Unbolting engine mounting lugs from engine itself - bad idea?

[skyflyer]

It is evident that the job of replacing my engine mounts will be a doddle, and avoid the need to physically lift the engine (although obviously it would need temporary support) by doing one corner at a time, if I remove the engine mounting lugs (the sort of L-shaped piece, where the upright of the L has two holes in it and is bolted to the engine with two bolts and then the horizontal of the L has one hole in it and sits on the adjusting nut on the vertical bolt of the mount itself). If the lug is not removed then the engine mount cannot be extricated without lifting the engine.

Is removing these lugs a really stupid idea, and if so why? I assume they will be torqued to a certain spec and probably have some form of thread lock applied but apart from that why not? If done carefully there would be minimal if any need to re-align propshaft etc.

Sounds too good to be true!

 

[sailorman]

you will need to check the engine /shaft alignment due to less squidgy mounts

 

[prv]

As sailorman says, I think your idea that no subsequent adjustment will be needed might well be wishful thinking. But I can't see any reason you shouldn't unbolt the lugs if it makes the job easier. I doubt they have any threadlock, and though there may be a torque spec I doubt it's critical.

Pete

 

[theoldsalt]

A perfectly acceptable method of replacing engine mounts thus avaiding the need to lift the engine. That's how we did it on my Thornycroft T80. Yes the engine alignment will need to be checked and, if necessaty, adjusted after.

 

[skyflyer]

not my engine but shows what i mean!

 

[VicMallows]

Depending on the engine, the bracket mounting holes may be open to the crankcase, in which case some form of sealant will be needed on reassembly. (such as Loctite blue silicone).

 

[PuffTheMagicDragon]

When I did that I took great care to pack the space beneath the engine with wooden blocks and wedges so that the engine itself was fully supported. This ensured that there would not be too much movement from its 'normal' position. When the new feet were in place I made sure that each adjusting nut (below the engine lugs) had taken up the slack and then some (little bit) so that the wedges were just released.

The coupling had one of those flexible disk things (R&D ?) and these can cover up minor misalignment. However, I still checked the alignment after a few days because new feet do settle a bit.

 

[Lakesailor]

No problem at all and makes good sense.
I installed a motor in my trials car and made such a precise job of it that I couldn't remove or refit the motor without taking off the engine bearer brackets. It meant there was much less heaving and hoeing to get everything aligned though. and less chance of damaging things which need a snug fit.

 

[richardabeattie]

"the job .... will be a doddle"

Love it.

 

[duncanmack]

"the job .... will be a doddle"

Love it.

Generally the kiss of death on almost any job.

 

[Tranona]

Generally the kiss of death on almost any job.

Yes - removing the brackets can be just as difficult as lifting the engine - all depends on the installation and what other bits are in the way. You have to separate the coupling to align the engine to suit the new mounts anyway. Swings and roundabouts.

 

[rosssavage]

Done it, got the t shirt. Replaced all eight mountings on my 2x TAMD61A's this way, and they weigh 750kg each!

Disconnecting shaft and proper realignment is a must. Also use a fail safe method - mine was big blocks of wood under the engine whilst unloading a corner with a bottle jack on big wooden spreaders. The hull isn't designed to support engine weight, so it's important to spread the load as much as possible.

When I changed each mount I measured the height of the old one and set the new one to the same dimension. This made realignment easier, but don't forget the new one won't compress as much with weight on as the old tired one.

I also used the opportunity to clean up and repainted the brackets too.

 

[skyflyer]

"the job .... will be a doddle"

Love it.

Haha - yes i should have added "relative to the conventional method"

Thanks for all the other replies and info. Alignment evidently will still need to be checked but i'm hoping it will be reasonably close if I use a vernier gauge to ensure the base of the mounting lug is the same distance - after replacement - above the engine bearer, which will help take account of different compressibility etc.

 

[rosssavage]

unfortunately I don't have any pictures of the lfting set up I used, but here's one of the eight mounts before and after...

 

[rosssavage]

Height measurement is step one!! You have to check lateral alignment and fore aft alignment too.

On mine, I have R&D couplings with a red bolt (machined flat head). You pop feeler gauges in between the bolt head and gearbox output flange, with the bolt at 12oclock position. Measure the gap. Rotate the shaft and check again at 3oclock, again at 6 & 9 o'clock. This will verify lateral alignment and vertical alignment. If the engine is too far fwd or aft you'll struggle to get the coupling bolts in, as fore / aft will raise or lower the whole engine with respect to an inclined prop shaft.

Do all of this again 24 hrs after refloating and again after 20hrs of engine run time to check everything has settled correctly.