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fan hits radiator


pjp90

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On my '71 2002 the cooling fan started hitting the radiator after I replaced the water pump. I then replaced the motor mounts and trans mount, and also changed fans to one slightly smaller in diameter. Problem continues. With hood open and engine either off or running clearance looks ok.

It seems that with the hood closed and less place for the air to move, the fan blades may be bending. Also on short trips, maybe a couple of miles, no problem. On longer trips it starts to hit. Does not seem to be related to hard acccelation. I found an old post on the subject that suggests the fan softens up and bends more when the plastic gets hot, which would be consistent with my observations. Yesterday after a few miles it started hitting hard and broke the radiator tank.

So why did the problem start only after replacing the water pump? The alignment of the water pump pulley with the crank and alternator pulleys looks good. Any ideas?

Paul

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I had this problem with the 72' I had replaced the alt and installed new factory rubber bushings. Had to tie the alt bracket back to the block to drive the car. That did work for the short term. I got poly bushings for the alternator and never had the problem again.

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your missing the right side mount (passenger side)limit strap.

The hooked strap limits the travel of the right mount,

Without it - the motor rocks foword - under changiing loads.

Normal

The hook is adjusted with no more than 3mm clearance with the rubber block.

look up past posts for photos of this

"motor mounts"

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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then your radiator is in the wrong place?

or something is really up with the 'new' pump?

or alternator to water pump pulley alignment?

what brand of pump ?

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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i had this issue as well with my Automatic 02 when i made the restoration.

The strap is not the CAUSE...it only prevent the motor to go hit the rad when you brakes real mad, so what do you do when it hits it when the car is at rest ?? when there is CLEARANCE issue ?

MY problem #1 was the lower rad tank that was wrong, Curt Ingraham(rip) asked me to send him so pics and he confirmed the lower tank was too large, ie, the wrong one.

It is common mistake when rads are re-cored or fixed.

I ended up sloting the engine mount tabs and had it back about 1/4 of an inch, then readjusted the DS and diff too. No more issues since then, but it was not realy obvious and the fan was still very close to the rad.

Problem #2, The fan blades where also bent-up, so Curt sent me a nice NOS fan, that completed the clearance issue.

===>Fan wear up with age and the blades bends up.

2006 530xi, 1974 2002 Automatic summer DD
1985 XR4TI, 22psi ±300hp
1986 yota pick-up, 2006 Smart FT diesel

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Where is the fan contacting the radiator? Bottom of radiator or top?

The Nose/radiator support is likely bent from an old accident causing the close conditions to begin with... Has the car ever been hit in the front? I see this often in '02s, where the nose is slightly pushed back due to an old accident and thus the radiator is closer to the engine than it should be Changing things, removing/reinstalling things in slightly different ways or new parts to slightly different standards can cause this very problem. It may not be the fault of any single part or the technician doing the work, but simply the old accident repair work. I have seen '02s where this problem was so bad that I/we had to remove the red fan entirely and install an electric fan in front of the radiator.

I have heard of a brace being built behind the nose and the nose being pulled back out enough to fix this without any other paint work. Grills out, body mounted on a frame rack at a body shop.

The radiator might be in a slightly different place than before... It can adjust around slightly.

Poor radiator core job where the bottom tank is too fat and the fan then hits.

There is some slight adjustment to both motor mounts that can help with this, slightly... Loosen both motor mounts, drop the trans mount a on a floor jack then tighten the motor mounts again. This can and has helped in situations like this before.

Yes, also can be bent/old fan blades. Wrangling the old fan off the old water pump could have caused this problem. New fans usually help if this is the cause.

Cheers & HTH,

Tom Jones

BMW wrench for 30 years, BMWCCA since 1984 at age 9
66 BMW16oo stored, 67 1600-2 lifelong project, 2 more 67-8 1600s, 86 528e 5sp 586k, 91 318i
Mom&Dad's, 65 1800TiSA, 70 2800, 72 2002Tii 2760007 orig owners, 15 Z4 N20

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thanks everyone for the input.

I can't say whether the car was ever in a front end collision. I bought it last year in nearly immaculate condition, a really first class body restoration. Hood fits perfectly, and no evidence that the radiator support is bent. It is an OEM radiator attached with OEM hardware.

Fan was hitting both sides, more on the right side than the left.

I don't see how alternator bushings affect the fan. How would movement of the alternator cause the fan pulley, which is rigidly bolted to a brand new water pump, to move out of alignment? I do have a brand new alternator.

Does anyone know what the static clearance should be between the fan blades and the radiator?

Paul

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  • 4 weeks later...
  • 3 years later...

Just did a trans swap and now there is a ticking coming from the front, not sure if it's the fan or from the pump it self. I think the fan got pressed into the rad and bent something during the instahl.

 

Get out your light and look for evidence on the radiator.  It won't last long if the fan blade is contacting it.

John in VA

'74 tii "Juanita"  '85 535i "Goldie"  '86 535i "M-POSSTR"  

'03 530i "Titan"  '06 330ci "ZHPY"

bmw_spin.gif

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