drs23

Long time lurker, first time thread starter.

Decided to start my own thread here as I was hijacking the OP's prior. Car is my wife's '97 LS400 that has developed several issues. The most important at this time being: NO HEAT!

After searching for days on here and following all this sound advise I was able to get a little warm air late last evening.

What I've done to this point is in my hijack posts here. Please reference as I posted what I've done to this point.

With what I posted in the other thread I will add that after following the steps that Vudugan posted I still had cold air. After reading about low coolant being a possible issue I checked the reservoir and it was dry. I filled it with universal Pre-dilluted coolant as that's all Oreilly had at the time. Drove it home and back to work yesterday and the reservoir was bone dry again. Filled it again. I started it and let it run with the cap off as to let it purge. The level would rise and fall and gurgle a little but still no heat at operating temp. Suddenly fluid erupted out of the reservoir. Shortly afterward (after doing the aforementioned steps in the other post) is when the air slowly got *warm* on MAX HOT. It's warm but not as hot as it should be.

A few things I've noticed:

The servo motor doesn't react to any movements in temp range input on the dash as it should. The heater only heated after I manually raised the lever on the bypass valve on the firewall.

I jumped the servo with a battery on the bench. The arm goes round and round. The purple wire is POWER-IN. I have power at the connector, car side which remains hot regardless of the temp setting on the dash. That, to me, doesn't make sense but is perhaps how it's supposed to be.

I've read about the A/C computer. Does the heater have it's own?

My next step is going to be doing a pressure test on the cooling system this afternoon when my buddy get off work and stops by with the pressure tester.

I'm thinking, guessing really that my problem lies in the electronics upstream since I can't get an apparently operating servo motor to operate the heater valve on the firewall and perhaps a clogged heater core.

Desperate for feedback, suggestions, ideas, questions...Anything really.

I know this was long winded, but thanks for looking.

steve2006

Have you checked the thermostat, if it has failed in the closed position the water circulation will be confined to the engine block, it is only when opened that full coolant flow occurs to the heater matrix, the fact that you had a blowback of coolant when trying to purge the system may also point to the thermostat as excess pressure will build up if the stat doesn't open as the coolant heats up.

drs23

Steve, yes I did. The first thing actually and should have mentioned that. I checked the one I took out with my heat gun and it opened too so it was a good unit and not the problem.

Thanks for the suggestion though.

timmy0tool

iTrader: (7)

from the other thread:
i believe the AC panel control pulses the voltage to get the servo to spin in increments as it needs it since we have auto climate controls. use a DMM and check the voltages at the connector going into the servo. that makes the most sense to me.

having an empty reservoir means that you introduced air into the system. when i did my water pump during my timing belt install, it look me a long time to bleed the coolant system. follow the DIY here:
http://www.lexls.com/tutorials/cooling/coolant.html

i went overboard when performed the bleeding steps to ensure no air was trapped in the system since the first time i had no heat as well.

drs23

Good news! Found where the coolant is going.

Bad news! The head gaskets are blown. Both of 'em. And after my buddy got finished I lost the heat that I was able to gain yesterday. Oh, well...easy come, easy go.

Ordering up all the parts tomorrow and will photo document the repair. Will probably jump in the week after the Super Bowl because I'm an NFL nut. I'm driving it right now so I'll just be chilly. Hopefully it'll warm up and be a no harm, no foul kinda thing.

drs23

Hate to quote myself, seems like I'm talking to, well, myself. Anyway...

Well it DID warm up again on the way to work the next A.M. and has been working since.

The top end parts are steadily trickling in from Rock Auto. Should still be on track to start the weekend after the Super Bowl.

billydpowe

iTrader: (1)

where in texas are you.. ?

LScowboyLS

this would be extraordinarily rare on LS400, especially both at once - about the same odds as winning the Powerball jackpot, so to say I am extremely skeptical of this diagnosis, would be putting it mildly!