Water Pump Leak - Help Please

[4129R]

Having just spent 2 days taking the engine out and replacing the water pump shaft and bearings, water is still pouring out of the hole behind the pump pulley driven by the belt from the crank. 

Does this mean there is a leak on the "O" ring where the 3" round casting is set in the pulley casing?

Having spent a very long time carefully pulling this apart, rebuilding it, and putting the engine back in, I need to know what I have to do to stop this leak. It is literally pouring out of that little hole.

[Pfreen]

I do not think it is the large oring leaking.  If that leaks, the water goes in the oil.
It is either the rubber seal seal to the front cover that is leaking or the rotating ceramic seal.  Or, I guess he housing could be cracked. 
At least you didn't put the engine back in the car.  I pressure check an engine before reinstalling.

[4129R]

I do not think it is the large oring leaking.  If that leaks, the water goes in the oil.
It is either the rubber seal seal to the front cover that is leaking or the rotating ceramic seal.  Or, I guess he housing could be cracked. 
At least you didn't put the engine back in the car.  I pressure check an engine before reinstalling.

The engine is in the car. The ceramic seal is new. I put the whole kit in except 1 of the 2 large O rings.

[jbcollier]

Water pumps have to be assembled very carefully.  It is very easy to damage the seal if not done properly.  If coolant is "pouring" out the drain hole, it's the seal for sure.

[EuropaTC]

Not what you want to hear but sadly I'd go with the mechanical seal as well.

You could try rotating it on the off chance it's not seated properly but the first time I had a pump failure was due to a split in that seal and it was a steady stream coming from the weep hole.

Brian

[Pfreen]

I do not think it is the large oring leaking.  If that leaks, the water goes in the oil.
It is either the rubber seal seal to the front cover that is leaking or the rotating ceramic seal.  Or, I guess he housing could be cracked. 
At least you didn't put the engine back in the car.  I pressure check an engine before reinstalling.

The engine is in the car. The ceramic seal is new. I put the whole kit in except 1 of the 2 large O rings.

I am sorry you put the engine back in the car.  I suggest you cobble up some hose caps and pressure test on the stand at 7 psi next time.
So what happened to the 2nd large O ring?  These seals are the most important because they prevent coolant from going into the timing case and then the sump.

[4129R]

The engine is out again. It took about 2h45m to get it out. Tomorrow I take the pump off to see how water can come out of that weep hole.

Only 1 large O ring was showing when I took the pump apart. I presume I will need a puller to get the circular casting out of the casing to get at the second large O ring.

[jbcollier]

If you are not sure, take the assembly to a Lotus specialist and have them overhaul it.  It's not hard but it is careful, methodical work.  You need the right amount of preload on the seal and the correct impeller gap for starters.

[Dilkris]

Out of interest - have you managed to do this with the head still on?? Or have I missed a bit here and you have a cartridge type water pump assembly?   

[4129R]

I have managed to take the pump off with the head still in place.

When fitting the pump, I use the 5/16 bolts to guide the pump back in place, and as the gap narrows to about 2mm, I inject silicone sealant around the perimeter to make an oil proof seal.

As you say, the large O ring seems to stop any water leaking into the oil.

I will ring QED Engineering to see why the water is pouring out of the weep hole. They are Lotus TC engine experts, and this must be a common problem.

[EuropaTC]

I have managed to take the pump off with the head still in place.

Impressive. The S1 Elan manual says you can do the pump with the head still in place but from the S3 onwards (don't know about S2) it says head & sump removal.

How did you get around the wear plate on the front cover, the bit that protrudes into the head ?  Is there enough wiggle room to rotate it round and out ?

Brian

[4129R]

I have managed to take the pump off with the head still in place.

Impressive. The S1 Elan manual says you can do the pump with the head still in place but from the S3 onwards (don't know about S2) it says head & sump removal.

How did you get around the wear plate on the front cover, the bit that protrudes into the head ?  Is there enough wiggle room to rotate it round and out ?

Brian

There is enough wiggle room.

Problem diagnosed.

Enclosed is how the pump shaft is supposed to be assembled. The water leak was between the chrome metal slinger and a bronze bush in the housing, which was covered with scale.

I cleaned the bush with a rotary wire brush, pressed the pump shaft into the housing using a vice, then smeared silicone around the chrome slinger, and pressed that into place using a socket and vice.

Then I fitted the washer white side towards the spring and slinger, rubber side towards the impeller.

Then I pressed the impeller onto the shaft in a vice, noting the small 20 thou clearance between the closest impeller blade and the housing. My blades were not uniform, so I had to rotate the impeller to find the closest.

Then I pressed the pulley hub onto the shaft.

Now I have to fit the whole pump back in again before it starts raining.

The seal is created by the washer and slinger but the slinger chrome part has to seal properly into the bronze housing.

I fear I will have to check all the other pumps I have go fitted. I have 9 engines in all, so that will be a task.

The diagram below is a huge help.

[EuropaTC]

There is enough wiggle room.

That's good to know, it's a heck of a lot of work to take the head/exhaust/carbs off. Not that I'm planning on doing the job again any time soon, but if I have to then I'll try your method.

Brian

[4129R]

Engine and gearbox back together in 3h45m.

I connected the water pipes when the gearbox was back in to test for leaks, before bolting everything back together.

Tomorrow I fire it up to see if everything works.

I put the gearbox upright to test the oil seal, no leaks.

My method of putting the gearbox back in worked first time. It would have been quicker if I had put that steel plate in before I put the two long bolts in to slide the gearbox into position.

Lesson to be learned, get a decent diagram of how the water pump goes together before assembly.

[4129R]

Water pump leak solved.

It was where the spring and cup seats against the bronze housing, so for future, I will press the seal into place with a bit of silicone sealant, before pressing the impeller onto the shaft.

I had to use a hydraulic press to get it apart (2-3 tonnes needed), but a normal bench vice was sufficient and easier to press the new one together, as you have very fine control in a vice.

I have sent QED the assembly diagram, so hopefully it will be much clearer now how to put together their pumps.