Help--Yellow Radiator light

[Lotusviper]

Can someone tell me why the yellow radiator light keeps going on? Temp gauge is in the normal range. It usually happens when the A/C is on. Any help would be appreciated!

[lotusguy]

Hi,

Are your fans operating with the AC on? You may have a relay or other electrical issue to solve. Happy Motoring! Jim'85TE

[madmike]

Perhaps I'm talking out my ass (wouldn't be the first time) but you should check the coolant level in your chargecooler resevoir. I had a leak in my CC pump, and the light came on whenever it got low. Rebuilt the pump, problem sorted.

(If it was your CC, your temp gauges would still read normal temps)

[kmaier]

The light is a dual-function indicator; Engine Coolant Temperature and Coolant Level. So, check to make sure that your coolant level is up as it could be indicating low coolant via the sensor in the overflow tank (note earlier cars have two overflow tanks, engine-coolant and charge-cooler coolant). Or it could be caused by high temperature of engine coolant. As Jim suggested, check to be sure all 3 fans are running when the A/C is engaged (just look underneath). If everything appears okay, you may have a bad sensor for coolant level in the overflow tank(s). Also, when was the coolant last changed? Hope this helps.

Regards, KM
2000 V8

[lotusman]

A similar thing was happening to my light on my '89 non-SE(ALWAYS good to say what year and type Lotus you have). It would come on when the temp would read 80 C but go out whenever I accelerated. Draining and removing the expansion tank, see my post on its removal, I say a large flat piece of rust that would probably slide over or sucked over the tank outlet which is also between the level sensor and the pick up. When accelerating it probably slide out of the way but would be sucked back to the opening when at constant speed. This opening allows the turbo coolant to return to the system. No damage I believe. I am having a new tank made in aluminum.

But a question. How does one do the CLR cleaning of the system? And particularly to the radiator. I saw several large flakes of rust in the lines so I will need to backflush the system instead of letting the pump circulate the system in the forward direction.

Lotusman
'89 non-SE

[Dr.Hess]

Not to hijack the thread, but... my '89 non SE is overheating in traffic or when driving slow with the AC on. Fans all working, etc. I am thinking that the radiator needs some service (rodding or boiling out or replaceing). I have tried to run radiator cleaner (Prestone brand) through other vehicles I own/have owned and then back flush the system, but have never, ever, successfully had one stop overheating from such treatment. So, what's with the CLR? The stuff from Wal-Mart, as advertised by Paul Harvey? People running this stuff through their systems and back flushing? I hate to experiment with such stuff on my Esprit.

I just really don't want to have to take the radiator out.

Dr.Hess

[kmaier]

According to the website FAQ attached below, I wouldn't recommend using it as a flushing additive. Certainly not for the radiator and defintely not with anything aluminum.

https://www.ontvstore.com/houseware/CLR-Calcium-Lime-Rust-Remover.cfm

If you need to remove the radiator, just do it. I recently took the entire front end down as my radiator developed a slight seeping on the end-tank solder seam. It's not that bad of a job... just somewhat involved.

Regards, KM
2000 V8

[Dr.Hess]

Yeah, looks like CLR is bad stuff for AL. I just need to get after it and fix the radiator. It is gonna cut into my Seven building time.



Dr.Hess

[cnh1990]

Do not run CLR through the system.
The CLR treatment we have been talking about is confined to the metal header tank with the tank disconnected from the system on SE cars.

To clean the radiator drop it and have it boiled or re-cored.

The coolant light coming on could be the header tank sensor. There is a single wire with a spade tip on it that hooks up to the sensor.

Sometimes corrosion, bad connection, or crap on the sensor on the inside will cause a light to show up on the dash on our cars.

Calvin 90 SE

[Lotusviper]

The car is a '94 S4. ( Thanks for hint Lotusguy) I just had the coolant changed and it turns out that it was an airpocket in the system. Therefore I had to fill the reserve twice because of it. All fans are working and since then, I have had no problems.