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Old 09-03-2007, 14:08   #1
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Perkins 4-108M Rusted Valve

I've owned my sailboat for just 6 months and for the fist 5 months my trusty 4-108 purred away nicely. Engine has 2,000 hours and is a 1985 model. In January it started to lose a little power and then I started to get white smoke from the exhaust.

To cut a long story short things got worse fairly quickly...power loss continued, smoke got worse. I pulled the head last weekend. Small amount of water in No 4 cylinder (the lowest as the engine slopes down at back), No 4 exhaust valve rusted and not sealing. No 3 exhaust valve looks a little rusty too. No sign of leaks on the head gasket. Checked out heat exchanger - very corroded at all pipe joins. Checked out exhaust elbow/riser (mine is the s-shaped one) - inner steel jacket totally corroded out with chunks of the metal partially blocking the exhaust outlet, outer aluminium looks perfect.

My conclusion is that the elbow/riser failure prevented salt water being injected into the exhaust on the downward slope (leading to the water lift muffler) and instead it let salt water settle in the manifold side of the "S" and back up into the exhaust manifold and then slosh on to the valves causing them (mainly No 4) to corrode over time. All preventable of course with a little basic maintenance...GRRRR.

My question is this. Should I rebuild the botom end (rebuild kit, etc) or just do the head, valves, etc and new heat excahnger and elbow? The bores all look and feel fine - no scratches, vertical marks, etc but they do have general wear with a lip. The No 4 piston looks a little rough and this may be rust, but I suspect this is from lack of efficient combusion due to the valve not sealing.

Thoughts and suggestions welcomed.

Mike
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Old 09-03-2007, 15:18   #2
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Hi Mike, nice to see another from close to home.
The first question you need toa nswer is how many hrs/yr do you tally up. Most yachties are in the 200hr range tops. That means you still have many years left on the block. So giving the head some TLC should all that is needed. I would get the injectors rebuilt and Injector Pump looked at while you are at it.
An important lesson that should be taken from this is, when you FIRST see a possible problem, take a look at it ASAP!! before any seriouse damage is done.
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Old 09-03-2007, 15:32   #3
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Lovely engine. IMHO Just do the valve job and head. Have the injectors tested and redone if necessary. Make certain all saltwater can be ejected out the waterlift and have a siphon break where it is recommended especially if the exhaust exits the engine below your waterline.

Good luck and don't ever change the engine. Perkins is #1

A rebuild on an injector pump here in Hawaii is $850 US Dollars. I wouldn't do it again unless I absolutely had to.

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Old 10-03-2007, 15:48   #4
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Thanks for the great advice Wheels and John.

Glad you saw this Wheels, as its always good to find someone 'local' on a forum.

I'd say you have both concluded the same as me and it does boil down to how much life is left in the engine. My feeling is that if I have 5,000+ hours total I'm not yet half way there. I costed a new engine and the total in $NZ is around $30,000 ($20,000 for engine, $10,000 for fitting,etc). I can do a heck of a lot of rebuilding and refurbishing for a lot leass than that so the choice for me is pretty straightforward....stick with the Perkins.

That said it just comes down to far do I go right now. The only thing that would make me want to consider a bottom end rebuild is possible damage to the bores and the pistons caused by the salt water. The bores look fine. There is no water in the oil. However I can't see the pistons and rings without taking them out of the bores. To take them out of the bores requires removing the engine which is a major job as you know. If I take the engine out them I might as well do the full rebuild anyway....

I've gone round in circles with this and I agree with you guys. It boils down to taking the risk. I'm doing the head (flush and clean, clean ports, skim, new valves, guides, remake seats, etc), servicing the injectors, new heat exchanger (its too corroded at all the pipe joins to stick with), new exhaust elbow, and a bigger water lift muffler (by my calcs it is too small for the volume of exhaust hose above it). John, I will include a siphon break - it already had one but the design was a bit suspect.

Wheels, I don't think the injector pump needs attention as the engine was running fine even with the valve problem (albeit down on power and smokey as you'd expect).

I' keep posting progress as I get the time to work on it over the next few weeks.

Fingers crosssed!

Mike
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Old 10-03-2007, 21:41   #5
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Aloha Mike,
I don't think I have as much experience with mechanicals as wheels has so please don't consider me an expert. I've had a couple of diesels apart and managed to get them back together and running properly but my opinions are just opinions. I had an old 4-107 which was just a great little engine and took a lot of abuse. Good service and attention should keep yours running for years.
I think you are doing the right thing.
Good luck,
JohnL
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Old 20-05-2007, 23:35   #6
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Its running again!!

Just thought I'd post an update.

I ve been waiting for the last months and a half for parts (a new heat exchanger and exhaust elbow) to arrive from the UK and USA respectively.

They finally came last week so I've spent the time since putting it all back together again. Last weekend was D-day...I set the tapets, finished off my new water lift muffler installation, fitted all the remaining hoses and belts, and reinstalled injectors an fuel lines. Last job was to bleed the fuel system which took me a couple of goes to get it clear.

Moment of truth was upon me. I turned the engine over with the stop button in to get the oil pressure up a bit then gave it a try. Nothing! Turned over just fine but no sign of ignition. So...re-bled the fuel, tried again. Still nothing. Had a beer, went home to think and watch the Americas Cup which starts at midnight in this part of the world.

Next morning I checked the fuel supply (OK), checked the cut off solenoid in case it had stuck closed (OK). My next boat neighbour at the marina (John the diesel expert) came over about then. Now I hate giving up on mechanical probelms but hey, when a friend offers what can you say.

John re-bled the fuel system, checked my tappet settings (they were fine of course!), tried it again and still it wouldn't start. Being a technical whiz he sugested a quick decider to help diagnose what was going on. Yes, you guessed it, a spray of ether Engine Start.

One turn on the starter moter and my trusty Perkins burst into life, and then surprised us both by keeping running. It was a bit smokey to start with but I put that down to all the oil I'd left in the bores, then settled down to a nice idle. As it warmed up to normal operating temp the smoke went away and the smile on my face increased with every minute.

Anyone figure why it wouldn't start straight up?

Mike
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Old 21-05-2007, 00:03   #7
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Quote:
My feeling is that if I have 5,000+ hours total I'm not yet half way there.
Aye mate, I know a guy with a CSY 37 charter boat in the US Virgin Islands: He ran his 4-108 up to 15,000 hours before overhaul.
At the time there was nothing wrong with the engine or the performance, he just got nervous with the high hours and decided to bite the bullet before something happened.

My 4-108 have around 4,500 hours on it and runs very good, I ain't even thinking about anything but basic maintenance.

That being said, last year I had a failure of the anti-siphooning valve while anchored overnight and the # 3 or # 4 cylinder filled up with salt water.
Could not get the Perkins started next morning, she would not even turn over...Hydraulic lock.

Long story short, loosened the injectors, spun the engine on the starter motor to clear out water/diesel/lube-oil then changed oil and cranked up..No problem.

These engines seem to be bullet proof and able to take tons of abuse.....perfect for us sailboaters I guess...
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Old 29-10-2007, 22:28   #8
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Update # 2

Well, I'm afraid the good news didn't last long. Engine got hard to start, still smoked and it got worse - blue and white, went away mostly under full load but always very smokey when under light load or warming up. So I decided (after period of depression) that it was time to do the job properly. Ordered full rebuild kit (liners, pistons, oil pump, bearings, valves and guildes and gaskets) plus a new water pump, lift pump, and valves springs from Trans Atlantic Diesels. Will send IP and injectors off for a check up too. This baby's getting the works! I've alrready had the engine removed ready to lift it out with my boom (fun for this weekend) then it's off to the rebuilders. While that's happening I'm repainting the bilge under the engine, replacing the shaft seal with a PSS and adding more insulation to the engine room.

Also sending my prop to be resized down 1.5 inches (see my earlier posts on this).

Hope to have it all finished in time to go away at Christmas.

Mike
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Old 29-10-2007, 22:41   #9
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That sucks...

Did you have the head magnafluxed or zyglo'd? It's possible the head is cracked ;-(

Now that you are doing the full tilt make sure you invest fully in the machine shop work for a long lasting end product. In addition to NDT inspections - Head and block milled, cam, crank journals and valve train bearings all spec'd out. Bores and conrod journals etc. etc...

You'll be happy in the end for sure...
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Old 29-10-2007, 23:00   #10
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Thanks Dan

Yep, its getting the Full Monty. Still reckon its worth rebuilding vs a complete new engine although I agonised over the decision and changed my mind several times. A new Yanmar 4JH was the alternative but it all still boiled down to $25-30K vs $10K for the remainder of a full rebuild and that $20K difference can be spent on lots of other needed boat goodies! The new engine option looks fine at $18K until you add in all the other things that need to be changed/replaced and then you realise that sticking to the Perkins is the best option (for me anyway).

Mike....soon to be happy!
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Old 30-10-2007, 00:17   #11
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Yep your doing the right thing. The Perkins in top condition will last you years....providing the manifold doesn't do that again.
I hope you have had better luck at finding a good mechanic, unlike Darryl on Seafox. Also realise that these engines are also used in Farming equipment. So a Marine mechanic is not your only choice to have these done up by and a Farming mechanical workshop may be cheaper.
I am not sure what would have caused your problem though. Unless water had got down the side of the piston and corroded Rings. That is a classic problem and would cause issues like you have had. Apart from that, make sure you do the warm up as in the Study hall, or glazing the bores can result.
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Old 31-10-2007, 01:13   #12
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Hiya Wheels

Thought you'd see this!

How about we catch up over Xmas. All things mechanical being fixed I'm planning to head down south. Hope to be in Torrent Bay for New Years. What you up to?

Mike
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Old 31-10-2007, 02:26   #13
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Yeah Seafox, Marauder and maybe one or two others are all heading my way for a catch up. So I will keep you upto date with when and where when we work that out ourselves.
We missed out on Torrent Bay last season. We did get over the season before thoough. We were there when the dipstick on Sweet Georgia decided to burn down teh park with a flare.
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