Ok I now own this ford ranger 88 2.9 litre, and at first my top radiator hose was collapsing when the engine was shut off and cooled down. Well I replaced the thermostat, upper hose, and radiator cap and that stopped that problem.
Well today I was out messing around under the hood checking things out and I decided to rev it up by the throttle body. While reving it up I noticed the TOP radiator hose is collapsing, and the more rpms you gave it the tighter it would collapse! Even sometimes at idle the hose would pulse. Now the ONLY thing I haven't replaced is the water pump and radiator. The pump that is on it MAY be original since it says motorcraft on it. However I really dont see how a new water pump would cause this problem to stop. The engine is not really over heating either, it stays at 1/2 way up on the temp guage and every now and then goes to 3/4 way up. It is not boiling over/steaming

My question is what do you think it may be?

thanks a ton
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usually first thing is the thermostat, if that was replaced and done properly then unfortunately sometimes it could be a headgasket problem which can cause that.

 

Even if it doesn't look like a steam out the tail pipe? The coolant level is remaining up and its not missing.. The engine just got rebuilt with the heads checked out at the machine shop and new head gaskets.

Thermostat was replaced with a 195* reverse poppet stant thermostat with the spring side of it intalled INTO the intake manifold.

 

bad headgasket might not have steam coming out of tailpipe. Was the engine rebuilt at a shop? If so I would bring it back and have them check it out if there is any kind of warranty. Maybe you have an air pocket in the cooling system. When a hose collapses there is some sort of vaccuum causing this. Are the hoses new? If not I would replace them. Start out simple. Maybe the hoses are VERY soft and old. Sounds like thermostat is installed properly from your description. Does this happen every time you start the vehicle?

 

Errr, I'm a V8 guy and not familiar with this engine, but isn't the top hose high pressure hot water from the engine to the radiator? If so it shouldn't collapse unless there's a restriction in the system between the waterpump and top hose, or a reverse rotation pump installed and the radiator is clogged.

A head gasket put on backwards, in some engines, can block water passages and make a restriction. The cylinders would seal normally.

 

The collasped hoses, after cool down part, sounded like the problem I had with my then new, 99 4.0L Ranger.

Dealer found that the radiator overflow tubing going to the recovery tank, was incorrectly routed under & being pinched shut by the air box. Correctly re~routing the tubing took care of things!!!!

Just another happening for consideration.

 

When they put the water pump back on could they have run the belt on the wrong side of the pulley giving you reverse flow? That might cause it.

 

I had the same problem with my 2.9l bII, the top hose collapsed and i was kinda in the middle of nowhere and had to limp back to civilization, it was caused by a blockage in the radiator, additionally i had to replace the water pump cause it was fried, now if that was from being 20 yrs old or the 3 mile drive with it collapsed ill never know.

so have the cooling system flushed,

if that doesnt work have the water pump checked.

hope that helps