loose glowplug

Yabby Fri Mar 01, 2024 7:09 am

I searched the forum but couldnt find anything. Ive got a TD 049 running standard cox head with 2 head gaskets - newly run in - the cox glowplug keeps coming loose. prop is balanced, conrod ball joint tightened. motor mounted solidly. no noticeable vibration. used new gasket or gaskets. tried 3 different cox heads. all came loose. I only put heads in and out when engine is cold. thoughts greatly appreciated. seems some engines do it and others never. Huh...

rdw777 Fri Mar 01, 2024 7:17 am

Hi Yabby, You might try and level the bottom of your glow head with some #400 sandpaper on a sheet of glass with oil for lube… It doesn’t take much, Just until you see uniform machine marks on the surface…. Also make sure the shoulder in the cylinder where the head mates is squeaky clean…. Reassemble with a little oil…

Yabby Fri Mar 01, 2024 8:11 am

Excellent. thank you for the advice, I will try it tomorrow. thank you. Thumbs Up

Ken Cook Fri Mar 01, 2024 5:45 pm

Heat your head gaskets until they glow cherry red and let them air cool. Re install and they shouldn't come loose. As Rob mentions, not only does lapping the mating surface improve the plug from coming loose, this could be your engine problem all along and your losing compression from a non sealing glow head.

Yabby Sat Mar 02, 2024 5:02 am

thanks Ken Thumbs Up

I will give it a go along with lapping the head.

Ken Cook Sat Mar 02, 2024 6:49 am

Personally, I just replace them but even doing so with new head gaskets the loosening can reoccur. The head might need to be tightened two times or more and then it usually stops loosening. The head lapping is critical not only for seal but to insure that it's mated correctly to the head gaskets. There's that useless stupid ridge on the high comp head on the mating surface that I can't figure out as to why they did that. I generally use that as a reference and lap the plug until it's completely gone.

Yabby Sat Mar 02, 2024 7:51 am

thanks Ken. I have been using new gaskets every time. 3 gaskets for a TD head tried standard heads, kamtechnic head, they all come loose quite quickly. got my magnifying glass out and the landing the gaskets site on is not square. its angled. Im getting tempted to use a kamtachnik head as it takes turbo plugs and works very well and loctite the head into the cylynder. rough and agricultural I know but it might be the answer.

Yabby Sat Mar 02, 2024 7:55 am

Ken, I have noted your comment on the ridge on the TD head. I will also use that as a reference tomorrow and the loctite can wait till im dark enough to do it. lol. Laughing

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