Ford Lehman 120 Engine Mounts

Time to replace the engine mounts and I am looking for feedback on brands, part numbers and overall experience.

I do know that I can phone up American Diesel and get suitable mounts, but I want to know what other options there are.

Thanks in advance.

I have used Barry Controls and Metalastic on various projects, with good results from both. Volvo and Aquadrive sometimes use Metalastic, Cummins uses Barry. Mounts must be specified to the weight per mount for it to "float" properly. The mount companies have websites with drawings and weight tables.

This can be quite a PITA as it is unlikely for everything to plug and play. Dimensions will be different and holes in wrong places.

The factory Lehman mounts were very stiff and transmitted alot of vibration near idle.

My preference right now is Barry mounts. Metalastic allowed a bit more motion than I was comfortable with.

I would look into installing: http://www.robush.co.uk/pdf/Cushyfloat.pdf
Along with: Federal Flexible Couplings

Used together these make for a very smooth, vibration free boat.

Capt.Bill11 said:

I would look into installing: http://www.robush.co.uk/pdf/Cushyfloat.pdf
Along with: Federal Flexible Couplings

Used together these make for a very smooth, vibration free boat.

Click to expand...

I whole heartedly agree, I used this combination (well the mounts were from Aquadrive front part #'s 014-6050222 55 shore and rear #'s 014-6050223 65 shore - $88 each - but they look almost identical to the Cushyfloats) and it made a HUGE difference.

Honestly don't notice any difference with the Federal Couplings (I ran for a month with just the mounts changed, just installed the couplings today) but at least they will take up some misalignment under high loads or in a rough sea.

Capt.Bill11 said:

I would look into installing: http://www.robush.co.uk/pdf/Cushyfloat.pdf
Along with: Federal Flexible Couplings

Used together these make for a very smooth, vibration free boat.

Click to expand...

Capt. Bill,

What part # for the cushyfloat?

Cushyfloat and Metalastic same thing. I think you look up metalastic on the web, there is a catalog there.

Thanks for the feedback guys - I'll sit down and have a look at your recommendations. Gearing up for some winter projects on the boat, this being one of them.

-- Hobbystuff

captrigney said:

Capt. Bill,

What part # for the cushyfloat?

Click to expand...

I don't recall. As Ski mentioned check out the catalog.

If you use the soft mounts, IMO you really need to use some sort of isolation coupler to make up for the fact that with softer mounts you're going to have more misalignment between the transmission and shaft since the engine will "float" more on the soft mounts.

Capt.Bill11 said:

I don't recall. As Ski mentioned check out the catalog.

If you use the soft mounts, IMO you really need to use some sort of isolation coupler to make up for the fact that with softer mounts you're going to have more misalignment between the transmission and shaft since the engine will "float" more on the soft mounts.

Click to expand...

While this does not relate specifically to Ford Lehman, here is an excerpt from the Yanmar engine installation manual as it relates to flexible engine mounting. For those who do not already know, Yanmar is known for supplying very flexible engine mounts on their marine diesels. They clearly state "When the engine is installed with the flexible engine mount method, a flexible coupling or flexible stern tube must be employed." The illustration in the manual actually shows R&D, Vetus and Aqua-Drive couplers.

I'm sure this advice is applicable to most marine engine installations. The softer the mounts, the more important a flexible coupling becomes. Here is a copy of that section of the manual.

I use Poly Flex.

Most engine mounts are rubber and allow movement but reflect it like a rubber ball. Poly Flex is some kind of new age plastic and actually absorbs some vibration.

Mine are quite smooth and I recomend them.

Hi
I'm looking to renew my original engine mounts on both of my Lehman 120's sometime soon.
Does anyone have any information as to what load/weight engine mounts I would require?
Jamie

Hi Eurobanker40,

Where in the UK are you? We lived in Ipswich for 2 years.

Welcome to POLYFLEX LEHMAN MASTER LISTING ENGINE MOUNTS - THERMOBOAT LTD. is the North American supplier of products to make your boat experience WARM, QUIET, COMFORTABLE and SAFE

This from American Diesel:

It's times like this when I wish I only had one Lehman

Check the attachment holes on the prospective mounts to the engine beds to see how they align with the existing mounts. Also, check the height/travel of the adjustment nuts. We changed the mounts on our FL SP135. There were a lot of mounts that fit the specs for the motor weight and hp but the mounting of the mounts and the adjustment studs/nuts/travel didn’t work. I ended up going with a direct replacement from Bomac Marine and I know American Diesel sells them. I didn’t want to deal with making modifications to the shaft log or the engine bed. A 1/4” difference at the mount is a lot by the time it gets to the shaft log. We paid about $120/mount US. The rear mounts were different than the front but the same cost.

Do Ford Lehmans have internal vibration dampers? Just asking, don’t have these engines but my buddies boat seems to create significant vibration at low/medium rpm and I wondered why.

They have drive dampers, according to AD, their replacement interval is 2500 hrs. When our twin Lehman's are idling you can literally see the water around the boat vibrate. My engines only have 1100 hours on them and there are far higher priorities for my boat bucks right now but when the time comes; I'm encouraged by what other's have reported using newer mounts and coupling.

I am in the middle of changing my motor mounts now. I have twin Lehman 120's.

My experience with Poly Flex ... The gentleman in Victoria was very helpful and even went and visited the boat when it was in Sidney to be sure we got the right mounts. He also delivered the mounts to the boat. Unfortunately, the first set he delivered didn't fit. The mounting stud was too wide for the holes on the engine side. He kindly returned them and ordered us new ones.

So two weekends ago, we went to change the mounts. The front mounts were straightforward. The back mounts didn't fit. They were too wide and hit the mounting arm on the back of the motor.

After going back and forth with Poly Flex for a couple days, they decided they didn't have motor mounts that would fit our old boat.

I exchanged a few calls, emails, and photos with Brian at American Diesel. New motor mounts I know will fit should arrive Friday. Just in time for the weekend.

I have just been down this road. On my boat, the rear engine mounts utilize brackets that come off the side of the transmission. When sourcing new mounts, I ran into all kinds of limitations: overall height, bolt spacing and stud diameter. I couldn't find a set of mounts that were low profile, had the existing spacing and required stud diameter that would fit with the old transmission brackets. They just didn't have enough clearance.

So I have just finished having new brackets for the transmission fabricated so they would provide proper clearance - which gave me several choices for a mount that would work. While it was a bit time consuming, I feel that this gives me the best options moving forwards.

Mounts purchased from Aqua Drive are also Cushyfloat.
The amount of movement can be selected by choosing a durometer (rubber hardness) of mount that will limit deflection to whatever you want. See attached deflection chart page 2. Be sure and include the weight of your gear in calculations, divide by 4.

The easiest is direct replacement. Too often other mounts are to too tall, the footprint won't fit the available space, or as noted the mount itself interferes with the brackets.

A nice feature of Cushyfloats is they can be purchased unassembled. This means if they will fit your application you can jack the engine up just enough to get a sawsall blade on the existing stud and just cut it off. Slide the old mount out and slide the new one in and thread in the new stud from above with some locktite on it. If your replacement mount stud is not removable you may have to jack the engine high enough to slip in the replacement. This probably means disconnecting things like exhaust, shaft, maybe plumbing and wire.

Another consideration as mentioned is a packing gland on a hose and/or a coupling. There are formula's using shaft diameter / alloy for figuring allowable deflection depending on the distance from the gear flange to the first bearing or fixed packing gland. The longer the shaft, the more flexible the mounts can be.

The Cushyfloat line is a very good mount and a great value, they are very reasonably priced.

And for you Eurobanker, Trelleborg (Cushyfloats) is a UK Company.

Ski in NC said:

Cushyfloat and Metalastic same thing. I think you look up metalastic on the web, there is a catalog there.

Click to expand...

Cushyfloat Product Range - Trelleborg IAVS

Hi all, really appreciate all this information. It's certainly made me realize there's a few important things to consider. I'm waiting to hear back from a few companies but will update you all as things progress.
Would anyone have any idea as to the weight of the Lehman 120?

Eurobanker40 said:

Hi all, really appreciate all this information. It's certainly made me realize there's a few important things to consider. I'm waiting to hear back from a few companies but will update you all as things progress.
Would anyone have any idea as to the weight of the Lehman 120?

Click to expand...

1100 lbs without transmission.

Eurobanker40 said:

...Would anyone have any idea as to the weight of the Lehman 120?

Click to expand...

One set of specs say 1092 lbs less running gear. The dry weight of a Velvet Drive running gear is from ~145-~200 lbs. the weights very with which model and gear ratio. I’ve seen weights for the combined at 1400 lbs.

Ryan:

hobbystuff said:

1100 lbs without transmission.

Click to expand...

My 1981 Lehman manual states dry weight of standard 120 is 1254 lbs.
Dry weight of a 10-13 CR2 Velvet Drive is 162 lbs.
I'd add a fudge factor of 10% to cover oil, anti-freeze, coolers, hoses, etc.

Eurobanker:

If your aft transmission brackets are like my originals, they limit the selection of mounts available significantly. I build my own new ones to get around this (as per my picture), however I see a different shaped pair on Ebay that look like they would do the same thing:

https://www.ebay.com/itm/Ford-Lehman-Marine-Diesel-120-6-Cylinder-rear-engine-mounts-/332553806753

These might be able to get a sandblast and powder coat to become serviceable. I might have done that if they had been available a few months ago.

-- Ryan

Ok, got my mounts from ADC. Now to change them. Do you just do one at a time or try to lift the front and do both, then the rear and do both?

Take prop shaft loose from gear. Lift front end of motor and swap mounts. Once those are secure, lift back end and change back mounts. Make sure cables, exhaust and other stuff does not get tweaked when moving engine. Once done, adjust mounts to align prop shaft.

Powdercoating a motor mount might not be a good idea. I know a rubber mount would not like the "baking" temp powdercoating calls for, and I doubt any composite polymer would like it either

hobbystuff said:

Eurobanker:
These might be able to get a sandblast and powder coat to become serviceable. I might have done that if they had been available a few months ago.
-- Ryan

Click to expand...

Keysdisease said:

Powdercoating a motor mount might not be a good idea. I know a rubber mount would not like the "baking" temp powdercoating calls for, and I doubt any composite polymer would like it either

Click to expand...

I was referring to the solid metal brackets from the engine to the isolator, not the isolator itself.....

So I replaced all four mounts and aligned the shaft. The difference is incredible. Though it still vibrates fairly good at idle it smooths out significantly at 1000 rpms or so. While running up to Sucia this weekend you can hear the water on the hull instead of vibration harmonics from the motor. Very happy with the results.

Aft motor mounts worn

This may seem like a foolish question, but can you just replace the after motor mounts? My forward motormounts look good.

I'm up on the hard doing my bottom, thru hauls and stuffing box and I noticed I was out by about a 1/16th of an inch on my stuffing box. I looked at my very sad looking after motor mounts and figured they were the culprit.

Once I'm back in the water I can re and re my after motor mounts and see how the vibration is.

As for the aqua drive mounts, how exact is the motor mount foot print compared to the oringinal Ford Lehman?

Where can you get Aqua drive in the Vancouver B.C. area?