Perkins 4108 cracked head

[Ardeleanu]

Hello, after believing to have blown the head gasket, I took it upon myself to rebuild the motor. All came off easy except the cylinder head who took a long time and a lot of muscle power to get out. Once off, I realized the 3rd cylinder was full with coolant and the head has a hair crack.
I am looking for solutions. EBay doesn't have the cast number and most places I called rework the core...
Thank you in advance. 37116500/3

[tkeithlu]

Welcome to the forum, Ardeleanu. There are bunches of 4108 owners hereabout. I'm not one of them, but I am concerned that you may have damage farther down, such as the connecting rod on #3 and wherever that coolant came from. I'm sorry you're facing a nasty situation.

[Engine man]

Perkins 4.108M engines are known for cracked heads and rear main seal oil leaks. Perkins no longer fully supports this engine, and many parts, including new heads, are no longer available from Perkins. Welding cracked heads sometimes works, but with questionable reliability.

The Beta 38 or Beta 43 is suggested as a modern replacement for the old Perkins. Smaller, lighter, MUCH quieter and smoother running, with no parts availability problems. Also, newer engines burn their fuel so cleanly, one cannot smell the exhaust. That's appreciated when powering downwind in light air !

NOTE - the 4.108M was factory derated, when installed in a displacement hull, to 40hp @ 3000 rpm. Planing powerboats used the same engine, rated 51hp @ 4000 rpm. Joe

Originally Posted by Ardeleanu

Hello, after believing to have blown the head gasket, I took it upon myself to rebuild the motor. All came off easy except the cylinder head who took a long time and a lot of muscle power to get out. Once off, I realized the 3rd cylinder was full with coolant and the head has a hair crack.
I am looking for solutions. EBay doesn't have the cast number and most places I called rework the core...
Thank you in advance. 37116500/3

[River Runner]

The good news is that the 4.108 can be found in multiple tractors brands, taxis and my Westerbeke 40 is also a 4.108. I just rebuilt the head on my engine and it was in good shape but also very hard to break loose.

[Allied39]

Clean and inspect all cylinders. A cracked head is a pretty common thing in motors generally (with an issue like an over heat) and most definitely does not doom the motor in most cases. You can get a pretty darn good idea if you have more problems than the crack.

Limited information doesn't help, did the engine lock? Did you try to crank the engine while the cylinder was full of coolant or is it more likely the coolant filled the cylinder after shut down and therefore the cylinder never tried to compress the uncompressible? How do the cylinders look? etc etc etc.

Yes if you have 15 plus G laying around and the ability to swap it out just whip in a new engine.....as suggested.

Depending on the answers to the above questions you may just be up for a new(new to you) head, a pretty easy thing to do.

Old motors are pretty good. When cared for , clean air, fuel and regular oil changes old motors will run a long time. And no pesky diodes and circuit boards.

Just my opinion, not interested in arguing about how all old engines should be changed to save the planet blah blah blah.....just giving the Op some info.

[Bill O]

If nothing else bad happened to your motor besides the cracked head, would purchase another head/gasket and reassemble.

I was a little shocked to see bare remanned heads going for >$1K, while full ones (valves, etc.) ~$1.5K


Edit: Found this thread from last year and a member (last post) said he had some sitting around in FL. https://www.cruisersforum.com/forums...ad-226956.html

[River Runner]

I have become a real believer in the durability of the Perkins 4.108. I didn’t know it at the time but mine took our Yacht from Alameda to Stockton running on three cylinders, smoked like crazy. I’m now in the process of putting over six hours on the rebuilt head so I can re-torque the head and re-adjust the valve clearance.

[Capt. Tom]

Trans Atlantic Diesel in Virginia has parts, try them. Have had good luck with dealing with them.

[Lepke]

A good automotive machine shop can fix a cracked cast iron head. Also a welding shop with cast iron skills can fix it, too.

[Marutji]

Originally Posted by Ardeleanu

Hello, after believing to have blown the head gasket, I took it upon myself to rebuild the motor. All came off easy except the cylinder head who took a long time and a lot of muscle power to get out. Once off, I realized the 3rd cylinder was full with coolant and the head has a hair crack.
I am looking for solutions. EBay doesn't have the cast number and most places I called rework the core...
Thank you in advance. 37116500/3

Get in touch with www.parts4engines.com. They are based in the UK, but they shipped out a new 4108 (not recon, new) to me in Tahiti for a very reasonable price. Send them an email because when they get new heads, they usually don't make it on to the website. Great company to deal with and can usually find all things 4108. Good luck!

[Ardeleanu]

Thank you for your reply. I saw that thread when I was not registered but had lost its address once in the forum. I was hoping it would show up. Thank you again, I reached out to the gentleman.

[Ardeleanu]

Thank you for your amazing reply. The motor was run, cracked with coolant in it for sure because once I removed the head, the third and forth valve were rusted and filled with coolant. The engine is somewhat locked as I can't see the valves actuate as the shaft is rotated by hand. The starter wheel would not move, even tapped with a hammer. Could the bottom part be toast and how do I further troubleshoot if the engine is repairable ?

[River Runner]

With the head removed put a large socket on the nut on the pulley on the crankshaft at the front of the engine. Use a 1/2” breaker bar on the socket. This should help you turn the engine over in a clockwise rotation. First clean and oil your cylinder walls and be sure the transmission is in neutral. If the engine turns over without any trouble you may be in luck.