Help on Engine Mount Bolt Torques

[Heavy Duty]

Guys.

Now that the weather is warming up I can now mount my transom bracket, engine, and get everything rigged up and ready for the up coming spring and summer fun 8) .

Anyone know what the torque specs are for the engine mount bolts? I called my friendly Grady-White service and they said around 75 ft lbs or "tight-nuff" . I'm not sure what "tight-nuff" means and the 75 ft lbs seems low for an engine that weighs almost 500 pounds and will most likely have a lot of stress on it. I looked in my service manual and it doesn't give any torque specs.


Thanks

Heavy Duty

 

[BobP]

The professional mechanics may have a better answer than this.

Not in owners manual? My bolts came with engine.

Do you have a torque wrench? If so, practice on your car lug nuts to see what 75 ftlbs is. If you don't have a torque wrench use a box end on the engine bolts - the length of box and open end wrenches are calibrated to limit torque, as long as you don't add a pipe to it ! Don't use a socket driver unless it is no longer than the proper box end or open end wrench.

Then snug it up well! Your hand will hurt before you over-torque, don't use any gloves when you do it.

If you know the grade of metal & bolt size, we can find out what the torque spec is, there are eestablished industry standards on this subject.

 

[Heavy Duty]

Thanks BobP.

I have several torque wrenchs. One goes to 400 Ft lb that I use on the farm equipment.

The bolts are metric and are suppose to be some really hard steel. I know that most standard fasteners have the marks on the head that help you determine the applications and torque specs. Since these are metric they do not have any such marks on the head. So perhaps the torque is "tight-nuff".

I just installed a car engine the other day (350 cid) and the torque specs for it was 110 ft lbs. Now that is is for an engine that is seated into a automotive engine mount..not hanging off the back of a boat.

Thanks again. May be someone will chime in.


HD

 

[BobP]

Heavy, anytime. I'm going to check my Yamaha manual tonight.

The bolts are stainless not sure what grade of material. I know the SAE bolts as you say have the head markings. Hardened metrics use number markings as I recall, but mine have none. I think it's because the head may be smaller than standard spec. relative to bolt diameter, or it's because it is stainless.

I still say pull on the box end wrench hard with one hand no gloves, just don't stand on it !

 

[Heavy Duty]

Thanks Bob. I just may do the box-end wrench thing.

I would rather under torque a bolt then over torque. When you over torque it puts way more stress on the bolt and they will snap without warning and at the worse time.

HD

 

[pthein]

I think you will find that 75 ft/lb's will be way to much!

yes the supplied bolts are special - they have a fine thread and some sort of coating on them.

When I mounted my engines I was told to tighten them until you just start to hear the fiberglass stress. I was looking for a torque spec, but when I did the install I found the dealers advice to be right on. I used 3M 5200 around the bolts as well.....

 

[BobP]

Heavy, I checked the owners manual last night, nothing there, the service manual has three pages of torque specs, nothing specific to the mount bolts.

There is a table for standard fasterners, standard iso threads, dry and clean, at room temp.
For a 17mm nut on a M12 bolt, it calls for 31 ftlbs.

The hardware that came with my HDPIs has a 17 MM nut and head, the Craftsman box end is just 8 inches long, so is my 3/8 in. drive ratchet. I don't know if the bolt is an M12

I placed a torque wrench on the nut on the boat, I didn't have to apply too much to reach 30 ft lbs, but the handle was 20 inches long. I would say the heavier force on the 8 in. long wrench handle, more than twice teh force, is about the same I applied to install it. I would also gestimate that to get 75 ftlbs on the box end, I would have to stand on it or cheater bar it.

I don't think you will ever break these bolts if you use an 8 inch long wrench with bare hand unless you have been living on human growth harmones. Also, bolts through conventional transoms are very long so they have plenty of stretch in them.

Use this info as you see fit.

 

[Heavy Duty]

Thanks Guys.

From the sounds of it I'll just do the box-end wrench approach. The bolts I have are shorter than the really long bolts that go through the transom. That is because the engine will be on the Grady-Drive bracket.

Bob I'll do as you said. I'm just so use to having a specified torque for critical items. I was a jet engine mech in the Navy and EVERYTHING had a torque and the torques on "Flight Safety" items had to be witnessed by QA. I know a boat engine is not an aircraft engine. But, I would think that making sure that the engine is mounted properly would be a critical item. As I recall, it did take considerable force to remove the primary nuts off the bolts once the jam nuts were removed.

Thanks again guys. I'll proceed and see what happens.


HD

 

[BobP]

Heavy, I'd also suggest you try Ande at the SIM vendor site on tht, he wil have an opinion I bet.

I too have the bracket, those bolts are very strong.

 

[Heavy Duty]

Alright guys......

First off thanks a bunch for your help on the engine mount bolt torques. I got a lot done this past weekend. Both the Grady-Drive bracket and the engine when on without any problems .

Got the Grady-Drive bracket on boat this past Friday and sealed with 5200. Sealed the bracket onto the transom and sealed the bolts both inside and outside of the transom. Let the bracket set over night so the 5200 had plenty of time to set up. Ran the waterhose over it Sunday and so far no leaks .

Sat evening mounted the engine. All I have to say is that it sure is nice having a tractor with a front bucket. Made the job MUCH easier. Bob, I took your advice and torqued the engine bolts with the box-end wrench and pulled them up until they were "tight-nuff" then put the jam-nuts on and got them "got-en tight). Sunday I hooked my jumper pack up to the engine and worked the tilt/trim to tilt the engine so I could move the boat out of the shop.

Now...here is my current problem and in one word...rigging.

I see how to hook-up the throttle, shift cables, power from the battery, fuel, and oil. I don't think I'll run into any problems there. However, there is a 10-pin cannon plug along with 2 other plugs at the front of the engine :? . My old engine ('91 175 yama) did not have these connections. The connections were made directly to the sensors and what not. I talked to a guy yesterday and he said that I may have to get a new tack, speed-o and a "Boat Wiring Harness" to get everything to work. I'm hoping I don't have to change the instruments out since they are working great. So here is my questions:

1. What is the 10-pin cannon plug and the other connectors for?
2. Are there any adaptors I can buy to get my old instruments to work with the newer engine (fyi; going from '91 carbed Yama to a '99 OX-66 fuel injection)?
3. What systems will I need to monitor on the newer engine that I didn't have on the older engine (Fuel pressure, coolent temp)?

Thanks guys for the info and yes the project is looking good 8) . Pics will be coming soon.

HD

 

[Grog]

When I went from '91's to '96's an adaptor was needed to use the old controls. Go see your Yamaha dealer for the adaptors.

 

[BobP]

I like it when a plan comes together.

If your local dealer is not preferred for a question like this, it is right up Andy's alley. Go to thehulltruth.com. Vendor sites, for Shipyard Island Marine. He's a Yamaha dealer. Not all Yamaha dealers are good with these interface/adapter questions, or don't want to be bothered, in my experience.

Andy is da bomb on these questions. And he has the parts, ships right away. If you are not a member at THT, just join, no charge. Or you can email him directly on his business website (as I do).

Coming out of my engines is three electrical control cables, one goes to the oil tank, the other two up to the dash, one connects to the controls/key panel, the other to the instruments. As I recall.

I'm not a professional on this site, nor affiliated with SIM, THT, or GG, so proceed at your own risk on above recommendation.

 

[Heavy Duty]

Thanks Guys.

The local Grady-White dealer is a Yamaha dealer. So I'll give them first chance to help and buy parts/adaptors from. I would let them do the rigging.....but at $100/hour I would think that with a little guidance I could do the job myself and save the $$ for gas since it is Sooo high.

If I don't get what I need there I'll give Andy a call of shoot him an e-mail.

So now on to the rigging phase. Heck before too long I'll have the boat ready for a sea trial .

HD

 

[Heavy Duty]

Update on the engine install and rigging. One word "DONE".

The only problem we ran into right off the bat is that we had to raise the engine one hole up. The guy who I helped (We Do it All Marine) took one look and said...nope..got to raise'er by one hole.

Bob thanks for putting me in touch with Andy. The connectors worked great and made the rigging easy. Best 70 bucks I've ever spent. I got the rigging tube while I was at it and it sure makes for a cleaner look to the operation.

We fired her up this past Friday for the first time...man I sure cannot wait for the sea trial . Took only a few cranks and she fired right off. Went to a high idle for about a minute and then settled down to a nice idel.

The weather has been a bit uncooperative down here. Plus my partner in crime showed me what a cracked thru-hull fitting looks like. So while I'm waiting for decent weather may-as-well change some thru-hulls. Thank goodness there are only 5 to deal with.

8)
HD

 

[BobP]

HeavyD - glad to hear it!

 

[JUST-IN-TIME]

SIM is a very very SMART MAN

next time it is all in the rigging guide

any GOOD yami dealer will print it off for u