Water leak

Hi all,

I changed the coolant on my Mk1 GTi Cabby at the weekend, drained the coolant by removing the bottom radiator hose as usual.  However I noticed a small coolant puddle under the car this morning.  On closer inspection, the leak is between the thermostat housing and the water pump.  So, naturally I looked at tightening the two housing bolts, but it looks as though some ham-fisted previous owner has stripped the thread on one of the bolts!  My removing the bottom hose must have disturbed it.  I can tighten it so far, but I'm obviously not too happy about driving around with a potential failure of the housing bolts.  My question is, does this require a new water pump, or is the threaded hole in the pump long enough to fit a longer bolt through and secure it on the other side with a nut?

What type of housing do you have, metal or a plastic one?
if it's the plastic type the leak may be from the housing so my be worth fitting a new one and you may be lucky and it bolts threads are stripped not the water pump if so fit some new bolts. Have you removed the bolts to check there condition, you may be able to remove one at a time so not to disturb the housing
You will need to fit a new rubber O ring seal if you remove the housing, it's worth checking that a new one comes with the seal.

http://www.ebay.co.uk/itm/THERMOSTAT-HOUSING-NEW-1-6-1-8-1-9-2-0-TRANSPORTER-T4-GOLF-MK1-SCIROCCO-CADDY-/351446609577?pt=LH_DefaultDomain_3&fits=Model%3AGolf&hash=item51d3d9aea9

When you change your coolant it's best to remove the thermostat to drain the water from the engine as just taking the hose off from the bottom of the radiator will only drain the radiator.

O ring gasket/seal.
http://www.eurocarparts.com/thermostat-housings-gasket

 

OK, thanks.  The housing is the plastic type.  I will try fitting some new bolts tomorrow (I assume these are M6?), hopefully its the bolts that are stripped and not the water pump's threaded holes.  Would be good to know if I can just use a longer bolt than standard though and stick a nut on the back.  Anyone know if this is possible?

I took my thermostat out today as I'm taking the engine out of my car I had a look, the bolt at the back near the engine you can go as long as you like as it goes through the water pump housing the bolt as the front will only go 20mm till it stops.

Some picture for you.
Rear bolt hole

Front bolt hole

Lengh of standard bolt


You can have a problem getting the housing past this bit of the engine block but with a bit of twisting and wobbling it will come out.
When I drained just the radiator I got 3 litres of antifreeze out and when I took the thermostat out a further 2 litres came out that why its a good idea to drain the engine and well as the radiator when changing the coolant.

 

That's excellent, thanks.  I used a new M6x30 stainless bolt in the end, there was enough thread left at the top of the hole in the pump to tighten up the housing, which seemed to work just fine.  There would be plenty of room to put a nut on the back if needed, although the pump would need to be out to do this.  There is still the merest hint of a leak from the housing gasket, it looks as though someone has had several attempts to unsuccessfully bodge a repair in the past.  The housing looks a bit worse for wear, so I think I'll grab a new one from eBay with a new seal and see how that gets on.

I also have a leak from the thermostat housing. The trouble with the plastic ones is that they deform once fitted as I recently found out. For the sake of a few £ it's well worth replacing the housing and seal. 

New housing and/or Heli-coil works!