Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Vintage Mercedes Forum

LinkBack Thread Tools Display Modes
Old 05-13-2019, 11:31 PM
Join Date: May 2019
Location: Connecticut
Posts: 53
Pagoda stripped spark plug hole!

In changing my plugs and despite being super careful, I did what I fear most...stripped a spark plug's been years since I changed them, and I can't remember if I had a problem in the past because the previous owner started a cross...the plug is holding for now, so I'm not messing with it. Given all the aluminum heads on our early MBs, has this happened to others, and if so, what did you do short of pulling the head? I've heard there is a better choice than Helicoil...appreciate any input...thanks...
Reply With Quote
Old 05-13-2019, 11:43 PM
Registered User
Join Date: Dec 2010
Posts: 1,782
I've seen this before but it's actually not all that common. You can fix it with a thread insert or helix-coil.
Reply With Quote
Old 05-14-2019, 08:20 AM
Stretch's Avatar a shield of steel
Join Date: Sep 2009
Location: Somewhere in the Netherlands
Posts: 14,453
The "better" Helicoil versions are called Time-sert or other brand names with "sert" stuck on the end. They are not cheap.

The safest way to fix is to remove the head - people try and mess about with compressed air to try and blow swarf out of the cylinder but I think that's potentially asking for trouble. If you have an engine with an aluminium alloy head it is probably a good idea to remove it anyway and check for corrosion (especially if the engine has been sitting for a while / poor maintenance). More modern engines such as the M102/3/4 and the OM603/6 suffer from head gasket corrosion related trouble.

For my M102 I used Hylomar spray on gasket dressing which is meant to help prevent corrosion as well as help with the seal.

If you decide to remove the head follow the reverse torque order procedure as specified in the FSM - this is particularly important for an aluminium alloy head.
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior

Don't leave that there - I'll take it to bits!
Reply With Quote
Old 05-14-2019, 10:08 AM
Registered User
Join Date: Apr 2009
Location: Los Angeles (Altadena)
Posts: 1,682
Joe, you have a lot of Pagoda comments. You might want to join if you haven't already. Great forum.
Reply With Quote
Old 05-14-2019, 11:40 AM
Registered User
Join Date: Jan 2012
Posts: 7,165
Define " Stripped " . Did the first thread in the hole become damaged or are all the threads worn out to the point the plug won't tighten up?
Reply With Quote
Old 05-14-2019, 12:33 PM
Registered User
Join Date: Sep 2013
Location: Alhambra California
Posts: 2,069
As Stretch has said, Time Sert is the best thread repair available. It comes as a certain size kit with a special tap, installation tool, and inserts. Removing the head is best as there is a pretty good certainty that metal chips will fall into the cylinder. The other advantage to completing this repair with the head on a bench is there is a lot better chance that the insert will be installed straight and true.
Reply With Quote
Old 05-14-2019, 10:04 PM
cth350's Avatar
Registered User
Join Date: Dec 2000
Location: Long Island, NY
Posts: 3,772
There's always the option of filling the cylinder with grease at not quite the top of the stroke and then bringing it to TDC when you're done to squeeze it out along with the metal chips (hopefully).

I've never done it myself, but it's been done.

Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 02:51 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page