Hello,
Iv"e owned this truck with the 300 CI engine for a couple of months now. Evertime I accelerate from a stop I hear a tinkling noise that reminds me of water running from under the dash. I think it may be coming from the heater core. When I got the truck, I changed all the hoses and flushed and changed the coolant. It made the noise before I did that work as well.
Has anyone had this problem or know what it is? I am thinking now that there may be some junk in the heater core that gets agitated when the coolant rushes thru.
Thanks, Paul

 

88 F-250 460ci. I had a similar problem. No "tinkling" noise but when I hit the gas I got a stream of coolant from under the dash. Changed the core and it was all good. Before you change the core I would recomend you bypass it at the fire wall. Just take the hose ends and couple them together. If you still get the noise it could be anything BUT the core.

 

It would be hard to believe the noise is the heater core and you don't have coolant leaking in the truck. You may have an underdash vacuum leak. Or your truck's bladder is full and it's relieving itself?

 

I had the same noise you are describing in my 90 351 and I bypassed the heater core and it went away. The bad news is, it wasn't a heater core problem. It was either a head gasket or cracket head or block, or something. My truck was using about a half gallon every week or so and I couldn't find any leaks. No water in the oil, no oil in the water. Ended up putting in a new motor shortly after.