LS4Lalonde

HELP I have a beautiful '93 Ls400 with 131,000 miles that recently overheats and overboils when driving for more than 15-20 minutes.

I've replaced the temperature sensor and the fan clutch.

I noticed the seal ring on the temperature sensor on the radiator resivior was not clamped so it couldn't build pressure. So I epoxy the seal and it works fine now. Ever since I sealed it, the coolant doesn't overboil as much, but the temp still rises to exteme red.

The water seems to be flowing. When I remove the bolt, I can physically see it running at decent pressure. PLEASE HELP. I will answer any questions. Very appreciated thank you.

Supralaju

Thermostat?Replace?

RA40

iTrader: (6)

When was the last time the coolant was flushed and thermostat changed?

LS4Lalonde

Stat was changed 3 months ago when this first started but have yet to do a flush. Planning on it Friday.

willhickey

iTrader: (1)

when mine was overboiling (if you mean blowing past the radiator cap) it was a leaking headgasket.. , it only takes one time to cause a hg to go or it may take a million id take it to a shop and have them test it..

emarknot

yup....sounds like a t-stat related problem.

well...was.

its very possible that the t-stat was replaced. but the system not properly bled.

left an air pocket...and now ?

so, after the very first time the car boiled and temp gauge went red...you should have replaced the t-stat again and check then....what was wrong.

instead of driving it repeatedly with the same results.

I would suggest finding a shop have them do a simple block test.
all it is is top off the coolant, do the test, check the color of the block test fluid. it starts off as blue, green to yellow is a headgasket.

I would have it towed if I were you.

some shops, will cover the cost of the tow and apply it to repairs. if no repairs are made, you just pay the tow bill and whatever checkout time.

LS4Lalonde

Wow. Alright. Thanks very much. Forgot to mention new ECU but that's regardless what you're talking about. THX!

LS4Lalonde

There is no white stuff in my oil. Blown head is not it. Just hot.

deanshark

If you can see the coolant flowing when you take the bolt out of the T-stat housing then that's good, the T-stat is open. But that also means there's not enough coolant in the system, (b/c you can take the bolt out) and that means,...air. When you say it goes in the red now, does it actually get hot and overheat now or is it just the gauge goes all the way up? If just the gauge then you have air. I'd say try filling the coolant, bleed the system through the bolt on the T-stat housing with the heat on high to open the heater valve. If you bring it to a shop and they pressure test it, that's what they will do and then hand you a bill.

cf3232

Run the car, if the return hose going to the radiator from the engine is not blazing hot to the touch when the temperature gauge in the car starts reading 3/4 of the way up then the thermostat is not opening, replace. If the return hose is really hot, then you have another issue that needs to be troubleshot further.

Skynet27

Have you checked the radiator cap yet. I have watched people replace almost
the entire cooling system and all that was bad was the radiator cap. If the cap is bad or weak it won't hold the pressure and will cause the coolant to boil at a lower temp. If you don't have a way to test it most auto part stores will, or just buy a new one there like 10 bucks.

LS4Lalonde

Ha! Yes, replaced that...do you think a flush could solve this? It may just be as simple as that.