Here is the scoop. I have recently rebuilt the 3.0L Vulcan enine in my 2005 xl 4x4 ranger.

ISSUE
(The top radiator hose pulses and makes a knocking and thumping sound at the thermostat. Also the top hose fells a bit solft to the squeeze. (New hose)

This issue does not occure, ONLY, when the heater is on, (floor, defrost, both floor and dash). Does not matter how hot or cold I set the gauge at this issue does not occure. This does not happen when the engine is cold.

The pulsing starts after the engine is at normal operating temp and driving. Most prominent when comming to a stop, but fades and stops after ideling after a few minutes.

What I have replaced [LIST][*]New factory block[*]all hoses[*]water pump[*]all pullies[*]belts[*]all fluids[*]push rods[*]roler lifters[*]replaced thermostat 2 times[*]Cam-synchronizer position sensor[*]oil pump[*]starter[*]power steering pump[*]Heads were all replaced included the valve seats ford had problems with[*]spark plugs and wires[*]Clutch [*]Cylinder Head Bolts[*]Cleaned out radiator
New Radiator Cap


The reason for the engine rebuild were the heads and high milage.

I have talked to a FORD DEALER and they said there must be air in your system or your head gaskets were put on wrong, which could be done if someone was not paying attention. But I have proof of before and after photos of assembeling the engine and taking it apart.

HOW IT RUNS
No lack in preformance, power. Does not burn oil or have white smoke comming from the tail-pipe. I get about 19 mpg highway and in town combined. No engine code. Temperatrue Gauge does NOT fluxuate. I do not smell coolant comming from my heater core.

Coolant
I have drained and refilled coolant 2 time and made no difference.
Coolant flows to and from the reservoir tank freely. No leaks!

I have looked online for this problem and have not found anything like the problem I am having.

What I have done
I have checked for metal shavings in the oil
I have pulled the valve covers off and there is no sing of a single metal shaving, and looks as new and clean as can be.

I have put about 2500 miles on the engine since then and oil is normal and coolant is normal. Like I said when I am driving with the heater on this issue does not happen. Though the upper hose seams normal and is not easily squeezed. I do have AC but have not used it being that it is winter, but I never broke the system lose so it does still blow cold air. Heater also blows hot air.

One thing I have not replaced is the heater air control valve, but it seems to be working just fine.

I mean Not even the dealer knows, Saying, "we would have to into it to see what the issue is."

Does anyone have any solutions or leads, openions?
I have no engine code to read.

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2005 Ford Ranger xl 3.0, 4x4, 5 speed manual, reg. cab

You have at least 1 air bubble in there. Gotta burp it on an incline.

The knocking and thumping sounds like the thermostat is in upside down.

Yep thats also possible !

I tried driving my truck up on some ramps an had ran it burped it so many times and I cant get any more air out of the system. Unless there is some air traped in my heater core.

No the thermostat is not upside down, and it does have the 1/8" pin hole in it.

Do you think I may need to put a "T" in one of the heater hoses? Like a by pass kit that I hear about that they use to flush out the system with?

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2005 Ford Ranger xl 3.0, 4x4, 5 speed manual, reg. cab

I don't get how it would help or what purpose it would serve.

No need for a T fitting for burping or flushing. Keep burping and keep driving it. Eventually they'll get worked out. Smashing and blurping is air, and a soft hose, especially a brand new one, is an air pocket.

Squeeze the upper radiator hose while burping to help get the air out. The upper hose should become hard to squeeze when the thermostat opens up.

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93 Ranger XL 3.0 V6
-Tint, wheels, K&N filter, Flowmaster super 44.
04 Mustang GT Vert.
-Tons of mods, supercharged 392/393

Thanks for the advice but I have squeezed the upper radiator hose while burping to help get the air out till the point that it wont burp no more bubbles. I did this when the truck was fully up to temp and waited for the thermostat to open. But as soon as the thermostat opens it gets solft. Unless I turn my heater fan on, then the hose stiffins up. I turn the heater off it becomes solft again. When I burped the system I used a tall funnel so that the fluid to be higher than the top radiator hose.

Oh and when the engine is cold the hose is rock solid.
This is a hard one that not even the dealer knows how to solve.

I have rebuild a few engines in my time, and this is the first issue of this kind that I have encountered.

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2005 Ford Ranger xl 3.0, 4x4, 5 speed manual, reg. cab

If it gets hard when you turn on the heater, that is strange. The heater is an additional reservoir for hot coolant (aka, heater core) when the heater is activated. This does help to circulate coolant through all passages in the cooling system to assist in burping air.

When you did the filling and burping, did you run the heater on high while burping the system? If not, this could be another option to try. Seems to work for most people.

Yes I did have the heater on high. Yah I don't get it either why when you have the heater on this the hose hardens up. It should be that way all the time. When I first found out that this was happening and could not get it to stop I desided to start over. I drained the fluid and tryed to fill it up again and burp the system and I changed nothing.

I have talked to a mechanic about this and what he had asid that the cause for a knocking, thumping, sound coming from the coolant is caused when something like a volve that opens and closes under pressure. (example when a dishwasher is running throug a cycle and you here thud) It makes a lot of since. Though it sounds more like a hammer under water tapping on metal.

Not that the hose pulses and you can feel it coming from the thermostat.

I have tryed the old thermostat tested it and it still open up at the correct temp. Put it back in made no difference. Bought a new thermostat put it in and made no difference.

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2005 Ford Ranger xl 3.0, 4x4, 5 speed manual, reg. cab

The only other thing that doesn't make sense but kinda would is if exhaust gasses are getting into the cooling system.

The thud you hear with a dish washer, or washing machine is the water valve closing instantly, a thermostat opens and closes slowly.

Ya your right, thremostas open and close slowly. But from what I am hearing and feeling makes no sence at all. I know my thermostat is working, because I have tested and put it back in.

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I have not thought about that but I am not seeing any bubbles in my reservoir tank. Which would also mean I would have a blown head gasket.

So how would exhaust gases get into the cooling system?

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2005 Ford Ranger xl 3.0, 4x4, 5 speed manual, reg. cab

Cracked or warped head. Bad gasket or gaskets put on wrong. Cracked block.