Engine coolant drain

[brummie]

Hi guys, I need some help. I am two years into my S2 Cab and what a joy it is. I want to change the coolant and I have drained down from the radiator plastic drain plug. So far so good, but I have only about half of the coolant out. Is there a drain on the block, and if so where. " Clarks " show it on the offside of the block but I suspect that the info is for earlier versions, or is there another way ?

 

[bmnelsc]

The S2 has NO drains on the block. AFAIK the technique is to remove the lower rad hose at the radiator and drain that way. There is a threaded plug on the top of the engine by the hose that must be loosened to allow air to get behind the water in the engine and facilitate draining. When re-filling, this plug must be loosened to allow air to escape out the top of the engine while coolant is being introduced. Once you seem to be full, you leave the top plug loose (don't remove it completely) to allow air to escape while running the engine. At first you will hear some air fizzing out eventually replaced by a trickle of coolant (if more than a trickle then you should tighten your plug up a little). Add coolant as required. Note that you should have your heater control set to full hot to ensure the coolant in the heater core is also drained/replaced. You can also jack up the rear of the car to facilitate draining and then raise the front of the car to facilitate filling but the threaded plug on the engine seems to be the high point in the cooling circuit when the car is on its wheels.

The preferred method for changing coolant on these is to use a vacuum assist machine that draws out the air while sucking the coolant into the engine. Otherwise using the bleed screw (the plug) on top of the engine is only way to release trapped air. It is said that it may take several rounds of "bleeding" to get all the air out. Unfortunately this trapped air is sitting in the head where it causes the most harm so thorough bleeding is a must. I checked for air three times after my last coolant change (slowly loosen the top plug while the engine is running listening for the hiss of escaping air until you get a trickle of coolant then tighten it up again) and all seemed OK so using the bleed screw works.

 

[brummie]

Good morning Bruce, thanks for such a comprehensive reply. I think this should be archived to " technical" so that it is easily found by all. Many thanks John Clayburn. 90 S2 Cab "Candy Apple "[] red

 

[944 man]

Do you mean Zyclamen Red Pearl? 'candy apple' not a Porsche colour.

You will probably think that I am being difficult, but I am very much against just making stuff up. The 944 field is now full of ignorantly made-up rubbish which is now becoming the norm, leaving actual knowledge out in the cold.