Coolant and Heating System overhaul 3

Introduction to removal of water pump or thermostat on 1.9DG Engine

(article penned by CovKid) Thread link: http://forum.club8090.co.uk/viewtopic.php?f=37&t=130628

Firstly, although you could in theory just change the thermostat if its playing up, its better to do both if the condition of them is unknown. Likewise, if the pump bearings have gone requiring a pump swap, you should change the thermostat too. In general, this job should be approached as an overhaul as there is so much work involved, it makes little sense not to fit new. The 1.9 differs from the 2.1 which has a different thermostat housing. If I had to give this job a grade in terms of difficulty, I'd give it a 10 out of 10 for testing patience and requiring tools most peoiple won't have to hand to remove stubborb bolts - be prepared for that! DO NOT underestimate this job. You can be faced with all kinds of problems due to old or stuck bolts. Allow a couple of days (minimum) to do this. It took me a week!

The pump for these engines isn't that expensive compared to others.

Tools required: Socket set, bolt head remover kit. Everything to be honest, and replacement M8 allen bolts from a decent tool shop, not a store chain which charges the earth.

Diagnosing Pump Wear & and thermostat problems

Noise from bearings - can sound like tappets (or just squeal initially), constant need to adjust fanbelt culminating in sudden loss of water pressure, extreme needle movement on temperature guage (ie Max) and clouds of steam. When cool, jiggling the water pump pulley (to left of main pulley) and ideally with belt off, will cause a dribbling or gush of water on the ground. The pulley will probably feel loose if the bearings have gone.

Heres my comparison between a new and worn water pump: https://www.youtube.com/watch?v=LghNy400HzI

The thermostat may give a cold reading at the temperature guage due to it being partially stuck open or readings that don't fit the norm.

Removal Process

OK, lets get it out (pump & thermostat as one).

1. Disconnect battery

2. Pulley wheels. Both waterpump and main pulley will need to come off. To loosen their grip (don't remove any yet) you need to overtighten fan belt, jame a screwdriver betwwen alternator fan blades and its casing (don't poke in there too far) and use that as a way to hold everything tight while you free waterpump bolts. Use a big adjustable or socket if you can get in there, on the main pulley and give it a sharp smack with a hammer to loosen it. Pulley comes off easier than you think if you lever gently behind it from different angles with a cold chisel. Its only a push fit with a keyway slot.

3. There are essentially four allen bolts that need to come out, two on the pump which will test your patience, and another two on the right hand side of the engine thats hold the pipe that goes from left to right and has the dipstick held in place by a small jubille clip. There are three 13mm nuts holdinm the pump on, and there are those two thermostat bolts. Theres a short hose which joins bottom pipe to right of bottom pulley wheel - remove right-hand jubilee clip and loosen the hose's grip with a blunt-ish screwdriver.

Expect stuck thermostat bolts (or just one stuck one) which may even require the use of a milling machine to drill out any that won't budge. Its certainly worth trying to see if they will come undone whilst still fixed in the engine as you'll have more to push against but removal will probably require more than you expect. However, the thermostat housing is (I believe) obsolete so treat it like its made of gold. You may need to partially grind away parts of old pump (off the vehicle) in order to remove thermostat housing from pump - then deal with bolts. Soak all pump/thermostat bolt heads in plus-gas (not WD40) constantly, particularly when they start to move.

If you do get a stuck bolt in the housing but have at least seperated housing from pump, there are a few ways of tackling it off the vehicle including applying gentle heat to the casing around the bolt. You could try a 'damaged bolt remover kit' (mine came out that way) or you could centre-punch bolt head, clamp it on an upright drill and drill through, but its easy to go off centre doing that and you should view it as a complete last resort.

If the allen bolts are rounded out, you CAN use a bolt head remover kit on these too but its tight for room and you may need to come in slightly askew and with the tool sticking slightly outside the socket. An easy-out is a possibility but allen bolts are so shallow, I doubt you'll get any grip. I didn't want to chance it. Again, lots of plus-gas (not WD40) will help.

4. Unclip attached hoses - it becomes obvious which, and if metal pipes are undone or loose enough, you should be able to wriggle pump towards you, off its three studs, and remove the assembly by pulling to the left.

Reassembly

1. The thermostat will likely be corroded in and need a screwdriver or small cold chisel to get it out. Clean all casting faces very carefully, removing deposits and any old gaskets before fitting new thermostat.

2. You'll need instant gasket, using a thin smear at major joints for a watertight fit. Consider replacing short stubby hoses with new. Fairly sure they're 32mm ID. Silicon hose would be great.

3. You slide thermostat and pump (as one unit) on to the two metal pipes, leaving long metal pipe loosely bolted on the right to give you enough room to do this. Poke the one with the rubber hose attached back where it came from. Its annoying, but it will go once you have pipes and pump lined up with its three studs. Use plenty of instant gasket around pipe that has the small O-ring - you do not want to chance leaks there. That O-ring has a habit of staying out so check carefully that it DID go in with pipe and its not hanging out somewhere. Instant gasket will help it slide in and help seal it properly.

4. Fit NEW allen bolts. Do not put the old ones back please. You could fit slightly longer ones, screwing a 13mm nut on them so it sits underneath the head. This would then give you TWO ways to get them out in the future.

5. You'll need to fill and bleed the system with plain water to make sure it doesn't actually leak, before draining and refilling with the 50/50 antifreeze mix. If your engine got very hot, change the oil.

6. Do not push yourself and don't attempt this job in the hope you'll be at some camper meet the next day. You will be disappointed.

7. Just pay someone else to do it - its a horrible, nasty, contemptuous job and there will be plenty of moments when you'll contemplate removing the engine in desperation or even suicide. Its not nice.