Heat compound on head button?

[PaulC]

Should the heat sink on a nitro engine not have heat compound underneath to ensure a perfect fit and heat transfer from the head to teh sink?

I took mine off the other night (threads are definately weakened though I can get a plug in on the right threads and it cranks down okay). There was no heat compound/paste between the head and the cylinder head. I thought there should be.

I'm not sure what the limits of the stuff used on PCs is, I've run PCs to 88C before and it didn't burn the heat compound, but I'm wondering if it would take the 110-150 of a nitro head.

Cheers

Paul

 

[Scrogg]

Absolutely do not ever put anything in, on, or around the glow plug area or cooling head and head button. It will ruin the engine. Most engines reqire glow plugs with copper washers, that is what seals the hole. If you have any doubts or you can see fuel bubbling up from the glow plug, replace the plug. If that does not do it, then you need a new head button.

 

[beason]

i think he means between the button and the crank case.

it seems like it would be a good idea, but I'm not sure you will see a major increase in cooling by doing so.

there are supposed to be very thin copper shims between the button and case, that will bend and conform to the surfaces to create a seal. in order for the compound to work (in my experience with pc's) you would need to lap the case and button to a mirror or near mirror finish for the compound to have much effect. the surfaces on the mills are too rough and would need a thick layer of compound to work, thus defeating the purpose of the compound.

 

[olds97_lss]

I could see maybe a coating on where the head makes contact with the button, but as suggested, the copper shim is your heat contact point between the sleeve/crankcase and head button. Putting anything between the button/shim/sleeve would just be more prone to squishing into your cylinder and breaking down due to high compression, vibration, fuel corrosion and temps. Between the button and head though, just heat and vibration would be the enemy of the compound.

Kind of similar to why the sanding of the anno off the head where it makes contact with the button seems useful in this thread:
https://www.rcnitrotalk.com/forum/showthread.php?t=78106

In theory... makes sense.

 

[PaulC]

I think I'll leave it as is, thanks.