Eeyore

Best guess is about 30mm of exposed thread (assuming 1.5 mm pitch), way too high. No wonder it required adjusting several times. If I "inherited" that as a maintenance job I might say something like "it needs sorting, but live with it till you've had the life out of the mounts, it will give you time to save up for the remedial works". I'm sure you've had a similar conversation. Minimum of 20mm shim/packer on the rear mounts, although I might go for 25mm given that you already know the static deflection. That would leave you with approx 2mm of exposed thread on a new mount for a 25mm shim or 7mm for a 20mm shim.; both figures will increase as the mount is adjusted for settlement.

Scary

I for one would be happy to see this deleted. I only have five of those digits in the registration number of my 30ish foot boat. Even I did a double take when I saw it. Now where do I direct this baying mob armed with torches and pitch forks.

@jessie can you post a few photos please. It would be good to see how high the engine is on the mount.

Wow indeed, I don't think I could manage that with my fat fingers 😇. The mounts should/would have been readjusted after the first 48 hours or so, did that happen? Sounds like the shim plate will be quite thick. In this case weld them in and drill and tap to allow the use of set bolts to hold the mount down. This makes them much easier to position during the set up as you don't need to grow a third arm to hold the nut under the beds! If other people do the servicing is it possible that someone did you a favour by tightening a loose mount; by tightening the top nuts instead of the bottom one. Other than that everything goes south with age as @IanD mentioned.

I quite like this image (borrowed from the AVI page) showing the optimal installation of a marine mount on what appears to be a piece of auxiliary equipment. Its highlights why we should install the engine leg as low as possible on the height adjuster, and use a shim plate beneath the mount to achieve this. You could of course install exactly as in the photo by using a variety of thin metal shims under the mount. Mounting high on the adjuster is a bit like handing the engine a crow bar to lever the mount.

K100 mounts would be a bit hard, but the K50, K75 and K100 (shore hardness 45, 55 and 65 respectively, and may be stamped on the base of the mount) are generally similar in appearance. K75 mounts all round if the weights are even, and are also good for up to approx 55% of the weight on the back end and 45% on the front. Should give static deflection a bit either side of 3mm. Between 55% and 60% on the back end is a bit of a grey area given the available choice of mount, but above 60% on the back will require K50 mounts on the front. K50, AVI SM1600-45 and Aquadrive 50212 are similar specs. K75, AVI SM1600-55 and Aquadrive 50213 are similar specs. K100 similar to AVI SM1600-65 which is a 90kg mount.

Green British = Lister Green Japanese = Beta

Yes, the static deflection is a compromise for a variable speed engine. The figure of 3mm static deflection mentioned in the document posted by @IanD equates to approx 70% vertical isolation at 1200rpm. In layman's terms that means you can sit watching tv whilst running the engine to charge the batteries without your fillings being vibrated out of your head. AVI, R&D and others manufacture mounts, whilst I suspect Aquadrive will sell you a mount in a box with their name on. The data is presented differently, but they appear functionally similar.

You can have a look here https://www.avindustrialproducts.co.uk No connection with them, just happen to have their page open to research a non boating application. Plenty of tech info for you to browse.

Has anyone else noticed that the kettle only dances off the hob at cruising revs? 😎

Having found the front to rear balance point on mine to be more or less midway between the front and rear legs it became something of a mystery as to why the manufacturer specified differently rated mounts.

There wasn’t anything wrong with the mounts other than the manufacturers insistence that it required mounts of a different rating for the back and front.

It was what is generally referred to as a challenging installation. The Westerbeke 44B used the Mitsubishi S4L2 engine as did the Vetus M4.17 (M4.45) and the Sole Mini 44. Sitting it on four identical mounts like it’s contemporaries was a major improvement. But the biggest issue was some thing I was told when considering the purchase “it’s a Mitsubishi, you can’t go wrong with a Mitsubishi”, big mistake!

@Tony Brooks Only because I spent a long time peering at Vetus and Sole documents trying to resolve mounting issues on my Westerbeke marinised Mitsubishi engine of the same core type! Mine did in fact come with different rated front and rear mounts, and that was the principle cause of the issues I was having. There was a variation in weight between the mounting points, but not sufficient that different rated mounts from any of the ranges investigated could be justified. The importer eventually relented and swopped the two softer mounts for two more of the harder ones.

Theres are some interesting typos in the Vetus parts book. The belt might be 995x10 SPZ, Same Vetus part number as the 885x10 SPZ. Also some parts for the 110amp alternator installation are still labeled as being for the 95amp alternator. Still a useful document providing you have the knowledge to avoid the pitfalls.

The 50amp alternators are usually Mitsubishi, the OPs is the standard Vetus Iskra 110amp (previously called a 95amp until the marketing boys got hold of it 😎) The OPs engine already has the mounting point for a second alternator, the one with the red cable tie going through it. Everything else can be found here https://vetus.com/cms/wp-content/uploads/341331.02-r21-2022-02-Parts-catalogus-M4.15_17_35_45-3.pdf page 4-10 onwards. I would recommend wiring any second alternator to a separate warning light fed from the domestic battery via an ignition controlled relay. The Vetus approach is not only expensive but also very complicated just to use the spare lamp on the panel. Vetus have been using this 110amp alternator for many years in defiance of best practice that suggests a max of about 90amps on a single belt. The 988x10 SPZ belt needs to be very tight for it to work without slipping. The cheapest way is to relocate the existing 110amp to the new mount where it will perform marginally better when driven by the larger additional crank pulley. A 50amp can then be fitted in the original position, this will ease the demand on the belt and reduce the loading on the water pump.

Best if you post a few pictures, it always helps if we can see your installation (every boat installation is different!).

The build code will vary, but its a S4L2 base engine. https://www.det-mitsubishi.com/sites/default/files/2020-07/Mitsubishi - Commercial Spec Sheets - Industrial Engine - Variable Speed - S4L2-Z363SPH.pdf You will notice that the 50amp alternator shown on the brochure is replaced by a 100amp+ unit on yours.

A few more pictures showing the general arrangement of the pipework and an overall view of the engine will help get you the best advice for your particular installation. Is there a brass coloured pump below the one in your first photo?

On my (blue) engine you can see the tube pass under the engine leg, but there is no sign of one on the OPs (green) engine. The engine in mine is very heavy at the front and both front legs had fractures and evidence of earlier repair attempts. The new reinforced legs haven't been on long enough to evaluate yet.

The (red) end of the dip stick can be seen top right of my second photo; not visible in the OPs photo because it is obscured by the fuel filter at the angle the photo was taken.

Every days a school day! The oil level is somewhere between the bend in the tube and the sump gasket, so the flexible dip stick doesn't need to go around the bend. The main bearing sub assemblies used in this type of construction means that the sump gasket is below the throw of the crank. Is anyone else wondering where the engine mounting leg is?

I have seen several of these engines (including mine) where the heat exchanger core has been removed to convert them to keel cooled. They all look similar, so the work was probably carried out by the supplier. Pictures to follow.