Is it safe to jack up an engine under the manifolds?

CAGE RATTLER

CAGE RATTLER

New Member
Apr 10, 2009
400
Essex, MD
Boat Info
85 Amberjack 255
Engines
2010 496 MAG MPI
I have a 2010 496 Mag MPI that I need to put a shim kit on. The shim kit is just a SS washer that goes between the rear engine mount and the transom plate mount. I have all 4 mounts loose and plan to try to raise the rear of the engine and put the shim in, one side at a time, and wondering if its safe to use a bottle jack under the manifold to lift it. The floor there is solid enough and I plan to use a 2x8 on the floor to spread out the load as well. Should only have to jack each rear corner up about a 1/2" or so. Im just am afraid of damaging the manifold or anything else on the motor. Any thoughts??
 
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Personally, I think that is a dumb idea. These engines are intended to be hoisted without point loading the hull. The only question I have is what will be broken first, the manifold or the hull?

Henry
 
Im really not to worried about the hull since i will be jacking at the same strength area as the front motor mounts and as I said i will use a 2x6 or 2x8 to spread the load out.
I will also only be jacking it up less than an inch on one corner at a time and not be lifting the entire 1200 pounds of engine weight. I'm just worried about the manifolds strength.
 
Just did the same thing with a Porta_power about 3 weeks ago. I actually had a friend make me a U shaped channel with a stud that fit in the bottom of the Porta Power, and stuck the U on the stringer to jack up.
On the other side the Porta Power was too long, so I had to do the same thing your thinking of. I used a 4X4, as long as would fit in the bilge and put it as close to the stringer as possible. Worked fine.
 
There's a difference of about 800-900 pounds between a Westerbeke sailboat engine and a 496 merc. The safest way in my mind is to lift the engine with an overhead hoist.

That someone used a jack under the engine to lift and it turned out ok does not make them right, just lucky. What you need to think about is what might happen if the engine slipped off the jack and shifted a couple of inches. I don't know about your engine compartment, but mine is already tight. I'd rather not think about being pinned down there by a 1200 pound big block.

That's also probably why you won't find jacking the manifolds in the merc service manual as a recommended practice.

For the past couple years I've been busy working as an expert witness in cases where guys working around transportation equipment cut corners and get themselves, or co workers or innocent bystanders maimed or killed. In nearly every case the accident happened because doing it the right way would "have taken too much time".

Henry
 
When jacking your engine: Go slow and cautiously. Use cribbing as you go to limit a fall if the jack rigging slips. Stop if things don't feel comfortable.

As far as those manifolds go; they are held onto the head with 8 bolts. GM factory lifting brackets have fastened to heads with only two bolts!

jm... 0.02
 
Lifting the engine from above is the correct way to do this, however, if you dont own a crane or boom lift you may be out of luck. My issue was that the beam is so wide, there is nothing to support a lift from above except a crane or boom lift. The gunnels are more than 7 ft off the ground, meaning a backhoe or front end loader are useless (unless its a major piece of equipment.) One other thing is that some of the engines sit under the radar arch, which is a heavy SOB to move.
Long story short, Lifting with a crane or piece of equipment is recommended, jacking up and shoring with blocks along the way works.
 
Henry Boyd, I have a question. If one were to use a lift, would it not be dangerous to work under a suspended load hanging from a lifting strap? I've pulled engines using chains and a forklift and I can say that the scariest part of the lift was while the engine was 'flying' over the gunwale cap and over the hull. A drop from a lift would be just as devastating to the hull/mechanic as slipping off a jack, if not more so.

For less than an inch of lift, a WELL SUPPORTED jack and WELL BLOCKED engine would be a risk I would undertake if I had to do what the OP is attempting. For greater lift, pulling from above as Henry stated is the preferred, safest way.

BTW where are these 1200lb weight figures coming from? That seems heavy even for a big block. I pulled a T444E diesel out of one of my trucks that didn't weigh much more than that.
 
SCORPIO said:
Henry Boyd, I have a question. If one were to use a lift, would it not be dangerous to work under a suspended load hanging from a lifting strap? I've pulled engines using chains and a forklift and I can say that the scariest part of the lift was while the engine was 'flying' over the gunwale cap and over the hull. A drop from a lift would be just as devastating to the hull/mechanic as slipping off a jack, if not more so.

For less than an inch of lift, a WELL SUPPORTED jack and WELL BLOCKED engine would be a risk I would undertake if I had to do what the OP is attempting. For greater lift, pulling from above as Henry stated is the preferred, safest way.

BTW where are these 1200lb weight figures coming from? That seems heavy even for a big block. I pulled a T444E diesel out of one of my trucks that didn't weigh much more than that.
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The intention is not to pull the engine, just get it high enough to make the adjustments. I would certainly advocate the use of blocks during this process as well. With a hoist, the engine can be raised high enough to work, and blocks set under it and the engine lowered onto the blocks just enough so it is steady with the hoist holding the majority of the weight. An engine supported this way is far safer than one with a jack under the manifolds. Those by the way on my 496 have an aluminum raw water manifold attached to the bottom of the exhaust manifold.

As for I don't have a hoist, or lift, or the radar arch is in the way arguments; If you don't have the right equipment, then maybe you should stop and consider this is one of those jobs you should not DIY.

Henry
 
Is there no way to put a jack under the bell housing? I wouldn't jack against a manifold as it that will unevenly lift the engine and also will point load the manifold and its attaching hardware.
 
SCORPIO said:
Is there no way to put a jack under the bell housing? I wouldn't jack against a manifold as it that will unevenly lift the engine and also will point load the manifold and its attaching hardware.
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He actually is trying to unevenly raise the engine. He has loosened the mounts and wants to jack up/tip one side an inch to slip the washer in, then do the other side. One of his reasons is that it'll be half the weight that way. Myself, I wouldn't jack on the manifolds.
 
I lifted my engine under the manifold when I had to replace my motor mounts 2 years ago. My motor is out of the boat and the manifolds off and I can verify there have been no ill effects on my motor.

Think about it, you pull a motor with (2) 3/8-16 bolts, so why wouldn't 6 of them hold up 1/2 the motor. Anyway, just my thoughts...
I did use blocks of wood and a small hydraulic jack.

Good luck,

Mark
 
I want to thank everyone for the their tips and concerns.

I took care of putting in new fiber washers and the shim washers today and it couldnt have gone smoother.

The post saying the manifolds are bolted on with 8 bolts and the engine hangers only bolted on with 2 made very good sense and gave me the confidence to use the 5 ton bottle jack under the manifolds. I was actually still worried about the manifolds being made of cast metal and possibly cracking them so I took it easy when i started.

With a 16" long 2x8 underneath the jack base and jacking at a wide flat area under the manifolds (right next to one of the mounting bolts) a couple pumps of the jack tilted the engine effortlessly and I was able to pull out the fiber washer, put in the new fiber washer and SS shim washer, make sure they were lined up and slide the bolt back in, in less than 5 minutes on each side. No creaking of the floor & no noise from the manifold. It felt solid as a rock and I'm glad i went this route. These manifolds are huge and obviously pretty strong as well.

I do have a neighbor that has a truck with a boom lift but thought that was overkill for this job. I was originally going to use a 9" long piece of boxed metal to run across the gunnels and then use a block and fall or come-along to raise the engine. I had 2 concerns doing that. The obvious one of damaging the fiberglass gunnels. The other was the fact that the lifting hooks for these motors are in a bad location for what i wanted to do. One on the right rear of the engine and the other at the left front. They are there to lift the engine straight up. The shaft on my coupler is the long extended type so the engine would have to come up and move forward to clear the transom plate and i would have to completely disconnect the front mounts to do that. By just tilting the engine I was able to do the job and not have to worry about the coupler shaft.

There was no worries of the engine shifting a couple inches. On the front mounts I just backed off the locking nuts about an inch and loosened both rear mounting bolts. Pulled one rear bolt out and jacked up that side. replaced that bolt and then removed the other side before jacking that side. I didnt want to have to deal with any major realignment issues.

And yes, The drive was removed before doing anything.

The reason I needed the shims were because my front mounts were maxed at all the way down and still wasnt getting a perfect alignment of the outdrive. I was getting a slight knocking sound at full lock left & right. Put the engine in 2 years ago and didnt find out till afterwards that the shim kit was an option needed on some boats with the newer motors and transom assembly. They dont use the double wound washers in the mounts anymore. They have a knurled contact area that supposedly locks the rear mounts in better but I guess now that the shim washers are in there, they kind of defeat the purpose of the knurled surfaces since the washers are smooth. Raising the rear will now allow me to raise the front and have more adjustment to get it dialed in.
 
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I didnt want to have to deal with any major realignment issues.

Sorry to inform you that you already have them.any time the engine is disturbed ,alignment is a MUST and must be checked/adjusted.
 
It obviously has to be adjusted since i put the shim kit in to raise the rear.
But completely removing the front mounts and having to reposition them would have involved the MAJOR re-alignment issues I didnt want to deal with.

I check the alignment every year before re-installing the drive and that was the reason for putting in the shim kit. I could never get it perfect and the front mounts were all the way down.
 
I'm glad it worked out - please let us know if this helped the knocking on extreme left/right positions.
 
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