Hi guys, 

 

I picked up a Mk2 breadvan the other day. From what i gather from the guy I bought it off it'd been off the road for a little bit.

I looked underneath today and there was a little puddle and from what I can see and have researched it is the O-ring on the thermostat housing that is coming from the engine.

I've found two different size O-rings on parts websites but neither say which size fits the one I want. 

One has an inner diameter of 43mm and a thickness of 3mm, the other is an inner diameter of 50mm and a thickness of 4mm.

I'd rather not take her apart to find out because the leak isn't that bad right now so if anybody knows what size I'm looking for that would be great.

I've attached an image of the system, the blue circle is where its leaking from.

And if anyone knows how difficult it is to do this that would be great too.

Or even if anybody reckons I'm completely off with what's wrong that would be great too.

Thanks, Dan

which year ?

engine code or size ?

 

Plastic or metal housing to block?

If plastic you might find the housing has a split from over tightening.

My metal housing has a flat gasket to block I reckon.

 

The thermostat valve itself is in the bent elbow shaped cover below your blue circle that one of the 4 jubilee clips number 19 attaches to from radiator bottom outlet and has its own o-ring. (also different sizes).

 

 

Edited 8 July, 20206 yr by dvderlm

It's a reasonably doable job for home mechanic.

 

Raise the car on ramps or axle stands.

Drain the coolant by removing bottom radiator hose and catching it in a bucket or tub below the car.

Move heater controls to max.

 

 

Keep it away from paintwork as you do this. Antirollbar seems to catch it on mine.

Rinse off spills with fresh water. It is poisonous to cats who are attracted by sweetness and to people.

Cover the container if you might leave it unattended.

 

 

The bottom hose jubilee clip needs long large screwdriver.

The hose might split if very perished, the rad outlet is barbed so pulling hose off needs patience, 

Be prepared to get a new bottom hose and clips.

 

Unbolt the thermostat housing.

Fit new o-ring.

 

(or the whole housing if on inspection there is a crack, with new clips as necessary. I've not found other hoses to be as bad as the bottom hose 

for longevity, but you never know)

 

Reverse what you did to refit.

Either filter the coolant and look for rust then reuse if good and not old. It stops rust as well as preventing freezing/boiling.

Lifespan is perhaps 5 years?

or get new blue coolant and distilled water (or ready mixed like Prestone).

May as well reverse flush with mains water from a hose before refilling.

 

Dispose of old coolant at recycling centre.

Capacity is 3.5 litres from memory, probably 50/50 mix. 

 

Refill system through reservoir using a funnel, squeezing pipes to move fluid around and remove bubbles from the top of radiator.

Finally loosen heater bleed screw below scuttle panel and wait until bubbles stop.

Keep squeezing and adding.

When car lowered check coolant is at max level. top up if needed.

Start car so pump circulates. Turn off. Check for drips.

If none restart and let engine reach operating temp until fan turns on and off again

faster with bonnet closed.

 

Watch the temp gauge.

Look whether coolant has dropped.

Recheck for drips.

 

 

Edited 8 July, 20206 yr by dvderlm

very very common for that plastic housing to have a crack in it , if i was taking it apart i would fit a new one regardless

 

can get one for 10-15 with the seals 

Thanks for responding guys, its a 1043cc with a plastic housing. I'll getting something order and hopefully fit it over the weekend, I've seen one in stock at a local shop.