headless hex bolt

2 Fast 4 U · 07-10-2009

Does anybody know what the headless hex bolt [middle of the pic] is for? these pic's are from my 2.2 head:

at the far right and left:

Tru-Craft · 07-10-2009

My guess is a pipe plug for a water or oil passage.
Lyle

GTJIM · 07-10-2009

Those are known as In-hex plugs (ie: the hex is in them for use of a hex or allen key).

PS: DON"T try to take them out - or tighten them. They will leak!

They are there to positively block off access holes that were used to get the core sand out of the water passages inside the head. I guess they are much less likely to cause water leakage problems than welch plugs, (aslo known as cup plugs or frost plugs) like are used on the outside of the engine block in holes used for the same purpose.

2 Fast 4 U · 07-11-2009

Originally Posted by GTJIM

Those are known as In-hex plugs (ie: the hex is in them for use of a hex or allen key).

I knew that the term hex bolt wasn't good

, but I didn't know what the real name was

[now I do]

Originally Posted by GTJIM

PS: DON"T try to take them out - or tighten them. They will leak!

Wasn't planning to, just didn't know what they were for

07-10-2009	#1 (permalink)
2 Fast 4 U Detroit,where my home was Join Date: Oct 2005 Location: Maria - Hoop, The Netherlands Posts: 2,216 Real Name: Erick Provided Answers: 5	Answered: headless hex bolt Does anybody know what the headless hex bolt [middle of the pic] is for? these pic's are from my 2.2 head: at the far right and left: __________________ Opel Ascona; driving one is like living on the edge. Only built from 1970 - 1975

07-10-2009	#3 (permalink)
GTJIM Old Opeler Join Date: Jun 2003 Location: New Zealand Posts: 5,686 Provided Answers: 12	In-hex plugs Those are known as In-hex plugs (ie: the hex is in them for use of a hex or allen key). PS: DON"T try to take them out - or tighten them. They will leak! They are there to positively block off access holes that were used to get the core sand out of the water passages inside the head. I guess they are much less likely to cause water leakage problems than welch plugs, (aslo known as cup plugs or frost plugs) like are used on the outside of the engine block in holes used for the same purpose. __________________ GTJim Opel Owner since last Century! Copyright © 2000-2009 J D Henry All Rights Reserved

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07-10-2009	#2 (permalink)
Tru-Craft 1970-GT Join Date: Sep 2005 Location: Clearwater, Florida Posts: 1,237 Provided Answers: 2	My guess is a pipe plug for a water or oil passage. Lyle

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