2.7crd stripped thread on injector bolt.

roadrunner1

New member
I have a Jeep grand Cherokee 2.7crd.
I have stripped the threads on number 3 injector retaining bolt hole. My intention is to do a helicoil repair on this. When looking through the forum I have noticed that the tappet cover has to be removed in order to do this. My first question is why. If I drill the hole out slowly and very carefully what harm can it do?
My second question is why you can’t re thread the hole and use a larger bolt.
 

sailquik

Well-known member
roadrunner1,
The correct fix for a stripped injector hold down bolt is NOT a helicoil!
Helicoils are way too short (thread engagement length) for a bolt with this much torque
and cyclic load on it.
There is solid insert kit specifically made to repair damaged 2.7 MB )M-612 and OM-647 injector hold down bolts.
The correct fix is written up by Dr. A somewhere on this forum.....check it out before you proceed...please!
Roger
 

roadrunner1

New member
Thanks for the reply sailquik. After further investigation it would appear that the helicoil repair idea is not a good one. Several cylinder head engineers have however said that they use time-sert inserts. So maybe this is the way to go.
I have sent a PM to Dr A, but have not had a reply yet.
 

kyblinc

New member
Hi roadrunner1, am a newby but i have gown down the same road as you. Did you ever find out about the solid inserts or heard from Dr A? Pls let me know, thanks

Oscar
 

kyblinc

New member
Thanks roadrunner1.
I had the same idea but i bought an insert with 6m internal and 7.5m external from Fastenal and am hoping its gonna do.
Am just worried about drilling the hole wider.
I had also thought of tapping it to 8m but am not sure about the idea on the aluminum. Any lasting solution Please?
 

Aqua Puttana

Poly - Thread Finder
Hi kyblinc,
I made an insert from a mild steel bolt.
Sounds interesting. I presume you used an engine lathe for the fabrication, or did you tap out an oversized bolt? Please provide more detail on the actual part and installation. Thanks. vic
 
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roadrunner1

New member
Firstly I took a FKE 10.9 bolt 30mm long, with an allen key head. This was drilled out to 5mm, then tapped out to 6mm. This should be done on a lathe, or if you are very careful you could do it by eye as I did. I then put a hacksaw blade cut just below the head of the bolt, about half way through.
As for the cylinder head I Drilled out the existing hole to 8.5mm, 30mm deep. I found it best to use a hand drill for this. Then tapped it out using an M10 No2 Sec M-coarse tap. I then inserted the bolt into head and screwed it down until the head of the bolt broke off. If you have done your measurements correctly this new insert should be level with the top of the hole in the cylinder head.
You now have an insert ready to take your new stretch bolt.
I torqued this to 7Nm then a further quarter turn.
 

Aqua Puttana

Poly - Thread Finder
Nice work! :thumbup::thumbup:

Thanks very much for the details. :cheers: vic

Firstly I took a FKE 10.9 bolt 30mm long, with an allen key head. This was drilled out to 5mm, then tapped out to 6mm. This should be done on a lathe, or if you are very careful you could do it by eye as I did. I then put a hacksaw blade cut just below the head of the bolt, about half way through.
As for the cylinder head I Drilled out the existing hole to 8.5mm, 30mm deep. I found it best to use a hand drill for this. Then tapped it out using an M10 No2 Sec M-coarse tap. I then inserted the bolt into head and screwed it down until the head of the bolt broke off. If you have done your measurements correctly this new insert should be level with the top of the hole in the cylinder head.
You now have an insert ready to take your new stretch bolt.
I torqued this to 7Nm then a further quarter turn.
 

smlmgd

New member
:thumbup:
Firstly I took a FKE 10.9 bolt 30mm long, with an allen key head. This was drilled out to 5mm, then tapped out to 6mm. This should be done on a lathe, or if you are very careful you could do it by eye as I did. I then put a hacksaw blade cut just below the head of the bolt, about half way through.
As for the cylinder head I Drilled out the existing hole to 8.5mm, 30mm deep. I found it best to use a hand drill for this. Then tapped it out using an M10 No2 Sec M-coarse tap. I then inserted the bolt into head and screwed it down until the head of the bolt broke off. If you have done your measurements correctly this new insert should be level with the top of the hole in the cylinder head.
You now have an insert ready to take your new stretch bolt.
I torqued this to 7Nm then a further quarter turn.
Brilliant Roadrunner!!!
The following is what I do daily. I use a thin or thick-walled M6 (iside) galvanized insert. Remove tappet-cover, drill and tapp top-end of bolt-hole so insert fits flush with top of hole. Now use 35 or 40mm M6 stretch bolt. Do not forget to vacuum out the drill and tapp debris. Install insert with locktite.
This job takes me 30mins per hole. Use copper-slip paste on sides of injectors and "Stag" gas sealer on copper whasher when installing injectors.
Go well Guys 'n Dolls and happy Sprinting.
Mac. Pretoria, South Africa. (not that I'm happy to be from here) :thumbup::smilewink:
 

Dingo

New member
Use copper-slip paste on sides of injectors and "Stag" gas sealer on copper whasher when installing injectors.

NO NO NO , use febi ceramic grease , it was made for the job , copper grease dries out does not resist heat like the ceramic stuff does

save yourself heartache later
 

Aqua Puttana

Poly - Thread Finder
Use copper-slip paste on sides of injectors and "Stag" gas sealer on copper whasher when installing injectors.

NO NO NO , use febi ceramic grease , it was made for the job , copper grease dries out does not resist heat like the ceramic stuff does

save yourself heartache later
+1

The copper stuff combined with the steel injector body and machined aluminum bores is not a good idea.

The MB ceramic grease is not readily available in the USA. A quick Google search showed no suppliers for Febi brand over here. Maybe from a MB dealership? :idunno:

My "factory" rebuilt Bosch injectors came with a packet of Counterman's Choice Permatex Anti-Sieze Lubricant Net Wt 5g SKU Bar Code 86226 09175 in with each injector. It appears to me to be the common silver paste consistency anti-sieze.

If I ever need to do another injector (I hope not as I replaced all 5) I will consider using a combination of the Permatex Anti-Sieze and Permatex-24125-Ceramic-Extreme-Lubricant. The ceramic lubricant is for disc brakes so drying out and heat should not be an issue. It does have ceramic. I haven't done this yet so a big FWIW.

Anyone have more detail on this Permatex ceramic lubricant? vic

http://www.amazon.com/Permatex-24125-Ceramic-Extreme-Lubricant/dp/B0018PSASU/ref=pd_sbs_auto_5
 

Dingo

New member
Here you go febi do supply the US from what i can see .

You can buy from Ebay , here are the two part numbers from a febi tub

nr 26712
nr 001 989 42 51

but this is the MB part no. 001 989 42 51
 

Aqua Puttana

Poly - Thread Finder
Here you go febi do supply the US from what i can see .

You can buy from Ebay , here are the two part numbers from a febi tub

nr 26712
nr 001 989 42 51

but this is the MB part no. 001 989 42 51
Only from eBay UK that I saw.

Using your part number.


http://www.factorymoparparts.com/001-989-42-51-10.html

Mercedes Benz 001-989-42-51-10 GREASE
001-989-42-51-10 Mercedes Benz GREASE
Item# 001-989-42-51-10
Dealer price: $26.49
Our price: $18.27

Thanks. vic
 

smlmgd

New member
Use copper-slip paste on sides of injectors and "Stag" gas sealer on copper whasher when installing injectors.

NO NO NO , use febi ceramic grease , it was made for the job , copper grease dries out does not resist heat like the ceramic stuff does

save yourself heartache later
Thanx Guys for your advice. I'm sure it works fine. Unfortunately these products are not so readily available here. So far the copperslip paste works fine under the circumstances.
:thumbup::thumbup::thumbup:
 

smlmgd

New member

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