Cooling Fan Housing

I have 1776 engine on which PO installed chrome fan housing. At about 3500 rpm's and above I have a rattling sound out of the engine compartment. I was told be a local previous VW guy that the shrouds in the chrome after market housing are the problem, get rid of it and go back to the VW housing. Any comments?
Can you tell that after 6 months of ownership that I am finally starting to use the car?
Norbert

Norbert,

All that I have read says the chrome is bad in the engine compartment. For heat reasons. the chrome does not absorb heat but reflects it back to the heads, case etc. That's a bad thing, probably OK this time of the year but look out this summer! A flat paint finish is best.

There are also different styles/years of doghouse fan/shrouds and the chrome ones are the earlier ones I think. It is fairly inexpensive to switch out and some members have switched with the engine in the car but dropping the engine would be easier. Get searching here and the Samba about doghouse shroud swaps.
If you have noise check it out soon though.

Good luck
Dave

Do a search here - aftermarket shrouds have been covered many times. Porsche/VW spent lots of engineering hours developing the cooling system. Jake Raby did comparison tests on many too (not sure where results are posted) when he developed the DTM system. Yup, the factory ones are far superior in cooling over aftermarket TAIWAN ones. Even the black color is superior to chromed ones. So even over eliminating the rattle, a stock one is preferred. (Note stock ones can rattle too if not secured properly or generator/fan is off).

Could also be the fan off balanced or coming apart - high RPM uses tend to use balanced welded fans.
https://www.speedsterowners.com/forum/readmsg.asp?t=12712

More than likely its the fan and not the shroud. There is not much in a shroud that would make a noise. Only if one of the welds breaks(and that almost never happens)

OEM shrouds are better but none are that bad(other than the slanted or centered ones) What you have described sounds like a cracked fan. If you take out the fan, look for some hairline cracks around the bolt hole(or washer thats under the bolt).

If you are going to replace the fan I would get a balanced new fan or an old VW fan.

Norbert,

The fan may just be loose and is rattling. Try tightening it and you might be okay.

The reason I believe it's the shrouds is when I strike the housing on the left side with the palm of my hand I hear a rattling sound. With the engine compartment open, when I rev the engine up it rattles in the same area. The housing is coming off. With the generator off,it looks as though it will clear the carbs. Do I need to remove the deck lid (hood) since it has to come straight up? What about the oil cooler? I hope it's not attached to the fan housing.
Norbert

It's probably the little doghouse shroud that covers the oil cooler.
It's that rectangular bump on the rear left of the fan shroud. Chances are the top is loose or missing a bolt.

Looking at an OEM shroud - there is only one bolt (or machine screw)that holds the top dog house piece on. One I have has no cork or rubber to keep it from rattling - so yeah it will really rattle if bent or not very tight. Also the shroud does have a bolt (or machine screw) holding it to mounting base of the oil cooler too (it might be thru breast plate but not a breast plate on one I looked at).

Here's part that probably rattles. See the 1 screw holding it! This one is bent - plus best to seal with somem silicon to the oil cooler bump out.

Terry and Wolfgang good call.

Thanks for the input. I will check the area around the cooler for any rattles. I intended to work on the car on Sunday, but the weather was so nice ( 75 and sunny) I decided to take the car for a ride. Made my day.

That right there tells us that you fit the profile of the rest of us maroons on this site - just a bunch of frigging car guys that like to drive their cars. Great group of folks I might add!!

The rattle is the oil cooler housing. Even with the screw tight, there is a gap causing it to rattle. It's not a very good fit at all. A gasket or sealer appears to be the fix. Since I am going to change to a 3:88 diff.and will need to pull the engine, I will replace the fan housing with the original VW unit. Also have 3rd latch for top ordered. Getting this baby ready for some highway cruising in the Spring.

That oil cooler tin is a small piece that usually has some sort of a foam rubber gasket between it and the main housing (opr if it doesn't, it should have).

That gasket can be duplicated easily with a piece of window weather strip available from a DIY (i.e.; Home Depot). The stuff I use is from Storm King and is 3/8" wide by 1/4" thick and comes as a tape. Cut to length, peel off the backing and stick it on, then re-apply the oil cooler tin and you're done. I think it comes in white, black and brown.

Once applied, any rattle should be gone.

gn

As you can see from photo I posted even the OEM one is poor fit. I think originally there was a rubber gasket with a channel to seal it. You can use silicon RTV sealer too. The one in photo is bent too - but still only one bolt to secure it and another to hold the scoop (not shown in photo) that goes at the very bottom.

I will try the sealer strip. I found the bolt on the top. What holds the cover on the bottom?

My easy fix, clean all surfaces, a bead of a good grade of caulk between both pieces, replace the one screw and don't disturb it until dry ~Alan

I did that swap a few years ago with the motor in the car; the decklid had to be removed. I also retrofitted the thermostat system which I think is very important for the motor to work properly. As Gordon says, the foam weatherstrip is easy to get; the roll I got at Home Depot and is the one with the adhesive on; just pull the tape off and set it in place. The fan is attached to the bottom of the oil cooler with a single bolt to a trim piece popularly called "the Hoover bit" that's attached to the bottom of the oil cooler.