Ved

Hey Guys,

I'm planning to do a cooling system flush on my C4 (1986 - L98). I bought the required specification coolant (concentrate - I plan to mix it by myself).

Does anyone know the fluid capacity of the system? (Edited post - I found an old manual - capacity is 13.29 L (14 qts.))

Is there anything I should look out for in particular?

Cheers,

Ved

c4cruiser

Certainly consider replacing the radiator hoses if they show any signs of cracking or dry rot. Same with the heater hoses. Does the car have the RPO KC4 oil cooler? There are a few rubber hoses that are part of that option. Just look for a tube coming off the oil filter boss and going into the block and another going around the front of the oil pan and up towards the right side exhaust manifold.

Can't hurt to replace the thermostat. A 180 'stat will work fine. Maybe the pressure cap too; look for any signs of tearing around the rubber seal.

To get all of the old coolant out, remove the knock sensor that is just in front of the starter. Chances are that there will be some brown sludge in the opening so you may have to use a rod to get coolant to come out.

If the old coolant looks good, close up everything and fill the system with water. Start the engine and get it to operating temp. Let it cool down, drain and refill and run the engine again. Then do it a 3rd time.
You can now fill with a 50-50 mix of coolant and distilled water. With the front of the car jacked up, start the engine and get temps to where the 'stat opens and the coolant level falls (leave the pressure cap off. Then raise the idle to around 1200 RPM and continue filling the radiator to the top of the opening. Replace the pressure cap.

You should remove the overflow container that is in the right-side headlight well. Clean it out as best you can and -re-install. I used some paint to make the "COLD" fill line to make it visible. Reinstall and add fresh coolant to the Cold line.

Ved

Many thanks for this detailed reply - I'll try to hit all the points you mentioned. A way to get much of the old coolant out (by also removing the knock sensor) was what I was particularly looking for. It doesn't have the KC4 oil cooler.

81c3

On the opposite side of the engine will be a pipe plug in the block.... remove that as well to get the crud and coolant out of that cylinder bank. Make sure you torque the knock sensor to 14 lb/ft.

Ved

Sounds good. I'll have a look for where this plug is! Thanks for the advice.