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14-11-2020, 15:04
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#1
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Registered User
Join Date: Jan 2020
Location: Norfolk, VA
Boat: Morgan OI Pilothouse 33'
Posts: 18
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Perkins 4.108 - Rebuild or ???
Thanks to this forum, I found a lightly used Perkins 4.180 engine off of a Kohler generator, and I'm in the process of getting this engine ready to replace the heavily used, smoking, leaking and overheating 4.108 on my Morgan 33' OI Pilothouse.
I've pulled the generator parts off of the engine, and am considering the following:
Replace rear main seal with Foley upgraded version.
Clean fuel injection system.
Replace gaskets
Paint the engine
My question to the group is, should I do a complete rebuild, or just what I'm planning to do here?
Should I consider doing any other upgrades, such as listed on https://www.foleyengines.com/perkins...4-108-update/? Anything else I should make sure to do while I have the engine out of the boat?
Attached are some pictures of the engine as it stands.
Thanks in advance!
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14-11-2020, 15:07
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#2
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Registered User
Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 9,626
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Re: Perkins 4.108 - Rebuild or ???
I would, at a minimum, since it’s easy now.
Change the front and rear seals, and clean/paint the engine.
The rest can be done once it’s in and proven to run well.
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14-11-2020, 15:10
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#3
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Registered User
Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 1,342
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Re: Perkins 4.108 - Rebuild or ???
Everything depends on the state it is in. Take off the head and you will know what your decision is for sure. My guess is a complete rebuild, I said guess.
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14-11-2020, 15:20
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#4
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,453
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by sailormed
Everything depends on the state it is in. Take off the head and you will know what your decision is for sure. My guess is a complete rebuild, I said guess.
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I agree about removing the head I think, you can find out how much cylinder ridge there is. Generators run full out rpm 100% of the time. Does it have the right governor for a power engine?
Strangely my '85 4-108 leaked zero oil.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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14-11-2020, 15:21
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#5
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Registered User
Join Date: Jun 2019
Posts: 2,604
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Re: Perkins 4.108 - Rebuild or ???
I seem to recall early episodes from Sailing Uma where they wanted to install a new-to-them engine they had scavenged from a generator. They had issues adapting the governor that ran the engine at a consistent 1800 RPM, so much of an issue that they abandoned the attempt and went withe their first install of an electric motor.
I forget exactly, and while I'm a decent garage mechanic, this is a bit beyond me. Any thoughts on taking a motor from a generator that runs at a consistent rpm and adapting for propulsion?
Peter
__________________
_______________________________________
Cruising our 36-foot trawler from California to Florida
Join our Instagram page @MVWeebles to follow along
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14-11-2020, 15:54
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#6
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Registered User
Join Date: Sep 2009
Location: Houston
Boat: '76 Allied Seawind II, 32'
Posts: 9,626
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by mvweebles
I
I forget exactly, and while I'm a decent garage mechanic, this is a bit beyond me. Any thoughts on taking a motor from a generator that runs at a consistent rpm and adapting for propulsion?
Peter
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A lot depends on the engine.
Engines like an 05 series Kubota may or maybe not have different injectors optimized for a specified rpm range, but typically use the same governor as a propulsion engine. If I wanted to I could adjust the stops on our throttle position arm and create a constant speed engine.
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14-11-2020, 16:33
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#7
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Registered User
Join Date: Sep 2017
Location: Langley, WA
Boat: Nordic 44
Posts: 2,496
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Re: Perkins 4.108 - Rebuild or ???
Do you know how many hours are on this engine? Have you checked the compression? Just replacing the crankshaft seals won't solve oil leaks if the blow-by pressure is too high. And, as already said, generator engines are run flat out for long periods of time. If the rings need replacing you are going to bore or replace the cylinder sleeves so at that point you may as well do the full rebuild.
When I was faced with the rebuild or replace decision with my 4-108 17 years ago I choose to replace. The rebuild cost may not be a viable solution, especially if you need a major part like an injection pump or a crankshaft.
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14-11-2020, 16:33
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#8
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Registered User
Join Date: Apr 2011
Location: Norfolk
Boat: Sea Sprite 34
Posts: 443
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Re: Perkins 4.108 - Rebuild or ???
I'd run a leak down and compression test. If both pass, I'd reseal it, change all coolant hoses.
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14-11-2020, 16:44
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#9
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Marine Service Provider
Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,803
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by Cruiser2B
I'd run a leak down and compression test. If both pass, I'd reseal it, change all coolant hoses.
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what he said,
+ Set tappet clearances since you have rocker cover off.
Clean hx if it has one.
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14-11-2020, 18:48
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#10
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Registered User
Join Date: Jan 2020
Location: Norfolk, VA
Boat: Morgan OI Pilothouse 33'
Posts: 18
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by Cheechako
I agree about removing the head I think, you can find out how much cylinder ridge there is. Generators run full out rpm 100% of the time. Does it have the right governor for a power engine?
Strangely my '85 4-108 leaked zero oil.
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I have wondered the same thing. The fuel governors look the same, but I have no idea. I can always swap out from my existing engine or at least that’s what I’ve been telling myself. 😂
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14-11-2020, 19:01
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#11
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Registered User
Join Date: May 2010
Location: Sydney Australia
Boat: Fisher pilothouse sloop 32'
Posts: 3,413
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by btompkins
I have wondered the same thing. The fuel governors look the same, but I have no idea. I can always swap out from my existing engine or at least that’s what I’ve been telling myself. 😂
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Providing that they are the same engine, treat the new one as a long block and transfer all the peripherals over.
I would ensure that the new one is a good runner before doing too much to it though.
__________________
Rob aka Uncle Bob Sydney Australia.
Life is 10% the cards you are dealt, 90% how you play em
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14-11-2020, 20:16
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#12
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Senior Cruiser
Join Date: May 2013
Location: Oregon to Alaska
Boat: Wheeler Shipyard 83' ex USCG
Posts: 3,494
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Re: Perkins 4.108 - Rebuild or ???
It's an easy engine to rebuild and it's out of the boat now.
Coming from generator service, the injector pump is probably optimized for 1800 rpm.
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15-11-2020, 07:23
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#13
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Registered User
Join Date: Jan 2020
Location: Norfolk, VA
Boat: Morgan OI Pilothouse 33'
Posts: 18
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by Lepke
It's an easy engine to rebuild and it's out of the boat now.
Coming from generator service, the injector pump is probably optimized for 1800 rpm.
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Yes, it looks like it's held open with a spring. I'll take some pictures, as this seems to be the main issue for now. Thanks!
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15-11-2020, 07:24
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#14
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Registered User
Join Date: Jan 2020
Location: Norfolk, VA
Boat: Morgan OI Pilothouse 33'
Posts: 18
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by Lepke
It's an easy engine to rebuild and it's out of the boat now.
Coming from generator service, the injector pump is probably optimized for 1800 rpm.
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It doesn't look hard, and I agree. Two things concern me, the special tools needed, and cutting the valve seats looks a little intimidating. Is it really that easy?
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15-11-2020, 07:27
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#15
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Registered User
Join Date: Jan 2020
Location: Norfolk, VA
Boat: Morgan OI Pilothouse 33'
Posts: 18
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Re: Perkins 4.108 - Rebuild or ???
Quote:
Originally Posted by Uncle Bob
Providing that they are the same engine, treat the new one as a long block and transfer all the peripherals over.
I would ensure that the new one is a good runner before doing too much to it though.
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I think it is a good runner. I do plan on moving some over, the transmission and bell housing, flywheel etc. It has the newer model heat exchanger, which is good I think, but the one thing that has me scratching my head is that it has a belt driven water pump">raw water pump. I like this better than the other option, but it seems like it will require a fourth pulley, which I'm not sure how to get setup. I was looking at the serpentine systems, but don't need a huge alternator as far as I know, but maybe I should JIK? Still wondering about the fourth pully. Probably could just use the engine driven raw pump if I have to.
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