Reading previous posts on here regarding water pump changes, some say its an engine out, others say it can be done with the engine in. It doesn't look too bad looking from underneath and Ive bought a new seal kit. What am I missing with regards the difficulty?
I think just replacing the seal can be done with the engine in place. I think the real problem would be if you also want to change the roller bearings from the water pump and the hose between the waterpump housing and front cover.
Yes that might be true, but if i remember correctly, to replace the bearings you need to remove the shaft, and that one can only be removed with the housing removed. And to remove the housing you need to remove the engine. The seal alone can be done with the engine and housing in place.
Thanks Stefan - Its just my curiosity but Im struggling to see why the housing cant be taken off with the engine in. There appears to be plenty of room for the housing to come off towards the front. Kit has just arrived with seal and bearing
The oil and water pumps are chain driven and you need the oil pan out of the way to remove them. Sent from my Pixel XL using Tapatalk
Its possible to remove the front cover of the water pump and replace the seal. Behind the seal are the ball bearings and chain drive for the water pump. Sometimes a leaky water pump seal allows coolant to corrode the bearing. To access the bearings you need to remove the entire front timing cover from the engine, which can't be done with the engine in the car, in fact it's a major PITA. There is a weep hole at the base of the water pump , that needs to be open. Its function is to allow any coolant that has made it past the seal to drain, rather than making its way in to the bearing. M Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
There is also an oil seal behind the water seal to prevent coolant from reaching the bearings & keep the engine oil in. My first attemp at replacing the seals I did not seat the oil seal all the way in resulting in oil leaking out the weep hole. I would replace the oil seal while your in there.
Got it, that makes much more sense. I have a small drip of water coming from the bottom weep hole, so hopefully its just the seals I need to be looking at. Many thanks.
Is it ever "normal" that the weep hole drips coolant, or does it always indicate a water pump problem? Any help is appreciated.
Not normal, it means your bearing(s) and seals are letting water through. I went through this recently. Sent from my MAR-LX1M using Tapatalk
That's what I thought as well, but a mechanic is telling me that is what the weep hole is for - not to warn of a problem, but to weep coolant.
Are there any water pump lubricant without corrosion inhibitors? These could help save the seals without messing with the additives & corrosion inhibitors that are already in the coolant. Looking at my water wetter formula, there is quite a significant amount of plasticiser , which softens seals (and silicon hoses ), time will tell if this is good for the pump seal. All in all, a dab of old school lubricant would not hurt.
Is there any other reason, no matter how minor, that would cause a water pump to leak? Also, if it is weeping coolant from the weep hole, does that necessarily mean coolant is getting into the oil (or vice versa)? Any help is appreciated.
You’d have to look at the shop manual and see the order of how things are laid out. I think you could safely say when the engine was running the oil psi would always be higher that the coolant pressure. Once the engine was shut down the opposite would be true.
Maybe overheating combined with a faulty radiator cap would cause the coolant to find another way out? This being said I would expect the hoses to inflate before.
Water Pump/Mechanical Seals 101 A typical automotive water pump seal is what we old pump guys call a mechanical seal. In the case of automotive water pump seals, the stationary seal face is ceramic and the rotating face is carbon. The stationary ceramic seal is mounted in an elastomer (rubber) holder that presses in the pump body. Under normal circumstances it will never leak (unless the housing corrodes).The real sealing action happens between the seal faces, but they seal the coolant to atmosphere – not to the oil sump. The seal can (and will) bed in when first fitted if there is some slight weeping from the witness hole. Note that weeping from a new seal is different from an old seal starting to weep after a lot of use. My GTC4 had a slight weep for 1K miles or so after a full engine rebuild before settling down. The witness hole gives a visual indication of seal leakage and it also ensures that there is a leakage path to atmospheric pressure for coolant. This means that there will be no leakage of coolant into engine oil (unless there is a catastrophic failure or incorrect assembly). In most automotive engines, the water pump is a self-contained bolt on unit that is cheap enough and easy enough, to replace as a unit. The water pump in 365/400 engines is more tricky, in that the pump is chain driven from inside the engine (rather than an external belt). The water pump bearings can only be accessed from inside the timing chest. This means a major tear down of the timing chest is necessary if they are to be replaced. Bottom line – If a new pump seal leaks, don’t panic (immediately). If it’s an older installation, get ready to replace the mechanical seal. This is bit of a pain if done in the car, but not impossible. Regards WM
Thanks for the information! I have about 2300 kilometers (1430 miles) on the new water pump seal (and all the seals behind the ceramic one, and new shaft) after a complete engine out total, down-to-the crank rebuild. I am hopeful that Bill24's comment plays out, but at what point do you acknowledge a seal failure and re-do it?
Not sure about this, I would probably call this a matter of time rather than use. I've changed the 40 year old seal on my car although it had not even reached 100.000km (we are usually told to replace the pump at 120.000km). it was not leaking either, but while the engine was out seemed a good idea. As a side note, I've installed a Gano filter in the upper hose, and I was shocked by the amount of debris. There is no way such large bits would get out of the system through the ridiculously tiny drain petcock. This is is probably doing no good to the pump. Finally I do not know how the coolants & additives impact the seals. Plasticisers (as found in dexcool and mocool) would make the seal softer (not sure if this is good or bad); additives used in the Us are likely to generate some particles when mixed with European water; water wetter tends to dislodge tons of crude (which again is probably doing not good to the pump), etc... At the end of the day, with regular fluid change, I just hope that my new seal will outlast my ownership...
Thanks reamin. I do wonder if the type of coolant has anything to do with the seal's ability to wear itself smooth enough to actually seal. I have BMW coolant (the blue stuff) in there now post rebuild. I always used to run the yellow stuff before. The radiator was supposedly flushed out by a radiator shop so I shouldn't have any crud/debris anywhere.
So has anyone else experienced bad replacement ceramic seals? I can't imagine what else it could be. Any suggestions?
In my case I had all new seals, but the shop forgot to install the second (outer) #40 bearing. This resulted in oil coming out the weep hole. Once the bearing was put in, it stopped leaking. I would check the bearings. Image Unavailable, Please Login
Fortunately (at the moment anyway) I don't have anything but coolant at the weep hole. Is there a trick or little-known factory way to install these outer seals?