LBZ: Rattle when block heater is plugged in

[Combine Pilot]

Haven't used the block heater since last winter and don't usually use it as my truck is parked in a garage. Plugged in at my friends tonight and heard a rattling noise. Sounds like the thermostat opening and closing and it's never made the noise before. It stops momentarily if I squeeze the top rad hose. Does this seem normal?

 

[MAXX IT OUT]

Mine does it........

 

[Combine Pilot]

Well that makes me feel better that it's not just mine.

 

[Ne-max]

My lb7 did it last week. First time I have plugged it in. worried me at first.

 

[DAVe3283]

Mine does it too. I don't think anything is wrong. I believe it is the little air purge tab rattling up and down due to very low coolant flow (convection only).

You don't hear it when the engine is running because:

1. The rate of coolant flow is much higher, forcing the tab full up.
2. The engine is way louder than the tiny rattle noise.

 

[Combine Pilot]

That makes sense. I just went and checked and it quit doing it now. Maybe it was making noise like it was due to the coolant still being warm. :dontknow:

 

[Hot COCOAL]

Mine makes the noise too, I've always thought it was normal

 

[Guns and Grease]

My block heater started make this weird noise a couple of months ago, it never has before, so I was a little concerned. Well, about 2 weeks later the block heater quit working. I replaced it an the new one doesn't make the rattle/humming noise. But seeing as this thread is over 2 years old... everyone has probably figured that out by now.