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Cylinder block drain plug for coolant/antifreeze

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Author Post
iang   
Mon Oct 12 2015, 04:25pm
Member No: #9662
Joined: May 28 2009
Location: Cambs
Hi,
I have a 2008 1.6 HDi 92bhp C4 Hatchback owned from new with 60K miles on the clock.

I would like to change the coolant/ antifreeze as the car is 7.5 years old and still with the original coolant.

It is clear that Citroen use Glysantin G33 (bluish green colour) PSA part number 9735K4.

BASF, the manufacturers of Glysantin G33, state on their Glysantin website " If the vehicle is six years old or older, you need to change the coolant every three to four years".

"This is important, because the additives contained in the coolant gradually break down. Glysantin® still prevents the cooling water from freezing, but it can no longer be fully ensured that the customized additives will still be able to protect the cooling system from corrosion".


The Citroen guide regarding draining, filling & bleeding the cooling system, downloaded from this site, simply says “Drain the radiator by uncoupling the bottom hose” and "Drain the cylinder block, removing plug (1) (accessible via the top of the engine).”Refit the drain plug (1) (with an O-ring seal and a new clip).

It has taken me not an inconsiderable amount of time to find this elusive cylinder block drain plug as even after removing the wipers and windscreen scuttle, it is not visible from above and can be located by feel from above with only one hand.

It is not possible to see or access the cylinder block drain plug from below even after removing the under-body panel.

My question is has anybody successfully removed & refitted the cylinder block drain plug, and if so, how on earth did you manage it?
iang   
Sat Oct 15 2016, 09:47pm
Member No: #9662
Joined: May 28 2009
Location: Cambs
A year on and now at 64K miles I have answered my own question.

I have also found it’s not necessary to remove the illusive cylinder block drain plug to drain the engine side of the cooling system.

A far easier/quicker way is to purchase a cheap (£6.50) hand pump like this one from ebay - Click Here -
Here’s a YouTube video with a demo of a hand pump being used which gave me the idea in the first place --- - Click Here -

The suction end of the hand pump can be fed down the rubber hose leading from the coolant expansion tank.
This removes the same amount of coolant as removing the cylinder block drain plug which is about 2 litres.
I know this is just as effective as removing the cylinder block drain plug because after sucking out the coolant via the expansion tank, I successfully removed the cylinder block drain plug, and got almost no further coolant draining out -- perhaps a further 50cc!!

Removing the cylinder block drain plug is very difficult to do.
It takes a long time and a lot of patience. You have to remove it by feel as you can only see it with a multi-adjustable mirror on a 3 foot rod in combination with a bright LED torch. I used a head torch with a sliding beam focus.
It’s very easy for the rubber O ring or the plug to get lost behind the engine or break/loose the plastic clip that holds the plug in. Also, a minor point is it’s messy to drain this way as there is no clear path for the coolant to drain away from the cylinder block drain.
It took an age to re assemble the drain plug, O ring and clip, but I did manage with great difficulty!!

Draining the radiator side by uncoupling the lower hose I drained about 2.5 litres, so in total I drained just over 4.5 litres out of a supposed 6.5 litres dry fill (Citroens’ figures).
With 1 litre of coolant needed to pressurise the system for filling I found I needed a minimum of 5.5 litres of diluted coolant.
That meant buying 3 x 1 litre bottles of undiluted PSA coolant (Glysantin G33) and 3 litres of distilled/top-up water (wilko 1litre “splash top-up water” x 3 @ 75 p a bottle) to create 6 litres at 50/50 dilution.

There is a special funnel (a Citroen dealers’ tool) and adapter to fit onto the expansion tank to pressure fill the system which costs over £100 to buy!
The best solution is probably to purchase a universal design type by Sealey for about £35 -- cheapest might be here - Click Here -
This would also be useful for other modern cars when you want to change the coolant.

However, I made my own expansion tank adapter out of a Wilko everyday bath shower spray (£3.50) - Click Here - using the tap fitting end which I covered with a bike inner-tube acting as a 1mm sleeve to make it a tight leak proof fit in the expansion tank filler neck but soft enough so as not to damage the expansion tank filler neck. This is important as there is a rubber O ring on a projection inside the expansion tank cap which is designed to create a seal with the inner surface of the expansion tank’s filler neck. This seal would be compromised if the filler neck’s inner surface got pitted or damaged.
I made the rubber sleeve a bit longer than the tap fitting end so it could be used as a pull tab to help remove the adapter from the coolant expansion tank as it is a fairly tight fit so that it doesn’t leak.
I then took the cap from an Iceland Trederwen still spring water bottle - Click Here -
Removed the white slider valve from the Trederwen bottle cap (as it’s too fat in diameter)
Stretched over/slid on about 1.5 inches inch of smooth garden hose using v hot water to soften the garden hose to completely cover the nozzle to the hilt & project about 1 inch beyond the nozzle’s end.
This now made the bottle caps covered nozzle a tight waterproof push/click fit inside the shower tap fitting.
The bottom can then be cut out of any standard 1.5 litre PET drinks bottle with a 24mm diameter neck to act as a screw-on header-funnel.
(The Trederwen bottle caps are the best as the thread is slightly deeper than other similar types, which means that a rubber O ring can be put inside the cap’s sealing recess for a completely watertight seal with any standard 24mm diameter PET bottle neck and still leave plenty of thread available to screw onto the bottle neck for a really secure fit.)

This adapter works very well but not worth the effort to make unless you enjoy making things!
Also my adapter is only likely to be useful for my C4 or maybe other PSA cars.

I also purchased some clear PVC tube from ebay which fitted tightly around the bleed valves after removing the caps. It is 7mm inner diameter/10mm outer diameter thick wall tubing so it’s easy to push on the valve stems & creates a waterproof fit, and is great for bleeding the system, whilst not having coolant leaking everywhere.
- Click Here -
I bought 4 metres (and received 424 cm) for £5.29 and cut it into two lengths 168cm & 256cm.
The short length to attach to the thermostat housing bleed valve and the longer length to attach to the heater matrix bleed valve.

Here is the step by step procedure that worked for me for draining filling & bleeding the coolant of my 1.6 HDI 92bhp Mark1 C4.
Do at your own risk.

Coolant is BASF Glysantin G33 PSA part no 9735K4
Can also use Glysantin G30 (both 50/50 dilution)
I needed 3 litres of concentrated/6 litres of diluted

I got 1 litre bottles of top-up water from Wilko @ 75p each x 3

Turn the car’s heater full on and leave like this for the whole procedure!!

Remove the battery and the 1st two sections of air pipe from the air inlet horn. This is to get access to the heater matrix bleed valve.

I drove the front of the car up onto my 4” high rubber ramps to make it easier to remove the under-body protection plates

Remove the under body protection plates (in hindsight it may only be necessary to remove the rear under-body protection plate).

Unscrew & remove the coolant/ antifreeze expansion tank cap.

Position a bowl under the lower radiation hose / lower radiator outlet bearing in mind that when the hose is removed the coolant will flow towards the rear of the car from the radiator, but also towards the front of the car from the hose!!!
Unscrew the jubilee clip on the lower radiator hose & remove the hose from the radiator. This will drain the coolant from the radiator half of the cooling system.

Pump this old drained coolant from the bowl into a waste container such as an old large milk container (6 pint/3+ litre) which has volume markings so you can measure fairly accurately what has drained.
N.B. take care not to pump too hard & to make sure the pump’s outlet tube is held securely in position inside the container so it doesn’t fly out of the container and spray everywhere especially when getting to the end, when the pump will suck air through and may shoot the end of the pump’s outlet hose out of the container.
You should find you have drained about 2.5 litres in total from the radiator half of the cooling system.

Undo the bleed cap (same as a tyre Schrader valve cap) on the thermostat housing and attach the shorter length clear PVC hose (7mm inner diameter/10mm outer diameter) to the valve stem and pass through the bonnet catch loop about 3 foot above which holds the tube high enough so the coolant will not flow out now or later when refilling the system.

Undo the bleed cap on the heater matrix at the engine bay bulk-head (will need an led torch to see it) and attach the longer length clear PVC hose (7mm inner diameter/10mm outer diameter) and position as above.

If possible, feed the suction tube from a hand pump down the pipe through the coolant expansion tank.
Alternatively, and probably more effective, is to remove the rubber hose from bottom of the expansion tank and feed the suction tube from a hand pump directly down the hose as far as possible to get to the lower level of the engine.
N.B. It may be necessary to remove the expansion tank from its engine bay fixings (undo one bolt) to be able to remove the expansion’s tank’s lower hose.
There is a spring clip to hold the hose tightly onto the expansion tank outlet which is tricky to slide off. I used mini mole grips.

Place the outflow tube from the hand pump in a waste container such as an old large milk container (6 pint/3+ litre) which has volume markings so you can measure fairly accurately what you remove.
Suck out the coolant from the engine side of the system with the hand pump.
You should find you have sucked out about 2 litres of old coolant in total from the engine side of the cooling system.
Doing it this way saves removing the cylinder block drain plug which is very difficult to do. It takes a long time and a lot of patience. (You have to do by feel as you can only see with a multi-adjustable mirror on a 3 foot rod in combination with a bright torch. I used an LED head torch with a sliding beam focus.
It’s very easy for the rubber O ring or the plug to get lost behind the engine or break/loose the plastic clip that holds the plug in. Also, a minor point is it’s messy to drain this way as there is no clear path for the coolant to drain away from the cylinder block drain.
Finally, it’s unnecessary as you can drain the cylinder block side of the cooling system from the expansion tank side!!
I did succeed in removing the cylinder block drain plug after sucking out the engine side coolant via the expansion tank hose and got almost no extra coolant out -- perhaps a further 50cc!!
It took an age to re assemble the drain plug, O ring and clip, but I did manage with great difficulty!!

In total, this removes a little over 4.5 litres of coolant from the cooling system out of a supposed 6.5 litres dry fill capacity.

Re attach the lower radiator hose & tighten the jubilee clip.

Re attach the expansion tank hose and reposition the spring clip (I used mini mole grips) and refit the expansion tank to the engine bay (one bolt).

Fit a 1.5 litre or 2 litre capacity pressure filling/header funnel into the expansion tank filler creating a watertight seal.

Place the free ends of the PVC bleed hoses into the top of the funnel

Fill the system, bearing in mind it will need about 4.5 litres to replace the coolant which has been removed.

When the system has filled as much as possible and with about a litre head of coolant in the expansion tank header funnel, start the engine, making sure the car’s heater is on max.

You should see coolant flowing along the bleed pipe from the thermostat housing back into the expansion tank funnel, with any air in the system coming out along the pipe.

The free end of the heater matrix bleed tube can be put into the BOTTOM of a CLEAN clear container (a 4 pint milk container will do nicely) and the container lowered so that the coolant will flow into it.
When the container starts to get about a pint in it, it can be raised above the engine, and the coolant will flow rapidly from the container, back into the cooling system!
This can be repeated once or twice until there is no air in the bleed tube, but I found once was more than enough to bleed the heater.
The tube can be put back through the bonnet loop with the free end back in the expansion tank funnel.

The engine can be run at about 1500rpm like this to expel as much air as possible, which will soon bleed out.
Stop the engine after about 5 or 10 minutes or if you are really keen you can leave the engine running until it reaches its first cooling cycle and the radiator fan cuts in and out.
Take care with the clear PVC hoses as they get much softer, floppier & pliable with the heat.

Take off the clear PVC bleed tubes and quickly cap the 2 bleed valves.
Suck out the excess new coolant from the cola funnel (or plug the neck of the cola funnel with a stopper on a rod from above) and drain/pump the excess coolant into a clean container for future topping up.

If the expansion tank reservoir is rather full, suck out a little with the pump, and screw on the expansion tank cap.

Run the engine again until the radiator fan cuts in & out and top up if necessary.

I hope this step by step guide is helpful enough to give other C4 owners the information and confidence to successfully have a go at a thorough coolant change for their C4’s.
3 User said Thank You to iang for this Post :
 Grumpy GrandPa (16 Oct 2016 : 06:07) , DeuxChevaux (19 Mar 2017 : 11:01) , macjake (20 Sep 2017 : 18:06)
 

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