I have a 99 rs 420a when I bought the car I replaced all the gaskets from top too bottom,also have replaced thermostat and radiator cap due to air getting in the system and causing coolant to bubble out into the overflow tank, that was about 3 months ago..
Tonight made a 50 mile trip when I shut the car off I heard the sound of the coolant bubbleing again into the overflow tank, I checked the fluid and it was a little low, topped it off and made the trip back home and no more bubbling but still hot under the hood any input would be great maybe how to keep it cooler under the hood?
Have a short ram intake with a flex tube from the fog light roted under the hood and a breather valve on the valve cover no new headers yet heard that might make a dif..
Thanks

I had a similar issue a couple of years ago and found that it was my radiator fan that stopped functioning. I would start the car, pop the hood, and let the engine run 5-10 minutes. If your radiator fan doesn't turn on by this time, I would unplug the radiator fan and connect jumper wire to the fan connector and battery. If you still don't have power to the fan at this point then then problem is the fan. If the fan does have power then the problem may be your coolant temp sensor.

I would also like to add that if you put too much coolant in the reservoir, say above the full line coolant will definitely bubble out.

Whoever owned the car before me wired the fans to both come on when you turn the ac switch on in the car so I keep it on at least low to make sure I got a new temp sending unit just haven't got it in yet.. Doing that this afternoon ill let you know if it keeps happing

Sounds like you may be leaking exhaust into your coolant, and looking at a bad head gasket... may want to test your coolant.


- J

Looks good so farhasnt happened yet not near as much pressure on the hoses no boiling over and the temp gauge now fluctuates and doesn't stay a a solid temp so I know it's reading but will post again if it keeps boilin into the overflow thanks

Well thanks to the two guys with input it's been a few days now and no problems so I'm about to start a new project

Good luck :)
- J