engine change out

[Richard Donovan]

Hello. I'm new to sailnet and have a project to share. I'm going to replace my old yanmar 3qm30 (32 years old) with a new yanmar 3ym30 in my 1979 C&C 36. Anybody out there done it or similar and have wisdom for me? I began trying to fix my old motor when it suddenly wouldn't crank after I replaced the motor mounts due to excessive vibration only in forward gear. Also ran rydlyme throuogh engine for 3 hours with a transfer pump. Mechanic says exhaust was plugged and raw water has been getting in cylinders for some time. After exhaust manifold was remachined for almost what a new one would cost, I got news that complete valve job would be next to the tune of another $1400. Then we'd be able to see if cylinders would make enough compression to get me by for a while. I pulled the plug and said enough. Thanks for any help.

[chucklesR]

Unless you are stuck on Yanmar's I'd suggest you look around at other engine manufacturers. I've heard lots of good about Beta Marine for example - they are made in the UK, using a Kubota base.

That means there is a ready made list of parts that are not 'marine' priced because Kubota makes tractor engines.

Check this thread out : Any pros cons on the Beta Marine engines please?

[chef2sail]

The yanmar 3ym30 is the direct replacement for your 3qm30 as well as our 3gm20 on our C&C 35 MKIII 1983. Since the engine compartments are so small and almost custom on our boats I would say its best to go through with the Yanmar. It will involve very little modification on your engine bed. We have looked at replacing our also in the future. I would get an upgrade on the alternator if possible and get an Electromaxx.

The Beta is a great engine too and has been getting good reviews.

Dave

[Faster]

No question the re&re will go much more smoothly with an engine with the same mount patterns, footprint, overall size, and mounting angle. Also you're more likely to maintain your gear ratios by sticking with yanmar. Unless there's a significant price difference that makes it worthwhile I'd probably stick with the direct replacement.

I've 'been there', hacking out motor beds to adapt a Volvo into a boat that started out with an Atomic.. it worked in the end, but was a lot of work and bother.

[Geoff54]

I don't know enough about Yanmar models to comment specifically but, whatever you consider, make sure you have accessibility for the things that you need to get to - oil filter(unless you remote mount), oil drain, impeller (and where the bits go if one breaks up), can you bleed the fuel lines? (unless self bleeding), etc. Think of routine maintenance and also things that are prone to give problems.

Most newer diesels are more compact so make sure you can connect everything - for example, will you need a longer drive shaft? Issues with running the exhaust?

Beta makes nice stuff, the key things are easy to reach from the front of the engine and they will supply custom mounts which MIGHT simplify installation.

If all the important stuff is the same on the new Yanmar, that is probably the easiest route. If not start talking to the other manufacturers and ask a lot of questions.

[chef2sail]

Footprint for the newer Yanmar is slightly smaller. The mounts were in the same positions so no new reconfig are necessary,

[aa3jy]

Originally Posted by Richard Donovan

Hello. I'm new to sailnet and have a project to share. I'm going to replace my old yanmar 3qm30 (32 years old) with a new yanmar 3ym30 in my 1979 C&C 36. Anybody out there done it or similar and have wisdom for me? I began trying to fix my old motor when it suddenly wouldn't crank after I replaced the motor mounts due to excessive vibration only in forward gear. Also ran rydlyme throuogh engine for 3 hours with a transfer pump. Mechanic says exhaust was plugged and raw water has been getting in cylinders for some time. After exhaust manifold was remachined for almost what a new one would cost, I got news that complete valve job would be next to the tune of another $1400. Then we'd be able to see if cylinders would make enough compression to get me by for a while. I pulled the plug and said enough. Thanks for any help.

We've been thru this as well.. Who was you mechanic and which marina?

[aa3jy]

Originally Posted by chef2sail

Footprint for the newer Yanmar is slightly smaller. The mounts were in the same positions so no new reconfig are necessary,

Actually the newer Yanmar is about 2 inches longer and the exhaust is on the right side where as the older 3GM30 is on the left when facing the engine(s). Fitting the 3YM30 would require some (major) re-cabinetry changes in our vessel.

I agree the Beta may have been a better choice..

[sailor25b]

We replaced our old 3GM30 with a new 3YM30 three years ago. It purrs like a kitten!

The only problem is that the engine is reversed, and the oil filter is on the wrong side for my boat. Just makes it a little more difficult to replace, but otherwise no big deal.
Go for it!

[chef2sail]

The OP has a C&C very similar to ours. Since the exhaust is basically centerline and in the back of the enginethe difference of the hose from the manifold to the water muffler is minimal that it would require no modification in our boat and propably not for his. We have plenty of room behind the engine on the C&Cs. Its the width where they have shoehorned the engine in.

I just checked the dealers spec which the engine installer at Haven Harbor supplied me when he worked up a proposal, with the website for accuracy

Beta 30 Hp-747mm X 451mm X 551mm (L X W X H)
Yanmar 29Hp- 714mm X 462mm X 545mm (L X W X H)


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