Perkins 4108 rear seal replacement

[Chuck Losness]

Hi everyone. I have a perkins 4108 in my sailboat and the rear seal is starting to leak again. This seems to happen about every 300 to 400 hours on the engine. no problem for me to just replace it with another factory seal but before I did that I thought that I would ask if there is a better rear seal then the factory two piece seal. Folley engine claims to have a new type of seal but want $130 for a 10" piece of graphite impregnated nylon rope. seems expensive to me. I also found a brief reference on the net of one person who had used one piece of flax prop shaft packing and said that this had solved the problem of short life of his rear seal. Any ideas, experience or suggestions would be appreciated. I just got to think that there is a better then the factory 2 piece seal.
Thanks for your help.
Chuck
cruising in Mexico where life is good and the living is easy

[hartley]

I don"t think the rope type rear seal fitted to the perkins is the problem,this type of seal has been fitted to countless engines and gives good service,a life of a few hundred hours is just not good enough.The problem is most likely the installation of the seal ,if the engine was out for overhaul there is no excuse for a botched installation,but if a attempt was made to install the seal by dropping the pan it is almost guaranteed to leak,sometimes the bottom half only,of the seal is replaced,once again it will leak,another problem is some installers will cut the seal flush with the mounting surfaces ,it mst stand proud at least 1mm.The only way to do the job properly and successfully is to dismantle the engine ,inspect the rubbbing surface of the crank and do a proper installation.I guess that this is not want you want to hear ?? a leaking seal is more of a annoyance than anything unless it is pouring out if it is (pouring out) there is only one remedy.I should point out it is quite possble to install the seal in a car engine in situ,but in the confined space of a boat a different matter .
cheers hartley

[alan white]

Yes, and check the surface the seal rides on. Could be pitted, though most likely it's fine and the installation is at fault.

[Chuck Losness]

Thanks for the responses. The rear seal on the perkins 4108 is not contained in the oil pan. It is held in a carrier that bolts to the back of the engine. So there is no need to remove the pan and the crankshaft as on most engines to replace the rear seal on a 4108.
Is there anybody out there who has actual experience with the replacement of the rear seal on a perkins 4108?
thanks again.
Chuck

[hartley]

Yes the 4-108 rear seal can be replaced just by removal of seal housing ,this housing usually has a lip type seal ,but not on the 4-108, but it should not leak.maybe you should buy complete assembly,pay particular attention to rolling the seal into the housing leaving it protuding 1mm on the 4 ends
part # for seal assembly is/was 90990.......part#for seal is/was 36883107 hope this helps ..........btw if anybody is interested I have complete microfich sets for perkins engines ,but unfortunately microfich reader is on the blink probably only the globe ???? will see if I can get it going.
If all else fails you may have to go down Foley's track.
cheers hartley

[FAST FRED]

With the proper number to ID the seal, It can probably be ordered from a supply house for 1/10 the Perkins price.

Perkins just buys them , not makes them .

Worth a try?

FF

[Chuck Losness]

Hartley, The part number you gave for a complete seal/housing according to my perkins 4108 parts manual is only for the housing and doesn't include the seal.

Fast Fred, The cost of the standard perkins seal is not that expensive even with perkins mark up. The foley seal is what I thought was really expensive.

What I am looking for is someone who has tried seals other than the standard perkins 2 piece seal and what their experience has been. Has anyone used the foley one piece seal or any other type of seal?

Thanks again for your responses.

Chuck
S/V Hale Moana
cruising in Mexico where life is good and the living is easy.

[CDK]

There is a fisherman here in the bay who has the seal changed every spring. He makes long days so already after 3-4 months the seal starts leaking again, but he keeps on going until late in autumn.
I offered to make him an adapter so he can use an off the shelve Simmer-ring instead of this obviously worthless 2 piece design. He just had the 5th seal installed and started fishing some 4 weeks ago.

[hartley]

The main problem here,as I see it ,is why is this seal leaking?????.this type of seal (2 piece rope seal) has been used on countless cars over the years (example american v8's) as well as numerous perkins variants, english,german cars as well ,so why is the poor little 108 getting a bad rap???.To give an example,my mercedes benz 300D has the same type of rear seal ,that is 2 piece rope ,this car has travelled over 500000 kilometres the engine has never been opened ,the rear seal does not even weep let alone leak ,so the question has to be asked .........why is it so........perhaps some others have the answer???
cheers hartley

[kenJ]

Perhaps it is the seal housing that is the problem. If it is warped or twisted it may not be providing a proper shape to allow the seal to do it's job.

[pistnbroke]

maybe sump pressue is blowing oil out the seal ...?

[GRIKO]

Sir,

We are OEM manufacture of rope seals in 146 different sizes for different engines in (Asbestos) Fire Proof and also in Heat Resistent & Leak Proof material (Non Asbestos) in white and graphited both types.

There can be many reasons you are facing this problem.

all the four ends of the 2 seals are not right angle 90* where they are connected.

the length of the seals is short and after fitting the seals there is a slight gap appears at joints when the seals absorbs the oil and run on shaft for some time, the seal fully sets deep in the groov and start leaking.

The thickness of the raw seal is less

The width / section of the seal is less

You need to buy good quality rope seals and fit them in gap, press with thumbs or a roller so they fit in the groov as deep as the space provided. See that after fitting, the seals are .5 MM excess long at all corners and also +.5 MM High from the metal core in the Internal side (Crank side). THis way the seals grips the crank with internal pressure.

Hope this is helpful for you.

Your welcome to ask anyhting in this matter

ANIL KUMAR SHARMA
SHARMA INDUSTRIES INDIA
DELHI INDIA.
gapl@vsnl.com