Collapsed lower radiator hose... (1 Viewer)

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Joined
Aug 21, 2014
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1973 Fj 40
F engine

I've been chasing an overheating issue and was about to throw in the towel when today I discovered that when I rev the motor the lower radiator hose collapsed. It appears my radiator is not suppling enough fluid as the water pump is pulling at higher rpm.

Obviously, this restricts cooling fluid to the block and cause overheating? I pulled the radiator today and will be dropping it at the repair shop for a re core.

Questions is? Anyone else see this issue with clogged and restricted radiator? Am I on the right track?
 
Back in the day (and still possibly today) auto parts stores sold a small coil spring that went inside the radiator hose to keep it from collapsing
 
The coil is a method of making a crappy hose work for the job. The toyota hoses won't collapse if the water pump is not creating a vacuum.. Fix the radiator and you'll be good.
 
The spring in the hose is a good piece of mind that the hose wont collapse, a lot of our hoses down here still come with them
 
Radiator is in the shop getting flow tested and boiled...ill keep everyone posted on the results. Thanks
 
My 1977 is overheating at cruising speeds and I have been wondering about the "collapsed hose" problem. The engine cools fine until I drive down the road for a few miles. The radiator was a new installation, not a rebuild. The t-stat has been removed and the heater has been bypassed. The oil cooler setup is off a later FJ60. Is there a way to plumb the oil cooler incorrectly?
 
My 1977 is overheating at cruising speeds and I have been wondering about the "collapsed hose" problem. The engine cools fine until I drive down the road for a few miles. The radiator was a new installation, not a rebuild. The t-stat has been removed and the heater has been bypassed. The oil cooler setup is off a later FJ60. Is there a way to plumb the oil cooler incorrectly?

sent you a message/conversation
 
Overheating of the coolant can only have 2 root causes, either insufficient heat transfer out of the rad, or too much heat transfer into the coolant. It's usually the former.
Is the T-stat tested good?
System full of clean water and some antifreeze, purged of air?
Is the radiator clean inside & out?
Is there good airflow into the rad?
Is there a shroud and good airflow out of the rad?
Is the FC working?
Fan belt correct size & tension?
 
New radiator and fan belt. Pulled the thermostat, no help. The coolant has been topped up. No airflow obstructions in or out. New cap. Pressure tested cooling system.
 
Removing the t-stat from an F-series completely opens the passageway to the radiator (yay) and uncovers the bypass (boo). Bypass is the large-ish hose from t-stat down to WP. Because the bypass is a short, unobstructed passage, most of the coolant will take that path (with no cooling), rather than going through the longer more restrictive radiator.

Install a known good (tested in a pot of boiling water, opens at 82*C) t-stat, w the correct gasket and top seal.
Then re-test.

Two other things to check:
The radiators are available as 2,3 or 4 row cores. Since you're in AZ it would be best to have a 4 row core. The 2row is marginal even in northern USA.
The gage and sender may not be accurate. Install a temporary aftermarket mechanical gage and duct tape it to the WS for test driving.
 
Agree w/FJ40jim--you also may be risking worse problems without a t-stat over time---the engine never makes it to operating temp--the pistons/rings/cylinders never expand as they should--result could be lowered compression and blowby into the crankcase, valves never get hot enough to close up the lash properly
 
I had the old radiator cleaned and patched, then put it in with a new thermostat. The thw water pump that I had planned to install wouldn't support the oil cooler so I'm retuning it. Filled and flushed the coolant and turned the key. So far, so good
 

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