Mercruiser 4.3L Engine mounts

[Ianfs]

I bought my boat back from the boatyard last week to give it a good service and clean up from Winter rubbish and discovered the engine mounts had finally given up. My goodness me what, a palaver in establishing which type it should have and then lack or supplies. In the end, instead (rightly or wrongly) I bought 2 mounts from

AV Engine Mounts

They are supposed to be Marine Mounts but it never ceases to amaze me that anything with a marine title is only protected by a Zinc coating. Don't get me wrong, they are very well made and you can get them with different strengths. So I coated them with an Epoxy paint and sprayed them black to match the engine.

I've already been round all the bolts to see if the move and luckily so far I'm managed to get them all to move.

I'll let you know how I get on changing them.

[shibbs]

Is it a big job to change? Can the engine stay in place?
Does the engine have to be realigned aftwards?

[Ianfs]

Is it a big job to change? Can the engine stay in place?
Does the engine have to be realigned aftwards?

So far its not too big. The original 1/2" adjustment bolts look as if they are welded to the mount bracket, so I'll have to cut them off, but the bracket has 3 bolts to connect it to the engine. So far all the bolts have moved when turned and only one was corroded down from 9/16" (14.2mm) to a tad over 13mm so a 6 sided socket lightly tapped on worked.

General opinion is that the engine can stay in place which at the moment I cannot see a problem with as long as each one is done individually. Some say the engine can be chocked by a jack under the exhaust manifolds other suggest something across the gunwales and attached to the eye on the water distribution pump (NOT to be used to lift the engine, only to hold it for alignment)

The Stern drive will have to be removed otherwise if the engine drops a fraction it could damage the gimbal housing or gimbal bearing or something else. Plus it will definitely have to be re - aligned but I'm hoping I can match the old heights with the new mounts somehow. I had an alignment tool made a few years ago by a local engineering firm.

[shibbs]

If your working on it this week let me know if you need a hand.. I’m not at work and would find it interesting to see how it’s done..?

[Ianfs]

Thanks Stu. According to the Met Office forecast for Christchurch Bay, I may not get around to it before Wednesday.

I would be happy for you to pop over but doubt 2 of us will fit in the small space to get at the parts, so there will be a lot of standing around drinking tea. Plus there may be some swearing too!!

[Ianfs]

Thank you Shibbs for offering to pop over to help, but I had to decline as I had some symptoms (although I was double jabbed) it turned out to be a false alarm, but best to be safe.

Here are some photos of the old mounts in place......

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Trying to get some new mounts was a challenge as most places were "Out Of Stock". I did find some at Repower Marine but I was advised their flex was a little weak for the engine and the weight capacity was a little low, but as I said earlier, I found some.

The mounts from AV came with 16mm ordinary zinc coated height adjusters, washers and nuts, so I bought some 16mm Stainless Rod, Nuts and washers from Sea Screw and fitted these. Cut the rod to size with a hacksaw and took some of the thread off with a Dremel Cutter to get a spanner on to tighten. The old mounts had ¾” adjusters (I said earlier they were ½” but that was the bolts holding the mounts to the boat mounts) with fine threads and the 16mm were rattling in the hole of the mount brackets, so I thought rather than have the work loose I found some Bronze Flanged Sleeve of the exact sizes. The height adjusters from AV mounts came with self locking nuts but were way too big as the Mercruiser mounts were fitted with half nuts. I was concerned that half nuts on an ordinary thread would not be strong enough but consulted with Gareth Jennison (Gazjen) who set my mind at ease, thanks Gaz.

New mount painted with Epoxy paint then covered with High Temp Plastikote....

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Bronze inserts in place

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I removed the Stern Drive and supported the engine by the manifolds with a bottle jack on one side and my wife’s Yaris scissor jack on the other side.
I dry fitted them, the Starboard mount lined up exactly with the holes in the boat mount support, but the Port mount holes were way out. Yet another setback and what to do, possible rebuild and boat mount modification? I posted on iBoats to ask about their thoughts and was advised it was probably installed originally with a 4x2 because they cut the holes in the wrong place, you naturally don’t like to think they would do this at the factory but it was a logical shout. After figuring it out I bought a plug cutter and filled the front hole with an oak plug and epoxy, the rear hole wasn’t far out so it only needed a little adjustment. Whilst doing this I figured I ought to check alignment each time and as I had only lifted the engine sufficiently to remove the mounts when I lowered it back on the new mounts, it wasn’t far out.

New mounts dry fitted

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Here's why the new mount wouldn't fit, the old one had a set in it just enough to fit the holes, definitely had been forced into place.....

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Now, I had to work out how to get a drill in under the Exhaust manifold as there was no room, possibly about 15cm. I settled on an angled drill bit and put in a 13mm drill bit to take the ½” retaining bolts.
After everything was painted and ready the job was completed and the engine aligned once more. I did find that turning the engine during the alignment process that the tool slipped in easier one way but after a 180° engine rotation it was stiffer but not too much, so I refitted the Stern drive. I added some new fuel and she turned over but wouldn’t start, so I added a bit more and she still didn’t start. I thought the best thing to do was to pour a little fuel down the carb intakes to see if it was fuel starvation and she fired immediately. After a few days I tried again and the same thing happened but fired after pouring some fuel into the carb. Mercruiser engines have an accelerator piston so I think this may be the problem, something to look at this week.
Whilst I had to wait for various parts I fitted a new Lowrance Fish finder and a new cut out switch as well as some minor repairs to the trailer including some nice shiny Galvanised mud guards and some shiny new cleats.

[shibbs]

Looks like it was quite a job, never as simple as it should be.
I think I would have been stumped at the point of not being able to get a drill in..
Very interesting to read though!
Glad you got it done.
Any plans to get her out.. if the weather changes back into summer mode that is..

[Ianfs]

Any plans to get her out.. if the weather changes back into summer mode that is..

Yes Stu, absolutely. One other tiny issue I have. As you know, Mercruiser Carbs have an Accelerator Piston which has two uses. One is to pump raw unvaporised fuel into the Intake Manifold by pumping the throttle forward 5 to 8 times so that starting from cold gives the engine enough to fire it up. My Accelerator Piston was giving one squirt, then nothing, so she fired for a second or two then died. Pouring fuel into the carb would start her and she ran beautifully.

I'm hoping that a carb rebuild will solve this problem, parts arriving tomorrow., but it's my birthday so may not be allowed to do boat work, by Mrs FS.

Sadly I'm told there's rain coming otherwise I'll have the carb back on and be ready to go. Can't wait!!

How about you?

[shibbs]

I rebuilt my cArb a few months back.
Due to a leak in the gaskets but also discovered that the rubber on the accelerator piston was worn.
That said, I’m still having starting problems. Such that I think my well plugs are leaking so I have to wait on cranking for the carb bowl to refil each first start ( if over a few days). Once started, it starts on the turn of key for the rest of the day.
I plan to strip the carb again over the winter and look into getting the well plugs sealed somehow.
As for use, it’s been a pretty poor year so far unfortunately.
If the weathers been good we have always seemed to have already made plans much to my disgust, but so far the weather seems to have been against.

I fully intend to get over to cowes on bank holiday to see the powerboats, if on my own then so be it!!!

[Ianfs]

What do the Well plugs do? I haven't got any in the Mercarb, but there are two little ball bearings glued in.
I'm thinking my fuel pump may be on its way out, but the Mercarb has a site tube which is supposed to fill with fuel if the diaphragm is faulty, but the tube is dry, so here's hoping.

Errrr, if you want crew for the 29th August, I might be free.