My Perkins 4.108 has 2400 hours and the oil leak is getting worse with time. Past posts have indicated that the engine is overdue for a new rear seal, and that is where the leak seems to be coming from. I read the Perkins manual on this subject and have some questions. The manual covers 3 different engines and is vague on a number of items.
Firstly, the manual claims that I should check the crankcase pressure, but does not say where or how. It claims there is a ventilator valve that may be malfunctioning, but does not show where it is or have a part number. Does anyone have any experience with a ventilator valve (PCV?) or how to check crankcase pressure or what an acceptable level is?
The next question has to do with the seal itself. The manual claims that the seal is an asbestos coated material that one has to cut to size and form the two halves into a housing. I have to think that the asbestos seal is no longer used and that there is a new seal of some sort. Has anyone had a new seal put in and know if there is a new seal?
Has anyone done the job themselves or witnessed the job being done as installed in the boat? I assume that the transmission and housing come out and then the flywheel must come off. After that does the oil pan need to come out? For a reasonably competent individual can this job be done in 4 to 5 hours or is it something that will require lifting the engine?
Your advise would be appreciated.
Matt
Perkins 4.108 oil leaks.
Moderator: Jim Walsh
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Matt Cawthorne
- Posts: 355
- Joined: Mar 2nd, '05, 17:33
- Location: CD 36, 1982
Hull # 79
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Perkins 4.108 Oil Leaks
Hi Matt,
I was waiting for someone else to jump in on this one, so I'll give it a shot.
What usually happens on other engines and could be happening on your engine to cause the leaks is positive crankcase pressure.
When an engine puts many hours on the clock, just like us, wear and tear take it's toll and things start to break down. The older the engine is, the looser it gets. Included in this aging process are the piston rings.
Obviously, the rings seal the combustion chamber so that the fuel can be compressed to the point of ignition. As the rings age, there is microscopic wear on them and some of the compressed charge leaks past them and goes into the next available place, the crankcase. This leakage is called blowby.
Depending on the severity of the blowby, positive pressure can build up in the sealed crankcase. This crankcase pressure is looking for a way to escape. The aged, well worn rear main seal is usually the path of least resistance and the pressure causes an oil leak through it.
Some engines are equipped with a PVC (Positive Crankcase Ventilation) valve. This valve, when working properly, does just as it's name implies, ventilates the crankcase. In many cases it is overlooked and neglected during routine maintenance. Because of the nature of it's duty, it can sludge up and become ineffective in ventilating the crankcase. This will cause pressure to build up in varying degrees, depending on the amount of ring wear and blowby.
I have no idea of what the specs call for on the crankcase pressure of your engine. In severe cases, if you remove the oil filler cap while the engine is running at idle, you might actually feel the pulsations of blowby with the palm of your hand pressed against the oil filler tube.
Some compression tester sets come with threaded adapters in various sizes. If you have a PCV valve on your engine, remove it and see if you have access to an adapter to match the PVC thread. Seal the filler tube (rubber ball pressed against it) and measure the crankcase compression.
There is a Mickey Mouse way to install a new rear main seal with out disconnecting all the connecting rod bearings and removing the crankshaft. However, this requires raising the vehicle on a lift and draining and removing the oil pan. A wire is passed through the main bearing journal, attached to new seal material and pulled through the journal, above the crankshaft.
I don't think that this will work for you. From what I see, you are probably going to have to pull your engine to do this kind of work on it.
Before you take the plunge, you might do a few things first. Install a new PVC valve and drain the oil and put in a heavier multiviscosity oil. Before adding the new oil, pour in a bottle of Lucas Heavy Duty Oil Stabilizer, about $8,00 at auto supply stores. It might help you, it has helped others.
Good luck,
O J
I was waiting for someone else to jump in on this one, so I'll give it a shot.
What usually happens on other engines and could be happening on your engine to cause the leaks is positive crankcase pressure.
When an engine puts many hours on the clock, just like us, wear and tear take it's toll and things start to break down. The older the engine is, the looser it gets. Included in this aging process are the piston rings.
Obviously, the rings seal the combustion chamber so that the fuel can be compressed to the point of ignition. As the rings age, there is microscopic wear on them and some of the compressed charge leaks past them and goes into the next available place, the crankcase. This leakage is called blowby.
Depending on the severity of the blowby, positive pressure can build up in the sealed crankcase. This crankcase pressure is looking for a way to escape. The aged, well worn rear main seal is usually the path of least resistance and the pressure causes an oil leak through it.
Some engines are equipped with a PVC (Positive Crankcase Ventilation) valve. This valve, when working properly, does just as it's name implies, ventilates the crankcase. In many cases it is overlooked and neglected during routine maintenance. Because of the nature of it's duty, it can sludge up and become ineffective in ventilating the crankcase. This will cause pressure to build up in varying degrees, depending on the amount of ring wear and blowby.
I have no idea of what the specs call for on the crankcase pressure of your engine. In severe cases, if you remove the oil filler cap while the engine is running at idle, you might actually feel the pulsations of blowby with the palm of your hand pressed against the oil filler tube.
Some compression tester sets come with threaded adapters in various sizes. If you have a PCV valve on your engine, remove it and see if you have access to an adapter to match the PVC thread. Seal the filler tube (rubber ball pressed against it) and measure the crankcase compression.
There is a Mickey Mouse way to install a new rear main seal with out disconnecting all the connecting rod bearings and removing the crankshaft. However, this requires raising the vehicle on a lift and draining and removing the oil pan. A wire is passed through the main bearing journal, attached to new seal material and pulled through the journal, above the crankshaft.
I don't think that this will work for you. From what I see, you are probably going to have to pull your engine to do this kind of work on it.
Before you take the plunge, you might do a few things first. Install a new PVC valve and drain the oil and put in a heavier multiviscosity oil. Before adding the new oil, pour in a bottle of Lucas Heavy Duty Oil Stabilizer, about $8,00 at auto supply stores. It might help you, it has helped others.
Good luck,
O J
"If I rest, I rust"
Voting Member #490
Voting Member #490
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Andy Denmark
- Posts: 630
- Joined: Feb 5th, '05, 11:38
Impossible to correct (well, nearly)
I have only heard of one 4-108 that didn't leak oil and I'll give him the unique pleasure of chiming in here. (Yo, Dennis) When someone would come into the yard with a 4-108 oil leakage problem, my engine mechanic would roll his eyes, throw up his hands, and tell the customer that he would try to fix it but, if successful on a long term basis, it would be equivalent to turning lead into gold.
Having delivered a lot of boats with 4-108's, I'd have to agree. I usually carry double the number of OilSorb pads on boat equipped with this engine and use most of them.
All that said, it's a great powerplant and the cost of lots of OilSorb pads is far less than a rebuild with questionable results.
FWIW
________
DODGE V. FORD MOTOR COMPANY
Having delivered a lot of boats with 4-108's, I'd have to agree. I usually carry double the number of OilSorb pads on boat equipped with this engine and use most of them.
All that said, it's a great powerplant and the cost of lots of OilSorb pads is far less than a rebuild with questionable results.
FWIW
________
DODGE V. FORD MOTOR COMPANY
Last edited by Andy Denmark on Feb 13th, '11, 03:19, edited 1 time in total.
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Guest
4-108 Oil Leaks
Seems to me that if all these engines leak its a mfgs design flaw. Time to go back to the drawing board. So what are the major leaks?
A R
A R
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Matt Cawthorne
- Posts: 355
- Joined: Mar 2nd, '05, 17:33
- Location: CD 36, 1982
Hull # 79
I have always taken this approach in the past. It, however, has gotten to the point of me not needing to change the oil. I just pour it in the top and before it needs changing it has run out the bottom. I don't want to haul it out to replace the seal. If I can do it in the boat for 5 or 8 hours worth of effort it will be worth it.I usually carry double the number of OilSorb pads on boat equipped with this engine and use most of them.
The only two leaks that I believe that I have is the rear seal and the front timing gear cover. The timing gear cover would be easy to fix except for the fact that the front pulley needs to be removed. To pull that pulley the engine has to be raised about 8 inches to clear a bulkhead......or I could cut the bulkhead and fix it later......
Matt
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Steve Alarcon
4-108 leaking
Matt,
Last year I got fed up with the smelly mess, and talked to my mechanic. Together we agreed that the best thing was to pull the engine, and replace all of the gaskets as I had leaks all over the place. It took him several hours to get it out, and the intake maniford, exhaust and coolant tank had to be removed. While it was out I took the oportunity to de-grease and paint the engine room, re-plumb everything, replace all the hoses, put in new sound insulation and generally make the engine room look like new. The only thing I didn't do was have the engine bed replaced - and I'm regretting that now as the mild steel is rusting under the paint. When it was reassembled, he did corosion control and repainted the engine. Now the engine looks like new, everything in the compartment is pretty and there are no greasy, burnt oil smells in the engine room or in bilge. Cost / benefit is a personal issue in my opinion, but I can tell you that from where I sit I'm glad I did it.
Steve Alarcon
CD36 Tenacity
Seattle
Last year I got fed up with the smelly mess, and talked to my mechanic. Together we agreed that the best thing was to pull the engine, and replace all of the gaskets as I had leaks all over the place. It took him several hours to get it out, and the intake maniford, exhaust and coolant tank had to be removed. While it was out I took the oportunity to de-grease and paint the engine room, re-plumb everything, replace all the hoses, put in new sound insulation and generally make the engine room look like new. The only thing I didn't do was have the engine bed replaced - and I'm regretting that now as the mild steel is rusting under the paint. When it was reassembled, he did corosion control and repainted the engine. Now the engine looks like new, everything in the compartment is pretty and there are no greasy, burnt oil smells in the engine room or in bilge. Cost / benefit is a personal issue in my opinion, but I can tell you that from where I sit I'm glad I did it.
Steve Alarcon
CD36 Tenacity
Seattle
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leopold fuchs
prekins 4108
Many years ago I asked a friend of mine who works in a boat yard what he thought about Perkins engines.
His Reply was, "Don't you know why the English don't build computers?"
"Cause they can't get them to leak oil!"
His Reply was, "Don't you know why the English don't build computers?"
"Cause they can't get them to leak oil!"
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Bill Cochrane
- Posts: 212
- Joined: Feb 5th, '05, 13:42
- Location: Cape Dory 36 #114
s/v Phoenix
Now that humor has crept in...
...I remember a review in the mid 60's of one of the latest creations from Leland Motors (or JRT, or...) in C&D or maybe R&T...can't remember the marque or the mag, but I remember one paragraph verbatim:
"Oil leaks? Of course; it's British."
And then there was Lucas Electrics, better known as the Prince of Darkness, and about which it was once said that the only thing they built that didn't suck was a vacuum cleaner...
From British cars to a British engine in a sailboat...with a Lucas starter...you'd think I'da learned something in 35 years...
"Oil leaks? Of course; it's British."
And then there was Lucas Electrics, better known as the Prince of Darkness, and about which it was once said that the only thing they built that didn't suck was a vacuum cleaner...
From British cars to a British engine in a sailboat...with a Lucas starter...you'd think I'da learned something in 35 years...
Regards, Bill
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Greg Kozlowski
Replaced front and rear oil seals 3 years ago
Hi Matt,
We replaced both oil seals on our 4-108 in Barcelona with the engine in the boat. They seem to be holding still 3 years and quite a few engine hours later.
The rear seal looks like it could very well be asbestos and it does come in 2 halves which can be fitted without taking the crank out.
I had to take the Herth gear, bellhousing, starter, and flywhell off and jack the back of the engine up under the oilpan and then the seal could be changed. A sort-of-mechanic worked with me who had done it before, and as he was smaller than me he did most of the work back behind the engine. It is more than a five hour job, but it is certainly doable and not a terribly big hassle.
Saw a guy do the same at anchor in Isle Margarita on the 4-108 in his Passport.
One hint regarding preventing the seal from failing: the seal is a splash seal so never, absolutely never overfill the oil as it will saturate the seal. I keep just slightly less than right full especially when leaving the boat for the winter.
Good luck,
Greg
s/v Sherpa, Marmaris Turkey
We replaced both oil seals on our 4-108 in Barcelona with the engine in the boat. They seem to be holding still 3 years and quite a few engine hours later.
The rear seal looks like it could very well be asbestos and it does come in 2 halves which can be fitted without taking the crank out.
I had to take the Herth gear, bellhousing, starter, and flywhell off and jack the back of the engine up under the oilpan and then the seal could be changed. A sort-of-mechanic worked with me who had done it before, and as he was smaller than me he did most of the work back behind the engine. It is more than a five hour job, but it is certainly doable and not a terribly big hassle.
Saw a guy do the same at anchor in Isle Margarita on the 4-108 in his Passport.
One hint regarding preventing the seal from failing: the seal is a splash seal so never, absolutely never overfill the oil as it will saturate the seal. I keep just slightly less than right full especially when leaving the boat for the winter.
Good luck,
Greg
s/v Sherpa, Marmaris Turkey