miles56

my 1992 ls400 temperture gauge stay on c(cold)all the time and heat blow warm not hot plus gas mileage is poor car some time seem slugglish or slow.
some times the temperture gauge goes up one mark from c(cold) and I get better heat.My gas mileage is low since this temperature problem any help i would be thankful!!

trbo1stgen

Have you tried replacing your temp sensor? That's where I would start.

miles56

Thank you will replace.

NjRican

iTrader: (1)

I just had the same problem. It was my thermostat.

Bali26

Thermostat

etex

Thermostat first.

miles56

Thanks Guys !!!

zukikat

A tired thermostat that's weak and opening early from the pressure of the water pump or one that's actually become stuck partially or fully open will never get the cooling system or the engine engine up to optimum operating temperature so the ECU, continually thinking the car hasn't warmed up yet, continues running the car in the warm-up procedure mode that it never succeeds at which is making the transmission wait longer to up-shift and/or delaying the torque converter lock-in at cruising speeds, revving the engine higher trying to warm it up which then results in reduced fuel economy and mediocre heat as it never succeeds in fully warming the engine due to the bad thermostat causing increased/undesireable constant coolant flow and unregulated coolant temperatures.

Fuel economy also seems to drop and rise seasonally with the "winter mix" and "summer mix" of fuels, dropping noticeably in the winter months in most vehicles, but that wouldn't account for your mediocre heat which a dying thermostat definitely would cause.

So yeah, replace your thermostat first!
And while you're at it, you might also consider doing a coolant flush and some of the other maintenance I'm suspecting your car probably needs if the thermostat is so tired your car can't ever fully warm up...

Good Luck!

miles56

My Freind Zukikat words can't say enough to thank you for your time and consideration.

twofanman

^^^heck of a sentence

Bali26

I can say it in one breath

zukikat

LOL! Yeah, sorry... OCD SUCKS!!!

But I hope the info proves helpful to at least one person with that problem.

sethjon

Do the temp sensor and t-stat together. That should fix the problem.

Jin3198

I had the same issue, and the thermostat was stuck open. I replaced the coolant temp sensor while I was in the area.

GL!

sethjon

The most obvious is the tstat and easy to replace. But I think it might be your water temp sensor. If it is not working right it will tell the computer the engine is not warmed up no matter how far you drive. It will also give you low gas mileage.