M3 - Busted Fan?

PhilFausz · **Posted:** Mon Jul 31, 2006 8:34 pm

So I pull in the garage and notice the car is leaking coolant. I've discovered a small hose at the top of the radiator between the radiator and the engine that has broke a fin off the fan. I think it helped catching the problem right away and getting two large fans on it immediately.

The good news is that the car never got past normal and only lost about a quart or less of coolant. Now the bad news.

The question is, what parts should I be getting? The water pump was replaced with a new (metal impeller) pump, new aluminum thermo housing, new thermo, and new belt less than 10k ago. The fan blade is toast, but I don't know about the other parts. Some concerns I have is that the fan clutch was damaged (how to verify?), or the coolant pump was damaged. Anything else I'm missing?

One more thing. Any special tools REQUIRED? I looked at the FSM and noted it calls for a 32mm wrench. RealOEM.com has a few other "special" tools it says you need.

Suggestions? Thanks folks, I'm going to try to drain the coolant, and get a better diagnosis of the situation and will be checking back.

phil

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

if its an original fan, its likely it just blew up. They tend to do that (and is why i run an electric fan w/ my snazzy radiator so it doesnt get ripped apart by a grenading fan). I'd just get a new BMW (not aftermarket) fan and clutch.

Also inspect your radiator to see if there is any scuffing or damage. Sometimes if the engine mounts are bad, the engine can shift enough for the fan blades to make contact w/ the radiator.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Wow, never heard of that failure. Phil, if you're pulling it all apart to replace the fan, just check everything out by hand. I doubt that the fan clutch or water pump have been damaged if it wasn't run that way for long. Spin them both by hand and if there is ANY roughness or out-of-roundness, toss 'em. If you're really risk averse, just go ahead and replace them both.

HOWEVER, if you suspect that your strange idle roughness was actually caused by the missing fan blade (again I doubt it) and you have been driving it like that for a long time, then replacing the clutch and water pump would be a good idea.

Read the Bentley manual for how to tear everything apart. It's a good guide. The only "odd" tool you'll need is a THIN 32mm long wrench. Crescent won't do. And yes, you put it on and bang it with a hammer (left hand threads!!!) about 20 times and it WILL eventually pop loose. You'll likely need to reposition it every 1-2 blows because the water pump slips on the belt. I have the wrench and you're welcome to borrow it.

Let us know how it turns out.

(PS, I get some cold-start roughness and poor throttle response too, but it goes away after like 60 seconds)

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

short link

happens all the damn time in bimmerforum land. infact the previous owner took off my fan and gave it to me in the parts box w/ the car. i looked at it wrong once and it fell apart.

I wouldnt recommend deleting the fan, though. The previous owner deleted mine and it SEEMED ok w/ a big aluminum radiator and a low temp fan switch, but i felt uneasy so i installed a Spal electric fan on a temp switch. the new fan kicks on quite often which makes me feel a bit uneasy about how it was w/o it. eek

I've also heard you should get a real BMW fan and that the aftermarkets are much more prone to breaking. *shrug*. i have a few friends w/ M3s who work at Shadetree so get my fill of opinions

Keith Quistorff · **Posted:** Tue Aug 01, 2006 9:43 am

MikeWhitney wrote:

The only "odd" tool you'll need is a THIN 32mm long wrench. Crescent won't do. And yes, you put it on and bang it with a hammer (left hand threads!!!) about 20 times and it WILL eventually pop loose. You'll likely need to reposition it every 1-2 blows because the water pump slips on the belt. I have the wrench and you're welcome to borrow it.

I made a special tool, similar to the BMW special tool, to keep the fan from rotating when loosening the 32 mm nut, and I also have the 32 mm open end wrench - anyone's welcome to borrow either/both. With this combo, there's no banging, slipping, etc., you just chock the special tool to keep the fan from rotating, and turn the 32 mm wrench in the 'wrong' (LH thread) direction.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Keith Quistorff wrote:

MikeWhitney wrote:

The only "odd" tool you'll need is a THIN 32mm long wrench. Crescent won't do. And yes, you put it on and bang it with a hammer (left hand threads!!!) about 20 times and it WILL eventually pop loose. You'll likely need to reposition it every 1-2 blows because the water pump slips on the belt. I have the wrench and you're welcome to borrow it.

I made a special tool, similar to the BMW special tool, to keep the fan from rotating when loosening the 32 mm nut, and I also have the 32 mm open end wrench - anyone's welcome to borrow either/both. With this combo, there's no banging, slipping, etc., you just chock the special tool to keep the fan from rotating, and turn the 32 mm wrench in the 'wrong' (LH thread) direction.

Sure, if you like doing things the easy way : I may hit you up on that offer next time I need to do something

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

DanDurusky wrote:

short link

happens all the damn time in bimmerforum land. infact the previous owner took off my fan and gave it to me in the parts box w/ the car. i looked at it wrong once and it fell apart.

I don't know about "all the time", it still seems rare and limited to (a) a batch of bad aftermarket fans and (b) driving around for a long time with a bad fan clutch.

Phil, you should probably read through the first link in Dan'd post above. Here it is:

http://forums.bimmerforums.com/forum/sh ... p?t=565367

If you did have a "bad" fan clutch, it may have been causing some of the vibration you were talking about. The fan breaking and slicing the rad hoses may have been symptoms of the real problem.

PhilFausz · **Posted:** Tue Aug 01, 2006 9:06 pm

Fan came off rather easy. About four gentle taps with a 4 lbs. hammer and she was free. I didn't feel anything wrong with the clutch, but I figured replacing it would be insurance. I put it all back together again, added coolant, and started it up. The little sqeak was gone and the car idled fine.

I let it idle for several minutes and no change. I went on a gentle five mile road test and noticed a very faint squeak that reminded me of the previous one just before the vibration. I got the car back in the garage and after shining the light in various positions that the fan isn't nice and smooth, it's fluctuating just slightly.

So, rather than risk it, I'll be back at the dealer getting a water pump (didn't have it in today or I would have then). Shouldn't bee too tough now that I'm an experienced fan puller. Any gotcha's with the pump?

BTW, thanks all for the quick posts. I'm still learning how to maintain, diagnose and fix my own autos and it's nice to get the confidence inspiring feedback from folks who know.

*** One more thing, FSM says to remove thermostat... is this a must?

Dan, what fan did you go with?

Update in a couple days, more work to do on the parents house tomorrow.

p

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

PhilFausz wrote:

*** One more thing, FSM says to remove thermostat... is this a must?

p

Only because it's in the way -- much easier to get to the water pump with the housing out of the way. Since the housing uses a nice rubber gasket, removing and replacing should be easy.

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

Yeh it'd make life easier to remove the tstat housing. Also be sure the water pump you buy is the new composite impeller type. its better than the old regular plastic and newer metal type. I'ld also pick up a new orange tstat housing gasket and new tstat gasket while youre there. its like $2 for both. I also used tstat housing silicone sealant around the perimeter of the housing, but its not really necessary. There was none there before.

I went w/ a Spal 16" electric fan, but i probably wouldnt go that route if you care about classing, etc. that'll bump you to BSPville. it is cool though, its hooked to the temp switch on the radiator and when it kicks on after a hot run and the car is idling it pulls temps down low enough to kick back off within a minute. i can also turn the engine off, and turn the key to ACC and itll turn on and push some heat out of the engine bay. i don't know how effective that is for actual engine cooling though since the coolant isnt circulating, but it can't hurt i guess.

its coo, but a new/good stock system should be fine

PhilFausz · **Posted:** Wed Aug 02, 2006 10:50 am

Of course, the Fayettenam BMW only caries the plastic impeller water pump. Anyone got a part number or source for the composite or metal one?

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

http://www.understeer.com/onlinestore-engine.shtml has the composite for $85

Looks like: 11 51 7 527 799 is the part number.

(slow day at work

)

PhilFausz · **Posted:** Wed Aug 02, 2006 11:29 am

Ignore my post below, I talked to another sales rep and he said they sell the composite, not the plastic. The other rep wasn't aware of a difference and said it looked like plastic to him! I'll pick up the parts tomorrow.

I didn't see a part # on the page, where'd you get that number? I'd like to compare that to the number the dealer has, maybe the salesman is just an idiot!

p

DanDurusky · **Joined:** Sun Apr 10, 2005 7:31 pm **Posts:** 686

i searched around bimmerforums for it. its pretty likely the dealer is selling the new composite type. it does look like black plastic. the crappy plastic ones are so old i doubt theyd be around. the metal ones were in between so *maybe* those would be around

PhilFausz · **Posted:** Wed Aug 02, 2006 9:11 pm

I talked to another parts guy who knew about the different versions, they only sell the composite pump for M3's now. I'll pick the parts up tomorrow and will head out of town for the weekend. This will now become Monday's project.

I'll fill you guys in on the outcome when I get back. BTW, I hate not knowing how tight that fan nut is when putting it on!!! What did you guys do?

phil

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