a heli coil situation and do i need all new bolts? this head has been opened once before.very frustrated with the car i seem to be getting into more and more things and the price keeps going up also. would appreciate some much needed advice.

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  #2  
Old 04-07-2008, 07:58 PM
t walgamuth's Avatar
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Join Date: Apr 2005
Location: Lafayette Indiana
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First check the length of the bolts. It is a long shot but possible that they are too short.

If they are indeed stripped helicoil should work fine. I think the head will have to come off though.

Tom W
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #3  
Old 04-07-2008, 09:02 PM
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Location: Gainesville FL
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Serious problem. The heads will have to come off.

Many techs do the heli coil repair to every aluminum v8 they have the heads off of. Unless the bolts have been switched and are the wrong length they are probably OK.

From doing hundreds of these heads, I can say that doing helicoils on every job is a serious waste. I have had maybe 4-5 engines pull threads. They had all been seriously overheated. Doing the coils adds seriously to the labor costs of doing the heads.
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  #4  
Old 04-07-2008, 09:37 PM
ILUVMILS's Avatar
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Posts: 2,744
Back in the day, we used to Heli-Coil all the head bolt holes whenever the cylinder heads were removed. The reason was simple. Nobody wanted to take the chance of stripping the threads during re-assembly (this happened frequently).

To make things easier, MB provided us with some special tools to perform this repair. One of them is a drilling jig (#117-589-02-23-00), which bolts on to the mating surface of the engine block. This jig was to assure that the original threads could be quickly and accurately drilled out. I'm sure that most MB dealers (like mine) still have this jig hanging on the wall of their tool room, although we don't use it much anymore.

MB also offered a Heli-Coil kit specifically for this job. It included a tap with a pilot shaft, a full depth tap, and enough Heli-Coils to do the job.

Once the heads were removed, it took the better part of a day to drill, tap, and install the Heli-Coils (there are thirty-eight in all), so like Steve says, it adds a considerable amount of labor to the job, and when I say labor, I mean labor. Anyone who has done this job will tell you that it's exhausting (especially on the wrists and forearms).

These days, many MB's that require this repair aren't worth the expense involved, so many owners look for cheaper alternatives (like used engines).
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  #5  
Old 04-08-2008, 11:50 AM
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Posts: 195
560 head bolt stripped what size heli coils do i need?

now that i know i need heli coils can some one tell me the size of the heli coils i am to buy?
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  #6  
Old 04-08-2008, 12:10 PM
ILUVMILS's Avatar
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The MB "Cylinder Head Bolt Thread Repair Kit" is part number 900-589-00-99-00. The Heli-Coil number is 5587-MB.
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  #7  
Old 04-08-2008, 12:11 PM
ILUVMILS's Avatar
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I posted some additional information in the original thread.
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  #8  
Old 04-08-2008, 01:33 PM
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Join Date: Apr 2000
Location: Falls Church, VA
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Not for the faint of heart

Here is another way to approach the problem. This comes from a very talented hobbyist for whom I have great respect. The threads stripped when the engine was completely together, and he was on the final round of torquing. This solution has been in place for more than three months.

The short story is that I made a hardened stud from a 10mm bolt and
epoxied it into the block.

I found a total of 38 mm of hole in the block. 11mm at the bottom
still had threads and 27 mm apparently was stripped out allowing a
bolt to slip in to the point of the remaining threads at the bottom.

With the cam and towers out of the way I was able to use a long 10mm
bolt with flutes cut in it to chase the remaining threads.

I ended up making three different studs from bolts. I used vinyl
tape to create a dam/squeegee at the top of the lower thread portion
of the stud. I did not want epoxy in the head hole and thought this
would help prevent that. I also put a single layer of vinyl tape on
the portion of the stud that would be in the head. I did not want a
bond with any stray epoxy between the stud and the head as I assumed
it would give me a false torque reading.

I raised the temperature of the workspace to 65 degrees and directed
a heat gun on the outside of the block closest to the hole assuming
this would improve the set up of the epoxy.

I used a funnel with a small hose extension to get lacquer thinner
into the bottom of the hole. I did not want to saturate the head
gasket around the bolt hole with lacquer thinner. I used an air
nozzle with an extension to blow oil and debris out of the hole. I
repeated this twice.

I mixed up a sample of JB Weld epoxy and applied it to one of the
extra studs I had made to see what its consistency was going to be
and watch its behavior on the threaded portion.

I applied epoxy to the stud that I had taped up. I made my best
guess on how much to apply. I did not apply any epoxy to the bottom
10mm of the stud. I had cut a slot in the top end of the stud to be
able to screw it in. I did my best to keep it off of the sides of
the hole in the head. I screwed it in with a screwdriver.

I put a nut on the stud and preloaded the assembly with 20ftlbs of
torque. I was confident the threads at the bottom would carry that
and I wanted the preload to give me a good final alignment while it
was setting up.

I directed the heat gun on the block for several hours to raise the
temperature and perhaps increase the flow of the epoxy.

Sixteen hours later I removed the nut and replaced it with a hardened
one. I had the "practice" stud that I had used to monitor the cure
of the epoxy. I torqued it down to 42ftlbs. It appears to be rock solid.

I am currently replacing the cam and towers and will proceed with the
final assembly as time permits.

If the stud holds I think a lot of credit can be given to the 11mm of
threads that were available at the bottom of the hole. They gave me
a foundation to work off of.
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Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #9  
Old 04-08-2008, 01:42 PM
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Join Date: Feb 2007
Posts: 174
not for the faint of heart...You Said It!

This sounds like a course in self abuse...or a russian Space Station repair procedure.

but if it works....?

My experience with epoxy anchorage into metals in a high heat environment has not been good. I have had better luck with JB Weld than most of the epoxy products (both professional/trade only and consumer) that are sold as "high heat specific".

Given the two repair procedures detailed, (MB and DIY/Mir), I'd go for a used engine.

Quote:
Originally Posted by ctaylor738 View Post
Here is another way to approach the problem. This comes from a very talented hobbyist for whom I have great respect. The threads stripped when the engine was completely together, and he was on the final round of torquing. This solution has been in place for more than three months.

The short story is that I made a hardened stud from a 10mm bolt and
epoxied it into the block.

I found a total of 38 mm of hole in the block. 11mm at the bottom
still had threads and 27 mm apparently was stripped out allowing a
bolt to slip in to the point of the remaining threads at the bottom.

With the cam and towers out of the way I was able to use a long 10mm
bolt with flutes cut in it to chase the remaining threads.

I ended up making three different studs from bolts. I used vinyl
tape to create a dam/squeegee at the top of the lower thread portion
of the stud. I did not want epoxy in the head hole and thought this
would help prevent that. I also put a single layer of vinyl tape on
the portion of the stud that would be in the head. I did not want a
bond with any stray epoxy between the stud and the head as I assumed
it would give me a false torque reading.

I raised the temperature of the workspace to 65 degrees and directed
a heat gun on the outside of the block closest to the hole assuming
this would improve the set up of the epoxy.

I used a funnel with a small hose extension to get lacquer thinner
into the bottom of the hole. I did not want to saturate the head
gasket around the bolt hole with lacquer thinner. I used an air
nozzle with an extension to blow oil and debris out of the hole. I
repeated this twice.

I mixed up a sample of JB Weld epoxy and applied it to one of the
extra studs I had made to see what its consistency was going to be
and watch its behavior on the threaded portion.

I applied epoxy to the stud that I had taped up. I made my best
guess on how much to apply. I did not apply any epoxy to the bottom
10mm of the stud. I had cut a slot in the top end of the stud to be
able to screw it in. I did my best to keep it off of the sides of
the hole in the head. I screwed it in with a screwdriver.

I put a nut on the stud and preloaded the assembly with 20ftlbs of
torque. I was confident the threads at the bottom would carry that
and I wanted the preload to give me a good final alignment while it
was setting up.

I directed the heat gun on the block for several hours to raise the
temperature and perhaps increase the flow of the epoxy.

Sixteen hours later I removed the nut and replaced it with a hardened
one. I had the "practice" stud that I had used to monitor the cure
of the epoxy. I torqued it down to 42ftlbs. It appears to be rock solid.

I am currently replacing the cam and towers and will proceed with the
final assembly as time permits.

If the stud holds I think a lot of credit can be given to the 11mm of
threads that were available at the bottom of the hole. They gave me
a foundation to work off of.
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  #10  
Old 04-08-2008, 06:54 PM
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Join Date: Aug 2006
Posts: 195
i called my local mb dealer in memphis they did not have the kit but i have one now . will do the deed this weekend if all goes well.
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  #11  
Old 04-09-2008, 02:31 PM
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Join Date: Feb 2007
Posts: 174
Best of Luck!

Take it slow and easy...

I would reccommend taking a few Tylenol to help with the carpal tunnel cramps before starting the procedure.
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  #12  
Old 04-10-2008, 10:54 PM
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Join Date: Aug 2006
Posts: 195
looking at the manual the ones i need to drill out are at 90 degrees but i am still nervous, if they are the slightest off well you know the phrase.
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  #13  
Old 04-10-2008, 10:55 PM
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Join Date: Aug 2006
Posts: 195
people told me that i needed 10mm 1.5 heli coils is that right?
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  #14  
Old 04-10-2008, 11:48 PM
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Join Date: Dec 2006
Location: beautiful Bucks Co, PA
Posts: 961
Drill a thick piece of aluminum or hard maple on a drill press and use it to keep the bit square when you drill the block. I drilled many Rolls engines for heli-coils this way.
Wait till the job is done before having that cuppa coffee.
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  #15  
Old 04-11-2008, 03:30 PM
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Join Date: Aug 2006
Posts: 195
coffee when i am done and i haven't messed anything up it is definetly budwiser time.

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