Coolant flow question

[Motorradmark]

Ok, noticed coolant leaking past expansion tank cap .
Opened and it was full to top. Started up, ran until temp above 188, fan came on, lower rad hose hot, top rad hose cool to touch. Cool fluid still coming out of expansion tank.

Temp keeps rising .

300tdi Land Rover 110.
Revotec electric fan.

Might I have a crapped out thermostat?
Thanks
Mark

 

[Overlander]

possibly. you might also have a failing head gasket that is pressurizing coolant with the turbo boost. pull the tstat and test it in boiling water. if it passes, get a sniffer test on your coolant. also keep in mind, for very small gasket leaks, you can pass a sniffer test at high idle and still have under load boost pressure that weeps pass the gasket. make sure the shop works that turbo for the sniffer.

coolant flow diagram attached in case you need it. Don't assume it's not head gasket because you don't want it to be. It's easy for diagnosis to drag on that way. coolant pressurization even under normal temps is a pretty clear diagnosis. once HG starts putting exhaust bubble into the radiator, there is less coolant in contact with the head and block in the coolant channels and the temp spike happens very quickly.

 

[Motorradmark]

Thanks.
IF it is head gasket, how do you know in advance with one-1 or 2 hole gaskets?

 

[rocky]

Similar thing happened to me. Radiator had internal failure and was blocked.

Think cheap stuff first!

 

[DefendersNW]

Thanks.
IF it is head gasket, how do you know in advance with one-1 or 2 hole gaskets?

Your existing head gasket has a hole marking - locate the indicator tab and note the number of holes.

Below example is a3-hole (lower right)

 

[Uncle Douglas]

Its very easy to pull your thermostat. Two bolts. Pop it out, put housing back together empty and see if problem persists.