Coolant Leak

During the process of putting parts back onto the car I reached a point where I was able to refill the coolant system.  With everything that had been taken apart and put back togegther I decided to take it slow refilling the coolant so that in the event of a leak occuring I would not have to try and collect the entire quantity of coolant.

Refilling was going pretty well but at what seemed about the halfway point I noticed a dropping starting to show near the front on the passenger side, nearby where the lower hose is to the radiator.  I poked my head underneath to see where it was coming from and saw that it was dropping down off of the alternator.  Not the radiator hose, more likely the thermostat housing or the water pump.  I was hoping for just a loose bolt since anything else would mean taking the timing belt off.

So I drained the coolant and took back off all of the components that had been installed up to the point that I had access to the thermostat housing.  I could now see that the leak was from the thermostat housing and not the water pump, that was good news.  The bad news was that all of the bolts were tight, so that wasn’t the problem, the timing belt was going to have to come off.  After getting the belt off a removing the thermostat cover I observed what looked like the o-ring not shaped as I’d suspect, I immediately concluded that I must have been careless putting the o-ring in and it was allowing the coolant to leak.  I careful put the the o-ring in place and put the thermostat and housing back on.  Buttoned things back up but took care only to do the minimum necessary to get another coolant check.

I started filling the coolant once more and again I had a leak dripping down at the same location as before.  Now I was thinking that maybe the plastic thermostat housing was damaged and decided that this time I would swap on the metal housing from my other motor.  So I pulled the front end apart once more, mind you it may sound like this was done quickly but taking care to drain the coolant and remove everything was taking a few hours each time, I wasn’t anxious to rush installing the timing belt, since I’d possibly managed to mess up installing the thermostat I was worried about being less than diligent about the timing belt and screwing it up.

This time when I got the thermostat housing off I looked carefully but could not find any obvious sign for what I’d done wrong or damage.  As I was looking at the parts it occurred to me that perhaps the o-ring was supposed to go on the outside of the thermostat.  I looked at the DIY guide that I was following and saw that it only said to put the thermostat and o-ring back onto the car.  I found another DIY guide and it too just said to put the parts back.  A while back I had purchased the JHM Timing Belt DIY DVD so I searched around and found it.  While watching the section that showed removing the o-ring I saw that the part was supposed to be on the outside of the thermostat, and I’d been putting it on the inside, doh!  So once more I put the thermostat back on, properly this time, and did the whole timing belt put all the parts back onto the car bit, and then I started filling the coolant for a third time.

Finally I was getting the system filled and it wasn’t leaking, that is until I started putting more fluid than I had before.  Now I was getting a leak from the backside of the engine, drivers side.  Aargh.  This was probably coming from the coolant hose that connects to the hard pipe at the back of the motor, I felt around behind the engine and sure enough I had either failed to connect it, or hadn’t connected it all the way, because it was leaking the fluid.  I pushed it on and got the reassuring click as it locked into place and the leaking stopped.

Some more coolant was added with no more signs of leakage.  Hopefully with the first long engine run when the system is pressurized no new leaks will appear.