1Uzfe getting hot only at idle

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Kentucky

New Member
Messages
3
I have a1UZFE (non VVti) in a 1934 coupe Hotrod. I’ve had it for 18 years trouble free . About 6 weeks ago it was idling for about 1/2 hour and it got hot. I trailered it back to my workshop to be safe and replaced ;

Water pump and timing belt etc
Thermostat
Radiator was sent away and split and cleaned
New 9 inch thermo fans by two
The problem I have is it all works perfectly and gauge sits on 85*C whilst driving all day ( 82*C thermo which opens as it should ) BUT it will idle at 85*C for about 10/15 mins and then the temp will start rising slowly up to about 108*C over another 10/15 mins .If I go for a drive around the block , within 1 klm the temp will come down to about 85*C straight away. Any thoughts please as I have replaced everything I can think of . Cheers
 

numbchux

Member
Messages
100
Location
Duluth, Minnesota
Generally speaking, that's an airflow issue.

Are your fans coming on? Are the new ones capable of adequate volume (maybe the old ones were wearing out, new one is not adequate...)? Pushing or pulling? If pulling, are they shrouded? Do you have A/C? If so, is the condenser clean? Anything else blocking air flow?
 

blackdemon_tt

Member
Messages
52
Sounds like a clutch fan type of issue. My Tundra had a similar situation at the border in Mexicali going back to the U.S. and it was like 110 degrees.. I was sitting for 10 to 15 minutes in 1 spot at a time with the AC on at 3/4 way full blast... I noticed my temperature gauge started moving up at the same time that my AC stopped working, so I dropped it to Neutral and the temperature went down some, but then my transmission temperature gauge started doing the same.. I then learned if I had revved it to 2k the fan clutch would kick in and cool everything down.

Now I'm not saying you have a clutch fan, just comparing a sorta similar situation... maybe it's the thermostat starting to stick and go bad?
 

Kentucky

New Member
Messages
3
Generally speaking, that's an airflow issue.

Are your fans coming on? Are the new ones capable of adequate volume (maybe the old ones were wearing out, new one is not adequate...)? Pushing or pulling? If pulling, are they shrouded? Do you have A/C? If so, is the condenser clean? Anything else blocking air flow?
Fans wired up to ignition so on all the time . Old ones were 18 years old so replaced with 2x 9” fans capable of 1800 cfm each. They are pushing as being a ‘34 Hotrod there is no room behind the radiator. Condenser perfect and radiator clean. I does idle at 1300 rpm which I will address but I can’t see that being a problem. There is nothing else blocking air flow as has been the same for 18 years
 

Kentucky

New Member
Messages
3
Sounds like a clutch fan type of issue. My Tundra had a similar situation at the border in Mexicali going back to the U.S. and it was like 110 degrees.. I was sitting for 10 to 15 minutes in 1 spot at a time with the AC on at 3/4 way full blast... I noticed my temperature gauge started moving up at the same time that my AC stopped working, so I dropped it to Neutral and the temperature went down some, but then my transmission temperature gauge started doing the same.. I then learned if I had revved it to 2k the fan clutch would kick in and cool everything down.

Now I'm not saying you have a clutch fan, just comparing a sorta similar situation... maybe it's the thermostat starting to stick and go bad?
Cheers for your reply as this has me really baffled. Thermo fans x 2 on all the time but you have given me some insight into something else to try . It is an auto with the auto cooler pipes plumbed into the bottom radiator tank... I might disconnect them from the radiator temporarily and see what happens.. cheers mate
 

Zuffen

Super Moderator
Staff member
Messages
5,515
Location
Sydney, Australia
1800 CFM each, but not in a pusher environment. A fan won't move anywhere as much air pushing as pulling, particularly with a good functional shroud,

The high idle won't help it one bit.

I know room is at a premium but I would try and fit an external oil cooler for the trans plus an oil cooler for the engine.

Have you thought about a second radiator in an inconspicuous place. I run 2 radiators in an OT LS3 custom I have. Works a treat.

Another point get the fans as close to the radiator as possible and even try putting a fence around the front/side of the radiator so the air your pumping isn't escaping around the sides of the radiator.
 
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