Problem changing glow plugs

[gamerunner2001]

I purchased a set of new glow plugs and began changing them out Sunday afternoon. Did the passenger side firsts, took all of 25 minutes. Went to the other side and ran into some problems with # 6 & # 8 on my engine. All of the old glow plugs(Short) came right out but I could not get the new glow plugs(Long) to seat in # 6 # and #8. It seemed as if the tip of the glow plug was being obstructed inside and it wouldn't quite reach to the threads I cleaned two of the old glow plugs and they went right back in no problem. So, now I have 6 or the 8 new glow plugs in and my truck starts in a 1/3 time as before. I'll go back and try again but thought I'd check and see if anyone else has run into this problem???
86 suburban, 6.2

Thanks
Brian

[britannic]

Assuming you compared the old and new plugs and found no differences, try the new ones that don't seem to fit in a different glow plug port that you already changed out. If the new glow plugs are physically the same as the old ones that fit, there shouldn't be any problem.

I did find that sometimes they get held up on the casting as they go into the hole (in the less accessible cylinders where there are obstructions and visibility is limited) and need some careful repositioning to locate properly.

Another tip, if you didn't already, use a little anti-sieze compound to make them easier to get out in the future and then tighten to 10ft/lbs.

[MechanicMike]

Check the glow plugs that came out. Hopefully there is not a little piece of it still in the port. Another thing, take a fine, circular wire brush and clean the hole.
Good Luck
Mike