water pump questions??

[fromtheashes]

So I have an 87 325e and I just picked up and I head and while I am swapping the head I am going to be doing the timing belt and water pump.

And my question is can I run the late model water pump or do I have to stay with the early model water pump.

I've looked up everything and I cant see a difference between the two for them to bolt up and I am just seeing if anyone has any more information on it.

Thanks in advance

[efficient]

If you do a late model water pump your going to need a late model radiator and some hoses and the coolant bottle for the drivers side. Don't forget the coolant crossover pipe for the front

[fromtheashes]

That is my plan. But I've never heard of the coolant crossover pipe?

[Som]

The early model water pump has 2 outlets -- one that goes to the tstat, and one that goes to the expansion tank.

The new model water pump has just the outlet to the tstat. Same hose between the two as the early model.

So if you use a late model water pump, you need a way to route a hose to the expansion tank. On the new model cooling system, there's a 3-way hose that connects between the tstat-heater core-expansion tank -- and that's with expecting the tank to be on the driver's side of the engine bay.

That said, there could be other ways to connect the system to the tank.



The crossover pipe is a metal pipe (#8 above) that connects to the front of the timing belt cover on new cooling systems. A hose plugs one side of the pipe to the lower radiator outlet and the another hose connects the other side to the tstat. Of course, this requires a newer style radiator as well. It's kind of a slippery slope to a full conversion unless you can find a simple way to get a hose to the expansion tank with the older configuration.

Som

[101]

The pumps have exactly the same mounting.

Owning both early and late model cooling systems I actually prefer the early model:

FOR the early model:

1) The expansion tank is on the right side. Putting it on the left side of the engine bay crowds things a bit since everything else is on the left side of the engine (except the washer fluid reservoir)

2) That hose #13 shown above for the late model is like $50+ dollars for a replacement

3) I don't have a lot of fun removing and replacing the crossover pipe when doing a timing belt change.


FOR the later model:

1) The lower radiator hose is not as vulnerable to being shredded by the alternator fan.


Again, just my opinion.

[Som]

Few other (minor) items for the late model.

1) Since the late model/E36 radiators are apparently the same, you have more options for aftermarket radiators.

2) (super minor) For me, removing the old model expansion tank made exhaust manifold work and spark plug replacement easier. You're not going to do a lot of manifold work, generally, but getting your spark plugs out (either to replace them, gap them, or do compression tests) is a bit more common. It's hardly "difficult" even with the tank in place, but it's certainly easier when it's moved aside.

3) (another super minor one) Looking for used parts/spares is likely easier if you've got a new model system since they're more common. That said, other than the expansion tank, you probably don't want to buy a used radiator / water pump anyway. My E30 is a SpecE30 car, and when I blew my radiator last weekend, I found fellow racers with spare radiators -- but only the new kind. Even the people running '87 cars had converted to the new style cooling system.

Full disclosure, I'm still mid-process of converting, so there may be other pros/cons.

Another pro that I've read for the old style is that getting to the distributor/rotor is easier on the old model. That said, looking at photos of the new style cooling, I don't really see how it would be different. Guess I'll find out. :)

Som

[McGyver]

The question is, why do you want to switch to a late model WP? The thermostat housing is the same for all of them, so you'd have to replace the radiator, all hoses, and coolant tank. Why?

[packratbimmer]

Take note that there are two different size holes in the stat. housings. Every late model I have had has had the smaller hole with matching thermostat. The early large hole unit might need to have the matching large flange stat.

[fromtheashes]

Im doing the 2.5l head conversation, The reason I was asking was because I didn't know the difference between the two WP other than the hoses ran differently. Im already planning on buying a new radiator because the one I have is cracked so I am seeing what will work on my car and what is interchangeable between the different years. Trying to gather as much information from people before I go spend money on parts that wont work on my car.

[Som]

What's the end goal? If you want to save money and effort, just hock the late style WP, buy an old style WP and you're good to go. You could potentially save more money (by keeping the late style WP) if you can come up with a way to run a hose to the expansion tank -- could be as easy as finding a T-fitting that accepts the large-diameter hoses on 2 ends, and a small diameter hose for the expansion tank on the 3rd end.

If you're trying to convert to the late model system altogether, you'll want to check out the following diagrams:

Late Model: http://www.realoem.com/bmw/enUS/show...diagId=11_1167

Old Model: http://www.realoem.com/bmw/enUS/show...diagId=11_1168

There are a number of parts that you'll need to do a full conversion. There may be ways of getting around one or two, though. Other than what I described above with mixing the WP with the old system, I can't really think of any other ways to do a "hybrid" system -- you'd probably have to either convert the whole thing, or leave it. If you convert, here are the parts I can think of that you'd be committing to (and I'm doing this conversion right now, so I may be missing 1 or 2 things):

- If you're running the heater core (I'm not), you'll need #13 in the diagram above. It's a funky 3-way hose, and it's kind pricey as hoses go. I'm also not running the hoses to the throttle body, so you'll have to check for yourself if you need these.
- You'll need hoses 4, 7, and 11 from the late model diagram above. Hose 1 is the same as the old style.
- Obviously need the new water pump
- You'll need the metal pipe that bolts to the timing cover
- You'll need a late style timing cover to bolt the pipe to. I haven't looked into how this connects, so it's possible simply drilling a hole into the old one would work.
- You'll need a late model radiator (the outlets are oriented on the opposite sides)
- You'll need a late model expansion tank -- though I guess it's possible you could couple in an extension hose to run from the 3-way hose all the way over to the old style tank. *shrug*
- You'll likely need the radiator mount for the new style radiator (I'm still trying to figure this out myself). I'm referring to #9 in this diagram -- http://www.realoem.com/bmw/enUS/show...diagId=17_0005. It doesn't look like the new style radiator has the same side flanges that the old style ones do.

Som

[fromtheashes]

The end goal for the car will be turbo.

The project so far is something is broke so make it better. And I dont want to spend a lot of money but I know to do one thing Ill have to do another and so on and so forth. So Im gonna try and work a way out of mix matching the old system with the new. A lot of what I am doing is replace as need be right now and a lot is being replaced

[stikrz]

I definitely prefer the early model setup. Coming from 528e to the e30 world I am glad that I got an early model 325.