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Oil seal on series 14 crank shaft (fan end)


147 Franklin Airman

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I am looking into replacing the felt seal on the crank shaft at the fan end and wondered if anyone has machined the timing chain cover for the fitment of a rubber seal and if so how well has it worked and for how long.


If someone has done this would you be able to let me know what seal was used?


I would attach drawing number 87934 but its not available.


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The felt washer you refer to (p/n 46X123), which is not shown or listed in the parts book is a dust shield.  The actual oil seal is an acme thread on the bore of the p/n 87934 "cheek piece assembly".  The threads neeed to be clean and if they are will work fine to return oil to the crankcase.

 

Gordon Howard

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Hi,

Not clear on what you are trying to do but i can tell you I have added a modern lip seal to the front of several side draft engines. What is important is to make sure the OD of the shaft on the fan hup is smooth as can be otherwise it will simply chew up the new seal. I have to add a sleeve to one or two fans to obtain a smooth surface. These are the sleeves used on modern engines on the crankshafts where the harmonic balancer goes.

Then you need to measure the OD of the fan hub and select a lip seel for that diameter. Next bore the front timing cover to match the od of the new seal. Bore only deep enough to secure the seal About as deep as the thickness of the seal. It is important to be sure you bore accuratly so you do not alter the allighnment ot the timing cover to the crank or fan hub. When installing the timing cover measure the gap between the seal and the crank. If not centered it will be necessary to drill new holes for the alighnment pins which you realy do not want to do. I have not had any leaks after installing new lip seals.

Bob

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Hi Martin - 

 

For a new seal - use Chicago Rawhide seal #CR23641. The timing cover must be carefully bored to the housing bore specs for the seal (3.000"). It is difficult to bore the hole exactly centered as there is always wear and it is not easy to center to an acme thread. One just has to do the best they can to center things. 

 

The fan hub is always in poor condition. You can use a harmonic balancer hub repair sleeve for a big-block Chevrolet. I use one from Pioneer Auto parts (available from engine parts jobbers) PioneerHB-4123.  You may be able to get one at NAPA.   You can buy one from a bearing house, but the price is triple that of the harmonic balancer sleeve.  This presses and locks (with loctite) to the fan hub, giving a new seal surface for the 23641 seal. 

 

To insure the seal is centered exactly to the crankshaft, the factory installed dowel pins, locking the cover in place. With the new seal, the dowel pins must be removed, or the seal will likely be off-center slightly, potentially leading to a leak, or early failure.  There are a couple options here.  To insure a perfect fit, you can install the timing cover loosely and then install the fan into the seal. This will align the cover. Then either new, or oversize dowel pins maw be installed to align the cover.  Pull the fan back off and assemble all. 

 

We tend to install the timing cover loosely, then the blower housing  and then use a dummy fan hub tool which simulates the fan hub into the seal. We can then tighten the cover in this position, knowing we are centered properly. We just leave the dowel pins out.  Without a dummy hub tool you would need to actually press the fan onto the crank with the fan housing in place, and carefully insure the cover is happily where it needs to be, install the timing cover bolts you can access, then pull the fan off to install the rest. 

 

I am making it sound more complicated than it is- one just needs to understand that the seal needs to be centered.  If engine main bearings are worn, or someone has re-machined the bearings, things are never centered, so it is pretty  important to not just put the cover back on using the old dowel point locations.

 

I would not put an engine together without the seal since the blowing oil is a real mess and a common problem. 

 

For more info or questions - call or email

 

Tom Rasmussen

odyrestorations@aol.com

763-786-1518 

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Hi Tom

 

Many thanks for your detailed instructions which I fully understand, and also for the part numbers and supplier details.

This will give me a great start to solving the oil leak and perhaps a clean engine one day.

 

From your part number I have found this seal which is available in the UK.

 

SKF CRW1 Viton Oil Seals: These radial shaft seals have Waveseal lip design to reduce friction and heat generation. The seals have a single steel shell to simplify installation and provide a tight fit in the housing bore. The outside diameter of the seals is coated with Bore-Tite, a non-hardening, water-based polyacrylate sealant, which enables the seals to accommodate small imperfections in the housing bore. This seal also has a carbon steel garter spring. These seals are primarily designed for lubricant retention.
Benefits: Reduced friction and heat generation, provides a tight fit in the housing bore, accommodates small imperfections in the housing bore.

SKF

Inside Diameter: 60.325mm = 2.375 inch

Outside Diameter: 76.2mm = 3 inch

Width: 9.525mm = 0.375 inch

 

And the sleeve (USA only)

Part Number: HB-4123 Weight: 0.1 lbs Notes: 0.780/.800 Depth.

Outside Diameter: 2.366 / 2.368

Inside Diameter: 2.328 / 2.330

Depth or Length: 0.780 / 0.800

Thickness: 0.019 in. Includes Sleeve Sealant: Yes

 

Does the 0.007" gap cause any leakage?

 

Martin

Edited by 147 Franklin Airman (see edit history)
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Hi Martin -

 

My apologies - in haste, I grabbed the wrong seal #

 

Thanks for pointing out the sizes.

 

We have used multiple seals over the years. All of them have worked well, but the one we tend to favor now is a CR23300

for a 2.328" shaft size

3.000 housing bore

 

This one gives a bit more 'bite' to the HB4123 over the 23641.  We have used it successfully with very careful alignment, but clearly it is not the best choice.

 

We have also used  a CR23046 which is for a proper 2.312 shaft size.   This is the seal to use if not using a hub repair sleeve (if your fan hub surface is clean and you can polish it up nicely).  We have also used this with a hub repair sleeve with good success, but it is a bit crowded over the hub sleeve.

 

By the way,  the Chicago Rawhide sleeve for the 2.312 fan hub is 99231.  It may have a smaller OD than the Chevrolet harmonic balancer sleeve... I don't use it primarily due to cost and poor availability from other seal vendors.

 

Sorry for the confusion - sometimes there are multiple answers.

 

tom

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  • 1 month later...

 

Hi Martin -
 
My apologies - in haste, I grabbed the wrong seal #
 
Thanks for pointing out the sizes.
 
We have used multiple seals over the years. All of them have worked well, but the one we tend to favor now is a CR23300
for a 2.328" shaft size
3.000 housing bore
 
This one gives a bit more 'bite' to the HB4123 over the 23641.  We have used it successfully with very careful alignment, but clearly it is not the best choice.
 
We have also used  a CR23046 which is for a proper 2.312 shaft size.   This is the seal to use if not using a hub repair sleeve (if your fan hub surface is clean and you can polish it up nicely).  We have also used this with a hub repair sleeve with good success, but it is a bit crowded over the hub sleeve.
 
By the way,  the Chicago Rawhide sleeve for the 2.312 fan hub is 99231.  It may have a smaller OD than the Chevrolet harmonic balancer sleeve... I don't use it primarily due to cost and poor availability from other seal vendors.
 
Sorry for the confusion - sometimes there are multiple answers.
 
tom

 

Hi Tom

 

One question that I have is that I am unsure if the sleeve is wide enough. How far does sleeve need to be pressed onto the shaft? The bevelled lip takes it to the top of the fan shaft. My measurements indicate that the seal will miss the sleeve if not pressed on further towards the body of the fan.

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Hi Martin -

 

Did you get the harmonic balance sleeve or the CR Speedi-Sleeve?  I'm not sure if the speedi sleeve is narrower, but there is no issue with the harmonic balance sleeve. Push it all the way onto the fan hub and all fits just fine.

 

 You also have a little leeway in terms of locating the seal in the timing cover, but really - this has never been an issue, so I'm not sure I completely understand how you are lookign at it or measuring.  If it still does not work out on paper for you - send me a photo or two. I seem to have lost my understanding of how to add a photo to replies, so will send you one via PM.

 

tom
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Hi Martin -

 

I understand what you are saying now.

 

The pioneer sleeve is a press fit onto the hub. We drive it on with a flat piece of wood and it goes on just fine, but if it does not start straight, it will cock and bind. If the fan hub had ridges from ACME thread wear, perhaps there is some raised metal that needs to be polished down? We have never run into this.

 

With the sleeve pressed all the way on (to the flange on the sleeve end), the seal rides on it about 3/16 - 1/4" in from the edge of the sleeve.   Perhaps you need to fit your seal deeper into the timing cover?

 

I hope this helps  -

 

tom

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Hi Tom

 

I have now turned my hub smooth,  trued and polished it up.

My finished size is 2.330” and looking at your previous posts on the forum I now realise that my hub was much bigger before I turned it true so this could be the reason for the sleeve not fitting.

I am sorry but I should have read the measurements  that you gave me in the first place.

 

Martin

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