Thunking noise from heater hose

[cargs]

occasionally i get a thunking or thudding noise coming from the engine compartment. i though it was the abs system acting up because it seemed to only happen when i pressed the brake, but it happens without as well.

the noise happens mostly when the engine is running, and occasionally when it has just stopped. i had an opportunity to "catch" it when i pulled into a gas station. i left the truck idling and popped the hood. the hose coming from the the block to the heater core was visibly moving back and forth. i put my hand on it and could feel a clicking/thudding/thunk, like a valve was slamming on and off, or air bubbles were forming and collapsing.

i thought it must be the thermostat slamming open and close, but the main radiator hose did not feel as "violent" as the heater hose.

i haven't had a chance to check the thermostat, but is less than 1 year old, the heater core is also less than 1 year old.

i am fairly confident that there is not a mechanial problem with any of the internals, the enigne runs perfectly smooth at all other times. Even when the thudding noise is happening the engine revs smooth.

any ideas?

has anyone had a similar problem?

air trapped in the system?

faulty thermostat?

thanks for the help.

 

[Big Jim M]

I betcha it has nothing to do with the thermostat. Sounds like there is air in there..
Big Jim

 

[evanesce69]

i had no advanced indications that my thermostat was taking a crap...

then it "froze" and i blew a head gasket. cost over $600 with rebuilt heads and gaskets. I did the labor........



Cheap insurance is to flush the system when COLD with cold H20: (gasses are more soluable when cold than hot, helps remove air pockets), and replace thermostat. The thermostat may not be a necessary replacement, but my logic is this: Heads = $600, thermo = $10.


Can you afford not to try it????




NOTE: i drive a '93 4x4 with 3.0L V6 everday

 

[cargs]

best way to get rid of air in the system?

 

[evanesce69]

when properly performed.... yes

 

[cargs]

let me try that again.

what is the best way to get rid of air in the system?

thanks.

 

[Big Jim M]

Seems rather obvious to me

let me try that again.

what is the best way to get rid of air in the system?

thanks.

But I'll give it a whirl anyway..
First park or jack the vehicle up to the point where the FILL CAP is the highest part of the coolant parts.

NOW open the cap!

THEN look closely at the hoses that are gurgling. THINK about where air could be trapped and not be able to get BACK to the radiator..
This would be a HIGH PLACE in the hose where an ARC up and then back down would be visable..

NOW start the engine and while running and HOT, so the thermostat is open. FLEX the hose for a minute or so making the HIGH SPOT disappear so the AIR can be on it's way thru the system..

It should make it's way out the OPEN CAP in a couple of minutes.. In any event it won't be in THAT hose anymore and will evacuate itself after a cople of cool-offs...which is the natural way.

Now if it needs a squirt of new coolant give it to the radiator and close it off..

Big JIm

 

[fixizin]

... could feel a clicking/thudding/thunk, like a valve was slamming on and off...

HOLD IT!... back on topic: The most LIKELY cause of your disturbing symptom would be... the vacuum-actuated HEATER CONTROL VALVE in the adjacent heater hose, eh? It looks like this:

Perhaps just the vacuum hose controlling it is getting leaky? Anyway, you can look at the exposed end of the plunger... it should be IN (closed) when your climate control know is OFF or MAX A/C, and open for all other positions. Yours sounds like it might be fluttering, oscillating, "acting up", etc...?

Anyway, check it out... it's easy, up-top... before you go tearing into a t-stat replacement, etc.

That's not to say your cooling system doesn't need a good burping, but first things first.

 

[289-tiger-]

The 93 does not have a valve in the system. Feel both lines from the core when warm and if there is a difference the sediment trap (heater core) is bad and will give you the symptoms of air in the system. It is a cheap and easy replacement and may be simply clogged.

Good luck

 

[fixizin]

My bad... so is this sediment trap separate from the heater core?... er, wait, you're saying it IS the heater core, and that's what it does, trap crap, lol...

I gather that swapping a heater core is easy prior to model year 19??, and a pain after that, due to dashboard/airbag tear-down...?

 

[289-tiger-]

My bad... so is this sediment trap separate from the heater core?... er, wait, you're saying it IS the heater core, and that's what it does, trap crap, lol...

I gather that swapping a heater core is easy prior to model year 19??, and a pain after that, due to dashboard/airbag tear-down...?

Yes, that's what I call the heater core, on 93 94 models they come straight out the passenger floorwell with no issues. Good call on the valve on later models.

 

[sparky]

Is this your 93? Have you ever changed the water pump? It being a 93 i would say yes on the water pump. The reson i ask is i had this same problem when i bought my truck 11 years ago, i changed t-stat, took rad out and had it check, still same problem. This went on for a few weeks, it didn't do it when i first bought it, started a while later. I think this is why it was traded with so low of miles. anyway, the rad shop that checked my radiator said he would like to see it doing it, so i took to him and it was hitting hard, sounded like someone hitting the dash with there fist very hard. He was puzzled and said he never seen it before, but had some literature that ford had sent to him and he hadn't looked at yet. We went in his office and he started reading it and found the same problem my truck was doing, temp fluxuating but not getting overheated, thumping in heater hose. according to his paper work this problem was in the 3.0 ranger and aerostar vans. Quote from ford literature, was to replace the water pump. I did and have not had the problem since. Now with that said, i wouldn't think you were still running the same pump or had this problem before now, but i thought i would share with you what happened to me.