Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 07-04-2016, 18:36   #1
Registered User
 
synclavier's Avatar

Join Date: Apr 2016
Location: Denver, CO
Boat: Allied Princess 36
Posts: 11
Perkins 4-108 swap questions

I have an Allied Princess 36 with a blown Perkins 4-108. The engine has been removed and I have another candidate 4-108 block available that came out of a genset.

Is there any reason I can't just swap the accessories, bellhousing and tranny from the old one to the new one and drop it back in?
__________________

synclavier is offline   Reply With Quote
Old 07-04-2016, 19:26   #2
Registered User

Join Date: Jan 2016
Posts: 429
Re: Perkins 4-108 swap questions

Depends on what "blown" means...

Would you rebuild your own engine if new parts were available and amazingly cheap?
Because they are

Last time I checked a complete rebuild kit was around 350 and a new crankshaft was another 350.

Wish I had a 4-108. A piston on mine is in the hundreds.

http://www.parts4engines.com/perkins...-overhaul-kit/
__________________

unclemack is offline   Reply With Quote
Old 07-04-2016, 21:02   #3
Registered User
 
synclavier's Avatar

Join Date: Apr 2016
Location: Denver, CO
Boat: Allied Princess 36
Posts: 11
Re: Perkins 4-108 swap questions

Blown means a rod through the crankcase. I was going to swap parts and drop the new one in as a short-term solution to getting her seaworthy enough to move her, then do a refit at a cheaper, DIY yard.

Yeah, the rebuild kits are about $550 for everything. If the shaft mics out ok, I might do a polish and back in she goes.
synclavier is offline   Reply With Quote
Old 07-04-2016, 21:39   #4
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,505
Re: Perkins 4-108 swap questions

Quote:
Originally Posted by synclavier View Post
Is there any reason I can't just swap the accessories, bellhousing and tranny from the old one to the new one and drop it back in?
the short answer is no. I've done short blocks in cars with no problems. I think the difference between the various 4108 version is in the accessories.
donradcliffe is offline   Reply With Quote
Old 08-04-2016, 10:16   #5
Registered User
 
artisanmach's Avatar

Join Date: Aug 2013
Location: Anacortes, WA
Boat: Gulfstar 37 Sloop
Posts: 130
Re: Perkins 4-108 swap questions

do a comparison and make your decision based on measurements you have made. I have a spare 4108 and the blocks are identical in every respect, 10 years difference in manufacturing dates. I have swapped out many parts, so I think its very possible. also my Perkins shop manual does have a cross reference for replacement parts.
artisanmach is offline   Reply With Quote
Old 08-04-2016, 10:33   #6
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 20,042
Re: Perkins 4-108 swap questions

Quote:
Originally Posted by donradcliffe View Post
the short answer is no. I've done short blocks in cars with no problems. I think the difference between the various 4108 version is in the accessories.
Don, I'm not sure what you mean? If the difference is only the accessories then... yes ... right?
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 08-04-2016, 10:35   #7
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 20,042
Re: Perkins 4-108 swap questions

Quote:
Originally Posted by synclavier View Post
I have an Allied Princess 36 with a blown Perkins 4-108. The engine has been removed and I have another candidate 4-108 block available that came out of a genset.

Is there any reason I can't just swap the accessories, bellhousing and tranny from the old one to the new one and drop it back in?
I would just look closely at the various attach points, especially the flywheel/plate/bellhousing area. It seems I've heard of differences in that area? but not sure really....
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 08-04-2016, 11:04   #8
Registered User
 
Jesse's Avatar

Join Date: Apr 2008
Location: Oro Bay Puget Sound
Boat: Irwin sloop
Posts: 378
Re: Perkins 4-108 swap questions

It works just fine. I did exactly what you are proposing with one small difference. I replaced a 4107 with a 4108 that had powered a compressor. I gained the advantage of glow plugs and eliminated the old hot start system. The conversion was done in1999 and it's still going strong.
Jesse is offline   Reply With Quote
Old 08-04-2016, 11:13   #9
Registered User

Join Date: Mar 2008
Posts: 29
Re: Perkins 4-108 swap questions

The 4-108 was built in at least 18 countries and has powered every conceivable device that required a lower horsepower, reliable diesel. The basic blocks are the same. The difference is in the parts used for marinization. Before you do anything, have you diagnosed the reason that the rod came through the block. Sounds like it could be an oil pressure (or lack therof) problem. If the replacement block is from a running take out, then you are probably OK. THis is also a good time to clean and inspect the heat exchanger, the damper plate and the motor mounts (relatively cheap and easy to replace).
Captain Bob is offline   Reply With Quote
Old 08-04-2016, 11:31   #10
Registered User

Join Date: Jan 2016
Posts: 429
Re: Perkins 4-108 swap questions

Do you know for sure what caused it to throw the rod - and what else needs replacing?

ie what Captain Bob said Jeez, did it really take me half an hour to write a sentence? Duh...
unclemack is offline   Reply With Quote
Old 08-04-2016, 15:22   #11
Registered User

Join Date: Dec 2012
Location: Mannum, Australia
Boat: Houseboat, 45ft.
Posts: 90
Re: Perkins 4-108 swap questions

Not sure about the Perkins but some generator motors have "fixed" fuel pumps /governor to maintain EXACT revs for either 50 or 60 Hz.
Might need to swap out the injector pump?
My Westerbeke has an independent belt driven governor.
BruceS is offline   Reply With Quote
Old 08-04-2016, 16:08   #12
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,505
Re: Perkins 4-108 swap questions

Quote:
Originally Posted by Cheechako View Post
Don, I'm not sure what you mean? If the difference is only the accessories then... yes ... right?
If you read the question the way it was written, no means there is no reason it can't be done...
donradcliffe is offline   Reply With Quote
Old 08-04-2016, 21:22   #13
Registered User
 
synclavier's Avatar

Join Date: Apr 2016
Location: Denver, CO
Boat: Allied Princess 36
Posts: 11
Re: Perkins 4-108 swap questions

I assume that it threw a rod due to oil starvation, but I'm not exactly sure why that happened. The boat yard pulled the engine without my being there, so I haven't gotten a closer look yet. Thanks for the replies.
__________________

synclavier is offline   Reply With Quote
Reply

Tags
perkins

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Repowering with Perkins 4.108 -- Have some questions... Astral Blue Engines and Propulsion Systems 30 23-11-2012 14:12
Westerbeke Swap for Perkins RedFalcon Engines and Propulsion Systems 7 22-02-2011 08:55
Perkins 4-108 vs Westerbeke 4-108 world spectator Engines and Propulsion Systems 14 15-08-2010 17:33
Perkins 4-108 Rebuild Questions bobfnbw Engines and Propulsion Systems 20 06-08-2009 10:16
Perkins 4.108 cburger Engines and Propulsion Systems 8 11-05-2006 10:31



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 19:19.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.