Cooling System Overhaul

I just completed a cooling system overhaul. I replaced the water pump, thermostat, belts, hoses, and radiator. I put BMW coolant back in with a mix of distilled water. The car run a little rough on startup now but smooths out. Has anyone had this kind of an issue after a cooling system overhaul or any ideas?

What prompted the cooling system overhaul?

The reluctant answer of most people is an overheat...

Cracked radiator

Sent from my HTC VLE_U using Bimmer App

You need the expansion tank too. This is a common failure mode.

The list of things to replace in a cooling system overhaul is long:
- List & picture of all the cooling system overhaul parts to replace (1) (2) (3)

If, as stated in the second post above, the engine overheated, worse things will happen:
- What happens if you drive one mile too far with an overheated BMW cooling system (1).

If you already drove with an overheated engine, then these come into play:
- Summary advice to provide users who suspect a major engine repair due to overheating (1)

Otherwise, these come into play:
- How to diagnose a typical BMW E39 engine misfire (1) o

Originally Posted by Fudman

You need the expansion tank too. This is a common failure mode.

I did replace the expansion tank as well. What caused failure mode and where should I look to correct this?

Originally Posted by bluebee

The list of things to replace in a cooling system overhaul is long:
- List & picture of all the cooling system overhaul parts to replace (1) (2) (3)

If, as stated in the second post above, the engine overheated, worse things will happen:
- What happens if you drive one mile too far with an overheated BMW cooling system (1).

If you already drove with an overheated engine, then these come into play:
- Summary advice to provide users who suspect a major engine repair due to overheating (1)

Otherwise, these come into play:
- How to diagnose a typical BMW E39 engine misfire (1) o

Thanks, I'll be looking into the misfire link. The car did not overheat, what happens is the the car gets shakey and rough when I start it up. Then it smooths out and runs fine. It has not overheated during this which is whats got me puzzled to what the issue is.

So if it worked fine before, it seems like something changed.

The cooling system itself won't have much of an impact on running since the engine doesn't really know it's there until it isn't working. With the exception of the thermostat which can play a significantly larger role. Make sure that the connector on top is well seated, it's an easy one to overlook.
Also check the VANOS plug if you removed it and any wiring that was disturbed.

I was poking around the overheat/head gasket issue, but if your temp stayed normal then you're fortunate that isn't the cause.

It could also be something mechanical out of balance causing the shaking. Some users have reported missing fan blades and old clutches causing odd vibrations. Just something to think about if it's not an engine shakiness.

Of course it could just be a coincidence too. How is the standard maintenance on the car? Spark plugs, etc? Do you have any codes set or pending? A Peake reader or INPA can likely find the issue in short order.

Originally Posted by waehrik

So if it worked fine before, it seems like something changed.

The cooling system itself won't have much of an impact on running since the engine doesn't really know it's there until it isn't working. With the exception of the thermostat which can play a significantly larger role. Make sure that the connector on top is well seated, it's an easy one to overlook.
Also check the VANOS plug if you removed it and any wiring that was disturbed.

I was poking around the overheat/head gasket issue, but if your temp stayed normal then you're fortunate that isn't the cause.

It could also be something mechanical out of balance causing the shaking. Some users have reported missing fan blades and old clutches causing odd vibrations. Just something to think about if it's not an engine shakiness.

Of course it could just be a coincidence too. How is the standard maintenance on the car? Spark plugs, etc? Do you have any codes set or pending? A Peake reader or INPA can likely find the issue in short order.

It's funny you say a missing fan blade. I dropped the fan clutch (which is new as well) when putting everything back together and broke one of the fan blades off. I didn't think something that small could cause something like that but I did order a replacement fan blade so when I get that in we'll be able to rule that out. I'll re-check to make sure everything is plugged in as well. The standard maintenance on the car was kept up well. Had plugs done about 20K miles ago. I don't have a peake reader or a INPA. Thanks a lot for the help.

Originally Posted by waehrik

So if it worked fine before, it seems like something changed.

The cooling system itself won't have much of an impact on running since the engine doesn't really know it's there until it isn't working. With the exception of the thermostat which can play a significantly larger role. Make sure that the connector on top is well seated, it's an easy one to overlook.
Also check the VANOS plug if you removed it and any wiring that was disturbed.

I was poking around the overheat/head gasket issue, but if your temp stayed normal then you're fortunate that isn't the cause.

It could also be something mechanical out of balance causing the shaking. Some users have reported missing fan blades and old clutches causing odd vibrations. Just something to think about if it's not an engine shakiness.

Of course it could just be a coincidence too. How is the standard maintenance on the car? Spark plugs, etc? Do you have any codes set or pending? A Peake reader or INPA can likely find the issue in short order.

You were right about the missing fan blade being the cause. I removed the fan clucth and the shaking went away. Thanks again.

I'm glad you got it fixed, and thanks for reporting back.

It's really amazing how much a small mass can throw off the balance of a big V8 engine. But you have to think, it's not only the small weight of plastic that's missing but the overall pressure of air forced against the blade at at least a couple hundred RPM that's missing.

The issues is resolved. I got the new fan blade installed and all is still well. Thanks for the help all.