Author Topic: Crankshaft center seal  (Read 1213 times)

0 Members and 1 Guest are viewing this topic.

Offline Joe

  • Trade Count: (0)
  • Registered Bridgestone Member
  • **
  • Posts: 16
Crankshaft center seal
« on: August 31, 2023, 02:45:49 PM »
Can someone school me on the crankshaft center seal ? Does it go because of age, mileage, abuse, all of the above? My DT sat for years . Any chance it will be ok ? Thanks !

Offline czmike

  • Trade Count: (0)
  • Full Bridgestone Member
  • ***
  • Posts: 48
Re: Crankshaft center seal
« Reply #1 on: August 31, 2023, 08:46:52 PM »

Hi Joe,

Age, mileage, extreme heat & cold are the main things that degrade any rubber/plastic lip-type seal.

I am in the middle of replacing the centre seal & bearing on my 175HS crankshaft.
I was hopeful of this being unnecessary but on close inspection of the centre seal, which you can do in-place, it had radial cracks in its sides.
My bike has only traveled 3,000 miles and has not been ridden since 1972.
The good condition of the bike and the engine confirmed the low miles and that it had been stored carefully under good conditions.
Nonetheless one main bearing was rusted solid (drive side) and the seals all need replacing including the crank centre seal.
I am replacing all main bearings and the centre bearing as well while it is apart.
I suspect your centre crank seal will be due for replacement as surely would all others that have never been replaced.
You could perform a pressure test on the motor to measure the seal leakage but I think you can safely assume it leaks.
None of this you want to hear of course but it is quite typical and well, just that thing called reality.

If your engine is not stuck and runs OK then you might consider continuing to use it. I wouldn't use it hard though (which is surely the way you would want to use it!).
If you have difficulty starting it, particularly when hot this could be an indication of crank seal problems.
Other users might be able to advise what are the tell-tale signs of a leaking centre seal.
Any running or tuning problems will probably be mystifying until you replace all the seals.

Best Regards,
Mike

Offline CL-100

  • Trade Count: (0)
  • Expert Registered Bridgestone Member
  • ****
  • Posts: 345
  • CL-100
Re: Crankshaft center seal
« Reply #2 on: September 01, 2023, 10:34:45 AM »
I bought an early model 175 engine (engine only) and when I received it I was delighted with how well the engine/crank turned over.  Once I had it disassembled I found that the crank center seal was trashed.  The spring around the lip had broken in two.  It took me a while to find the correct seal for my engine as it looks as though the earlier models used a couple of different setups for the center bearing and seals.  I ended up sending the crank with new bearings and seals to Northern Crankshaft for replacement of the parts and correct reassembly.  They rebuild a lot of two-stroke crankshafts, mostly for snow-mobiles, and have always done a good job for me. 

Offline Joe

  • Trade Count: (0)
  • Registered Bridgestone Member
  • **
  • Posts: 16
Re: Crankshaft center seal
« Reply #3 on: September 02, 2023, 06:12:21 AM »
Thanks for the information! I do have a replacement center seal. I have applied for a bonded title for my DT and the dmv reply is in the mail. If it’s approved the bike will be professionally restored (Mechanically) next year. If it’s denied I will sell it and hope to find a running, titled bike. In the meantime I have my recently acquired HS to zip around the county.

 


Gallery


Views:530
Comments (0)
By: hod928

Views:527
Comments (0)
By: hod928

Views:524
Comments (0)
By: hod928

Views:691
Comments (0)
By: hod928

Classifieds

Deleted

Price: $0.00
Date: 08/09/2024 07:09 am
Time Left:
Deleted

Price: $0.00
Date: 06/12/2024 07:57 am
Time Left:
BS 175 DT Carburettors Mikuni VM 17 s

Price: 120.00 EUR
Date: 04/14/2024 09:55 am
Time Left:
BS175 DT 1966 Gas Tank

Price: 150.00 EUR
Date: 04/14/2024 09:37 am
Time Left:

Recent Downloads added

Parts Manual BS-7 Std & Deluxe with new style part numbers
Rating: (None)
Filesize: 5483.15KB
Date: April 17, 2024, 10:15:22 AM
Chibi, Chibi Deluxe, Tora Service Manual
Rating: (None)
Filesize: 20383.27KB
Date: May 01, 2023, 08:35:39 PM
Chibi_Tora_Parts_Manual
Rating: (None)
Filesize: 14301.44KB
Date: May 01, 2023, 08:25:53 PM
BS200 Mk II RS & MK II SS Exclusive Parts
Rating: (None)
Filesize: 358.29KB
Date: March 07, 2021, 07:30:10 PM

Powered by EzPortal