sc400 slowly overheating

[stevechumo]

Does your fan have a shroud? I don't think your temp sensor is wrong, but you can install an aftermarket temp sensor (connecting to the block) as a secondary reading device.

I'm suspecting about the head gaskets.

 

[spf_lexus]

I hope its not HG's but it does not burn coolant, the coolant level NEVER drops, nothing leaks. when the sun starts to go down and the temps drop a bit I never see the temp gauge move from half way. Tonight I will change my oil to make sure there isnt any coolant mixed in.

I just put in a new OEM t-stat and to my surprise I opened the coolant neck and there was no t-stat to be found! I have not test driven since putting ANY t-stat back in but it should not matter.

I just ordered a new radiator and should have it monday/tuesday. I am almost 100% sure I am running an OEM 20yr old rad. It could just be scaled up inside allowing flow... but no heat transfer. My last plan until the rad gets here is to swap my dual 14" elec. fans from LS470 to double my airflow. Also, I dont have my radiator top shroud, would this make a difference at all?

 

[spf_lexus]

Well this was my first oil change since I bought this car and once drained into a clear tupperware container I held it up to the light and I couldn't find any signs of cross contamination. Whew. The oil looked dark with a hint of gold still there so I dont think the motor was totally neglected. I decided to replace everything my LS had under its hood. Coils, caps, rotors, wires, iridium plugs + her 19's + supra BBK, seats, and maybe the blower if it passes CR test. I know, I feel guilty using it like a local napa store but I need this ride reliable for my fearful california-to-colorado trip next week.

Now im wondering if I should go the last 10 yards and just replace the pump just to keep it out of mind? Broken down in the mohave desert during August in the middle of no where isnt a fun thought...

 

[stevechumo]

.... Also, I dont have my radiator top shroud, would this make a difference at all?

Yep. It'll make a big difference. I've seen that on my friend's car. He took out the fan shroud and it almost overheated. Putting it back in cured the problem.

 

[spf_lexus]

Well its still 90 degrees outside and I just drove for an hour straight with the only changes being an OEM toyota t-stat and the **TOP** radiator shroud. The small thin plastic wedge that seals the gap up top. City streets, freeway, mountain roads... I put it through everything and I never got the needle to even hit the exact 1/2 way mark... just a hair below middle which is the ideal temperature. Anyway after cancelling out the blown HG and t-stat scenarios I can only conclude that my radiator is on its way out.

Just on a side note this exhaust setup is PERFECT. I can lay off the gas and the entire engine sounds like it shut off (prius style) so cruising by cops is no sweat. When you mash it to WOT it sounds almost exotic. I wouldn't change a thing if I had a 2nd chance. Only problem is my feet! i have no carpet or sound deadening whatsoever and on a hot day my sandles feel like their melting to the floor. I can see heat radiating from the floor boards but its worth it.

 

[Zuffen]

Easy fix for the heat.

Don't wear sandles and they won't melt!

 

[zen]

its has all the symptoms of shagged rad..ie what mine had..faster/harder you go worse it gets..fine in traffic

i replaced mine (ok with a hand made extra big one) all sorted...
the fan shroud makes no difference to the cooling at all untill the fans are on..after all the air is going through rad wether it there or not when you are moving..fans on makes a big/all the difference....

 

[spf_lexus]

Easy fix for the heat.

Don't wear sandles and they won't melt!

I plan to attach some heat blanket material on the underside of the floor boards just to take the edge off. Im used to seeing the heat radiating from the hood, not the floors haha.

its has all the symptoms of shagged rad..ie what mine had..faster/harder you go worse it gets..fine in traffic

i replaced mine (ok with a hand made extra big one) all sorted...
the fan shroud makes no difference to the cooling at all untill the fans are on..after all the air is going through rad wether it there or not when you are moving..fans on makes a big/all the difference....

Yeah that sounds exactly like mine but lately the temps havent been rising whatsoever. It may have been an air pocket or a chunk of crud that broke loose. I should get my repalcement radiator today and I plan to swap from a single 16 incher to dual 14 inchers just to be safe.

 

[Zuffen]

A single 16" fan with a good shroud should cool it easilly.

Do a google search on fans and shrouds as the fan needs to be placed fairly accurately withing the shroud to get the best from it.

A vehicle with an inadaquate radiator can get by with a good fan/shroud whilst a good radiator can't get by without a good/fan shroud arrangement.

Get your fan right and your problems are gone.

 

[stevechumo]

Fan shroud only becomes effective when the fan is on and that's correct. However, try to remove the fan shroud and you'll see how it'll effect the cooling.